Esterificação de ácidos graxos utilizando zircônia sulfatada e compósitos carvão ativado/zircônia sulfatada como catalisadores

In this work sulfated zirconia (SZr) and activated carbon/SZr composites produced by impregnation method with or without heating treatment step (CABC/SZr-I and CABC/SZr-I SC) and by the method of synthesis of SZr on the carbon (CABC/SZr-S) was used as catalysts in the esterification reactions of fatty acids. The SZr presented very active, conversions higher than 90% were obtained after 2 h of reaction. The activity of the composite CABC/SZr-I20%SC was up to 92%, however, this was directly related to time and temperature reactions. CABC/SZr-I and CABC/SZr-S were less active in esterification reactions, what could be attributed to its low acidity

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.

Otimização das condições de extração de saponinas em Ampelozizyphus amazonicus usando planejamento experimental e metodologia de superfície de resposta

This works describes the use of experimental design and surface response methodology for optimization of saponin extraction from Ampelozizyphus amazonicus. For this purpose, a method employing extraction based on maceration assisted by ultrasound technique was utilized. The following factors were studied: extraction length of time and solvent composition. The total saponin was determined by using a gravimetric method and the results expressed by their relative proportion to total crude extract. For the specific condition, 60% hydro-alcoholic solution and 18 minutes extraction length of time has shown the best results. This method can be useful for extraction of substances with biological importance

Chumbo e zinco em águas e sedimentos de área de mineração e metalurgia de metais

Lead metallurgy at Adrianópolis is the largest environmental problem of Paraná, Brazil. The objective of this study was to determine Pb and Zn levels in water and sediment in two catchments by different extraction methods. The high levels of lead in water in most of samples do not allow the human use. Total Pb concentration as high as 795.3 µg L-1 was observed in Ribeira River bank, in a pluvial water stream flowering from a abandoned factory. Due to the high Pb levels in sediments from some sites (maximum of 24,300 mg kg-1) is recommended to avoid the water turbulence.

Oxidação de glicerol sobre nanopartículas de ouro suportadas em carvão ativado: monitoramento quimiométrico da reação por ESI-MS e MIR

A study on the monitoring of glycerol oxidation catalyzed by gold nanoparticles supported on activated carbon under mild conditions by chemometric methods is presented. The reaction was monitored by mass spectrometry-electrospray ionization (ESI-MS) and comparatively by mid infrared spectroscopy (MIR). Concentration profiles of reagent and products were determined by chemometric tools such as Principal Component Analysis (PCA), Evolving Factor Analysis (EFA) and Multivariate Curve Resolution (MCR). The gold nanoparticle catalyst was relatively active in glycerol oxidation, favoring formation of high added value products. It was found that the reaction stabilization was reached at four hours, with approximately 70% glycerol conversion and high selectivity for glycerate.

Extração de bifenilas policloradas de amostras de leite materno: otimização univariada versus planejamento experimental

The convenience of the multivariate optimization of SPME procedures through ANOVA calculated using Doehlert designs has been demonstrated for twelve PCBs in the complex matrix of milk. For this study, the main parameters of the extraction were selected and valued through univariate and multivariate optimization. In addition, the analysis of variance allowed identification of the statistically significant variables in this model: high temperature (95 ºC) and ionic strength (36% m/v) proved significant for all the PCBs while intermediate time (70 min) and low methanol concentration (5% v/v) also contributed to the extraction of the majority of these PCBs.

Caracterização detalhada de material de referência certificado de carvão brasileiro

The use and characterization of the first Certified Reference Material (CRM) of Brazilian coal for analytical quality control are presented. All results were determined within the limits of repeatability and reproducibility allowed under the standards. Notable among the characterization parameters was the mineral matter content (45.39%) obtained by an alternative procedure showing a low relative error (-2.1%) compared to the standard technique (low ashing temperature). The possible expanded application of this CRM application in national laboratories, beyond the certificated and reference parameters, has advantages such as lower cost and easy availability, but round robin tests must be performed.

Remoção de compostos fenólicos de soluções aquosas utilizando carvão ativado preparado a partir do aguapé (Eichhornia crassipes): estudo cinético e de equilíbrio termodinâmico

Activated carbon was produced from the water hyacinth (CAA) by impregnation with ZnCl2 (1:2), followed by pyrolysis at 700 ºC, under N2. CAA was used for the adsorption of phenol, m-cresol and o-cresol from aqueous solutions, using batch adsorption. The effects of contact time, pH, temperature and concentration on sorption were investigated. Adsorption capacity, calculated using the Langmuir model proved to be dependent on temperature, reaching values of 163.7, 130.2 and 142.3 mg g-1 for phenol, m-cresol and o-cresol, respectively, at 45 ºC. Thermodynamic data at the solid-liquid interface suggests an endothermic, spontaneous and environmentally-friendly process.

Análise dos produtos de degradação do esfenvalerato por SBSE/CLAE-UV/DAD utilizando planejamento fatorial fracionário

A simple procedure based on stir bar sorptive extraction and high-performance liquid chromatography-ultraviolet/photodiode array detection (SBSE/LC-UV/PAD) to determine intermediates and by-products of esfenvalerate is described. The influence of organic modifier, ionic strength, extraction time, temperature and pH were simultaneously evaluated by using a factorial experimental design. The utilization of different organic solvents and desorption times were also investigated to establish the optimal conditions for SBSE liquid desorption. Among the ten different peaks (intermediates and by-products) detected after degradation of esfenvalerate, eight (including 3-phenoxybenzoic acid and 3-phenoxybenzaldehyde) were successfully extracted by SBSE under the optimized conditions.

Experimento didático de quimiometria para planejamento de experimentos: avaliação das condições experimentais na determinação espectrofotométrica de ferro II com o-fenantrolina. Um tutorial, parte III

The objective of this manuscript is to describe a practical experiment that can be employed for teaching concepts related to design of experiments using Matlab or Octave computing environment to beginners, undergraduate and graduate students. The classical experiment for determination of Fe (II) using o-phenanthroline was selected because it is easy to understand, and all the required materials are readily available in most analytical laboratories. The approach used in this tutorial is divided in two steps: first, the students are introduced to the concept of multivariate effects, how to calculate and interpret them, and the construction and evaluation of a linear model to describe the experimental domain by using a 2³ factorial design. Second, an extension of the factorial design by adding axial points is described, thereby, providing a central composite design. The quadratic model is then introduced and used to build the response surface.

Estudo da liberação controlada do herbicida ametrina em compósitos à base de PVA: carvão ativado

Herbicides have great importance in agricultural productivity for weed control, given their competition with crops. However, inadequate application of herbicides may lead to environmental problems, which can be minimized through controlled release of the active compounds. This may be achieved by protecting the herbicide in a structure with adequate porosity, where the diffusional behavior can determine release. Thus, in this study we evaluated a novel structure, a composite based on activated carbon bonded by polyvinyl alcohol (PVA) as pellets, to deliver a triazine herbicide. The product obtained was shown to be adequate for its purpose, since it was possible to process regular pellets, where the PVA percentage determined the properties.

Remoção do ácido mefenâmico em água utilizando carvão ativado em pó, lama vermelha e oxidação com cloro

The use of activated carbon powder (ACP), red mud and oxidation with chlorine to remove mefenamic acid in water are described, aimed at their application as a complement to sewage treatment processes in Brazil. A study on the behavior of mefenamic acid in water was performed by evaluating its dissolution for different concentrations and times. Subsequently, the optimal conditions for removal of mefenamic acid were investigated using ACP adsorption at different pH and concentrations, and red mud adsorption using different pH. The utilization of different pH and times was also investigated to establish the ideal conditions for chemical oxidation of the drug. Among the different conditions studied, the best condition for drug removal by ACP and red mud were 100% and 96%, respectively, while the best condition for chemical oxidation occurred using solutions with pH 6 and 7 and reaction times of 30 and 60 minutes.

ANÁLISE EXPLORATÓRIA DAS CONCENTRAÇÕES DOS METAIS NA, CA, MG, SR E FE EM EXTRATO AQUOSO DE PETRÓLEO, DETERMINADOS POR ICP OES, APÓS OTIMIZAÇÃO EMPREGANDO PLANEJAMENTO DE EXPERIMENTOS

AbstractThe purpose of this study was to evaluate the best operating conditions of ICP OES for the determination of Na, Ca, Mg, Sr and Fe in aqueous extract of crude oil obtained after hot extraction with organic solvents (ASTM D 6470-99 modified). Thus, the full factorial design and central composite design were used to optimize the best conditions for the flow of nebulization gas, the flow of auxiliary gas, and radio frequency power. After optimization of variables, a study to obtain correct classification of the 18 samples of aqueous extract of crude oils (E1 to E18) from three production and refining fields was carried out. Exploratory analysis of these extracts was performed by principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA), using the original variables as the concentration of the metals Na, Ca, Mg, Sr and Fe determined by ICP OES.

TRATAMENTO DA VINHAÇA POR ADSORÇÃO EM CARVÃO DE BAGAÇO DE CANA-DE-AÇÚCAR

The aim of this study was to develop an effective and economically viable technology for the treatment of vinasse, prior to its disposal in the soil for fertirrigation, aiming this way at reducing the environmental impacts generated by inadequately discarding this effluent. The primary treatment of vinasse by adsorption was evaluated. Adsorbents were prepared from sugar cane bagasse and their efficiency evaluated in relation to the treatment of vinasse. The process of preparation of activated carbon consisted of carbonizing bagasse at different temperatures followed by chemical activation with NaOH. The carbon samples obtained by solely carbonizing sugar cane bagasse were more efficient for removing turbidity of vinasse than samples activated with NaOH. The sample carbonized at 800 °C was the most efficient for removing turbidity of wastewater (83%). During a process of adsorption of vinasse in two stages, it was possible to obtain color removal, turbidity and COD of approximately 76, 85 and 69%, respectively. After the adsorption step of vinasse, the solid waste generated in the second stage of adsorption can be burned in the boilers of the power plant itself, affording an energy of 4606 cal g-1.

USO DO PLANEJAMENTO EXPERIMENTAL PARA OTIMIZAÇÃO DE UM PROCEDIMENTO VOLTAMÉTRICO PARA DETERMINAÇÃO SIMULTÂNEA DAS CONCENTRAÇÕES DOS METAIS Zn, Cd, Pb E Cu LIVRES EM ÁGUA DE COCO

Optimization of the main parameters of SWASV using boron-doped diamond electrode was described for the simultaneous determination of Zn, Cd, Pb and Cu free in coconut water. The values of electroanalytical parameters studied were optimized with the factorial design and center composite design. The optimized parameters for the preconcentration of metals were -1.50 V for potential, and 240 s for deposition time. For SWV, the optimized value was 11.56 mV for step potential. In addition, frequency and pulse height were defined at 100 Hz and 55 mV, respectively. Furthermore, the concentration of the supporting electrolyte (acetate buffer, pH 4.7) was optimized in 0.206 mol L-1. The optimized procedure was applied in two samples of coconut water: natural and processed. The limits of detection (LOD) obtained for Zn, Cd, Pb and Cu were 7.2; 4.4; 3.3 and 1.5 µg L-1, respectively. The concentrations of Cd and Pb were not detected. On the other hand, the values found for the concentrations of Zn and Cu were: < LOD (29 µg L-1) and (6.8 ± 0.9) µg L-1 for the natural sample; and (85.8 ± 4.2) µg L-1 and (7.7 ± 0.6) µg L-1 for the processed sample, respectively.