L. C. S. de Oliveira

Bio: L. C. S. de Oliveira is an academic researcher from Federal University of Mato Grosso do Sul. The author has contributed to research in topics: Thermal decomposition & Thermal analysis. The author has an hindex of 8, co-authored 13 publications receiving 204 citations. Previous affiliations of L. C. S. de Oliveira include Sao Paulo State University.

Thermal decomposition mechanism of iron(III) nitrate and characterization of intermediate products by the technique of computerized modeling

Abstract: The nonahydrate of iron(III) nitrate shows no phase transitions in the range of −40 to 0 °C. Both hexahydrate Fe(NO3)3·6H2O and nonahydrate Fe(NO3)3·9H2O have practically the same thermal behavior. Thermal decomposition of iron nitrate is a complex process which has a different mechanism than those described for other trivalent elements. Thermolysis begins with the successive condensation of 4 mol of the initial monomer accompanied by the loss of 4 mol of nitric acid. At higher temperature, hydrolytic processes continue with the gradual elimination of nitric acid from resulting tetramer and dimeric iron oxyhydroxide Fe4O4(OH)4 is formed. After complete dehydration, oxyhydroxide is destroyed leaving behind 2 mol of Fe2O3. The molecular mechanics method provides a helpful insight into the structural arrangement of intermediate compounds.

Preparation and thermal decomposition of solid state compounds of 4-methoxybenzylidenepyruvate and trivalent lanthanides and yttrium

Abstract: Solid state Ln-DMBP compounds, where Ln represents trivalent lanthanides (except for promethium) and yttrium, and DMBP is 4-dimethylaminobenzylidenepyruvate, were prepared. Thermogravimetry (TG), differential thermal analysis (DTA), and other methods of analysis were used to characterize and to study the thermal stability and thermal decomposition of these compounds.

Forage turnip, sunflower, and soybean biodiesel obtained by ethanol synthesis: Production protocols and thermal behavior

Abstract: In this work it is reported a detailed investigation of the effect of different production protocols based on alkaline ethanolysis on conversion yield of forage turnip, soybean, sunflower, and castor oil into the respective biodiesel. Parameters such as catalyst contents, reaction times and temperatures were evaluated. Additionally, it was also investigated the relationship between the conversion yield and the chemical composition of the fatty acids in the feedstock. Conversion yields ranging between 70% and 100% point out the viability of the production of biodiesel using ethanol. Based on thermal analysis, sequential steps of weight loss were observed indicating that biodiesel undergoes oxidative thermal decomposition with the elimination of different portions of the molecules in each step. Besides, the energies released by the samples during thermal decomposition were determined.

Preparation and thermal decomposition of solid state compounds of 4-methoxybenzylidenepyruvate with alkali earth metals, except beryllium and radium

Abstract: Solid compounds of general formula ML 2 · n H 2 O [where M is Mg, Ca, Sr or Ba; L = 4 methoxybenzylidenepyruvate (4-MeO-BP); n = 4, 1 or 0] have been synthetized. Thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), x-ray diffraction powder patterns and elemental analysis have been used to characterize the compounds. The thermal stability of these compounds as well as that of the decomposition products were studied using Pt or Al 2 O 3 crucibles in an air or a CO 2 atmosphere.

Thermolysis mechanism of chromium nitrate nonahydrate and computerized modeling of intermediate products

Abstract: Thermal decomposition of chromium nitrate nonahydrate was studied by thermal analysis, differential scanning calorimetry, infrared spectroscopy, and high temperature X-ray diffraction, so that mass losses were related to the exactly coincident endothermic effects and vibrational energy levels of the evolved gases. The thermal decomposition of chromium nitrate is a complex process, which begins with the simultaneous dehydration and concurrent condensation of 4 mol of the initial monomer Cr(NO3)3·9H2O. Soon after that, the resulting product Cr4N12O36·31H2O gradually loses water and azeotrope HNO3 + H2O, and is transformed into tetrameric oxynitrate Cr4N4O16. At higher temperatures, the tetramer loses N2O3 and O2 and a simultaneous oxidation of Cr(III) to Cr(IV) occurs. The resulting composition at this stage is chromium dioxide dimer Cr4O8. Finally, at 447 °C the unstable dimer loses oxygen and is transformed into 2Cr2O3. The models of intermediate amorphous compounds represent a reasonably good approximation to the real structures and a proper interpretation of experimental data.

The Basics of Crystallography and Diffraction

Abstract: the basics of crystallography and diffraction are a good way to achieve details about operating certainproducts. Many products that you buy can be obtained using instruction manuals. These user guides are clearlybuilt to give step-by-step information about how you ought to go ahead in operating certain equipments. Ahandbook is really a user's guide to operating the equipments. Should you loose your best guide or even the productwould not provide an instructions, you can easily obtain one on the net. You can search for the manual of yourchoice online. Here, it is possible to work with google to browse through the available user guide and find the mainone you'll need. On the net, you'll be able to discover the manual that you might want with great ease andsimplicity

The production of biodiesel from vegetable oils by ethanolysis: Current state and perspectives

Abstract: At present, the homogeneous base-catalyzed methanolysis reaction of vegetable oils is a most often used process for the industrial biodiesel production. The toxicity of methanol, the risk of the methanol vapor explosion and the possibility of the ethanol production from biorenewable resources have contributed to the development of a vegetable oil ethanolysis process for the biodiesel production. In the reaction of vegetable oils and ethanol in the presence of a catalyst, completely agricultural fuels consisted of fatty acid ethyl esters (FAEE) are obtained having physico-chemical properties similar to those of the appropriate methyl esters and diesel fuel. The ethanolysis reaction of various oily feedstocks has been widely studied to optimize the reaction conditions and to develop new catalytic systems and processes based on chemical and biological catalysts, as well as the development of non-catalytic processes. Most researches investigate the application of homogeneous base catalysts. This paper studies the review of vegetable oil ethanolysis investigations for the biodiesel production done so far. The goals of the paper are to present the development of FAEE synthesis by catalytic and non-catalytic processes, their advantages and disadvantages, the influence of some operating and reaction conditions on the process rate and ethyl esters yield, the kinetics models describing the ethanolysis process rate, the process optimization and the possibilities for improving the FAEE synthesis process.

Radish seed oil: Ultrasound-assisted extraction using ethanol as solvent and assessment of its potential for ester production

Abstract: In this study, the ultrasound-assisted extraction (UAE) of radish seed oil (RSO) using ethanol as the solvent was investigated with the aim of ester synthesis by in situ reaction. An experimental design was used to evaluate the effects of temperature, solvent to seed ratio and time on the efficiency of the UAE method and to enable the determination of the conditions that maximize the oil removal. The results were compared to those obtained with the classical extraction method, using ethanol and n-hexane as solvents, in terms of yield and oil characterization. The in situ reaction using the oil obtained by UAE was conducted applying different reaction times and enzyme loadings. The effect of using ultrasonic irradiation in the oil extraction and the in situ reaction was evaluated. The results showed that, under the conditions evaluated, the temperature had the greatest influence on the oil extraction, the maximum yield (˜25%) being obtained at 60 °C, with a solvent to seed ratio of 12 mL g−1 and extraction time of 60 min. This corresponds to ˜89% of the yield obtained by the classical method using n-hexane. The RSO was predominantly composed of oleic and erucic acids. The UAE allowed the extraction of a greater amount of phytosterols and tocopherols and, consequently, this oil presented greater oxidative stability. In addition, it was observed that the greater availability of the catalyst in the reaction medium favored the conversion of the oil to esters. The application of ultrasonic irradiation provided higher yields of the oil and ethyl esters.