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5631 articles

A1319 – Effect of the support on the basic and catalytic properties of KF

KF supported by various supports was characterized by DTG-DTA coupled with mass spectral analysis of the gases evolved by the solid, in situ XRD, calorimetry, 19F NMR spectroscopy, and tested in the Michael addition of cyclohexene-2-one with nitroalkanes. After dehydration at low temperatures, from 19F NMR spectroscopy F is in part as KF when the support is alpha-alumina but only as K3AlF6 when the support is gamma-alumina. During activation no fluorine is lost. On alpha-alumina KF is detected by XRD only after calcination at about 723 K and results in part of the decomposition of K3AlF6; it disappears with formation of K2AlF5 and KAlO2 at higher temperatures. A comparison of the results obtained by XRD and NMR suggests that KF is well dispersed on alpha-alumina. KF/alpha-alumina is a strong base, stronger than KF on gamma-alumina, and more active for Michael reactions. On KF/alpha-alumina the Michael condensation of 2-cyclohexen-1-one with nitroalkanes can be achieved in 5 min with an equimolar mixture of reactants. Solvent-free reactions can also be achieved reaching 75% yield in adduct after 8 h, and KF/alpha-alumina is also active after simple drying at 393 K, avoiding the usual activation at higher temperatures.
J-M. Clacens, D. Genuit, L. Delmotte, A. Garcia-Ruiz, G. Bergeret, R. Montiel, J. Lopez, and F. Figueras, Journal of Catalysis 221 (2004) 483-490

A1318 – Standard molar enthalpies of formation of Ln(C9H6NO)2(C2H3O2) (Ln: Nd, Sm)

Using an on-line solution-reaction isoperibol calorimeter, the standard molar enthalpies of reaction for the general thermochemical reaction: LnCl3.6H2O(s) + 2C9H7NO(s) + CH3COONa(s) = Ln(C9H6NO)2(C2H3O2)(s) + NaCl(s) + 2HCl(g) + 6H2O(l) (Ln: Nd, Sm), were determined at T = 298.15 K, as -(56.9 ± 1.4) and - (67.9 ± 1.5) kJ mol-1, respectively. From the mentioned standard molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of Ln(C9H6NO)2(C2H3O2)(s) (Ln: Nd, Sm), at T = 298.15 K, have been derived to be: -(1494.7 ± 3.3) and -(1501.5 ± 3.4) kJ mol-1, respectively.
H-G. Yu, Y. Liu., S-S. Zhao, X-F. Guo, S-S. Qu, Thermochimica Acta 409 (2004) 195-199

A1321 – Poly(ethylene oxide)-based surfactants as templates for the synthesis of mesoporous silica materials

Various mesoporous silica solids were prepared by using poly(ethylene oxide)-based surfactants as templates in a neutral, fluoride, or moderately acidic medium, and their properties examined by different physical techniques. Precipitation in an acid or neutral medium provided materials of pore size in between those of micropores and mesopores irrespective of the molecular size of the surfactant. On the other hand, syntheses in a fluoride-containing medium yielded mesoporous materials with pore diameters over the range 36-84 Å that increased with increasing surfactant size. All materials possessed specific surface areas above 650 m2 g-1 and high pore volumes-particularly those obtained in a fluorinated medium. The conditions used in the syntheses and the fact that all produced highly disordered porous materials suggest that their mechanism of formation is essentially of the N°I° neutral type. The materials obtained in the presence of fluoride ion, which promote the condensation of siliceous species, retain greater amounts of surfactant and exhibit increased cross-linking and decreased particle sizes, which results in textural mesoporosity.
M.A. Aramendia, V. Borau, C. Jiménez, J.M. Marinas, and F.J. Romero, Journal of Colloid and Interface Science 269 (2004) 394-402

A1320 – Porous structure evolution of cellulose carbon fibres during heating in the initial activation stage

This paper is focused on the description of changes in the porous structure during fast heating to the activation temperature of the viscose fibres, pyrolysed to different final temperatures. Standard regenerated cellulose fibre structures were tested. Fabrics were subjected to pyrolysis, the samples being heated to final temperatures of 400, 600 and 850°C. Carbon fibres were subsequently heated to activation temperature (850°C) at a rate of 100°C/ min, and then the samples were cooled down. The characteristics of obtained carbon preparations were examined. We have defined a level of restructuring and internal ordering of fibres which originated during slow pyrolysis as well as the range of temperature differences of pyrolysis and activation where fast increase of carbon fibre temperature before activation is advantageous for the development of porous structure. It allows for partial release of pores and fast rebuilding of structure accompanied by a considerable number of defects in the carbon matrix with higher reactivity to oxidiser which, in turn, promotes the development of pores in active carbon during oxidation. Temperature difference for viscose carbon fibres is approximately 150-300°C at pyrolysis temperature of 550-700°C.
K. Babel, Fuel Processing Technology 85 (2003) 75-89

A1323 – Influence of boron on structure and oxidation behavior of graphite fiber, P120

P120 fibers, derived from mesophase pitch, were substitutionally doped with boron in the concentration ranges of 200-4600 ppm. An oxidation study was carried out in dry air at 973, 1023, and 1073 K at 95 kPa. Boron is preferentially positioned into the less disordered core region and in the external surface area (skin) of the fiber. Upon oxidation these regions are preferentially protected. Oxidation rates decreased by a factor up to 3, varying with boron concentration, burn-off level and oxidation temperature. The activation energy of oxidation increased from 151 kJ/mol for heat-treated P120 fibers to 180 kJ/mol for fibers with 3300 ppm B, then decreased to 122 kJ/mol for fibers containing 4600 ppm of boron. The observed decrease in oxidation rate is directly attributed to the location and concentration of boron. Boron doping inhibits oxidation by blocking specific active sites. It is proposed that 1000 ppm B as a threshold concentration at which the electronic, chemical, and physical (structural) behavior could be modified.
J.Y. Howe, L.E. Jones, Carbon 42 (2004) 461-467

A1322 – Biomimetic nucleation and growth of CaCO3 in hydrogels incorporating carboxylate groups

Poly-acrylamide hydrogels were modified by copolymerization with acrylic acid and used as growth medium for CaCO3 in a double-diffusion arrangement. The carboxylate functionalities in the gel network facilitate the nucleation of a multitude of small crystallites of vaterite and calcite, which are temporarily stabilized even while supersaturation is increasing within the hydrogel. After an extended induction period the rapid spherulitic growth of calcite crystals along their c-axis is observed yielding spheres with diameters exceeding 300 µm. In the center of those aggregates disordered, porous regions can be identified as starting point of this rapid crystallization. The results are compared to previous studies on native poly-acrylamide hydrogels and networks modified with -SO3H functional groups. The mineralization mechanism is significantly altered by specific interactions between the -COOH functionalized network and the evolving mineral phase.
O. Grassmann, P. Lobmann, Biomaterials 25 (2004) 277-282

A1325 – Analysis of the microporosity shrinkage upon thermal post-treatment of H3PO4 activated carbons

Starting from a commercial pelletized phosphoric acid based activated carbon, with a typical opened and developed micro and mesoporosity, a post-heat-treatment in KOH, at different KOH/activated carbon ratios, has been studied. In all the cases, a pore size shrinkage has been observed. To find an explanation for the reason of this micropore size distribution shrinkage different factors have been studied, among them: (a) effect of the presence of impurities coming from the activation process with phosphoric acid; (b) effect of the KOH post-treatment temperature; (c) heat-treatment temperature of the precursor (without chemical agent); (d) effect of the reagent nature (NaOH, NaCl and KCl vs. KOH). The variable that produces the most intense shrinkage effect, and the disappearance of the mesoporosity, is the heat-treatment in presence of hydroxide, which affects even using a low hydroxide/activated carbon ratio. Such a low hydroxide/activated carbon ratio does not produce activation, nor porosity development of the starting activated carbon during the treatment. This shrinkage phenomenon, which seems to be independent of the method of preparation used to prepare the activated carbon, can be understood considering our previous studies about the reactions involved during chemical activation by hydroxides.
I. Martin-Gullon, J.P. Marco-Lozar, D. Cazorla-Amoros, A. Linares-Solano, Carbon 42 (2004) 1339-1343

A1324 – Synthesis and characterization of carbon nanotubes-TiO2 nanocomposites

The main objective of this paper is to coat carbon multiwall nanotubes surface with TiO2 as anatase in view of photocatalytic application for these nanocomposites. Carbon nanotubes were produced by catalytic decomposition of acetylene at 600°C. The coating was performed by a sol-gel method using classical alkoxides as Ti(OEt)4 and Ti(OPri)4 and by hydrothermal hydrolysis of TiOSO4, leading to different TiO2 morphologies. In using the sol-gel method, nanotubes are coated either with a continuous TiO2 thin film when the precursor is Ti(OEt)4, or with TiO2 nanoparticles when the precursor is Ti(OPri)4. By hydrothermal treament, more compact and crystalline nanocomposites are obtained.
A. Jitianu, T. Cacciaguerra, R. Benoit, S. Delpeux, F. Béguin, S. Bonnamy, Carbon 42 (2004) 1147-1151

A1326 – Carbon nanotubes as a template for mild synthesis of magnetic CoFe2O4 nanowires

Hundred nanometers outer diameter multi-walled carbon nanotubes have been used as suitable host template for synthesizing CoFe2O4 nanowires encapsulated inside nanotubes under mild conditions, i.e. 100°C and atmospheric pressure, with a high filling yield of the nanotubes, using an aqueous nitrate precursor solution and the confinement effect provided by the surrounding walls. The formation of caps near the tube tips at the beginning of the nitrate decomposition led to consider each nanotube as a closed nanoreactor, in which the reaction conditions could be far different from the macroscopic conditions outside the tube. The structure of the CoFe2O4 nanowires could be continuously changed from a disordered hair-like dendritic structure at 100°C to highly crystallized domains when increasing the temperature. A material with high coercivity at room temperature for small particles of about 25 nm in diameter was obtained by submitting the nanowires to an Ar treatment at 550°C for 2 h.
N. Keller, C. Pham-Huu, C. Estournes, J-M. Greneche, G. Ehret, M.J. Ledoux, Carbon 42 (2004) 1395-1399

A1328 – Novel MoVSbOx-type catalysts for selective isobutane oxidation

A new sol-gel synthesis procedure is proposed for the preparation of MoVSbOx catalysts for the selective oxidation of isobutane. Physico-chemical characterization of the materials calcined at 400°C, showed essentially amorphous catalysts, with long-range order. Increase of calcination temperature, however, resulted in the formation of small crystalline regions, confirmed through TEM. EPR measurements on the calcined samples pointed to the presence of isolated and magnetically interacting V(IV) species. The reported catalysts proved to be much more selective for partial oxidation compared to a literature reference catalyst. Furthermore, it is shown that this versatile synthesis recipe forms an excellent start for high-throughput and combinatorial studies.
J.S. Paul, M.H. Groothaert, C.E.A. Kirschhock, O.I. Lebedev, PA. Jacobs, WF. Maier, Catalysis Today 91-92 (2004) 265-269

A1327 – A study of mesophase formation from a low temperature coal tar pitch using formaldehyde as a promoter for polymerisation

J.L. Crespo, A. Arenillas, J.A. Vina, R. Garcia, C.E. Snape, S.R. Moinelo, Letters to the Editor / Carbon 42 (2004) 2735-2777

A1331 – Fabrication and characterization of porous tricalcium phosphate ceramics

Preforms of beta tricalcium phosphate (beta-TCP) ceramics were produced byusing a modified slip casting technique. The slip was prepared bysuspending custom-made TCP powder and PMMA beads in an aqueous medium stabilized with an acrylic deflocculant. Porous TCP ceramics were obtained bysintering the polymer-free preforms for 2 h at 1000°C. The XRD pattern for the TCP ceramic indicated that the product was essentiallypure beta-TCP. SEM examination of pore size and pore size distribution revealed that the ceramic was appropriate for repair of cortical defects.
N. Koç, M. Timuçin, F. Korkusuz, Ceramics International 30 (2004) 205-211

A1330 – Synthesis of lithium aluminosilicate glass and glass-ceramics from spodumene material

The synthesis of lithium aluminosilicate glasses and glass-ceramics from spodumene material was investigated. Basing on the general formula Li(2-2(x+y))MgxZnyAl(2-m)BmSizO(2z+4), 40 mol% of the Li2O was replaced with 20 mol% of MgO and 20 mol% of ZnO, and 40 mol% of Al2O3 with B2O3. BaO was also introduced for improving glass melting behaviour. 2 and 5 wt.% TiO2 was used as nucleation agent. In the TiO2-containing glasses, virgilite was primarily crystallized. The degree of crystallinity was considerably improved at 900°C. Virgilite was transformed into crystals of spodumene solid solutions embedded in a glass matrix, while Zn-gahnite formed a second crystalline phase. Rutile was crystallized in the glasses containing 5 wt.% TiO2. The thermal expansion coefficient for the 2% and the 5 wt.% TiO2-containing glass-ceramics was 6.39 x 10-7 and 17.1 x 10-7 K-1, respectively (70-300°C).
D.U. Tulyaganov, S. Agathopoulos, H.R. Fernandes, J.M.F. Ferreira, Ceramics International 30 (2004) 1023-1030

A1329 – Characterization of lalithe, a new bentonite-type Algerian clay, for intercalation and catalysts preparation

Iron-intercalated clay has been obtained starting from a natural bentonite-type clay sample from Maghnia (Algeria). The natural compound contained, besides the clay material, impurities such as quartz, beta-cristobalite and calcite. The quartz phase was removed by applying a purification protocol based on sedimentation. The two other phases remained in the solid but did not apparently affect the intercalation process. The intercalation process has been optimized to lead a microporous solid with a reticular distance of 16 Å and a specific surface area of 260m2 g-1. High-resolution electron microscopy with EDX analyses showed that the sample had a relatively inhomogeneous composition with a typical delaminated structure. It confirmed the pillaring but also showed some goethite particles. These particles certainly formed because of the delamination are few and small and do not affect the Mössbauer spectra showing only one ferric iron species and confirming that most of the iron was in the pillars. The thermal stability of the iron-pillared clay has been studied. It was shown that the structure started to collapse before 773K which is rather low for polyoxocations-intercalated clay but comparable for other iron-intercalated clays.
L.S. Belaroui, J.M.M. Millet, A. Bengueddach, Catalysis Today 89 (2004) 279-286

A1333 – Effect of alkaline-earth oxides on phase formation and morphology development of mullite ceramics

The effect of alkaline-earth oxides, including MgO, CaO, SrO and BaO, on the phase formation and morphology development of mullite (3Al2O3.2SiO2) ceramics from oxide mixtures activated by a high-energy ball milling process, were investigated. Different alkaline-earth oxides demonstrated different influences on the mullitization behavior and morphology/microstructure development of the mullite ceramics. Mullitization temperature increased as the additives were from MgO to BaO. Well developed mullite whiskers were formed in the MgO doped group, while grains with normal shapes were observed in the cases of CaO, SrO and BaO. The dependence of both mullite formation temperature and morphology development on the kinds of alkaline-earth oxides were explained in terms of the mullitization mechanism of dissolution-precipitation.
L.B. Kong, Y.Z. Chen, T.S. Zhang, J. Ma, F. Boey, H. Huang, Ceramics International 30 (2004) 1319-1323

A1332 – Effect of homogenizing procedures on the slip casting of reaction sialon suspensions

Reaction sialon suspensions were prepared using 3-wt.% KD1 (a polyester/polyamine condensation copolymer) as dispersant in organic media of 60-vol.% methyletheylketone and 40-vol.% ethanol. Different homogenizing procedures were used and compared, such as: high energetic planetary milling, low energetic ball milling and ultrasonic disaggregation. The effect of different homogenizing routes and solids loading on the rheology of suspensions and on the properties of slip casting green bodies has been studied. The differences observed among the various mixing procedures could be attributed to the different degrees of disaggregation and therefore to different fractions of surface coverage of the reaction sialon powders by the dispersant.
X. Xu, R. Fu, J.M.F. Ferreira, Ceramics International 30 (2004) 745-749

A1334 – Synthesis of La(2-x)NiO(4+d) oxides by polymeric route: non-stoichoimetry control

The synthesis of La(2-x)NiO(4+d) oxides has been done via a polymeric route. This method allows the preparation of a wide range of non-stoichoimetry values. Oxides with values as high as 0.25 have been synthesised. Correlations between processing parameters such as sol composition and heat treatment have been done with structural and microstructural properties of the oxides. In our synthesis conditions, the higher the mean grain size, the higher the non-stoichoimetry level. Transmission electron microscopy on these oxides has shown that whatever the non-stoichoimetry level, the extra-oxygen arranges in the structure according to two superstructures which correspond to d = 0.25 and d = 0.17. This shows that our grains consist of a mixture of these compositions.
M-L. Fontaine, C. Laberty-Robert, A. Barnabé, F. Ansart, P. Tailhades, Ceramics International 30 (2004) 2087-2098

A1335 – Morphology and sintering behaviour of yttria stabilised zirconia (8-YSZ) powders synthesised by spray pyrolysis

This work is focused on the synthesis of nano-crystallised yttria stabilised zirconia (YSZ) powders by the spray pyrolysis method, the aim of the study being a better understanding of the influence of the spray pyrolysis parameters on the morphology of the produced powders. Spray pyrolysed powder consists of polycrystalline particles, which are spherical. Each particle consists of nanometric primary grains. The morphology of these polycrystalline particles was characterised by scanning electron microscopy (SEM), helium pycnometry, thermogravimetric analysis (TGA) and mass spectroscopy (MS), and the results are compared. Thus, particle size, particle size distribution and particle porosity were determined and correlated to the process parameters. Finally, by dilatometric measurements, sintering curves of pellets prepared from different sets of powders were analysed in regard of their morphologies. Two main conclusions could be deduced from these studies. Firstly, the process parameters influence both internal porosity and particle size distribution of the synthesised powders. Secondly, the morphologies of the spray pyrolysed nano-powders lead to particularly high sintering activities.
M. Gaudon, E. Djurado, N.H. Menzler, Ceramics International 30 (2004) 2295-2303

A1337 – INSEDELF: method of studying separation in liquid-liquid phase application to water-diesel fuel emulsions

The use of the INSEDELF method to measure solid-liquid phase separation was extended to water/diesel fuel emulsions to study liquid-liquid phase separation. We have demonstrated that this method is a pertinent tool for characterising the stability of these emulsions and for optimising complex formulations intended for winter use of these fuels. It permitted determination of the optimal content of antifreeze in the aqueous phase. A similar optimisation can be carried out on the diesel fuel phase. The INSEDELF method now constitutes a method that can be used in research to develop new emulsions and anti -settling additives as well as to control the fabrication of these different products.
P. Schulz, L. Dalix, J.M. Letoffe, Y. Faure, Fuel 83 (2004) 137-142

A1336 – Upgrading of carbonaceous phosphate rocks by direct carbonation with CO2-water solutions

This work is an investigation of a relatively new process to upgrade carbonaceous phosphate rocks via direct carbonation with CO2-water solution. The process is mainly based on the reaction of the CaCO3 present in the phosphate ore with CO2-water solutions to convert the former to a water-soluble compound (i.e. calcium bicarbonate). The carbonation experiments were carried out in a 0.054m inner diameter column and 1.7m high. The parameters that may affect the dissolution of CaCO3 in the CO2-water solution such as column pressure and temperature, CO2-bubbler perforation diameter, CO2 flow rate, phosphate particles size, solid/liquid ratio in the slurry mixture, and the slurry height in the column were investigated. The effects of before-carbonation phosphate ore preheating as well as multiple carbonations were also examined. It was found out that the rate of dissolution of CaCO3 increased with the increase of pressure inside the column, CO2-bubbler perforation diameter, and CO2 flow rate. Furthermore, it increased with the decrease of phosphate ore particles size, slurry height in the column, and temperature. Low solid/liquid ratio of 30-50 g phosphate ore per liter of CO2-water solution were found to give better dissolution rates. The heating of the phosphate ore to 150°C for 15 min (before carbonation) gave better dissolution than other preheating temperatures and time intervals. By multiple carbonation, it was possible to remove about 90% of the CaCO3 present in the phosphate ore in 10 stages. The recovery of CO2 and production of CaCO3 precipitate is possible and can be easily handled by heating the calcium bicarbonate solution under vacuum.
S.I. Abu-Eishah, M.J.J. Anabtawi, S.L. Isaac, Chemical Engineering and Processing 43 (2004) 1085-1094

A1339 – Towards single step production of multi-layer inorganic hollow fibers

In this work we propose a generic synthesis route for the single step production of multi-layer inorganic hollow fibers, based on polymer wet spinning combined with a heat treatment. With this new method, membranes with a high surface area per unit volume ratio can be produced, while production time and costs are dramatically reduced. The proof-of-principle of the concept will be demonstrated with the production of double layer alpha-alumina hollow fibers. Although various problems were anticipated at the interface of the layers, the adhesion between the two layers is surprisingly good, both in the precursor and the sintered fiber. Produced fibers show an asymmetric structure with a porosity between 37 and 45%. The macrostructure of the sintered fiber is largely determined by the macrostructure of the precursor fiber, while differences in microstructure disappear during the heat treatment step. The proposed method is not limited to alpha-alumina membranes; in principle many ceramic or metallic powders may be used. This means that this method can open up the way for a new generation of membranes.
J. de Jong, N.E. Benes, G.H. Koops, M. Wessling., Journal of Membrane Science 239 (2004) 265-269

A1338 – Mechanical alloying and electronic simulations of (MgH2+M) systems (M=Al, Ti, Fe, Ni, Cu and Nb) for hydrogen storage

Mg-based alloys are promising candidates for hydrogen storage applications. Here, mechanical alloying (MA) was used to process powder mixtures of MgH2 with 8 mol% M (M = Al, Ti, Fe, Ni, Cu and Nb) in order to modify hydrogen storage properties of the Mg hydride. Electronic simulations of the systems were carried out to clarify the mechanisms of the alloy effects. X-ray di:raction (XRD) of the milled samples revealed the formation of new phases: a bcc solid solution phase for the (MgH2 + Nb) mixture; TiH2 phase for the (MgH2 + Ti); and MgCu2 phase for the (MgH2 + Cu). For all the mixtures, a high-pressure phase, gamma-MgH2, was also identified after mechanical alloying. Further qualitative and quantitative phase analyses were carried out using the Rietveld method. Scanning electron microscopy (SEM) of the milled powder clearly showed substantial particle size reduction after milling. Dehydrogenation at 300°C under vacuum shows that the (MgH2+Ni) mixture gives the highest level of hydrogen desorption and the most rapid kinetics, followed by MgH2 with Al, Fe, Nb, Ti and Cu. Theoretical predictions show that the (MgH2 + Cu) system is the most unstable, followed by (MgH2 + Ni), (MgH2 + Fe), (MgH2 + Al), (MgH2 + Nb), (MgH2 + Ti). The predicted alloying effects on the stability of MgH2 generally agree with the experimentally observed change in the hydrogen desorption capacity. The di:erences were discussed in the text.
C.X. Shang, M. Bououdina, Y. Song, Z.X. Guo, International Journal of Hydrogen Energy 29 (2004) 73-80

A1341 – Biopolymer immobilization duringthe crystalline growth of layered double hydroxide

Alginic acid, a biopolymer produced by brown seaweed, is incorporated between the sheets of a layered double hydroxide (LDH) via direct coprecipitation. The growth of the inorganic crystalline seeds over the polymer gives rise to a lamellar structure. The obtained nanocomposite presents a basal spacingin agreement with the ideal picture of the polymer lyingperpendicularly to the inorganic sheets. A study using FTIR and 13C CP-MAS spectroscopies suggests that the interaction between the organic guest and the inorganic framework is weak. However, the polymer has a stabilizing effect in temperature, since ZnO is observed at 350°C, whereas it appears at 200°C for the chloride LDH pristine material.
F. Leroux, J. Gachon, and J-P. Besse, Journal of Solid State Chemistry 177 (2004) 245-250

A1340 – Disproportionation of stoichiometric LiMn2O4 on annealing in oxygen

The evolution of stoichiometric LiMn2O4 upon annealing under oxygen pressures in the range 0.2-5 atm at moderate temperature (450°C) was studied with a combination of thermogravimetry, X-ray and neutron diffraction. It is shown that such treatments result in a slight, but significant mass increase. Structural analyses show that the resulting spinel is a manganese-deficient spinel phase with lower cell parameter and higher manganese valence, and that the expelled manganese forms Mn2O3. The presence of this second phase, which was not identified in a recent study of oxygen annealing on this compound (Nakamura and Kajiyama, Solid State Ionics 133 (2000) 195), is compatible with the initial stoichiometry and does not require any oxygen vacancies in the initial LiMn2O4, as supposed earlier. The most likely formula of the resulting lithium-rich spinel with increased manganese valence is Li(Mn(2-e)e)O4 with e in the range 0.02-0.03 at 5 atm O2.
P. Strobel, G. Rousse, A. Ibarra-Palos, and C. Masquelier, Journal of Solid State Chemistry 177 (2004) 1-5

A1343 – Synthesis and characterization of (La1-xMx)2Mo2O9-d ; M=Ca2+, Sr2+ or Ba2+

The system (La(1-x)Cax)2Mo2O(9-d) was characterized in the region x=0.01
R. Subasri, D. Matusch, H. Näfe, F. Aldinger, Journal of the European Ceramic Society 24 (2004) 129-137

A1342 – Hydrothermal processing of nanocrystalline anatase films from tetraethylammonium hydroxide peptized titania sols

Nanocrystalline anatase films were obtained by hydrothermally treating dip-coated TiO2 gel films onto silicon substrates from tetraethylammonium hydroxide (TENOH) peptized titania aqueous sols diluted with different solvents (isoproponol, acetone and propanediol) at 240°C for 2 h. SEM, AFM and XRD analysis were used to characterize the microstructure and phase evolution of the films. The highest degree of homogeneity and good wettability towards the substrate could only be obtained with mixed solvents of acetone and isopropanol, yielding denser structure with homogeneously distributed fine grains among all the three solvents. A uniform distribution of fine grains of around 50 nm was obtained after hydrothermal treatment, while the film calcined at 500°C/2 h displayed larger grains of around 80 nm and were not so uniformly developed. All these results suggest that (a) TENOH peptized titania sol is a promising novel stock precursor for synthesizing TiO2 films; (b) hydrothermal technique is quite efficient in preparing titania nanocrystalline films compared with calcination method.
J. Yang, S. Mei, J.M.F. Ferreira, Journal of the European Ceramic Society 24 (2004) 335-339

A1344 – Synthesis and characterisation of LiNi(1-x-y)CoxAlyO2 cathodes for lithium-ion batteries by the PVA precursor method

Polycrystalline powders of LiNi(1-x)CoxO2 and LiNi(1-x-y)CoxAlyO2 were synthesized at 720°C from the nitrate-PVA precursor method. The water was removed by two different processes: (i) evaporation-drying at 110°C, (ii) spray-drying at 150°C. In both cases a gel is obtained wherein LiNO3 crystallizes in evaporated-dried samples but not in spray-dried samples which are more amorphous. All precursors give single phase powders with micronic well-shaped grains. The best electrochemical performances are obtained from evaporated samples with a capacity remaining higher than 160 mAh/g for LiNi0.82Co0.18O2 and 140 mAh/g for LiNi0.82Co0.13Al0.05O2 after 20 cycles. The lower performances of the spray-dried samples seem to be related to Li2CO3 formation with subsequent non-stoichiometry as a consequence of the improved homogeneous distribution of the constituent cations in the polymer.
P.H. Duvigneaud, T. Segato, Journal of the European Ceramic Society 24 (2004) 1375-1380

A1346 – Synthesis of a silica monolith with textural pores and ordered mesopores

Silica monolith with textural pores and ordered mesopores was fabricated through a sol-gel process by using triblock polymer of F127 as pore directing reagent. In the reaction, F127 demonstrated its dual functions-phase separation inducing function and template function. The former resulted in co-continuous structure of silica skeletons and textural pores, while the latter led to the formation of ordered mesopores.
Z-G. Shi, Y-Q. Feng, L. Xu, S-L. Da, Y-Y. Ren, Microporous and Mesoporous Materials 68 (2004) 55-59

A1345 – Synthesis of AlPO4-31 from nonaqueous systems

The aluminophosphate molecular sieve AlPO4-31 has been synthesized from a nonaqueous system in the presence of hexamethyleneimine as templating agent and has been characterized by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), FT-IR, differential thermal analysis (DTA) and thermogravimetric analysis (TG) and 27Al and 31P MAS NMR techniques.
N. Venkatathri, Materials Letters 58 (2003) 241-244

A1347 – Synthesis of zeolite beta in fluoride media under microwave irradiation

Zeolite beta has been successfully prepared at 150°C within 4 h by direct synthesis under microwave irradiation. Addition of seeds into the synthesis solution under microwave irradiation did not affect overall synthesis time of the material significantly, while addition of ammonium fluoride accelerated the crystallization of zeolite beta. In particular, microwave technique combined with fluoride species and seeding led to more rapid synthesis of crystalline zeolite beta. Upon microwave irradiation fluoride species and the microwave-activated water in the synthesis solution might be ascribed to shortening an induction period at the nucleation step, resulting in the rapid synthesis of the material.
D.S. Kim, J-S. Chang, J-S. Hwang, S-E. Park, J.M. Kim, Microporous and Mesoporous Materials 68 (2004) 77-82

A1351 – Application of thermogravimetric analysis to the evaluation of aminated solid sorbents for CO2 capture

In this work a series of solid sorbents were synthesized by immobilizing liquid amines on the surface of a mesoporous alumina. The samples were chemically characterized and BET surface areas calculated from the N2 adsorption isotherms at 77 K. The CO2 capture performance of the sorbents and their thermal stability was studied by thermogravimetric methods. The effect of amine loading on the CO2 capture performance of the prepared sorbents was also evaluated. Analysis of TG-DTG curves showed that thermal stabilization of the amines is significantly improved by immobilizing them on an inorganic support. Temperature-programmed CO2 adsorption tests from 298 K up to 373 K at atmospheric pressure, proved to be a useful technique for assessing the capacity of sorbents for CO2 capture. Alumina impregnated with diethylenetriamine presented the highest CO2 adsorption capacities throughout the tested temperature range.
M. G. Plaza, C. Pevida, B. Arias, J. Fermoso, A. Arenillas, F. Rubiera and J. J. Pis, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 2, 601–606

A1350 – Re-cycling of sugar-ash: a raw feed material for rotary kilns

Large amounts of sugar-ash, a material rich in calcium carbonate, are produced as a by-product in the Greek Sugar Industry. This work explores the possibility of re-cycling sugar-ash for use in the lime industry. A representative sample of sugar-ash from the Plati Imathias sugar plant was studied by PXRD, TG/DTG, calcination experiments at temperatures between 650 and 1150°C and experiments to determine the quality of the quicklime produced at temperatures between 850 and 1150°C following methods described in ASTM C110 standard. The sugar-ash was found to consist of 90 wt% calcium rich minerals (calcite and monohydrocalcite) and 10 wt% amorphous material. Traces of quartz were also detected. The quicklime of highest quality was produced at 950°C. It is concluded that this "useless" material (sugar-ash) can be re-cycled for use in rotary kilns in the lime industry at calcination temperatures up to 950-1000°C.
N. Kantiranis, Waste Management 24 (2004) 999-1004

A1349 – Characterization of thin solid films containing yttrium formed by electrogeneration of base for high temperature corrosion applications

Mixed water-ethyl alcohol solutions of Y(NO3)3, 6H2O at 0.01 M were used for cathodic electrodeposition of Y(OH)3 thin films on Ni- 20 wt.% Cr-1.5 wt.% Si substrate. Y(OH)3, xH2O deposits were obtained using a conventional three electrode cell. Current density and duration of deposition were optimized in order to obtain thin (<1 µm), uniform and adherent films. These deposited films were further transformed by thermal treatment into Y2O3 coatings, expected to increase the high temperature oxidation resistance of the substrate. Thermal stability, microstructure and formed phase of as deposited films and thermally treated films were characterized by differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron and atomic force microscopies (SEM, AFM), inductively coupled plasmaoptical emission spectroscopy (ICP-OES) and X-ray diffraction.
J-M. Brossard, J. Balmain, J. Creus, G. Bonnet, Surface & Coatings Technology 185 (2004) 275-282

A1348 – Vinyl acetate/butyl acrylate copolymers-part 1: mechanism of degradation

This work deals with the mechanism of degradation of vinyl acetate/butyl acrylate (VA/BA) copolymers varying the VA/BA ratio. It is shown that for higher VA contents, the degradation starts at comparatively lower temperature but a more thermally stable material is formed. The mechanism of degradation of VA/BA copolymers is then compared with PVA and PBA homopolymers. It appears that the fractions of degradation (gases, high boiling products and residue) for VA/BA copolymer is a combination of those of polyvinyl acetate (PVA) and polybutyl acrylate (PBA). However, a slight stabilisation occurs when VA/BA are co-polymerised together compared with a VA and BA combination. Moreover, the comparison of the thermo-oxidative degradation with the pyrolysis demonstrates that the mechanisms are similar at least up to 450°C.
S. Duquesne, J. Lefebvre, R. Delobel, G. Camino, M. LeBras, G. Seeley, Polymer Degradation and Stability 83 (2004) 19-28

A1353 – Investigation of surface properties of lunar regolith Part III

We investigated lunar regolith collected during the Apollo 11, 12 and the Apollo 16 missions. The Apollo 11 and the Apollo 12 samples come from the lunar mare, whereas the Apollo 16 expedition brought back material from a highland region of the near side of the Moon. In paper series we summarise in brief the results of measurements using photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), nitrogen adsorption, thermal analysis (TG, DTA) and temperature-programmed reduction and oxidation (TPRO) method. Parts of samples were examined by means of scanning electron (SEM/EDS) and atomic force microscopy (AFM).
A. Dabrowski, E. Mendyk, E. Robens, K. Skrzypiec, J. Goworek, Mariola Iwan and Zofia Rzaczynska, Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 3, 633–639

A1352 – Thermal behavior and water adsorption of natural and modified sepiolite having dolomite from Turkey

The water adsorption properties of sepiolite having dolomite supplied from Eskisehir region and their exchanged forms (K+, Na+, Mg2+ and Ca2+) were investigated. The sepiolite samples were characterized using XRD, TG-DTA, DSC and nitrogen adsorption methods. The temperature ranges were determined for the dehydrations of hydroscopic and zeolitic water as 30–200°C, for the dehydration of the bound water as 250–750°C and for the dehydroxylation of hydroxyls as 810–850°C in the sample. It was observed that the value of percent mass loss for natural and modified samples varied in the range from 36.70 to 39.05%. Two mass loss steps for all samples were observed using a differential scanning calorimetry (DSC) in the range of 30–550°C. Adsorption isotherms for water on natural and modified forms were obtained at pressures up to 2.39 kPa. Uptake of water increased as K-SEP.
B. Erdogan Alver, M. Sakici, E. Yörükogullari, Y. Yilmaz and M. Güven, Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 3, 835–840

A1355 – Thermal analysis and microstructural characterization of ceramic green tapes prepared by aqueous tape casting

In this study, aqueous lead magnesium niobate (PMN) slurry formulations were developed for tape casting using a poly(acrylic acid) – poly(ethylene) oxide comb polymer as the dispersant, nonionic acrylic latex as the binder phase and hydroxypropylmethylcellulose as the wetting agent. Concentrated suspensions were cast onto a silicone-coated mylar film, and the effect of acrylic latex on deposition was investigated. Thermal analyses were performed to investigate the mass loss of the green tapes as a function of calcination temperature. Differential scanning calorimetric analyses were made under air and nitrogen atmospheres to investigate the binder distribution through the green tapes. Results showed that it is possible to prepare flexible, crack free PMN thick films using a proper slurry composition in the presence of acrylic latex binder, without using any plasticizer. Additionally, decomposing mechanisms of the acrylic based binder were essentially different in the two atmospheres
A. Sakar-Deliormanli, E. Celik and M. Polat, Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 3, 663–667

A1354 – Influence of lime-containing additives on the thermal behaviour of ammonium nitrate

Ammonium nitrate (AN) is one of the main nitrogen fertilizers used in fertilization programs. However, AN has some serious disadvantages being well soluble in water hardly 50% of the N-species contained are assimilated by plants. The second disadvantage of AN is associated with its explosive properties. The aim of this paper was to clarify the influence of different lime-containing substances mainly Estonian limestone and dolomite – as internal additives on thermal behaviour of AN. Commercial fertilizer grade AN was under investigation. The amount of additives used was 5, 10 or 20 mass%, or calculated on the mole ratio of AN/(CaO,MgO)=2:1 in the blends. Experiments were carried out under dynamic heating condition up to 900°C (10°C min–1) in a stream of dry air or N2 by using Setaram Labsys 2000 equipment coupled to Fourier transform infrared spectrometer (FTIR). The results of analyses of the gaseous compounds evolved at thermal treatment of neat AN indicated some differences in the decomposition of AN in air or in N2. At the thermal treatment of AN’s blends with CaCO3, MgCO3, limestone and dolomite samples the decomposition of AN proceeds through a completely different mechanism – depending on the origin and the content of additives, partially or completely, through the formation of Mg(NO3)2 and Ca(NO3)2.
T. Kaljuvee, E. Edro and R. Kuusik, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 1, 215–221

A1357 – Effect of alkylresorcinols on curing behaviour of phenol-formaldehyde resol resin

Thermal behaviour of cure-accelerated phenol-formaldehyde (PF) resins was studied using the addition of commercial mixture of water soluble oil shale alkylresorcinols (AR) to PF resin, 5-MR being as model compound. The acceleration effect of AR is based on the promotion of condensation of resin methylol groups and subsequent reaction of released formaldehyde with AR. Commercial PF resins SF -3013VL and SF -3014 from the Estonian factory VKG Resins have been used. The chemical structure of resins was characterised by 13C NMR spectroscopy. TG-DTA analysis was carried out using labsysTM instrument Setaram. By TG-DTA measurements, the shift of exothermic and endothermic peaks and the changes of mass loss rate in the ranges of 1.5–10 g AR/100 g PF resin were studied. The effect of AR on the curing behaviour of PF resins was also followed by gel time. Testing of the plywood when using PF resin with 5 mass% of AR shows that the press time could be reduced by about 15%.
K. Siimer, T. Kaljuvee, P. Christjanson, T. Pehk and I. Saks, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 2, 365–373

A1356 – Kinetic model identification and parameters estimation from TGA experiments

The presented work is a part of an ongoing research effort on the development of a general methodology for the determination of kinetic models of solid thermal decomposition under pyrolysis conditions with thermogravimetric analysis (TGA) devices. The goal is to determine a simple and robust kinetic model for a given solid with the minimum of TGA experiments. From the latter point of view, this work can be seen as the optimal design of TGA experiments for pyrolysis kinetic modelling. In this paper, a general procedure is presented and more precise results are given about the influence of the sensitivity matrix on the estimation of the kinetic parameters and about the important influence of the specific TGA runs used for parameter estimation on the precision of the fitted parameters. The first results are shown for simulated applications; in the final part, the presented results concern cellulose pyrolysis in a Setaram TGA device.
Cedric Reverte, Jean-Louis Dirion, Michel Cabassud, J. Anal. Appl. Pyrolysis 79 (2007) 297–305

A1359 – Kinetic parameter estimation from TGA: Optimal design of TGA experiments

This work presents a general methodology to determine kinetic models of solid thermal decomposition with thermogravimetric analysis (TGA) instruments. The goal is to determine a simple and robust kinetic model for a given solid with the minimum of TGA experiments. From this last point of view, this work can be seen as an attempt to find the optimal design of TGA experiments for kinetic modelling. Two computation tools were developed. The first is a nonlinear parameter estimation procedure for identifying parameters in nonlinear dynamical models. The second tool computes the thermogravimetric experiment (here, the programmed temperature profile applied to the thermobalance) required in order to identify the best kinetic parameters, i.e. parameters with a higher statistical reliability. The combination of the two tools can be integrated in an iterative approach generally called sequential strategy. The application concerns the thermal degradation of cardboard in a Setaram TGA instrument and the results that are presented demonstrate the improvements in the kinetic parameter estimation process.
Jean-Louis Dirion, Cedric Reverte, Michel Cabassud, Chemical Engineering Research and Design 8 6 ( 2 0 0 8 ) 618–625

A1358 – TG-DTA study of melamine-urea-formaldehyde resins

The thermal behaviour of MUF resins from different suppliers with different content of melamine was studied, along with the 13C NMR spectroscopic analysis of resin structure and the testing of particleboards in current production at Estonian PB factory P¬rnu Plaaditehas AS. The chemical structure of resins from DMSO-d6 solutions was analysed by 13C NMR spectroscopy on a Bruker AMX500 NMR spectrometer. The melamine level in different MUF resins is compared by the ratios of carbonyl carbon of urea and triazine carbon of melamine in 13C NMR spectra. Curing behaviour of MUF resins was studied by simultaneous TG-DTA techniques on the Labsysä instrument Setaram. The shape of DTA curves characterisises the resin synthesis procedure by the extent of polymerisation of UF and MF components and is in accordance with structural data.
K. Siimer, P. Christjanson, T. Kaljuvee, T. Pehk, I. Lasn and I. Saks, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 1, 19–27

A1361 – A kinetic analysis of thermal decomposition of polyaniline/ZrO2 composite

Synthesis, characterization and thermal analysis of polyaniline (PANI)/ZrO2 composite and PANI was reported in our early work. In this present, the kinetic analysis of decomposition process for these two materials was performed under non-isothermal conditions. The activation energies were calculated through Friedman and Ozawa–Flynn–Wall methods, and the possible kinetic model functions have been estimated through the multiple linear regression method. The results show that the kinetic models for the decomposition process of PANI/ZrO2 composite and PANI are all D3, and the corresponding function is f(?)=1.5(1–?)2/3[1–(1–?)1/3]–1. The correlated kinetic parameters are Ea=112.7±9.2 kJ mol–1, lnA=13.9 and Ea=81.8±5.6 kJ mol–1, lnA=8.8 for PANI/ZrO2 composite and PANI, respectively.
S.-X. Wang, Z.-C. Tan, Y.-S. Li, L.-X. Sun, Y. Li, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 2, 483–487

A1360 – The effect of zinc stearate on thermal degradation of paraffin wax

In this research, the effects of zinc stearate addition on paraffin wax degradation were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). The apparent activation energies of wax decomposition in nitrogen and air atmospheres were determined as 76 and 37 kJ mol–1, respectively applying Kissinger method to TG data. The degradation rate constants of paraffin containing zinc stearate (0.1–0.5%) were found to be almost two times greater than that of paraffin only in air atmosphere. However, zinc stearate did not affect the rate constants in nitrogen significantly.
M. Gönen, D. Balköse, F. Inal and S. Ülkü, Journal of Thermal Analysis and Calorimetry, Vol. 94 (2008) 3, 737–742

A1365 – Thermal decomposition of polymeric aminoborane (H2BNH2)x under hydrogen release

Polymeric aminoborane (H2BNH2)x has been isolated during the thermal decomposition of solid borazane H3BNH3 at temperatures below 370 K. Polymeric aminoborane is a white noncrystalline solid, stable at room temperature and up to 380 K. In the temperature range of 380–500K polymeric aminoborane undergoes a thermal decomposition, which was studied by differential scanning calorimetry (DSC), by thermogravimetry (TG) and by volumetric measurements. The solid residuewas characterized by IR spectroscopy, by powder X-ray diffraction (XRD) analysis and by solid state 11B NMR spectroscopy. The thermal decomposition of polymeric aminoborane (H2BNH2)x is an exothermic process accompanied by evolution of nearly 1 mol hydrogen per mole H2BNH2 unit corresponding to the volumetric measurements. The detected mass loss of the solid phase indicates the formation of further gaseous products beside hydrogen. The final mass loss increases with rising heating rate, in contrast to the final amount of evolved hydrogen, which still remains constant
J. Baumann , F. Baitalow, G. Wolf, Thermochimica Acta 430 (2005) 9–14

A1364 – Continuous Thermogravimetric Analysis During the Cyclic Oxidation of Ni22Al15Pt+1wt%Hf at 1200°C.

Cyclic thermogravimetric analysis (CTGA) provided a quantitative assessment of cyclic oxidation kinetics for a Ni-22Al-15Pt+1wt%Hf alloy. This alloy showed a very low extent of oxide spallation and a slow oxidation rate. The adherent oxide thickness calculated from observed weight changes (due to both oxidation and scale loss) was found to be closely similar to the directly measured scale thickness. It is concluded that a previously developed description of cyclic oxidation thermogravimetry is applicable, and that the alloy exhibits excellent performance.
R. Kartono, D. Monceau, D. J. Young, Scripta Materialia

A1363 – Cyclic thermogravimetry of TBC systems

The previously developed cyclic thermogravimetry analysis (CTGA) method is applied to the cyclic oxidation at 1100 °C of ZrO2–Y2O3/NiPtAl or NiCoCrAlYTa/single crystal nickel-base AM3 superalloy TBC systems. Cyclic thermogravimetry with fast heating and cooling and high accuracy in mass measurement allows to measure oxidation kinetics of the bond coating and also to detect and quantify the occurrence of the top coating cracking and spalling. The resulting data could be used later on, for time of life modelling of TBC systems
Aurélie Vande Put, Daniel Monceau, Djar Oquab, Surface & Coatings Technology 202 (2007) 665–669

A1362 – Continuous Thermogravimetry under Cyclic Conditions

Thermogravimetry during cyclic oxidation of metallic alloys is described. A methodology is given in order to determine the Net Mass Gain, the GrossMass Gain, the total mass of spalled oxide, the rate of metal consumption and the average oxide scale thickness as a function of the number of cycles. The fraction of oxide scale which spalls at each cycle can be also calculated, and the parabolic constant can be estimated at each cycle. Two examples are given: the cyclic oxidation of a NiAl single crystal in flowing oxygen at 1150xC, and the cyclic oxidation of alloy P91 at 800xC in laboratory air. Advantages and disadvantages of this technique are discussed in regards to classical interrupted tests in crucibles. Thermogravimetry during cyclic oxidation appears to be a powerful tool in order to model and quantify the cyclic oxidation test which is of great interest in order to qualify the resistance of materials to oxidation in conditions close to their actual use, but a specific aspparatus need to be developed in order to obtain data in an efficient and economical manner. A new apparatus designed for this purpose is described briefly.
D. Monceau and D. Poquillon, Oxidation of Metals, Vol. 61, Nos. 1/2, February 2004

A1366 – Semi-continuous operation of chemical-looping combustion with metal oxides supported on bentonite in an annular fluidized bed reactor

The chemical-looping combustion (CLC) process has an advantage of no energy loss for CO2 separation without NOx formation. This process consists of oxidation and reduction reactors where metal oxides particles are circulating through these two reactors. Nickel oxide supported on bentonite was selected based on their good reactivity, and semi-continuous operation was conducted in an annular fluidized bed reactor. The reaction efficiency is determined by analyzing concentrations of CO and H2 in flue gas and their concentrations are below 10 % at the optimum operating conditions.
Sung Real Son, Sang Done Kim

A1367 – A mechanistic investigation of a calcium-based oxygen carrier for chemical looping combustion

Chemical looping combustion (CLC) has been suggested as an energy-efficient method for the capture of carbon dioxide from combustion. It is indirect combustion by the use of an oxygen carrier, which can be used for CO2 capture in power-generating processes. The possibility of CLC using a calcium-based oxygen carrier is investigated in this paper. In the air reactor air is supplied to oxidize CaS to CaSO4, where oxygen is transferred from air to the oxygen carrier; the reduction of CaSO4 to CaS takes place in the fuel reactor. The exit gas from the fuel reactor is CO2 and H2O. After condensation of water, almost pure CO2 could be obtained. The thermodynamic and kinetic problem of the reduction reactions of CaSO4 with CO and H2 and the oxidization reactions of CaS with O2 is discussed in the paper to investigate the technique possibility. To prevent SO2 release from the process of chemical looping combustion using a calcium-based oxygen carrier, thermochemical CaSO4 reduction and CaS oxidation are discussed. Thermal simulation experiments are carried out using a thermogravimetric analyzer (TGA). The properties of the products are characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffractometry (XRD), and the optimal reaction parameters are evaluated. The effects of reaction temperature, reductive gas mixture, and oxygen partial pressure on the composition of flue gas are discussed. The suitable temperature of the air reactor is between 1050 and 1150 ?C and the optimal temperature of the fuel reactor between 900 and 950 ?C
Laihong Shen, Min Zheng, Jun Xiao, Rui Xiao, Combustion and Flame 154 (2008) 489–506

A1369 – Potential of thermogravimetric analysis coupled with mass spectrometry for the evaluation of kerogen in source rocks

The molecular composition of oil and yield from a source rock depends on the temperature to which the source rock is subjected. However, the yield of oil and gas represents hydrocarbons generated over a range of temperatures. A technique that measures both volatile yields and bulk and molecular compositions during volatile evolution would determine the differential effects of temperature change, thereby giving information on the effect of thermal gradients. Attaching a mass spectrometer to a thermogravimetric analyser assists in this goal since it allows gases to be analysed during petroleum source rock evaluation by pyrolysis. Single ion monitoring allows unambiguous identification of thermal events. It reveals temperature at which water, methane and carbon dioxide evolve. This allows organic and inorganic transitions to be distinguished. Parameters that describe the yields of oil and gas can also be derived from thermogravimetric analysis (TGA) in much the same way as they can for Rock–Eval pyrolysis data and are useful when combined with solid state 13C nuclear magnetic resonance (NMR) spectroscopy and Rock–Eval data for elucidating mineral matter effects
Craig P. Marshall, G.S. Kamali Kannangara, Michael A. Wilson, Jean-Pierre Guerbois, Birgitta Hartung-Kagi, Gwenda Hart, Chemical Geology 184 (2002) 185–194

A1368 – Synthesis and characterization of bimetallic Fe/Mn oxides for chemical looping combustion

Fe-Mn mixed oxides have been prepared by different routes, characterized, and tested with TGA for application as oxygen carriers in the CLC process. These mixed oxides exhibit a lower oxygen transfer capacity than Ni based materials which is also dependant on synthesis method. In-situ XRD analysis was performed with one sample and allowed to clearly demonstrate the reaction pathway, reduction and oxidation reactions occurring stepwise, with little phase coexistence. SEM-EDS analysis on reduced and re-oxidized samples show atom migration occurs on a rather long distance, forming Fe0 and MnO particles during reduction which are oxidized back to (Fe,Mn)2O3.
Arnold Lambert, Céline Delquié, I. Clémençon, Elodie Comte, Véronique Lefebvre, J. Rousseau, B. Durand, Energy Procedia 1 (2009) 375–381

A1373 – A certain symmetry

Different European programs, especially TESTCORR and COTEST have defined experimental conditions for the assessment of oxidation and corrosion on metallic or ceramic samples at high temperature. These tests typically require a sample to be placed in a high-temperature furnace with a controlled atmosphere, and the sample is periodically removed for the measurement of mass variation. However, this method is labor intensive and prone to error. In addition, since the sample is removed from the controlled atmosphere numerous times, contamination and reproducibility cannot be discounted. In order to solve the problems linked to the manipulation of the samples during the test, a modern high-temperature thermogravimetric technique can be used to obtain an automatic and continuous record of the mass variation of the sample throughout the test. With such a technique, the sample always remains in the furnace in a controlled atmosphere at a controlled temperature.
Pierre Le Parlouër, Andre Levchenko, Ceramic Industry, June 2010

A1372 – Statistical quantification and characterization of material properties influencing the reactivity of activated carbons

Activated carbons (ACs) are nanoporous adsorbent widely used to remove organic compounds from air. Due to rather low oxidation temperatures, these materials are prone to ignition which causes safety problems in industrial practice. This study aims at identifying the physical and chemical properties of the carbon materials which control the process of oxidation and ignition. For that purpose, the point of initial oxidation (PIO) and self ignition temperature (SIT) were measured and compared for a wide variety of ACs, produced from diverse raw materials by physical or chemical activation. The set of temperature data was correlated to the physical properties and chemical composition of the materials by using a multiple linear regression approach to point out the most influent variables. These ones were shown to be connected to the organization of the graphitic structure, analysed from high resolution transmission electron microscopy (HRTEM), the presence of the functional oxygen groups on the carbon surface and the mineral content. The analysis enabled to explain the deviations observed between the different types of materials regarding their oxy-reactivity.
Thangavelu Jayabalan, Pascaline Pré, Valérie Héquet, Jean-Noël Rouzaud, Pierre Le Cloirec

A1371 – Water properties in wheat ¯our dough. I: Classical thermogravimetry approach

Thermogravimetric analysis allowed inspection of the behavior of water within a wheat ¯our dough. In such a system water is partitioned between coexisting phases which are none the less far from the true thermodynamic equilibrium. The vaporization rate revealed that water is released in two main steps, the ®rst corresponding to a mere di€usion process, the second being instead related to the desorption of water more tightly bound to the gluten network. It was observed that the overall dough moisture, the extent of mixing, the dough resting time after mixing can modify water partition between phases and the way water is released during the temperature scan. Some e€ect was also recognized in dough samples to which original water soluble proteins had been added
Dimitrios Fessas, Alberto Schiraldi, Food Chemistry 72 (2001) 237-244

A1370 – Description of organic compound vapor-phase sorption by geosorbents: Adequacy of the isotherm approximation

The approximation of isotherms of vapor-phase sorption of organic compounds (OC) is a long-standing problem. It is especially difficult to solve in case of natural heterogeneous sorbents (soils, sediments, aquifers, etc.) since these sorbents contain sites with different sorption activity. The aim of this work was the statistical evaluation of the adequacy of the approximation of isotherms of vapor-phase sorption of OC by geosorbents in water-unsaturated conditions by employing various fitting equations. Vapor sorption isotherms were measured by the static headspace gas-chromatographic analysis method for 27 various organic sorbates (13 hydrocarbons and 5 chlorinated hydrocarbons, 7 oxygenated and 2 nitrogenated OC) on geosorbents (6 soils typical for Middle Russia regions, separate soil layers of 2 dark-gray forest soils, natural zeolitecontaining material and bentonite clay, and two clay-humic complexes). The computer-assisted special sorption database with the corresponding software was created, and on the whole, 103 experimental sorption isotherms (86 isotherms measured and 17 taken from the literature) were used for the approximation. The adequacy of isotherm approximation by different sorption models was compared: Brunauer–Emmett–Teller (BET), modified BET (MBET), Pickett–Dellyes (PD), Guggenheim–Anderson–De Boer (GAB), Aranovich–Donohue (AD), Hinz (HZ) and polynomial (PN) equation. For the comparison of the adequacy of isotherm approximation by different equations, the following three criteria were used: (a) s5%—the average probability of the location of experimental sorption values within the range of 5% of the theoretical curve; (b) two interconnected parameters: R2—the square of correlation coefficient and k—the slope tangent for the linear regression (VE; VT) at various sorbate activities; (c) ¯D —relative sample variance as a characteristics of the optimal ratio between numbers of parameters of the fitting equation and its approximation quality. For the description of the vapor sorption of OC by geosorbents, the new MGAB equation (the modified GAB equation) was suggested. It is characterized by the optimal ratio between the ‘complexity’ of an equation (MGAB is a four-parametrical equation) and its approximation quality (MGAB shows one of the best isotherm approximations). The following rank of the decrease of the adequacy (upon ¯D criterion) of examined fitting equations in relation to the OC sorption isotherm approximation in the whole isotherm range was formed: MGAB>HZ > PD>GAB>AD> PN.
Irina P. Breus, Artem A. Mishchenko, Konstantin A. Potashev, Vladimir A. Breus, Colloids and Surfaces A: Physicochem. Eng. Aspects 276 (2006) 122–133

A1375 – Effect of mechanochemical treatment on petroleum coke–CO2 gasification

The effect of mechanochemical treatment during the grinding of petroleum coke on its gasification by CO2 was studied. An additive derived by drying the black liquor in papermaking industry is adopted in grinding process. Results show that the gasification reactivity of petroleum coke is effectively improved by grinding, and the activation by wet grinding is more noticeable than that by dry grinding. Besides, by wet grinding petroleum coke and additive together, the active metal species in additive are not easily volatilized in gasification, and retain a high catalytic reactivity to the coke–CO2 reaction throughout most of the conversion range. Changes in crystal structure of the petroleum coke induced by mechanochemical treatment is related to its gasification reactivity. In general, the crystalline amorphous phase transition is the tendency of long time mechanical grinding, while a crystal structure re-formation stage is observed after wet grinding of petroleum coke with and without additive for some time. Similar phenomenon has also been found in the reported data, but not given attention. Some discussion is made in the paper, and more work should be undertaken to disclose the mechanism.
Jianhui Zou, Boli Yang, Kaifeng Gong, Shiyong Wu, Zhijie Zhou, Fuchen Wang, Zunhong Yu, Fuel 87 (2008) 622–627

A1374 – Hybrid Mesoporous Materials for Carbon Dioxide Separation

One common method for CO2 separation from mixed gas streams is by absorption in aqueous solutions of alkanolamines4, for example monoethanolamine (MEA) or diethanolamine (DEA). It is widely accepted that CO2 becomes absorbed via the formation of both carbamates and bicarbonates.In this study, solid phase hexagonal mesoporous silicas (HMS) of known porosity (pore diameter) were modified using aminopropyltrimethoxysilane and related compounds to provide very high surface area materials with varied concentrations of surface bound amine and hydroxyl functional groups
Seamus W Delaney, Gregory P Knowles, Alan L Chaffee, Fuel Chemistry Division Preprints 2002, 47(1), 65

A1376 – Surface modification of activated carbons for CO2 capture

The reduction of anthropogenic CO2 emissions to address the consequences of climate change is a matter of concern for all developed countries. In the short term, one of the most viable options for reducing carbon emissions is to capture and store CO2 at large stationary sources. Adsorption with solid sorbents is one of the most promising options. In this work, two series of materials were prepared from two commercial activated carbons, C and R, by heat treatment with gaseous ammonia at temperatures in the 200–800 8C range. The aim was to improve the selectivity and capacity of the sorbents to capture CO2, by introducing basic nitrogen-functionalities into the carbons. The sorbents were characterised in terms of texture and chemical composition. Their surface chemistry was studied through temperature programmed desorption tests and X-ray photoelectron spectroscopy. The capture performance of the carbons was evaluated by using a thermogravimetric analyser to record mass uptakes by the samples when exposed to a CO2 atmosphere.
C. Pevida, M.G. Plaza, B. Arias, J. Fermoso, F. Rubiera, J.J. Pis, Applied Surface Science 254 (2008) 7165–7172

A1378 – Development of low-cost biomass-based adsorbents for postcombustion CO2 capture

In this work a series of carbon adsorbents were prepared from a low-cost biomass residue, olive stones. Two different approaches were studied: activation with CO2 and heat treatment with gaseous ammonia. The results showed that both methods are suitable for the production of adsorbents with a high CO2 adsorption capacity, and their potential application in VSA or TSA systems for postcombustion CO2 capture. It was found that the presence of nitrogen functionalities enhances CO2 adsorption capacity, especially at low partial pressures.
M.G. Plaza, C. Pevida, B. Arias, J. Fermoso, M.D. Casal, C.F. Martín, F. Rubiera, J.J. Pis, Fuel 88 (2009) 2442–2447

A1377 – CO2 capture by adsorption with nitrogen enriched carbons

The success of CO2 capture with solid sorbents is dependent on the development of a low cost sorbent with high CO2 selectivity and adsorption capacity. Immobilised amines are expected to offer the benefits of liquid amines in the typical absorption process, with the added advantages that solids are easy to handle and that they do not give rise to corrosion problems. In this work, different alkylamines were evaluated as a potential source of basic sites for CO2 capture, and a commercial activated carbon was used as a preliminary support in order to study the effect of the impregnation. The amine coating increased the basicity and nitrogen content of the carbon. However, it drastically reduced the microporous volume of the activated carbon, which is chiefly responsible for CO2 physisorption, thus decreasing the capacity of raw carbon at room temperature.
M.G. Plaza, C. Pevida, A. Arenillas, F. Rubiera, J.J. Pis, Fuel 86 (2007) 2204–2212

A1382 – Kinetic models comparison for steam gasification of different nature fuel chars

The reactivity in steam of five different types of solid fuels (two coals, two types of biomass and a petcoke) has been studied. The fuel chars were obtained by pyrolysis in a fixed-bed reactor at a temperature of 1373 K for 30 min. The gasification tests were carried out by thermogravimetric analysis (TG) at different temperatures and steam concentrations. The reactivity study was conducted in the kinetically controlled regime and three representative gas-solid models, volumetric model (VM), grain model (GM) and random pore model (RPM), were applied in order to describe the reactive behaviour of the chars during steam gasification. The kinetic parameters of these models were derived and the ability of the models to predict conversion and char reactivity during gasification was assessed. The best model for describing the behaviour of the samples was the RPM. The effect of the partial pressure of steam in gasification was studied, and the reaction order with respect to steam was determined. The reactivity of the chars was compared by means of a reactivity index. Biomass exhibited a higher reactivity than coals and petcoke. However, significant differences in reactivity were observed between the two types of biomass used, which could be due to catalytic effects.
J. Fermoso, B. Arias, C. Pevida, M. G. Plaza, F. Rubiera, J. J. Pis, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 3, 779–786

A1381 – Uncertainty Determination Methodology, Sampling Maps Generation and Trend Studies with Biomass Thermogravimetric Analysis

This paper investigates a method for the determination of the maximum sampling error and confidence intervals of thermal properties obtained from thermogravimetric analysis (TG analysis) for several lignocellulosic materials (ground olive stone, almond shell, pine pellets and oak pellets), completing previous work of the same authors. A comparison has been made between results of TG analysis and prompt analysis. Levels of uncertainty and errors were obtained, demonstrating that properties evaluated by TG analysis were representative of the overall fuel composition, and no correlation between prompt and TG analysis exists. Additionally, a study of trends and time correlations is indicated. These results are particularly interesting for biomass energy applications.
Jose A. Pazó, Enrique Granada, Ángeles Saavedra, Pablo Eguía, Joaquín Collazo, Int. J. Mol. Sci. 2010, 11, 3660-3674

A1380 – Behavior of Different Calcium-Based Sorbents in a Calcination/Carbonation Cycle for CO2 Capture

The aim of this work is to identify the characteristics of natural carbonates which upon calcination generate an optimum material for use as a CO2-capturing sorbent in large-scale industrial CO2-producing sources. Nine different naturally occurring Ca/Mg carbonates were selected for this study. The carbonates were fully characterized by a variety of analytical techniques including atomic absorption and redox volumetry, for the chemical characterization of the carbonates, and optical and scanning electron microscopy (SEM), X-ray diffraction, and Fourier transform infrared spectroscopy, to determine their crystallinity, morphology, and the presence of impurities. They were then subjected to successive (up to 100) calcination/recarbonation cycles, and their conversion decay curves were interpreted on the basis of the physical and chemical characteristics of the parent carbonates. The textural development of the sorbents during cycling was studied by Hg porosimetry and SEM. Hardness tests were also conducted on selected samples. It was concluded that both carbonate purity and crystallinity are important parameters in determining the performance of the sorbents. The activity of all the sorbents tested turned out to be highly dependent on the pore structure of the calcines and their variation during cycling. In turn, the natural tendency of the sorbents to develop low surface areas (poor efficiencies) during cycling seems to be enhanced by the presence of moderate amounts of Mg.
Diego Alvarez,Miguel Pena, Angeles G. Borrego, Energy & Fuels 2007, 21, 1534-1542

A1379 – Ammoxidation of carbon materials for CO2 capture

Ammoxidised carbons were produced from three different starting materials: an activated carbon obtained from wood by chemical activation using the phosphoric acid process, a steam activated peatbased carbon, and a char obtained from a lowcost biomass feedstock, olive stones. Nitrogen was successfully incorporated into the carbon matrix of the different materials, the amount of nitrogen uptake being proportional to the oxygen content of the precursor. At room temperature the CO2 capture capacity of the samples was found to be related to the narrow micropore volume, while at 100 ?C other factors such as surface basicity took on more relevance. At 100 ?C all the ammoxidised samples presented an enhancement in CO2 uptake compared to the parent carbons.
M.G. Plaza, F. Rubiera, J.J. Pis, C. Pevida, Applied Surface Science 256 (2010) 6843–6849

A1385 – Combustion and pyrolysis characteristics of Tunçbilek lignite

In this study, thermal characteristics and kinetic parameters of cleaned Tunçbilek lignite were determined by using a Setaram Labsys DTA/TG/DSC thermal analysis system both for combustion and pyrolysis reactions. Experiments were performed at a heating rate of 10°C min–1 under reactive (air) and inert (nitrogen) gases up to 1000°C. Non-isothermal heating conditions were applied and reaction intervals were determined for combustion and pyrolysis reactions from obtained curves. The combustion properties were evaluation by considering the burning profile of the lignite sample. Burning temperatures and rate of combustion were determined from TG/DTG curves. Calorific value of the lignite sample was measured by DSC curve and compared with the adiabatic bomb calorimeter result. In addition to investigation of the combustion properties, pyrolysis characteristics of the lignite sample were investigated based on TG/DTG/DSC curves. Activation energy (E) and pre-exponential factor (A) were calculated from the TG data by using a Coats–Redfern kinetic model both for combustion and pyrolysis reactions of cleaned Tunçbilek lignite.
Y. Elbeyli, S. Piskin, Journal of Thermal Analysis and Calorimetry, Vol. 83 (2006) 3, 721–726

A1384 – Influence of some minerals on the cellulose thermal degradation mechanisms. Thermogravimetic and pyrolysis-mass spectrometry studies

The influence of different inorganic salts (MgCl2, ZnCl2, NiCl2 and H2PtCl6) on the primary mechanisms of cellulose thermal degradation has been conducted by using thermogravimetric (TG-DTG) and pyrolysis-mass spectrometry (Py-MS) analysis at low heating rate (10°C min–1 ) from ambient temperature to 500°C. The results clearly demonstrate that the used salts influence the primary degradation mechanisms. Furthermore, we can assume that some inorganic salts could be considered as specific catalysts and some others as inhibitors. MgCl2 promotes selectively initial low temperature dehydration as observed both by TG and Py-MS. ZnCl2 strongly changes the thermal behaviour of impregnated sample. The maximum mass loss rate temperature is shifted to lower temperature and on the basis of our results we can conclude that ZnCl2 acts as catalyst in all primary degradation mechanisms. NiCl2 and H2PtCl6 do not modify significantly the cellulose thermal behaviour but change the composition of both produced gases and liquids suggesting that these minerals catalyse some secondary reactions.
Anissa Khelfa, Gisèle Finqueneisel, M. Auber, J. V. Weber, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 3, 795–799

A1383 – Thermal degradation of lignins isolated from wood

The lignin preparations isolated from pine and beech wood were subjected to a thermogravimetric analysis (TG). The lignin preparations were also used to obtain samples of different degrees of thermal degradation characterised by mass-losses in the interval from 10 to 60% of their initial mass. These samples were subjected to elementary analysis and the content of methoxy groups. It was observed that the content of these functional groups declined in products in which the degree of thermal degradation exceeded 30%, which corresponds to temperatures over 450°C.
M. Bartkowiak, R. Zakrzewski, Journal of Thermal Analysis and Calorimetry, Vol. 77 (2004) 295–304

A1387 – Production of Calcium Carbide from Fine Biochars

Carbon is the most abundant source of energy and chemicals on the earth. Biomass produced from photon-activated conversion of atmospheric CO2, and biomass fossils such as coal and petroleum are all carbon-rich sources. In around only one century of heavy industrial use of petroleum, this hydrocarbon source has already depleted to a point of a widespread concern over its scarcity in the decades to follow.[1] Biocarbon, also known as biochar, can be readily produced from a vast sustainable supply of lignocellulosic biomass through pyrolysis.[2] It is often in fine form and characterized by low mechanical strength and high activity in comparison to coal-derived chars. The ability to use biochar for the production of chemicals with high energy efficiency will largely alleviate our dependence on shrinking petroleum feedstock. Herein, we show reaction of fine biochars with fine CaO for the production of CaC2, an important starting material for production of many commodity chemicals. The process offers the potential to redirect the carbon conversion pathway.
Guodong Li, Qingya Liu, Zhenyu Liu, Z. Conrad Zhang, Chengyue Li, Weize Wu, Angew. Chem. Int. Ed. 2010, 49, 8480 –8483

A1386 – Pyrolysis gases released during the thermal decomposition of three Mediterranean species

The aim of this work is to improve the understanding of the pyrolysis of species involved in fires of Mediterranean vegetation and to propose a description and a quantification of the gases released during their degradation. TG–MS and FTIR analyses were performed with three Mediterranean species: Cistus creticus, Myrtus communis and Genista corsica. The pyrolysis behaviour of these plants was studied. TG curves show differences between plants. Then, the evolution of the pyrolysis gases was investigated. The main gases released were H2O, CO2, CO, CH4 and H2. The use of FTIR and mass spectrometry allowed identifying the different stages of the gas formation. The last part of the study was devoted to the gas quantification from the results obtained with the TG–MS. The results showed variations of the gas composition in function to the temperature and of the plant species
Virginie Tihay, Philippe Gillard, Journal of Analytical and Applied Pyrolysis 88 (2010) 168–174

A1392 – Thermochemical study of clathrate-forming host-guest reaction for the detection of organic solvent vapours

The clathrate formation of a cristalline host with acetone and methanol vapours has been studied by means of simultaneous TG-DSC measurements in isothermal and sacnning mode of operation.
J. Seidel, G. Wolf, E. Weber, Thermochimica Acta 271 (1996) 141-148

A1391 – Water properties in wheat flour dough II: classical and knudsen thermogravimetry approach

Thermo-Gravimetric Analysis (TGA) investigations suggest that water in a wheat flour dough is partitioned in various states related to the different disperse phases of the system. Classical TGA results indicate the gross water partition at the macroscopic level, while Knudsen TGA investigations, that allow evaluation of the relative humidity of the dough at room temperature, suggest the involvement of water in the structure of the dough at a supra-molecular level. The overall moisture content, the mechanical stresses and the presence of extra non-starch polysaccharides and/or soluble proteins, can affect this partition, either promoting water displacements across the inter-phases, or modifying the supra-molecular structure of the system. The investigations, extended to bread crumb during ageing, indicate that water undergoes displacements and forms stronger links with the components of the aged crumb with a kinetic law that can be influenced by the presence of extra non-starch polysaccharides.
Dimitrios Fessas, Alberto Schiraldi, Food Chemistry 90 (2005) 61–68

A1390 – Equilibrium desorption isotherms of water, ethanol, ethyl acetate, and toluene on a sodium smectite clay

Desorption isotherms for water, ethanol, ethyl acetate and toluene from a sodium smectite clay have been determined by both dynamic vapor sorption (DVS) measurements and Knudsen thermogravimetry (KTGA), at the exception of toluene that was measured only by the DVS method. The results obtained using these two methods were in satisfactory agreement, providing reliable insight into the desorption process, with certain lack of precision for ethyl acetate. The observed desorption behaviour suggests a liquid like phase at high volatile load, and a sorbed state in which molecules interact with the counter ions, at low volatile contents. However, the isotherms for water determinedat various temperatures nearly superposed when plotted as a function of water activity, indicating the strength of the interactions in the clay–water system to remain of the same order of magnitude as that in bulk water, consistent with previous ab initio calculations.
Pascal Clausen, Marco Signorelli, Andreas Schreiber,,Eric Hughes,,Christopher J. G. Plummer, Dimitrios Fessas,,Alberto Schiraldi, Jan-Anders E. Manson, J Therm Anal Calorim, 2009

A1389 – Classical and Knudsen thermogravimetry to check states and displacements of water in food systems

Water states and displacements can be investigated with thermogravimetry (TG) either in its classical or in the Knudsen version (where standard pans are replaced with Knudsen cells). The case of wheat flour dough is considered in various steps of bread making, namely, mixing, proofing, baking, staling. The split of DTG signals into various components (gaussian functions) support the assumption that the overall dough water is partitioned into various fractions. Few comments are devoted to water displacements during freezing.
A. Schiraldi, D. Fessas, Journal of Thermal Analysis and Calorimetry, Vol. 71 (2003) 221–231

A1388 – Carbon dioxide sequestration in municipal solid waste incinerator (MSWI) bottom ash

During bottom ash weathering, carbonation under atmospheric conditions induces physico-chemical evolutions leading to the pacification of the material. Fresh bottom ash samples were subjected to an accelerated carbonation using pure CO2. The aim of this work was to quantify the volume of CO2 that could be sequestrated with a view to reduce greenhouse gas emissions and investigate the possibility of upgrading some specific properties of the material with accelerated carbonation. Carbonation was performed by putting 4 mm-sieved samples in a CO2 chamber. The CO2 pressure and the humidity of the samples were varied to optimize the reaction parameters. Unsieved material was also tested. Calcite formation resulting from accelerated carbonation was investigated by thermogravimetry and differential scanning calorimetry (TG/DSC) and metal leaching tests were performed. The volume of sequestrated CO2 was on average 12.5 L/kg dry matter (DM) for unsieved material and 24 L/kg DM for 4 mm-sieved samples. An ash humidity of 15% appeared to give the best results. The reaction was drastically accelerated at high pressure but it did not increase the volume of sequestrated CO2. Accelerated carbonation, like the natural phenomenon, reduces the dangerous nature of the material. It decreases the pH from 11.8 to 8.2 and causes Pb, Cr and Cd leaching to decrease. This process could reduce incinerator CO2 emissions by 0.5–1%.
Eva Rendek, Gaëlle Ducom, Patrick Germain, Journal of Hazardous Materials B128 (2006) 73–79

A1395 – Mechanism of thermal decomposition of a pesticide for safety concerns: Case of Mancozeb

Thermal decomposition under both air and inert atmospheres of a commercial Mancozeb product was investigated through thermogravimetric analysis and laboratory scale thermal treatment from 20 ?C to 950 ?C, with analysis of gaseous and solid products. The aim of this study is the understanding of the thermal degradation mechanisms of a pesticide under different atmospheres and the chemical identification of the solid and gaseous pollutants which can be emitted during warehouse fires and which can constitute a threat for health and environment. Pyrolysis of Mancozeb takes place between 20 ?C and 950 ?C and lead essentially to CS2 and H2S emissions with formation at 950 ?C of MnS and ZnS. Thermal oxidation of Mancozeb under air occurs between 150 ?C and 950 ?C with formation of CO, CO2 and sulphur gases (CS2 and SO2). The first step (155–226 ?C) is the loss of CS2 and the formation of ethylene thiourea, ZnS and MnS. The metallic sulphides are oxidized in ZnO and MnSO4 between 226 ?C and 650 ?C (steps 2 and 3). MnSO4 is then oxidized in Mn3O4 during the last step (step 4) between 650 ?C and 950 ?C. At 950 ?C, carbon recovery is close to 95%. Sulphur recovery is close to 98% with an equal partition between SO2 and CS2.
N. Giroud, S. Dorge, G. Trouvé, Journal of Hazardous Materials 184 (2010) 6–15

A1394 – Effects of Carbon on the Rates of Reduction in Iron-based Chemical Looping

The availability and low cost of coal and natural gas make them favorable fuels for energy conversion processes. However, the combustion of carbon-based fuels inevitably results in production of CO2. To avert climate change and comply with likely future regulations, the CO2 byproduct must be efficiently captured. Unfortunately, existing carbon capture methods result in up to a 2-fold increase in capital and operating costs. Chemical looping technologies are a group of processes that can separate the CO2 stream in-situ by utilizing iron oxide composite particles as oxygen carriers. The process allows for efficient total carbon capture, therefore ensuring a sustainable future for carbon-fueled hydrogen production. The objective of this study was to explore the effect the presence of carbon has on the reduction rates of 11 iron oxide-based particle compositions. The 11 particles have been isolated from previous recyclability tests of 126 different particle compositions. Faster reduction rates allows for a reduction in capital costs in scale-up design and a smaller oxygen carrier requirement, both of which are required to ensure the success of CDCL. The experiments use TGA to determine the rate of reduction at 900°C and 1 atmosphere in a methane (CH4) environment. T-7, T-2 and T-3 compositions have the fastest rate of reduction. The addition of CeO2 and ZrO2 based promoters are shown to enhance these rates even more and reduce the rate of carbon deposition. The use of promoters needs to be explored more extensively to find the optimal composition for an acceptable trade-off in cost for performance.
Sean H Lee, Thesis, The Ohio State University, 2010

A1393 – Thermogravimetry-evolved gas analysis–mass spectrometry system for materials research

Thermal analysis is a widely used analytical technique for materials research. However, thermal analysis with simultaneous evolved gas analysis describes the thermal event more precisely and completely. Among various gas analytical techniques, mass spectrometry has many advantages. Hence, an ultra high vacuum (UHV) compatible mass spectrometry based evolved gas analysis (EGA–MS) system has been developed. This system consists of a measurement chamber housing a mass spectrometer, spinning rotor gauge and vacuum gauges coupled to a high vacuum, high temperature reaction chamber. A commercial thermogravimetric analyser (TGA: TG + DTA) is interfaced to it. Additional mass flow based gas/vapour delivery system and calibration gas inlets have been added to make it a versatile TGA–EGA–MS facility. This system which gives complete information on weight change, heat change, nature and content of evolved gases is being used for (i) temperature programmed decomposition (TPD), (ii) synthesis of nanocrystalline materials, (iii) gas–solid interactions and (iv) analysis of gas mixtures. The TPD of various inorganic oxyanion solids are studied and reaction intermediates/products are analysed off-line. The dynamic operating conditions are found to yield nanocrystalline products in many cases. This paper essentially describes design features involved in coupling the existing EGA–MS system to TGA, associated fluid handling systems, the system calibration procedures and results on temperature programmed decomposition. In addition, synthesis of a few nanocrystalline oxides by vacuum thermal decomposition, gas analysis and potential use of this facility as controlled atmosphere exposure facility for studying gas–solid interactions are also described.
M. Kamruddin, P. K. Ajikumar, S. Dash, A. K. Tyagi, Baldev Raj, Bull. Mater. Sci., Vol. 26, No. 4, June 2003, pp. 449–460

A1397 – High Temperature Oxidation Behavior of the AISI 430A and AISI 430E Stainless Steels in Ar/H2/H2O Atmosphere

The high temperature oxidation behavior of two ferritic stainless steels type AISI 430A and AISI 430E is examined at low oxygen pressure and high temperatures. The AISI 430A steel is ferritic up to 860 °C. Above this temperature, this steel is bi-phased: presence of austenite and ferrite phases. The 430E steel is stabilized with Nb, and is ferritic at all temperatures. The oxidation experiments were performed in a thermobalance SETARAM TGDTA 92, in the range of 850-950 °C, in Ar/H2/H2O atmosphere, under oxygen partial pressures lower than 1.3 x 10–18 atm. The microstructure and the composition of the oxide scales were analysed by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). Different oxidation behaviors in AISI 430A and AISI 430E stainless steels were observed. At 850 °C, the oxidation of the 430A steel is greater than that of the 430E steel, but above 900 °C the oxidation of the 430A steels is lower than that of the 430E steel. The oxidationrate of the 430A steel shows low dependence on temperature, while the oxidation of the 430E follows an Arrhenius law, with an activation energy corresponding to the chromia scale growth.
Maria de Fátima Salgado, Antônio Claret Soares Sabioni, Anne-Marie Huntz, Édson Hugo Rossi, Materials Research, Vol. 11, No. 2, 227-232, 2008

A1396 – Critical conditions for ignition of metal particles in a condensed explosive

The critical conditions for the ignition of spherical magnesium particles dispersed during the detonation of a heterogeneous charge consisting of a packed bed of particles saturated with a liquid explosive have been investigated experimentally and numerically. For spherical charges, the experiments demonstrate that there exists a critical particle size (between 85 and 240 ?m) for prompt particle ignition for charges with a diameter of 12.3 cm or less. For a given particle size, there also exists a critical charge diameter for prompt particle ignition, where the rate of particle combustion is sufficiently rapid to augment the strength of the blast wave. Calculations with a multiphase model suggest that the critical charge diameter for ignition will scale with particle size according to dcrit ~ dparticle 1.75, consistent with the experimental results. The critical charge diameter for prompt particle ignition has also been observed in cylindrical charges.
David L. Frost, Fan Zhang, Stephen B. Murray, Susan McCahan,

A1398 – Effect of the gas mixture composition on high-temperature behavior of magnetron sputtered Si–B–C–N coatings

The effect of the gas mixture composition on the high-temperature behavior of amorphous Si–B–C–N coatings was systematically investigated up to 1700 °C in a flowing air and inert gases (He and Ar). The Si–B–C–N coatings were deposited by reactive dc magnetron co-sputtering using a single B4C–Si target in two nitrogen–argon gas mixtures (50% N2+50% Ar or 25% N2+75% Ar). A fixed 75% Si fraction in the target erosion area, an rf induced negative substrate bias voltage of ?100 V, a substrate temperature of 350 °C and a total pressure of 0.5 Pa were held constant in depositions. The high-temperature behavior of the coatings, including their oxidation resistance in air and thermal stability in inert gases, was characterized by means of high-resolution thermogravimetry, differential scanning calorimetry, X-ray diffraction, Rutherford backscattering spectrometry and elastic recoil detection analysis. It was found that the Ar fraction in the gas mixture determines an important N/ (Si+B+C) concentration ratio in the coatings, and hence their hightemperature behavior. The coating prepared with a 50% Ar fraction exhibits extremely high oxidation resistance (?m=0) up to 1400 °C and very high oxidation resistance (?mb0.02 mg/cm2) up to 1600 °C in air, and extremely high thermal stability up to 1600 °C in inert gases. The stability of the coating prepared with a 75% Ar fraction is very high up to the onset (at about 1250 °C) of crystallization of its initial amorphous structure.
J. ?apek, S. H?eben, P. Zeman, J. Vl?ek, R. ?erstvý, J. Houška, Surface & Coatings Technology 203 (2008) 466–469

A1399 – Metal sulfate water-splitting thermochemical hydrogen production cycles

A compilation of 350 thermochemical cycles to split water and the subsequent assessment of these cycles has pointed to several metal sulfate cycle as viable candidate cycles with high thermal efficiency. However, studies of the hydrogen generation step in two of the cycles showed alternate side reactions that make this class of metal sulfate cycles a poor candidate for further study.
Barry W. McQuillan, Gottfried E. Besenbruch, Lloyd E. Brown, Roger A. Rennels, Bunsen Y. Wong,

A1400 – Nano structure et propriétés de revêtements d’alumine obtenus par dépôt chimique en phase vapeur à partir d’isopropoxyde d’aluminium

Des revêtements d’alumine ont été préparés par la technique MOCVD, en utilisant le tri-iso-propoxyde d’aluminium comme précurseur, sur des substrats d’acier inoxydable, de silicium et de titane, à des températures modérées comprises entre 350°C et 700°C. Ces films ont été soumis à diverses techniques d’analyse et de caractérisation (EDS, EMPA, ERDA-RBS, DRX, MEB, MET, FTIR, ATG, tests de corrosion). La composition des dépôts préparés par simple pyrolyse du précurseur transporté par de l’azote sec dépend de la température : à 350°C, le dépôt est constitué d’AlOOH amorphe ; au-dessus de 415°C, il est constitué d’alumine Al2O3, amorphe ou nanocristallin suivant la température ; entre 350°C et 415°C le dépôt se comporte comme un mélange des deux espèces. Par contre, en ajoutant de la vapeur d’eau dans la phase vapeur, on obtient uniquement des dépôts d’alumine Al2O3 amorphe ou nanocristalline, sur tout le domaine de température étudié. Des revêtements déposés en présence de vapeur d’eau, à différentes températures, sur des disques de Ti 6242, ont été testés comme couches protectrices contre la corrosion. On constate dans tous les cas une amélioration de la résistance à la corrosion, le revêtement déposé à 480°C se distinguant cependant très nettement des autres.
C. Vahlas, M.-M. Sovar, A. Gleizes, M. Raciulete, G. Boisier, N. Pébère, D. Samélor, MATERIAUX 2006 13-17 Novembre 2006 – Dijon, France

A1402 – Adsorbent materials from paper industry waste materials and their use in Cu(II) removal from water

This paper deals with the removal of Cu2+ from water using adsorbent materials prepared from paper industry waste materials (one de-inking paper sludge and other sludge from virgin pulp mill).
A. Mendez, S. Barriga, J.M. Figalgo, G. Gasco,

A1401 – Mesure en temps réel de composés organiques volatils émis par la thermodégradation d’un matériau au moyen d’un couplage associant un analyseur thermogravimétrique avec un spectromètre de masse haute résolution (FT-ICR)

Cet article présente un nouveau couplage pour l’analyse de matériaux organiques. Celui-ci associe un analyseur thermogravimétrique avec un spectromètre de masse haute résolution de technologie FTICR (Fourier Transform Ion Cyclotron Resonance). Il présente l’avantage de permettre l’identification et la quantification simultanées et en temps réel (1 à 3 secondes) d’une grande variété de composés. La technique ne nécessite pas d’étape de séparation ou de préparation de l’échantillon. Pour cela des méthodes d’ionisation chimique sont exploitées, associées à la haute résolution en masse qui permet d’obtenir la formule moléculaire brute des composés. Après une introduction à la technique mise en oeuvre, nous illustrerons par quelques exemples l’intérêt de ce nouveau couplage pour la compréhension des mécanismes de dégradation ou encore l’analyse d’échantillons complexes.
Michel Heninger, Julien Le Provost, Xavier Colin, Pierre Le Parlouër, Christine Mayoux, Nicolas Bouton, Hélène Mestdagh, SPECTRA ANALYSE n° 274 • Juin - Juillet 2010

A1405 – TG-DTA study of melamine-urea-formaldehyde resins

The thermal behaviour of MUF resins from different suppliers with different content of melamine was studied, along with the 13C NMR spectroscopic analysis of resin structure and the testing of particleboards in current production at Estonian PB factory P¬rnu Plaaditehas AS. The chemical structure of resins from DMSO-d6 solutions was analysed by 13C NMR spectroscopy on a Bruker AMX500 NMR spectrometer. The melamine level in different MUF resins is compared by the ratios of carbonyl carbon of urea and triazine carbon of melamine in 13C NMR spectra. Curing behaviour of MUF resins was studied by simultaneous TG-DTA techniques on the Labsysä instrument Setaram. The shape of DTA curves characterisises the resin synthesis procedure by the extent of polymerisation of UF and MF components and is in accordance with structural data.
K. Siimer, P. Christjanson, T. Kaljuvee, T. Pehk, I. Lasn, I. Saks, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 1, 19–27

A1404 – Thermal behaviour of melamine-modified urea–formaldehyde resins

Thermal behaviour of industrial UF resins modified by low level of melamine was followed by TG-DTA technique on the labsysTM instrument Setaram together with the 13C NMR analysis of resin structure and testing boards in current production at Estonian particleboard factory Pa¨rnu Plaaditehas AS. DTA curve of UF resin which has been cocondensed during synthesis with even low level of melamine shows the shift of condensation exotherm and water evaporation endotherm to considerable higher temperatures. The effect of melamine monomer introduced to UF resin just before curing was compared. The effect of addition of urea as formaldehyde scavenger was studied.
Kadri Siimer, Tiit Kaljuvee, Tönis Pehk, Ilmar Lasn, J Therm Anal Calorim (2010) 99, 755–762

A1403 – Thermal stability of new complexes bearing both acrylate and aliphatic amine as ligands

This paper reports the investigation of the thermal stability of a series of new complexes with mixed ligands of the type [M(en)(C3H3O2)2]×nH2O ((1) M=Ni, n=2; (2) M=Cu, n=0; (3) M=Zn, n=2; en=ethylenediamine and (C3H3O2)=acrylate anion). The thermal behaviour steps were investigated in a nitrogen flow. The thermal transformations are complex processes according to TG and DTA curves including dehydration, ethylenediamine elimination as well as acrylate thermolysis. The final products of decomposition are the most stable metal oxides except for complex (2) that generates metallic copper.
Mihaela Badea, Rodica Olar, Dana Marinescu, Gina Vasile, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 1, 205–208

A1407 – Temperature-induced changes in crystal lattice of bioaragonite of tapes decussatus linnaeus (mollusca bivalvia)

The characteristics of bioaragonite of shells of recent T. decussatus during heating were studied by the means of TG-DTA-EGA (FTIR), XRD, XRF and FTIR. The mass loss recorded up to 2.5% appeared with the higher rates at 110–150, 200–250, 295–300, and 390–415°C at heating of 10°C min–1 up to 500°C. IR analysis of the evolved gases revealed the emission of water and CO2. The lattice constants tend to change with anisotropy character (parameters a and c diminish whilst b tends to grows) and with an overall contraction of cell volume (from 227.36 to 226.84 ?3) during heating was established. The peculiarity of bioaragonite was explained by substitution of H2O and sulphate ion into the lattice. In spite of those substitutions, bioaragonite reveals an orthorhombic structure, which is preserved during the changes up to calcite formation above 380°C.
J. Nemliher, K. Tonsuaadu, T. Kallaste, Journal of Thermal Analysis and Calorimetry, Vol. 97 (2009) 1, 27–32

A1406 – Thermal behaviour of hydroxymethyl compounds as models for adhesive resins

Urea–formaldehyde (UF) and phenol–formaldehyde (PF) resins are the most widely used wood adhesives. The first stage in resin manufacturing is the formation of methylol derivatives which polycondensation leads to building the tridimensional network. Understanding the behaviour of methylol compounds in curing provides useful information for developing appropriate resin structures. Thermal behaviour of N,N0-dihydroxymethylurea, 2- and 4-hydroxymethylphenols, urea and phenol as model compounds for UF, PF and phenol–urea–formaldehyde (PUF) resins was followed by TG-DTA method. The measurements were carried out by the labsys instrument Setaram at 30–450 °C in nitrogen flow. The characteristic signals for model compounds and for some reaction mixtures were measured by high resolution 13C NMR spectroscopy.
K. Siimer, P. Christjanson, T. Kaljuvee, T. Pehk, I. Saks, J Therm Anal Calorim (2009) 97,459–466

A1408 – Thermal behaviour of ammonium nitrate prills coated with limestone and dolomite powder

The thermal behaviour of ammonium nitrate (AN) and its prills coated with limestone and dolomite powder was studied on the basis of commercial fertilizergrade AN and six Estonian limestone and dolomite samples. Coating of AN prills was carried out on a plate granulator and a saturated solution of AN was used as a binding agent. The mass of AN prills and coating material was calculated based on the mole ratio of AN/(CaO ? MgO) = 2:1. Thermal behaviour of AN and its coated prills was studied using combined TG-DTA-FTIR equipment. The experiments were carried out under dynamic heating conditions up to 900 °C at the heating rate of 10 °C min-1 and for calculation of kinetic parameters, additionally, at 2, 5 and 20 °C min-1 in a stream of dry air. A model-free kinetic analysis approach based on the differential isoconversional method of Friedman was used to calculate the kinetic parameters. The results of TG-DTA- FTIR analyses and the variation of the value of activation energy E along the reaction progress a indicate the complex character of the decomposition of neat AN as well as of the interactions occurring at thermal treatment of AN prills coated with limestone and dolomite powder.
I. Rudjak, T. Kaljuvee, A. Trikkel, V. Mikli, J Therm Anal Calorim (2010) 99, 749–754

A1409 – Heating rate effect on the thermal behavior of ammonium nitrate and its blends with limestone and dolomite

The effect of heating rate on the thermal behavior of ammonium nitrate (AN) and on the kinetic parameters of decomposition of AN and its blends with limestone and dolomite was studied on the basis of commercial fertilizer-grade AN and several Estonian limestone and dolomite samples. Experiments were carried out under dynamic heating conditions up to 900 °C at heating rates of 2, 5, 10 and 20 °C min-1 in a stream of dry air using Setaram Labsys 2000 equipment. For calculation of kinetic parameters, the TG data were processed by differential isoconversional method of Friedman. The variation of the value of activation energy E along the reaction progress a showed a complex character of decomposition of AN—interaction of AN with limestone and dolomite additives with the formation of nitrates as well as decomposition of these nitrates at higher temperatures.
T. Kaljuvee, I. Rudjak, E. Edro, A. Trikkel, J Therm Anal Calorim (2009) 97, 215–221

A1412 – Thermal analysis of Al–Cu–Mg–Si alloy with Ag/Zr additions

Heat-treatable aluminium alloys are widely used for structural applications. Their strength is obtained through age hardening phenomena, that are sensitive to microalloying.In the present paper the results of thermal analyses on the ageing behaviour of an Al–Cu–Mg–Si alloy with silver and zirconium additions are presented. Specimens were water quenched after solution heat treatment, then aged at 453 K and a hardness-versus-time plot was drawn. Samples representative of different ageing conditions were subjected to DSC scans. Peaks were identified taking into account and Q phases precipitation sequences. Solution treated samples showed GP/?''/?'/Q sequence, while in peak aged condition GP and ?'' precipitation peaks disappeared and a reduction of peak area was observed, witnessing the concurrent presence of ?'' and ?' phases at peak hardness condition. Experimental data were compared with results from analogous investigations performed on a conventional commercial Al–Cu–Mg–Si alloy.
Paola Bassani, E. Gariboldi, D. Ripamonti, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 1, 29–35

A1411 – Calorimetric analyes on aged Al–4.4Cu–0.5Mg–0.9Si–0.8Mn alloy (AA2014 grade)

An Al–4.4Cu–0.5Mg–0.9Si–0.8Mn alloy (IADS 2014 grade) in the solution annealed and peak aged condition was exposed at 170°C for relatively long times (up to about 1800 h) in order to check the stability of the alloy. The investigated aging temperature was in the frame of a research on the long-term mechanical behaviour of such alloy. Microstructure evolution was monitored via calorimetric analyses, metallographic inspections and hardness measurements. Further, X-ray analyses were carried out on selected samples. The attention was focused on differential scanning calorimetry performed at different scanning rates, with the aim of evaluating the kinetics of the precipitation phenomena. Notwithstanding the wide industrial diffusion of this alloy, literature survey showed that there is not a consensus view on the precipitation sequences and on calorimetric peak identification. The present results show the progressive evolution of calorimetric peaks, corresponding to that of strengthening particles towardsmore stable phases, proved by the disappearance of exothermic peaks. Activation energy from Kissinger kinetic analysis in the case of aged samples provided scattered values that could be reasonably attributed to an overlapping of transformation peaks. Moreover, in these samples transformations partially occurred before DSC scans, providing non-constant transformation fraction at signal peak temperatures and resulting in different activation energies.
Paola Bassani, E. Gariboldi, G. Vimercati, Journal of Thermal Analysis and Calorimetry, Vol. 87 (2007) 1, 247–253

A1410 – CO2 and SO2 uptake by oil shale ashes. Effect of pre-treatment on kinetics

In the present research, CO2 and SO2 binding ability of different oil shale ashes and the effect of pretreatment (grinding, preceding calcination) of these ashes on their binding properties and kinetics was studied using thermogravimetric, SEM, X-ray, and energy dispersive X-ray analysis methods. It was shown that at 700 °C, 0.03–0.28 mmol of CO2 or 0.16–0.47 mmol of SO2 was bound by 100 mg of ash in 30 min. Pre-treatment conditions influenced remarkably binding parameters. Grinding decreased CO2 binding capacities, but enhanced SO2 binding in the case of fluidized bed ashes. Grinding of pulverized firing ashes increased binding parameters with both gases. Calcination at higher temperatures decreased binding parameters of both types of ashes with both gases studied. Clarification of this phenomenon was given. Kinetic analysis of the binding process was carried out, mechanism of the reactions and respective kinetic con- stants were determined. It was shown that the binding process with both gases was controlled by diffusion. Activation energies in the temperature interval of 500–700 °C for CO2 binding with circulating fluidized bed combustion ashes were in the range of 48–82 kJ mol-1, for SO2 binding 43–107 kJ mol-1. The effect of pre-treatment on the kinetic parameters was estimated.
Andres Trikkel, Merli Keelmann, Tiit Kaljuvee, Rein Kuusik, J Therm Anal Calorim (2010) 99, 763–769

A1414 – Pyrolysis study of a hydride sol-gel silica. Part II. Kinetic aspects

The thermal behaviour of a sol–gel prepared hydride silica gel (HSiO sample) in the 20–1000°C interval was studied by coupled thermogravimetric-mass spectrometric (TG-MS) analyses carried out at various heating rates. Thermogravimetric curve elaboration allowed the determination of the flex temperatures, corresponding to the maximum release rate of gas-evolved compounds, and to calculate the activation energy of the overall process. The mass spectrometric data, registered in the TG-MS measurements, were treated to discriminate the single reactions accounting for the release of each compound, among which water, dihydrofuran and various silane- and siloxane-derived species. These results were used to calculate the comprehensive activation energy and also those of each of the released species. Different methods of data processing were used to achieve better reliability of calculated activation energies. The discussion focuses on the high extension of kinetic information arising from MS data processing and on the advantage of identifying the contribution of single reactions, although they occur simultaneously during the heating process. In this respect, good agreement was found between the activation energies of the overall process calculated by separately processing TG and MS data. By processing MS data, the same agreement was observed in the comparison between the activation energy calculated for the overall thermal process and in the sum of the weighed activation energies of the reaction of each released compound.
R. Campostrini, A. Sicurelli, M. Ischia and G. Carturan, Journal of Thermal Analysis and Calorimetry, Vol. 90 (2007) 1, 179–184

A1413 – Pyrolysis study of a hydride sol-gel silica. Part I. Chemical aspects

A homogeneous silica gel sample bearing Si–H groups was prepared, via sol–gel method, by hydrolysis of trimethoxysilane under acid condition in tetrahydrofuran. Preliminary NMR experiments in liquid phase indicated an immediate and complete hydrolysis of Si–OCH3, followed by a slower condensation of the Si–OH groups, with maintenance of Si–H bonds. The crude-gel, and samples heated to various temperatures, were characterized by different instrumental methods, including FTIR, density, porosity, and specific surface area. These data indicate that the crude-gel was a dense material which, on heating, increases porosity and surface area up to ca. 500°C. The thermal behavior was studied in inert atmosphere by means of coupled thermogravimetric, gas chromatographic, mass spectrometric analyses. The pyrolysis process was described by the fundamental chemical reactions occurring among the siloxane chains of the gel network and by the qualitative and semiquantitative chemical analysis of the compounds released in gas-phase. The proposed pyrolysis mechanism was discussed and interpreted in agreement with the change of the morphological properties of the gel. The pyrolysis data and the mass balance between the compounds released in gas-phase and the solid residue at 1000°C allowed the determination of a nominal chemical formula to describe the crude-gel composition.
R. Campostrini, A. Sicurelli, M. Ischia and G. Carturan, Journal of Thermal Analysis and Calorimetry, Vol. 89 (2007) 2, 633–641

A1419 – Copper(II) complexes with N,N-dimethylbiguanide. Thermal, spectroscopic and biological characterization

The N,N-dimethylbiguanide (HDMBG) complexes [Cu2(HDMBG)2Cl4] (1) and respectively [Cu(HDMBG)2]Cl2·2H2O (2) exhibit in vitro antimicrobial activity. The complexes were characterised by IR, electronic as well as EPR spectra. The IR spectra of complexes show the pattern of N,N-dimethylbiguanide coordinated as chelate. The electronic and EPR data are in agreement with a square pyramidal stereochemistry for (1) and a square planar one for (2). The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against Gram-negative strains (Escherichia coli, Klebsiella spp. and Enterobacter sp.) isolated from the hospital environment. The thermal analysis has evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. The thermal behaviour in nitrogen is complex according to TG and DTA curves including melting, dehydration as well as compounds decomposition.
Rodica Olar, Mihaela Badea, Maria Nicoleta Grecu, Dana Marinescu, Veronica Lazar, Carmen Balotescu, Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 1, 239–243

A1418 – Thermal behaviour of new biological active cadmium mixed ligands complexes

This paper reports the investigation on the thermal stability of new complexes with mixed ligands of the type [Cd(NN)(C3H3O2)2(H2O)m] nH2O [(1) NN: 1, 10-phenantroline, m = 1, n = 0; (2) NN: 2,20-bipyridine, m = 0, n = 1.5 and (C3H3O2): acrylate anion]. The IR data indicate a bidentate coordination mode for both heterocyclic amine and acrylate. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against planktonic as well as biofilm embedded Gram-negative (Escherichia coli, Klebsiella sp., Proteus sp., Salmonella sp., Shigella sp., Acinetobacter boumani, Pseudomonas aeruginosa), Gram-positive (Bacillus subtilis, Staphylococcus aureus) and fungal (Candida albicans) strains, reference and isolated ones from the hospital environment. The thermal behaviour steps were investigated in synthetic air flow. The thermal transformations are complex processes according to TG and DTA curves including dehydration, amine as well as acrylate thermolysis. The final products of decomposition are the most stable metal oxides.
Mihaela Badea, Rodica Olar, Dana Marinescu, Veronica Lazar, Carmen Chifiriuc, Gina Vasile, J Therm Anal Calorim (2009) 97, 781–785

A1417 – Thermal, spectral and antimicrobial study on some Cu(II) complexes with ligands bearing biguanide moieties

New complexes of type [Cu(HTBG)2]Cl2 (1), [Cu(TBG)2] 3H2O (2) and [CuL] nH2O (3) L:L1, n = 2 and (4) L:L2, n = 1 (HTBG: 2-tolylbiguanide, L1 and L2: ligands resulted from 2-tolylbiguanide, ammonia/hydrazine and formaldehyde one pot condensation) were synthesised and characterised. The features of complexes have been assigned from microanalytical, IR and UV–Vis data. Redox behaviour was established by cyclic voltammetry. The invitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable anti- microbial activity against Gram-negative and Gram-positive strains isolated from the hospital environment. The thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. After water elimination, complexes have a similar thermal behaviour. Processes as water elimination, melting, chloride anion removal as well as oxidative degradation of the organic ligands were observed. The final product of decomposition was copper (II) oxide.
Rodica Olar, Mihaela Badea, Dana Marinescu, Emilia Elena Iorgulescu, Eliza Frunza, Veronica Lazar, Carmen Chifiriuc, J Therm Anal Calorim (2010) 99, 815–821