Utilização de microemulsões como agentes modificadores de superfícies para remoção de íons metálicos

The heavy metals are used in many industrial processes and when discharged to the environment can cause harmful effects to human, plants and animals. The adsorption technology has been used as an effective methodology to remove metallic ions. The search for new adsorbents motivated the development of this research, accomplished with the purpose of removing Cr (III) from aqueous solutions. Diatomite, chitosan, Filtrol 24TM and active carbon were used as adsorbents. To modify the adsorbent surface was used a bicontinuous microemulsion composed by water (25%), kerosene (25%), saponified coconut oil (10%) and as co-surfactant isoamyl or butyl alcohols (40%). With the objective of developing the best operational conditions the research started with the surfactant synthesis and after that the pseudo-ternary diagrams were plotted. It was decided to use the system composed with isoamyl alcohol as co-surfactant due its smallest solubility in water. The methodology to impregnate the microemulsion on the adsorbents was developed and to prepare each sample was used 10 g of adsorbent and 20 mL of microemulsion. The effect of drying time and temperature was evaluated and the best results were obtained with T = 65 ºC and t = 48 h. After evaluating the efficiency of the tested adsorbents it was decided to use chitosan and diatomite. The influence of the agitation speed, granule size, heavy metal synthetic solution concentration, pH, contact time between adsorbent and metal solution, presence or not of NaCl and others metallic ions in the solution (copper and nickel) were evaluated. The adsorption isotherms were obtained and Freundlich and Langmuir models were tested. The last one correlated better the data. With the purpose to evaluate if using a surfactant solution would supply similar results, the adsorbent surface was modified with this solution. It was verified that the adsorbent impregnated with a microemulsion was more effective than the one with a surfactant solution, showing that the organic phase (kerosene) was important in the heavy metal removal process. It was studied the desorption process and verified that the concentrated minerals acids removed the chromium from the adsorbent surface better than others tested solutions. The treatment showed to be effective, being obtained an increase of approximately 10% in the chitosan s adsorption capacity (132 mg of Cr3+ / g adsorbent), that was already quite efficient, and for diatomite, that was not capable to remove the metal without the microemulsion treatment, it was obtained a capacity of 10 mg of Cr3+ / g adsorbent, checking the applied treatment effectiveness

Estudo da modificação de bentonita para a remoção de fenol em águas produzidas na indústria de petróleo

This study evaluates the inclusion of quaternary ammonium salt, bromide hexadecyl trimethyl ammonium (HDTMA-Br) on sodium bentonite to evaluate their performance on the adsorption of phenol present in produced water. It was observed an increase in d001 samples modified with HDTMA-Br by diffraction of X-rays, showing the intercalation of quaternary ammonium cations in the interlamellar layers of clay. Through the adsorption isotherms could be abserver adsorption behavior of sodium bentonite and organophilic bentonite produced in three different concentrations of HDTMA-Br for adsorption of phenol, which is the main phenolic compound found in the product water. Different concentrations of synthetic solutions of phenol were placed in contact with these adsorbents under the same conditions of agitation and temperature. The adsorbent showed adsorptive favorable, especially the clay modified with the highest concentration of HDTMA-Br, 150% CEC of clay, BEN30-14, with higher amounts of phenol adsorbed per gram of adsorbent (mg.g-1)

Estudo da corrosão no aço carbono 1020 protegido com óleo de coco saponificado: análise físico-química do comportamento químico do tensoativo

Corrosion inhibitors in solution are utilized to minimize processes from corrosion in steel. Of the present dissertation was evaluated the efficiency by inhibition from the surfactant saponified coconut oil (OCS) in the carbon steel 1020 through in linear polarization electrochemistry technique, well as, studied the process from adsorption through from the isotherms from Langmuir, Frumkin and Temkin. The corrosion current was determined through in Tafel extrapolation from the curves in the polarization, and then, was calculated the efficiency in the inhibitor to each concentration and temperature. Were studied four concentrations (12,5 ppm, 25 ppm, 50 ppm, and 75 ppm) in the inhibitor OCS and one in the NaCl salt (10.000 ppm) in six temperatures (301 K, 308 K, 313 K, 318 K, 323 K, and 328 K) in triplicate. By the results obtained observed that the technique applied can evaluated with rapidity and efficiency corrosion inhibitors. In relation to the isotherms, the than best appropriated was the in Langmuir and in the concentrations studied, the that obtained the best efficiency was the concentration of 75 ppm

Estudo da eficácia do tensoativo sorbitano tween 80 veiculado em nanoemulsão contendo óleo de soja, como inibidor de corrosão

Nowadays, the use of chemicals that satisfactorily meet the needs of different sectors of the chemical industry is linked to the consumption of biodegradable materials. In this context, this work contemplated biotechnological aspects with the objective of developing a more environmentally-friendly corrosion inhibitor. In order to achieve this goal, nanoemulsion-type systems (NE) were obtained by varying the amount of Tween 80 (9 to 85 ppm) a sortitan surfactant named polyoxyethylene (20) monooleate. This NE-system was analyzed using phase diagrams in which the percentage of the oil phase (commercial soybean oil, codenamed as OS) was kept constant. By changing the amount of Tween 80, several polar NE-OS derived systems (O/W-type nanoemulsion) were obtained and characterized through light scattering, conductivity and pH, and further subjected to electrochemical studies. The interfacial behavior of these NE-OS derived systems (codenamed NE-OS1, S2, S3, S4 and S5) as corrosion inhibitors on carbon steel AISI 1020 in saline media (NaCl 3.5%) were evaluated by measurement of Open Circuit Potential (OCP), Polarization Curves (Tafel extrapolation method) and Electrochemical Impedance Spectroscopy (EIS). The analyzed NE-OS1 and NE-OS2 systems were found to be mixed inhibitors with quantitative efficacy (98.6% - 99.7%) for concentrations of Tween 80 ranging between 9 and 85 ppm. According to the EIS technique, maximum corrosion efficiency was observed for some tested NE-OS samples. Additionaly to the electrochemical studies, Analysis of Variance (ANOVA) and Principal Component Analysis (PCA) were used, characterization of the nanoemulsion tested systems and adsorption studies, respectively, which confirmed the results observed in the experimental analyses using diluted NE-OS samples in lower concentrations of Tween 80 (0.5 1.75 ppm)

Desenvolvimento de sistema magnético polimérico contendo antimicrobianos para tratamento de infecções por Helicobacter pylori

Helicobacter pylori is the main cause of gastritis, gastroduodenal ulcer disease and gastric cancer. The most recommended treatment for eradication of this bacteria often leads to side effects and patient poor compliance, which induce treatment failure. Magnetic drug targeting is a very efficient method that overcomes these drawbacks through association of the drug with a magnetic compound. Such approach may allow such systems to be placed slowed down to a specific target area by an external magnetic field. This work reports a study of the synthesis and characterization of polymeric magnetic particles loaded with the currently used antimicrobial agents for the treatment of Helicobacter pylori infections, aiming the production of magnetic drug delivery system by oral route. Optical microscopy, scanning electron microscopy, transmission electron microscopy, x-ray powder diffraction, nitrogen adsorption/desorption isotherms and vibrating sample magnetometry revealed that the magnetite particles, produced by the co-precipitation method, consisted of a large number of aggregated nanometer-size crystallites (about 6 nm), creating superparamagnetic micrometer with high magnetic susceptibility particles with an average diameter of 6.8 ± 0.2 μm. Also, the polymeric magnetic particles produced by spray drying had a core-shell structure based on magnetite microparticles, amoxicillin and clarithromycin and coated with Eudragit® S100. The system presented an average diameter of 14.2 ± 0.2 μm. The amount of magnetite present in the system may be tailored by suitably controlling the suspension used to feed the spray dryer. In the present work it was 2.9% (w/w). The magnetic system produced may prove to be very promising for eradication of Helicobacter pylori infections

Enthalpy-entropy compensation based on isotherms of mango

Dados de equilíbrio da umidade da polpa de manga foram determinados utilizando-se o método estático gravimétrico. As isotermas de adsorção e dessorção foram obtidas na faixa de 30-70 ºC e as atividades de água (a w) de 0,02 a 0,97. A utilização do modelo de GAB nos resultados experimentais, através da análise de regressão não linear, proporcionou um bom ajuste entre os dados experimentais e os valores calculados. O calor isostérico de sorção foi estimado a partir dos dados de equilíbrio de sorção, utilizando-se a equação de Clausius-Clayperon. Notou-se que os calores isostéricos de sorção crescem com o aumento da temperatura e pode ser bem ajustado através de uma relação exponencial. A teoria da compensação entalpia-entropia foi aplicada às isotermas de sorção e gráficos deltaH versus deltaS forneceram as temperaturas isocinéticas, indicando um processo de sorção entalpicamente controlado.

Study of adsorption isotherms of green coconut pulp

O Brasil é considerado um dos maiores produtores e consumidores de frutas tropicais. O coco verde (Cocos nucifera L.) se destaca tanto em termos de produção e consumo quanto em quantidade de resíduos gerada por indústrias de água de coco e pelo consumo in natura. Portanto, existe uma necessidade de aproveitamento deste subproduto. Este trabalho teve por objetivo estudar as isotermas de adsorção da polpa de coco verde e determinação do calor isostérico de sorção. As isotermas de adsorção para as temperaturas de 30, 40, 50, 60 e 70 °C foram analisadas e evidenciaram curvas do tipo III, típicas de alimentos ricos em açúcares. Os dados experimentais de umidade de equilíbrio foram correlacionados por modelos da literatura. O modelo de GAB apresentou melhor concordância com os dados experimentais, entre os modelos avaliados. O calor isostérico de sorção é considerado um indicativo de forças atrativas intermoleculares entre os sítios de sorção de vapor de água, consequentemente, um importante fator para predizer a vida de prateleira de produtos desidratados.

Influência do uso do forno de microondas ou convencional na síntese de ZrO2

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Transformação do glicerol em compostos de interesse petroquímico catalisada por zeólitas com ordem hierárquica de poros

Pós-graduação em Química - IQ

Adsorsão e coeficientes de distribuição de selênio em solos do Estado de São Paulo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da secagem de polpa de coco verde em leito de jorro e viabilidade de sua utilização na indústria

Pós-graduação em Engenharia e Ciência de Alimentos - IBILCE

Calcinação e estabilidade térmica de Sílicas mesoporoas preparadas com Pluronic P123

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

Micro-extração em fase sólida de Cu(II) e Cd(II) em meio aquoso utilizando sílica organicamente modificada para quantificação por espectrometria de absorção atômica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades analíticas e eletroanalíticas de um silsesquioxano nanoestruturado organofuncionalizado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese, caracterização e aplicação de filmes a base de óxido de zinco

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)