Authors:P. Álvarez-Iglesias, M. Araújo, A. Gouveia, and T. Drago
Two sediment cores (~30 m long) were retrieved at the mouth of the Minho Estuary to assess its palaeoenvironmental evolution
for the last millennia. Samples were characterized by Energy-Dispersive X-Ray Fluorescence Spectrometry and Instrumental Neutron
Activation Analysis, complemented by sedimentological analyses. Provenance of major and trace element contents (lithogenic
or biogenic, continental or marine) is assessed. The influence of grain size effect on total element concentration is discussed.
Most of the samples present a negative Eu anomaly. Sedimentological and geochemical parameters allow differentiating four
geological units––fluvial, marine, estuarine and sand barrier––which reflects the temporal evolution of the Minho Estuary.
Authors:C. Corredeira, M. Araújo, A. Gouveia, and J.-M. Jouanneau
A geochemical study was carried out in sediment cores along the Galician Continental Shelf and at the mouth of the Vigo and
Pontevedra Rias. Multielemental analysis was performed by Instrumental Neutron Activation Analysis and Energy Dispersive X-ray
Fluorescence Spectrometry. Sedimentological and geochemical characterisation (lithogenic, biogenic and anthropogenic elements)
indicates different supplies for the fine-grained, deposited sediments. No significant heavy metal enrichment could be detected
in coastal sediments despite the current sediment contamination in adjacent Rias. Variations in the accumulation rates suggest
different factors controlling the sedimentation processes including sediment sources and geomorphology.
Authors:A. Araújo, E. Fernandes, E. França, and M. Bacchi
Environmental quality assessment studies have been conducted with tree species largely distributed in the Atlantic Forest.
Leaf and soil samples were collected in the conservation unit Parque Estadual da Serra do Mar (PESM) nearby the industrial
complex of Cubatão, São Paulo State, Brazil, and analyzed for chemical elements by instrumental neutron activation analysis.
Results were compared to background values obtained in the Parque Estadual Carlos Botelho (PECB). The higher As, Fe, Hg and
Zn mass fractions in the tree leaves of PESM indicated anthropogenic influence on this conservation unit.
Authors:H. Polli, L. Pontes, A. Araujo, Joana Barros, and V. Fernandes
The degradation kinetics of the ABS terpolymer (acrylonitrile-butadiene-styrene) was investigated by means of thermogravimetric
analysis. The samples were heated from 30 to 900°C in nitrogen atmosphere applying three different heating rates: 5, 10 and
20°C min−1. The Vyazovkin model-free kinetic method was used to calculate the activation energy (E) of the degradation process as a function of conversion and temperature. Between 20 and 80% of conversion, E was calculated
and the figures were: for ABS GP, E is 204.5±11.5 kJ mol−1 (medium value); for ABS HI, E is 239.0±9.8 kJ mol−1; for ABS HH, E is 242.4±5.4 kJ mol−1.
Authors:A. Garrido Pedrosa, M. Souza, S. Lima, Dulce Melo, A. Souza, and A. Araújo
bifunctional catalysts were synthesized using impregnation and polymeric precursor
methods. After the synthesis process the samples were calcined at 600, 700
and 800C and characterized by X-ray diffraction, nitrogen adsorption
and temperature programmed reduction study by thermogravimetry. DTG-TPR profiles
showed between three and five reduction events at different temperatures attributed
to platinum reduction and to different stages of tungsten species reduction.
A comparative study of the synthesis method influence on the DTG-TPR curves
Authors:A. M. Garrido Pedrosa, M. J. B. Souza, D. M. A. Melo, and A. S. Araujo
The thermo-programmed reduction study of Pt/WOx–ZrO2 materials prepared with different tungsten loading were performed by thermogravimetry. The samples were synthesized by impregnation method and calcined at 600, 700 and 800°C. The characterizations of both un-calcined and calcined materials were carried out using different techniques: thermal analysis (TG and DTA), X-ray diffraction (XRD) and thermo-programmed reduction (TPR). TG and DTA analysis of un-calcined were used to determination of calcination temperatures of the samples. XRD diffractograms were useful to help us in the determination of phase presents. TPR profiles showed between three and four events at different temperatures attributed to platinum reduction and the different stages of tungsten specie reduction.
Authors:Anne Garrido Pedrosa, M. Souza, A. Silva, Dulce Melo, and A. Araujo
The study of the incorporation
of rare earth elements as additives in Y zeolites is a very interesting field
of research, mainly by its potential application as additives in catalytic
cracking process. In this work was studied the thermal and structural properties
of cerium, holmium and samarium supported on HZSM-12 zeolite. The obtained
materials were characterized by X-ray diffraction (XRD), infrared spectroscopy
(FTIR), nitrogen adsorption, thermogravimetry (TG/DTG), differential scanning
calorimetry (DSC) and differential thermal analysis (DTA). TG/DSC/DTA analyses
showed that the dehydration temperatures of RE/HZSM-12 zeolites (RE=Ce, Ho, Sm) increase in relation to pure HZSM-12.
The acid properties were investigated by pyridine thermo desorption via TG.
The results showed two events of mass loss attributed to elimination of pyridine
adsorbed on the weak+medium acid sites and on the strong acid sites.
Authors:A. Garrido Pedrosa, P. Pimentel, D. Araújo Melo, H. Scatena, F. Borges, A. Souza, and L. Zinner
Ln(TFA)3⋅3AZA (Ln=La, Sm, Er; TFA=trifluoroacetate and AZA=2-azacyclononanone)compounds were synthesized and characterized by microanalytical procedures, IR spectroscopy, X-ray powder
diffraction, and thermal analysis. A kinetic study using La, Sm and Er thermogravimetric curves was carried out aiming to
proposing a mechanism for the thermal decomposition of such complexes.
Authors:S. Silva, M. Conceiçăo, A. Souza, S. Prasad, M. Silva, V. Fernandes, A. Araújo, and F. Sinfrônio
The powder and the bran of algaroba pods, submitted to drying temperatures of 55, 65, 75, 85, 95 and 105C, were studied by
conventional and thermogravimetric methods. The dynamic thermogravimetric curves of the samples indicated the following thermal
stability order: 105>55>65>95>85>75C. The powder and the bran of algaroba pods, dried at 55C, presented protein content
higher and isothermal thermogravimetric profiles comparable. The calorimetric curves of samples, dried at 55C, indicated
the gelatinization of starch.