The curing kinetics of nanocomposites based on phenolic resol cured with triethylamine (TEA) containing different amounts
of organic montmorillonite was analyzed by differential scanning calorimetry. Kissinger-Akahira-Sunose (KAS) model-free kinetics
has been applied to correlate the dynamic cure behaviour in the presence of modified montmorillonite. The effect in the curing
of the use of different clay modifiers has also been studied. A commercial clay with hydroxyl groups (Cloisite 30B) and a
customized montmorillonite (PheMMT) whose reactive groups induce condensation reactions with the resol matrix have been used.
Strong dependency of activation energy on apparent conversion has been observed for all compounds.
The catalytic behaviour of ceria, zirconia
and ceria–zirconia mixed oxides in the temperature-programmed degradation
of toluene and n-hexane was analysed by
means of evolved gas analysis (mass spectrometry). Pure cerium oxide resulted
the most active catalyst in the oxidation of both compounds. This fact revealed
the crucial role of the surface oxygen species in the decomposition of this
type of hydrocarbons. The low affinity of CeO2 for
H2O and CO2, the major oxidation
products, may be also responsible for the observed highly active catalytic
This work is a ‘historical’
revision of the evolution of an experimental procedure developed by Prof.
Lisardo Nez and his research group TERBIPROMAT to study the
sustainability and the soil health state.
From the very beginning,
in 1993, the microbial activity was the main bioindicator selected to analyse
the ‘soil health state’. For this reason, a microcalorimetric
technique was used lately to analyse the influence of different human activities
such as reforestations, agricultural exploitation or pollution on the microbial
activity in different soils. Microcalorimetry is the main scientific technique
used in this research to follow the stimulation of the microbial activity
by addition of glucose. The data obtained were complemented by a study of
physical, chemical and biological parameters of soil and allowed to follow
the microbial activity in soils of Galicia (Spain) along the year.
The final results, still in revision, will be helpful in establishing
a data basis for real maps of the ‘health state’ of different
soils. Such maps could be used to design processes that help us to decide
how we should exploit soils ensuring their sustainability.
Microcalorimetry was used
to study the seasonal evolution over one year of the microbial activity in
a humic-eutrophic Cambisol soil as a function of its forest cover. The study
was carried out on three soils with identical origin but covered with different
forest species: pine, eucalyptus, and a typical Atlantic-humid riverside forest.
Some other physical, chemical and biological
properties and environmental parameters, mainly humidity and environmental
temperature, were considered to analyze their influence on soil microbial
The study was performed using a microcalorimeter Thermal
Analysis Monitor 2277 in which the experiments were carried out with 1 g soil
samples treated with 1.25 mg glucose g–1
soil. From the measured results it follows that pine forest soil is the least
productive of the three, as it generates an average heat of 2.7 vs. 5.9 J g–1 generated
by the eucalyptus forest soil and 3.1 J g–1
generated by the riverside forest soil. These results are dependent on the
remaining physical, chemical and biological features analysed and because
of this, pine forest soil, with a pH value 3.3 in spring, shows a small capacity
to maintain a stable microbial population which is the lowest of the three
(0.079108 to 0.46108
microorganisms g–1 soil) while riverside
soil microbial population is in the range from 7.9108
to 17108 microorganisms g–1
Calorimetric measurements of the heat of adsorption of CO2 on zeolites with variable content of mono- and divalent cations lead to common conclusions. High initial heats (up to 120 kJ·mol−1 for NaA), generally associated with a slow and activated rate of adsorption, are found for high contents of Na+, Li+ or Ca2+. They are attributed to a limited number of chemisorption sites (0.3 per α cage in NaA).
A Spanish red mud was thermally characterized. Chemical and mineralogical composition were determined by XRF and XRD.The thermal
events observed in the range from room temperature to 1300°C were related to the sample composition. The first mass loss step
was related to free water content, while many of the other processes were related to dehydration processes. It was found that
most of the decomposition reactions of hydrohematite, ferrihydrite, aluminogoethite, boehmite, silicates and carbonates were
strongly overlapping. It was also explained the formation of silicates and calcium titanate, which presence was confirmed
at 1000°C by XRD.
A survey on the effect of ionic liquids (ILs) over the thermal stability of a heavy Mexican oil was performed. ILs used were
based on [Cnim]+ and [Cnpyr]+ organic cations with FeCl4− metal anion. Mixtures of heavy crude oil (HCO) with ILs show three oxidation zones: low temperature oxidation (LTO), full
deposition (FD) and high temperature oxidation (HTO). Thermal stability and mass loss decrease in the LTO zone but increase
in the FD and HTO zones for every ILs used. The activation energy of the oxidation is influenced by the ILs in the HTO zone.
It decreases when increasing the size of the organic radical substitute in the cation of the ILs while it increases with the
presence of hydroxyl groups. The influence of electronic structure and reactivity indexes are rationalized to understand the
variations of activation energy obtained of the reaction systems. Among all cations used, cation-3 (IL-3) shows the greater
value of HOMO-LUMO gap as well as the lower activation energy.
Summary Non-isothermal thermogravimetric data were used to evaluate the Arrhenius parameters (activation energy and the pre-exponential factor) of the combustion of two carbonaceous materials, selected as diesel soot surrogates. The paper reports on the application of model-free isoconversional methods (Flynn-Wall-Ozawa and Kissinger methods) for evaluating the activation energy of the combustion process. On the other hand, by means of the compensation relation between E and lnA, which was established by the model-dependent Coats-Redfern method, the value of the pre-exponential factor was estimated from the known value of the model-independent activation energy.