Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates.
These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC2O4 as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite
High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two
higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and
857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison
the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost
at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II)
oxalate as compared to the synthetic compound which is the dihydrate.
Authors:Masakazu Nakanishi, Tomoko Ogi, and Yoshio Fukuda
We modified a commercially available thermogravimetric analyzer to introduce helium alone or with steam, oxygen or both, atmosphere
of which was controllable to be similar to that in a fixed-bed or an entrained-flow type gasifier, for studying basic properties
of biomass gasification. We also connected it to a gas chromatograph-mass selective detector for identifying materials produced
during the thermogravimetric analyses. Thermogravimetric analyses of Japanese cedar wood and identifications of the produced
materials at around 365 °C were measured as demonstrations.
Authors:Susan Moreno-Molek, Salaam Saleh, Druthiman Reddy Mantheni, Manik Pavan Kumar Maheswaram, Tobili Sam-Yellowe, and Alan T. Riga
constant or permittivity (∊′), the dielectric loss factor (∊″) or ionic conductivity, and the loss tangent (tan δ = ∊″/∊′).
A TAI 2950 TG was used to measure the percent (%) mass loss from the
The kinetics of individual stages of thermal decomposition of Al2(SO4)3·18H2O were studied by TG method. It is found that Al2(SO4)3·18H2O decomposes to Al2O3 in four major stages, all of endothermic. Some of these major stages are formed by sub-stages. The first three major stages
are dehydration reactions in which two, ten and six moles water are lost, respectively. The last major stage is sulfate decomposition.
In this study the kinetic parameter values of these major and sub-stages were calculated by integral and differential methods.
The alterations of activation energies with respect to the decomposition ratio and to the method were investigated.
Authors:I. Blanco, L. Abate, F. A. Bottino, and P. Bottino
Six polyhedral oligomeric silsesquioxanes (POSSs) with general formula R7 R′1 (SiO1.5)8, where R- was an isobutyl group and R′- a variously substituted phenyl group, namely hepta isobutyl polyhedral oligomeric silsesquioxane (hib-POSS), were prepared and their composition was checked by elemental analysis and 1H NMR spectroscopy. The degradation of compounds obtained was studied by simultaneous differential thermal analysis/thermogravimetry (DTA/TG) technique, in both inert (flowing nitrogen) and oxidative (static air atmosphere) environments, in order to draw useful information about their thermal stability. Experiments, performed in the 35–700 °C temperature range, showed different behaviour between the two used atmospheres. The formation of volatile compounds only, with an about complete mass loss, was observed under nitrogen, while a solid residue (≈40–50% in every case), due to the formation of SiO2, as indicated by the FTIR spectra, was obtained in static air atmosphere. The results obtained were discussed and compared, and the classifications of resistance to thermal degradation in the studied environments were made. A comparison between the thermal stabilities of hib-POSSs and analogous cyclopentyl POSSs previously studied was also performed.
Authors:H. Geßwein, N. Schlechtriemen, J. Binder, and J. Haußelt
A kinetic model for the reaction sintering of oxide ceramics in the system Al2O3–SiO2–ZrO2 using mixtures of intermetallic compounds is presented. A 2D finite-difference model is developed to describe the exothermic
gas-solid reactions taking place during the firing of ZrAl3/ZrSi2 powder compacts. The model accounts for the oxidation kinetics of the powder particles, as well as the consumption and diffusion
of gaseous oxygen through the porous matrix. Additionally, possible changes in the pore structure of the green body due to
the oxidation reactions and sintering effects are incorporated in the model. The resulting differential equations are coupled
with a two-dimensional Fourier heat balance equation leading to a system of nonlinear partial differential equations, which
is solved by the numerical method of lines. The influence of different processing parameters like sample composition and heating
cycle on the reaction sintering process is investigated and the model-predicted reaction behaviour is compared to experimental
The title terpolymer (8-HQ5-SAMF-II) is synthesized by the condensation of 8-hydroxyquinoline 5-sulfonic acid (8-HQ5-SA) and
melamine (M) with formaldehyde (F) in the presence of acid catalyst and using 2:1:3 M proportions of the reacting monomers.
The synthesized terpolymer resin is then characterized by different physicochemical techniques viz. number average molecular
mass determination, intrinsic viscosity determination, and spectral studies like UV–Visible, IR, 1H NMR, and 13C NMR spectra. The morphology of synthesized terpolymer was studied by scanning electron microscopy (SEM). The thermogravimetry
of the terpolymer resin prepared in this study has been carried out by non-isothermal thermogravimetry technique in which
sample is subjected to condition of continuous increase in temperature at linear rate. Thermal study of the resin was carried
out to determine their mode of decomposition and relative thermal stabilities. Thermal decomposition curves were studied carefully
with minute details. The Freeman-Carroll and Sharp-Wentworth methods have been used in the present investigation to calculate
thermal activation energy and different kinetic parameter of the terpolymer resins. Thermal activation energy Ea calculated with the two above-mentioned methods are in close agreement. The advantage of Freeman-Carroll method is to calculate
both the order of reaction n and energy of activation in one single stage by keeping heating rate constant. By using data of thermogravimetry, various
thermodynamic parameters like frequency factor Z, entropy change ΔS, free energy change ΔF, and apparent entropy S* have been determined using Freeman-Carroll method.
Authors:Charu Dwivedi, Naina Raje, Manmohan Kumar, A. Reddy, and P. Bajaj
The present work describes the application of radiotracer technique for studying uptake of arsenic on titanium hydroxide,
commercial titanium dioxide (TiO2) powder (anatase) and synthesized mesoporous titania beads in acidic, neutral, and alkaline conditions. Sol–gel templating
method was used to prepare titania–polysaccharide composites, with different polymer contents. Mesoporous titania was obtained
by heat treatment of the composite beads in a controlled environment. The synthesis process was optimized, using thermogravimetry
analysis. X-ray diffraction patterns confirmed the formation of anatase pure phase titania (TiO2) at 700 °C in different environments, and scanning electron microscopy studies confirmed uniform pore size distribution.
The effect of surface area, polymer content and pH on uptake of arsenic(III) and (V) on the synthesized titania beads was
also investigated. Arsenic(V) was found to be retained quantitatively on the titania beads synthesized from 0.8% polymer content
titania–polymer composite precursor in neutral to alkaline conditions. Details of the results obtained are discussed.