Determinação de misturas de sulfametoxazol e trimetoprima por espectroscopia eletrônica multivariada

In this work a multivariate spectroscopic methodology is proposed for quantitative determination of sulfamethoxazole and trimethoprim in pharmaceutical associations. The multivariate model was developed by partial least-squares regression, using twenty synthetic mixtures and the spectral region between 190 and 350 nm. In the validation stage, which involved the analysis of five synthetic mixtures, prediction errors lower that 3% were observed. The predictive capacity of the multivariate models is seriously affected by spectral changes induced by pH variations, a fact that acquires a great significance in the analysis of real samples (pharmaceuticals) that contain chemical additives.

Efeito antagônico do ferro e do zinco em uma formulação de alimentação enteral utilizando planejamento de misturas da metodologia de superfície de resposta

Nutritional therapy with enteral diets became substantially specialized over the last years. This work's aim was to study the effect of the components of a formulation: fiber, calcium and medium-chain triglycerides for dialysability of minerals. Analysis of multiple variables was carried out using response surface methodology. The level curve showed an antagonic effect of interaction between iron and zinc. TCM was the variable responsible for characterizing competition between the two minerals in the formulation. More studies on foods are needed for knowing the effecs of minerals in formulations.

Adsorção e propriedades de volume de misturas binárias água álcool: um experimento didático com base em medidas de tensão superficial

An undergraduate physical chemistry experiment based on the drop counting method for surface tension measurements is proposed to demonstrate adsorption isotherms of binary aqueous solutions of ethanol, n-propanol, and n-butanol. Excess surface is obtained by the derivative of surface tension taken with respect to alcohol activity, after this activity calculation using van Laar equation. Laboratory class contents are surface tension, excess surface, percolation of hydrogen bonds, micelle, activity, and ideal solution.

Reciclagem do crômio de resíduos químicos provenientes da determinação de carbono oxidável em fertilizantes orgânicos

This work proposes a separation, recovery and reuse procedure of chemical residues with chromium. This residue was generated by the determination of oxidizable carbon in organic fertilizers samples. The Cr(VI) of the residue was reduced with ethanol and precipitated with NaOH. The Cr(OH)3 precipitate was separated and oxidized to dichromate ions with hydrogen peroxide. This solution was used another time in organic carbon determination. The uses of recycled dichromate solution were appropriated in four successive recycling. The accuracy was proven using potassium hydrogen phthalate and ten organic fertilizer samples. The organic carbon results, determined with recycled solutions, were similar the conventional solution.

A gestão do conhecimento aplicada à reciclagem de componentes automotivos através do tratamento das informações contidas em documentos de patentes

This article evaluates the technologies adopted for recycling and reuse of automobile components, through the analysis of patents documents. The automobile batteries recycling is the main topic, followed by the automatic disassembly of vehicles, tires recycling and polyurethane recycling. None document approached recycling of steel and aluminum or ceramics products. The reduced number of technologies for the recycling of the polymeric compounds (including polyurethane) indicates that a bigger number of research and inventions must be elaborated in the next years, aiming at to the reduction of costs of processes and adequacy to the more restricted environmental legislation.

Autoassociação de misturas dos Surfactantes Dodecanoato de Sódio (SDoD) e Decanoato de Sódio (SDeC) com o Polímero Hidrofobicamente Modificado Etil(Hidroxietil)Celulose (EHEC)

In this work, the interactions between the non-ionic polymer of ethyl(hydroxyethyl)cellulose (EHEC) and mixed anionic surfactant sodium dodecanoate (SDoD)-sodium decanoate (SDeC) in aqueous media, at pH 9.2 (20 mM borate/NaOH buffer) were investigated by electric conductivity and light transmittance measurements at 25 ºC. The parameters of the surfactant to polymer association processes such as the critical aggregation concentration and saturation of the polymer by surfactants were determined from plots of specific conductivity vs total surfactant concentration, [surfactant]tot = [SDoD] + [SDeC]. Through the results was not observed a specific link of polymer with the surfactant, implying therefore a phenomenon only cooperative association.

Uso da cromatografia gasosa bidimensional abrangente (GC×GC) na caracterização de misturas biodiesel/diesel: aplicação ao biodiesel de sebo bovino

The growth of biodiesel market and the implementation of regulations related to biodiesel production and biodiesel/diesel blending has encouraged the development of appropriate analytical methods to control the composition of this type of mixture. In this study, an evaluation of the potential of GC×GC for the characterization of samples of beef tallow biodiesel and the composition of blends of biodiesel/diesel is presented. The methodology was applied to beef tallow biodiesel and its mixtures with petrodiesel, ranging from B2 to B50. Results allowed not only the identification and quantification of the biodiesel esters, but also the biodiesel percentage in biodiesel/diesel blends.

Caracterização cromatográfica de compostos orgânicos presentes nos resíduos sólidos provenientes de indústria de reciclagem de papel e sua aplicação na produção de briquetes de carvão vegetal

Recycling of paper in industrial scale has become an established practice worldwide. In this work, organic compositions of three different kinds of sludge generated in recycle paper industry were studied, and the incorporation of one of those sludge in briket was also investigated. The characterization of organic compounds in sludge samples and briket was performed using Gas Chromatography coupled with Mass Spectrometry after a Soxhlet extraction. Different chemical classes were identified in each type of sludge, but just the sludge composed by cellulose residue did not presented polyaromatic hydrocarbons. Four formulations of sludge incorporated with charcoal for briket production were evaluated.

Uso de redes neurais recorrentes na determinação das constantes de acidez para a 7-epiclusianona em misturas etanol-água

This work propose a recursive neural network to solve inverse equilibrium problem. The acidity constants of 7-epiclusianone in ethanol-water binary mixtures were determined from multiwavelength spectrophotmetric data. A linear relationship between acidity constants and the %w/v of ethanol in the solvent mixture was observed. The proposed method efficiency is compared with the Simplex method, commonly used in nonlinear optimization techniques. The neural network method is simple, numerically stable and has a broad range of applicability.

Reciclagem do lixo de informática: uma oportunidade para a química

Recycling and sustainable development are increasing in importance around the world. In Brazil, the new National Policy on Solid Wastes has prompted discussion on the future of electronic waste (e-waste). Brazil generates the greatest amount of e-waste among Latin American countries. Nevertheless complete recycling, including end processing of e-waste, does not occur in Brazil. This paper discusses the physical and chemical technologies currently used worldwide and in Brazil for printed circuit board recycling, with emphasis on metal recovery and plastic processing. The goal is to put in evidence the important role that chemistry can play in developing cheaper processes to recycle e-waste.

Modelos ridge em planejamentos de misturas: uma aplicação na extração da polpa de pequi

Mixture Models can be used in experimental situations involving areas related to food science and chemistry. Some problems of a statistical nature can be found, such as effects of multicollinearity that result in uncertainty in the optimization of a dependent variable. This study proposes the application of the ridge model adapted for mixture planning considering the Kronecker (K-model) and Scheffe (S-Model) methods applied to response surfaces. The method determined the proportions of hexane, acetone and alcohol proportions that resulted in the maximum response of percentage of extracted pequi (Caryocar brasiliense) pulp oil.

Método hidrometalúrgico para reciclagem de metais terras raras, cobalto, níquel, ferro e manganês de eletrodos negativos de baterias exauridas de Ni-MH de telefone celular

A hydrometallurgical method for the recovery of rare earth metals, cobalt, nickel, iron, and manganese from the negative electrodes of spent Ni - MH mobile phone batteries was developed. The rare earth compounds were obtained by chemical precipitation at pH 1.5, with sodium cerium sulfate (NaCe(SO4)2.H2O) and lanthanum sulfate (La2(SO4)3.H2O) as the major recovered components. Iron was recovered as Fe(OH)3 and FeO. Manganese was obtained as Mn3O4.The recovered Ni(OH)2 and Co(OH)2 were subsequently used to synthesize LiCoO2, LiNiO2 and CoO, for use as cathodes in ion-Li batteries. The anodes and recycled materials were characterized by analytical techniques.

Otimização da etapa de extração do ácido clavulânico presente no caldo de fermentação utilizando misturas de solventes

The purpose of this work was to study four different solvent mixtures intended to increase the yield of the extraction stage of clavulanic acid (CA), which is one of the steps in the purification process. Four central composite rotatable designs (CCRD) were utilized to optimize the solvent mixtures. The variables selected for the factorial design were solvent mixture ratio (mL/mL) and temperature (ºC). The results showed that the yield of CA extracted from fermentation broth with the solvent mixtures of methyl-ethyl-ketone and ethyl acetate, and methyl-isobutyl-ketone and ethyl acetate (44.7 and 50.0%, respectively) was higher than that of the individual ethyl acetate alone (36.5%).

DESENVOLVIMENTO DE ENSAIO PARA ANÁLISE QUALITATIVA DE BIODIESEL EM MISTURAS DIESEL-BIODIESEL PARA APLICAÇÃO EM POSTOS REVENDEDORES DE COMBUSTÍVEIS

In this study, we developed a method for the visual detection of biodiesel in petrodiesel-biodiesel (BX) blends through the aminolysis of the methyl or ethyl esters of fatty acids that are found in biodiesel and that are absent from diesel and vegetable oils. This method is based on three reactional stages, which produce a dark red and easily visualized complex in the presence of biodiesel. In the absence of biodiesel, there is no dark red coloring, whereas in the presence of diesel or vegetable oil, there is a light red to yellow coloring. This simple, practical, inexpensive, and effective procedure may be applied by petrol stations to guarantee to consumers and resellers the presence of biodiesel in diesel blends, regardless of the BX blend's initial coloring or of the sulfur found in the diesel. In short, it ensures a safe fuel tank fill-up with BX blend.

Lixo e reciclagem como tema motivador no ensino de química

Este trabalho se constituiu em um estudo de ação-reflexão sobre a prática pedagógica de Educação Ambiental (EA) desenvolvida no contexto do ensino de Química na Escola Municipal Monsenhor Stanislaw localizada no município de Olivedos-PB. O objetivo da pesquisa foi desenvolver e analisar ações pedagógicas de inserção de práticas educativas ambientais articuladas com o ensino de Química, com a implantação de coleta seletiva na escola, oficinas de reciclagens tais como a de papel reciclado, óleo utilizado em frituras para fabricação de sabão e reutilização de garrafas PET'S. Para a reflexão sobre a prática vivenciada, foi feita uma coleta de dados, por meio de registro de observações em diário de campo, aplicação de questionários, fotografias como documentos visuais, realização de várias oficinas de caráter educacional relacionado ao meio ambiente. As ações desenvolvidas consistiram na abordagem de temas ambientais por meio do livro didático; no desenvolvimento de um projeto de Educação Ambiental para identificar problemas ambientais em volta da escola como também na cidade em geral. Pôde-se observar a importância do uso do livro didático, mas também evidencia a necessidade do desenvolvimento de projetos de ações comunitárias de educação ambiental (EA) e de projetos que envolvam a comunidade escolar. Constatou-se que a EA no ensino de Química requer um processo longo de construção de ações coletivas, em que alunos e professores sejam sensibilizados e mobilizados para se engajarem em ações socioambientais. Isso significa construir um processo contínuo de renovar estratégias, recriar ações, dialogar nas aulas, utilizar técnicas para desenvolver no aluno autonomia e criatividade. Nesse sentido, envolver práticas educativas ambientais na comunidade escolar é deixar aflorar os valores, as atitudes, os conceitos e as habilidades para transformá-las em ação com a esperança em criar trilhas para construir uma nova realidade.