NON-ISOTHERMAL STUDIES on CRYSTALLIZATION KINETICS of TELLURITE 20Li(2)O-80TeO(2) GLASS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudos de adsorção de tetraciclina e cromoglicato em partículas de quitosana

Among the polymers that stand out most in recent decades, chitosan, a biopolymer with physico-chemical and biological promising properties has been the subject of a broad field of research. Chitosan comes as a great choice in the field of adsorption, due to their adsorbents properties, low cost and abundance. The presence of amino groups in its chain govern the majority of their properties and define which application a sample of chitosan may be used, so it is essential to determine their average degree of deacetylation. In this work we developed kinetic and equilibrium studies to monitor and characterize the adsorption process of two drugs, tetracycline hydrochloride and sodium cromoglycate, in chitosan particles. Kinetic models and the adsorption isotherms were applied to the experimental data. For both studies, the zeta potential analyzes were also performed. The adsorption of each drug showed distinct aspects. Through the studies developed in this work was possible to describe a kinetic model for the adsorption of tetracycline on chitosan particles, thus demonstrating that it can be described by two kinetics of adsorption, one for protonated tetracycline and another one for unprotonated tetracycline. In the adsorption of sodium cromoglycate on chitosan particles, equilibrium studies were developed at different temperatures, allowing the determination of thermodynamic parameters

Estudos de adsorção de tetraciclina em partículas de quitosana

Due to its physico-chemical and biological properties, related to the abundance and low cost of raw material, chitosan has been recognized as a material of wide application in various fields, such as in drug delivery systems. Many of these properties are associated with the presence of amino groups in its polymer chain. A proper determination of these amino groups is very important, in order to properly specify if a given chitosan sample can be used in a particular application. Thus, in this work, initially, a comparison between the determination of the deacetylation degree by conductometry and elemental analysis was carried out using a detailed analysis of error propagation. It was shown that the conductometric analysis resulted in a simple and safe method for the determining the degree of deacetylation of chitosan. Subsequently, experiments were performed to monitor and characterize the adsorption of tetracycline on chitosan particles through kinetic and equilibrium studies. The main models of kinetics and adsorption isotherms, widely used to describe the adsorption on wastewater treatment systems and the drug loading, were used to treat the experimental data. Firstly, it was shown that an apparent linear t/q(t) × t relationship did not imply in a pseudo-second-order adsorption kinetics, differently of what has been repeatedly reported in the literature. It was found that this misinterpretation can be avoided by using non-linear regression. Finally, the adsorption of tetracycline on chitosan particles was analyzed using insights obtained from theoretical analysis, and the parameters generated were used to analyze the kinetics of adsorption, the isotherm of adsorption and to ropose a mechanism of adsorption

Investigation about the copper adsorption on the chloropropylsilica gel surface modified with a nanostructured dendrimer DAB-Am-16: an analytical application for determination of copper in different samples

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Síntese, caracterização, propriedades e aplicação dos sistemas Mg- Al, Zn-Al e Mg-Fe

The Layered Double Hydroxides has become extremely promising materials due to its range of applications, easily obtained in the laboratory and reusability after calcination, so the knowledge regarding their properties is of utmost importance. In this study were synthesized layered double hydroxides of two systems, Mg-Al and Zn-Al, and such materials were analyzed with X-ray diffraction and, from these data, we determined the volume density, planar atomic density, size crystallite, lattice parameters, interplanar spacing and interlayer space available. Such materials were also subjected to thermogravimetric analysis reasons for heating 5, 10, 20 and 25 ° C / min to determine kinetic parameters for the formation of metaphases HTD and HTB based on theoretical models Ozawa, Flynn-Wall Starink and Model Free Kinetics. In addition, the layered double hydroxides synthesized in this working ratios were calcined heating 2.5 ° C / min and 20 ° C / min, and tested for adsorption of nitrate anion in aqueous solution batch system at time intervals 5 min, 15 min, 30 min, 1h, 2h and 4h. Such calcined materials were also subjected to exposure to the atmosphere and at intervals of 1 week, 2 weeks and 1 month were analyzed by infrared spectroscopy to study the kinetics of regeneration determining structural called "memory effect"

Estudos de sorção de um corante aniônico modelo em partículas de quitosana reticulada

Textile activity results in effluents with a variety of dyes. Among the several processes for dye-uptaking from these wastewaters, sorption is one of the most effective methods, chitosan being a very promising alternative for this end. The sorption of Methyl Orange by chitosan crosslinked particles was approached using equilibrium and kinetic analyses at different pH s. Besides the standard pseudo-order analysis normally effectuated (i.e. pseudo-first-order and pseudo-second-order), a novel approach involving a pseudo-nth-order kinetics was used, nbeing determined via non-linear regression, using the Levenberg-Marquardt method. Zeta potential measurements indicated that electrostatic interactions were important for the sorption process. Regarding equilibrium experiments, data were well fitted to a hybrid Langmuir-Freundlich isotherm, and estimated Gibbs free energy of adsorption as a function of mass of dye per area of chitosan showed that the process of adsorption becomes more homogeneous as the pH of the continuous phase decreased. Considering the kinetics of sorption, although a pseudo-nth-order description yielded good fits, a kinetic equation involving diffusion adsorption phenomena was found to be more consistent in terms of a physicochemical description of the sorption process

Estudo cinético da degradação térmica e catalítica de petróleo pesado usando Al-MCM-41

The mesoporous nanostructured materials have been studied for application in the oil industry, in particular Al-MCM-41, due to the surface area around 800 to 1.000 m2 g-1 and, pore diameters ranging from 2 to 10 nm, suitable for catalysis to large molecules such as heavy oil. The MCM-41 has been synthesized by hydrothermal method, on which aluminum was added, in the ratio Si/Al equal to 50, to increase the generation of active acid sites in the nanotubes. The catalyst was characterized by X-ray diffraction (XRD), surface area by the BET method and, the average pore volume BJH method using the N2 adsorption, absorption spectroscopy in the infrared Fourier Transform (FT-IR) and determination of surface acidity with application of a probe molecule - n-butylamine. The catalyst showed well-defined structural properties and consistent with the literature. The overall objective was to test the Al-MCM-41 as catalyst and thermogravimetric perform tests, using two samples of heavy oil with API º equal to 14.0 and 18.5. Assays were performed using a temperature range of 30-900 ° C and heating ratios (β) ranging from 5, 10 and 20 °C min-1.The aim was to verify the thermogravimetric profiles of these oils when subjected to the action of the catalyst Al- MCM-41. Therefore, the percentage ranged catalyst applied 1, 3, 5, 10 and 20 wt%, and from the TG data were applied two different kinetic models: Ozawa-Flynn-Wall (OFW) and Kissinger-Akahrira-Sunose (KAS).The apparent activation energies found for both models had similar values and were lower for the second event of mass loss known as cracking zone, indicating a more effective performance of Al-MCM-41 in that area. Furthermore, there was a more pronounced reduction in the value of activation energy for between 10 and 20% by weight of the oil-catalyst mixture. It was concluded that the Al-MCM-41 catalyst has applicability in heavy oils to reduce the apparent activation energy of a catalyst-oil system, and the best result with 20% by weight of Al-MCM-41

Kinetics of venom and antivenom serum levels, clinical evaluation and therapeutic effectiveness in dogs inoculated with Crotalus durissus terrificus venom

This work evaluated the clinical and therapeutic aspects as well as serum levels of venom and antivenom IgG by enzyme-linked immunosorbent assay (ELISA) in experimental envenomation of dogs with Crotalus durissus terrificus venom. Twenty-eight mixed breed adult dogs were divided into four groups of seven animals each, Group I: only venom; Group II, venom + 50 ml of anti-bothropic-crotalic serum (50mg) + fluid therapy; Group III, venom + 50 ml of anti-bothropic-crotalic serum + fluid therapy + urine alkalination; Group IV, 50 ml of anti-bothropic-crotalic serum. The lyophilized venom of Crotalus durissus terrificus was reconstituted in saline solution and subcutaneously inoculated at the dose of 1mg/kg body weight. The dogs presented clinical signs of local pain, weakness, mandibular ptosis, mydriasis, emesis and salivation. The venom levels detected by ELISA ranged from 0 to 90ng/ml, according to the severity of the clinical signs. Serum antivenom ranged from 0 to 3ug/ml and was detected for up to 138h after treatment. ELISA results showed the effectiveness of the serum therapy for the venom neutralization.

Shikimate Kinase (EC 2.7.1.71) from Mycobacterium tuberculosis: Kinetics and Structural Dynamics of a Potential Molecular Target for Drug Development

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Applied models to biodegradation kinetics of lubricant and vegetable oils in wastewater

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Muscle damage slows oxygen uptake kinetics during moderate-intensity exercise performed at high pedal rate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ascorbic acid degradation kinetics in tomatoes at different drying conditions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)