Crislene Rodrigues da Silva Morais

Synthesis, Characterization and Thermal Properties of an Europium (III) Nanocomplex

The coordination of lanthanide íons with organic ligands has provided good luminescent properties and allows its application in molecular light converter devices, which motivates the scientific interest of seeking coordination of these íons with organic ligands that potentiate the luminescence and associate biological properties of the complexes formed. From this perspective the complex was synthesized Eu (III) with mesoionic 2(4-chlorophenyl)-3-methyl (methoxyphenyl)-1,3-thiazole-5-thiolate (MS-1) and bipy, with the aim of its possible application in the areas of photoluminescence and drug. Analyses were performed using TG, DSC, XRD and IR. The complex obtained after reaction of the lanthanide salt and organic ligands showed five stages of decomposition and different fusion of the isolated ligands.

Synthesis and kinetic study by ozawa method of the thermal decomposition of complexes Ln(thd)3phen

Recently, highly luminescent lanthanide complexes with mixed ligands such as and β-diketone and two herobiaryl ligands have been synthesized and suggested as promising light-conversion molecular devices as described by several authors. The synthesis, luminescence, quantum yields, spectroscopic characteristics, structure, among others properties of these complexes, including the possibility of production thin film films from these materials have been discussed, but little is known about their thermal decomposition kinetics. In this work we report the determination of kinetic parameters of thermal decomposition of the complexes Gd(thd)3phen and Er(thd)3phen (thd=2,2,6,6-tetramethyl-3,5- heptanodione; phen=1,10-phenantroline) using the method proposed by Ozawa (1965). The kinetic parameters obtained for activation energy were: 90 and 87 kJ.mol-1, the values of frequency factor were: 2.3x107 and 2.0x107 s-1 for Gd(thd)3phen and Er(thd)3phen, respectively. On the kinetic energy of the complexes, we notice the following order in thermal stability: Gd(thd)3phen < Er(thd)3phen.

Synthesis and determination of the kinetic parameters for non-isothermal decomposition of complexes Ln(thd)3phen

In this work the kinetics of the thermal decomposition of two ß-diketone lanthanide complexes of the general formula Ln(thd)3phen (where Ln = Nd+3 or Tm+3, thd = 2,2,6,6- tetramethyl-3,5-heptanodione and phen = 1,10-phenantroline) has been studied. The powders were characterized by several techniques. Thermal decomposition of the complexes was studied by non-isothermal thermogravimetry techniques. The kinetic model that best describes the process of the thermal decomposition of the complexes it was determined through the method proposed by Coats-Redfern. The average values the activation energy obtained were 136 and 114 kJ.mol-1 for the complexes Nd(thd)3phen and Tm(thd)3phen, respectively. The kinetic models that best described the thermal decomposition reaction the both complexes were R2. The model R2 indicating that the mechanism is controlled by phase-boundary reaction (cylindrical symmetry) and is defined by the function g(α) = 2[1-(1-a)1/2], indicating a mean reaction order. The values of activation energy suggests the following decreasing order of stability: Nd(thd)3phen > Tm(thd)3phen.

Synthesis, Characterization and Thermal Decomposition of Samarium Complexes

This work deals with the synthesis, characterization and kinetics of the thermal decomposition of complexes of general formula: Ln(ß-dik)3L (where Ln = Sm, ß-dik = 4,4,4-trifluoro-1-phenyl-1,3butanedione (btfa) and L = 1,10-fenantroline (phen) or 2,2-bipiridine (bipy). The complexes in the power form were synthesized from the direct reaction of SmCl3 with ß-diketone and the ligands. The synthesized complexes presented a weak red luminescence. The powders were characterized by melting point, FTIR spectroscopy, UV-visible absorption spectrophotometry, elemental analysis, scanning differential calorimeter (DSC) and thermogravimetry (TG). The kinetic parameters were obtained from the thermogravimetric data by the non-isothermal integral methods proposed by Coats-Redfern and Madhusudanan, as well as by approximation methods proposed by Horowitz-Metzger and Van Krevelen. The kinetic parameters in the dynamic heating method were determined with the Coats-Redfern equation, using the thermal decomposition model with the data obtained in the isothermal heating experiments. The IR spectra evinced that the metal ion is coordinated to the ß-diketone via C=O and is coordinated to the ligand second via C-N groups. The TG/DTG/DSC curves of the complexes show that they decompose before melting. The profiles of the thermal decomposition of the Sm(btfa)3phen and Sm(btfa)3bipy showed three and four decomposition stages, respectively. Our data suggests that the thermal stability of the complexes under investigation followed the order: Sm(btfa)3phen > Sm(btfa)3bipy. The kinetic models that best described the thermal decomposition reaction for the Sm(btfa)3bipy was R2, for the Sm(btfa)3phen was F1.

Evaluation of Incorporation of Special Vitreous Residues in Mass for Porcelain Stoneware: Physical and Mechanical Properties

This study aimed to technological alternatives for reuse of vitreous residues from fluorescent lamps, which cause damage to the environment. It was prepared mass to white ceramic with and without lamps residues replacing partially feldspar in proportions of 5% and 10%. Samples were molded and fired at 1000 ° C, 1100 ° C, 1150 ° C, 1200 ° C and 1250 ° C. Physical and mechanical tests were: water absorption, linear shrinkage and rupture by flexural modulus. Samples with 10% of residues reached stability at temperature less than 1250 ° C in all determined properties, confirming the feasibility of these residues in ceramic masses. To optimize the study, it was prepared other samples in proportions of 15% and 20% of waste, at the same level of burning and testing. Results obtained ratified the possibility of using these residues as a flux in ceramic slurries.

Physical - Chemistry Characterization of Sweet Sorghum Bagasse in Nature and Delignificate with NaOH to Produce Bioethanol

Lignocellulosic wastes are the most abundant in the world and there is currently a global concern to harness them as biomass to produce cellulosic ethanol, being possible due to the materials being rich in cellulose. The main goal of this work is to produce the delignification from Sweet Sorghum waste free from extractives as well as the physico-chemical characterization in the natural state after being delignificated aiming to remove the lignin that acts as a barrier preventing access of the enzyme to the cellulose in the enzymatic hydrolysis processes. The following tests were performed: moisture, ash, cellulose, lignin, hemicelluloses, AR, extractives, XRD and SEM. Aftter the procedure of delignification, it was characterized as cellulose, lignin, XRD and SEM to check if there was removal of the lignin and if there was no change in crystallinity. The characterization showed that the Sweet Sorghum waste is a viable alternative for the production of bioethanol and proved to be an important source of cellulose presenting a content of glucose of 45.99 ± 0.63% and a lignin content of 14.63 ± 0.23%. The Sweet Sorghum waste was deslignificated by pulping with sodium hydroxide (NaOH) process, using as an experimental tool design type 23 with 3 replications at the center point, to evaluate the effect of independent variables temperature, such as concentration of the NaOH solution and the time dependent variable in the delignification. The planning showed through the Pareto ́s diagram that the most influential variable in the process was the concentration which showed a response of 75.1258 and a greater interaction occurred on the variables temperature and concentration with a response of 1.653117. The regression model as well as being a statistically significant predictor, also presents a reason F calculated and F tabulated of 10.10 and achieving a maximum yield of 57.85% delignification. After delignification processes the waste showed a rate of 5.81 ± 0.18% lignin and 43.13 ± 0.53% cellulose , as well as an increase in crystallinity, verified by analysis of SEM and XRD .

Catalytic Hydrolysis of Pretreated Sugarcane Bagasse over Acid-Activated Vermiculite Catalysts

Aiming at obtaining glucose, we studied the chemical pretreatment (NaOH + H2SO4) and the hydrolysis of sugarcane bagasse using as catalyst the acid-treated vermiculite clay. Samples of the bagasse before and after the treatment were characterized as to the fiber content and XRD. It has been found that the chemical pretreatment showed satisfactory results providing a decrease of 40% in the lignin content and of 43% in the hemicellulose content, regarding to the bagasse in natura. Catalytic tests in aqueous solution were performed at 200°C, to evaluate the use of vermiculite treated as a catalyst for the hydrolysis of sugarcane bagasse. The reaction product was filtered and the supernatant was analyzed by high performance liquid chromatography. A yield of 6.18% in glucose was achieved.

Scientific and Technological Study of the Modulus of Elasticity and Chemical Abnormalities of a Titanium Alloy and Stainless Steel Alloy Used in Hip Prosthesis

Titanium alloys and stainless steel have been widely used in the production of prostheses, medical and dental devices, due to resistance and anticorrosive properties. Despite that, the values of the elastic modulus of these alloys are about 3-5 times higher than the human bone. So, many researches have sought alternatives to these alloys, in order to obtain alloys with good mechanical strength, low modulus of elasticity and excellent biofunctionality. This work highlights by scientific and technological form, the collection and analysis of the module of elasticity and chemical composition, related to normalizations. The properties obtained, being inadequate, highlights the danger of bone absorption, causing loss of adhesion of the prosthesis and reducing its useful life, In addition, chemical abnormalities are a fundamental problem in terms of risk. Results of this study are shown and analyzed.

Evaluation of the Thermal and Kinetic Behavior of the SS Obtained from the Combined Treatment of Liquid Leachate with Domestic Sewage in UASB Reactor

The present study reports the results obtained from Sewage Sludge SS for the obtainment of bio-oil through the pyrolysis process. The research aimed to evaluate the thermal and kinetic behavior of the bio-solid. In this work studies were made on physicochemical, elemental analysis (CHNO). Thermogravimetry (TG) with heating rate of 10o C min-1 over two atmospheres (synthetic air and N2), Thermodynamics (ΔH, ΔS e ΔG), kinetic and spectroscopic. The thermalgravimetric study stated a thermal stability at 30°C. The kinetic calculations were made aiming to observe parameters such as: Activation energy (Ae), frequency factor (s-1), standard deviation (sd) and linear coefficient (r), which were calculated by Thermogravimetry by the methods of Coats-Redfern (CR); Madhusudanan (MD); Van Krevelen (VK); Horowitz-Metzger (HM). In the spectrometry in the infrared (IR) region it was observed bands referring to the presence of water, organic material and silicon oxides in the SS samples analyzed.

Evaluation of the Thermal Stability of Biofuel Obtained from Oil Plant Pyrolysis and Animal Fat

The present study reports obtaining biofuel by pyrolysis of plant oil and animal fat. This process consists in breaking of molecules at high temperatures, obtaining hydrocarbons, similar to oil, and oxygenates such as esters, carboxylic acids, aldehydes, etc. The research aimed to evaluate the thermal and kinetic behaviour and the heat of combustion of bio-oil and bio-oil mixtures / diesel oil. In this work, Thermogravimetric studies were performed (TG) at a heating rate of 10 ° C min-1 under air atmosphere synthetic, Thermodynamic studies (ΔH, ΔS and ΔG) and about heat of combustion also were done. Thermal stability at 30°C was observed from thermogravimetric study. The kinetic calculations were performed in order to observe parameters such as activation energy (Ea) and Arrhenius factor.