600 resultados para Glicerina - Purificação


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The synthesis of zeolites from natural sources of silicon and aluminum are promising alternative routes to obtain porous or zeolite MCM family. Such materials are typically used in catalytic processes and / or adsorption is to obtain new products or for separation and purification processes thereof. Environmental legislation is becoming stricter and requires the use of materials more efficient, aiming to achieve pollution prevention, by gas or liquid contaminants in the environment. In order to obtain a material with environmentally friendly features, this study aimed at the synthesis of zeolite A, from an amorphous sediment, diatomite, which is found in abundance in the northeast region of Brazil, may be substituted for conventional products the production of zeolite, involving higher costs. The methodology for obtaining the "Zeolite A" using as a source of silica and alumina diatomite is simple, since this is a source of silicon, not requiring therefore a structural driver, but also by heat treatment, only drying conventional to remove water. The "zeolite A" was obtained from diatomite, but as an intermediate step we obtained the sodalite. The characterization was made by the following techniques: EDX, XRD, FT-IR, SEM and determining a specific area by the BET method and the BJH method for checking the diameter of pores. By characterization of the obtained material was first demonstrated the achievement of sodalite and after modification of the same, there was obtained zeolite A

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação de mestrado, Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2014

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação de Mestrado, Oncobiologia: Mecanismos Moleculares do Cancro, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2015

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação de Mestrado, Oncobiologia: Mecanismos Moleculares do Cancro, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2015

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tese de dout. em Química, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2002

Relevância:

10.00% 10.00%

Publicador:

Resumo:

El reemplazo de terapéutica de tipo alópata por agentes naturales resulta una alternativa para pacientes con compromiso sistémico o síndrome de polifarmacia. El propóleo constituye una opción debido a sus propiedades antimicrobianas, analgésica y antiinflamatorias. Debido a las características bioquímicas de la mucosa oral es necesario emplear un vehículo para su colocación y aprovechar las propiedades del propóleo. En este estudio se propone la utilización de un gel a base de carbopol 934, trietanolamina y glicerina como vehículo. MATERIALES Y MÉTODOS. Se elaboró el gel base mediante la fusión de 100 ml de agua desmineralizada, glicerina 3.5 g y 1 g de carbopol 934 P. Pasadas 24 horas se incorporó trietanolamina 50% 0.8 g hasta lograr un pH 7. En una proporción 1:1 se adiciona lentamente el extracto de propóleo 65% al gel base. RESULTADOS. Al evaluar la consistencia del producto se oservó una mezcla homogénea, sin embargo al dejarlo en reposo se observó tres horas después un decaimiento en la viscosidad del mismo. CONCLUSIONES. Es necesario reevaluar los componentes del gel base con el fin de lograr una mucoadhesión deseada así como mejorar las propiedades físicas del mismo.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Brazil has vast amounts of hydric resources, whose quality has been deteriorating due to pollutant dumping. Household waste disposal is one of the main sources of water pollution, stimulating bacteria proliferation and introducing microorganisms, including those from fecal matter. Conventional water disinfection methods are a solution, but on the downside, they lead to the formation byproducts hazardous to human health. In this study, aiming to develop bactericidal filters for the disinfection of drinking water; silver nanoparticles were deposited on alumina foams through three routes: sputtering DC, dip coating and in situ chemical reduction of silver nitrate. The depositions were characterized through X-ray diffraction, scanning electron microscopy and EDS element mapping. The influence of the depositions on permeability and mechanical properties of the ceramic foams was assessed and, in sequence, a preliminary antibacterial efficiency analysis was carried out. Characterization results indicate that the chemical reduction routes were efficient in depositing homogeneously distributed silver particles and that the concentration of the metallic precursor salt affects size and morphology of the particles. The antibacterial efficiency analysis indicates that the chemical reduction filters have potential for water disinfection

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Sugar esters are substances which possess surfactant, antifungical and bactericidal actions and can be obtained through two renewable sources of raw materials: sugars and vegetable oils. Their excellent biodegradability, allied to lhe fact that they are non toxic, insipid, inodorous, biocompatible, no-ionic, digestible and because they can resist to adverse conditions of temperature, pH and salinity, explain lhe crescent use of these substances in several sections of lhe industry. The objective of this thesis was to synthesize and characterize surfactants and polymers containing sugar branched in their structures, through enzymatic transesterification of vinyl esters and sugars, using alkaline protease from Bacillus subtilis as catalyst, in organic medium (DMF).Three types of sugars were used: L-arabinose, D-glucose and sucrose and two types of vinyl esters: vinyl laurate and vinyl adipate. Aiming to reach high conversions from substrates to products for a possible future large scale industrial production, a serie of variables was optimized, through Design of Experiments (DOE), using Response Surface Methodology (RSM).The investigated variables were: (1) enzyme concentration; (2) molar reason of substrates; (3) water/solvent rale; (4) temperature and (5) time. We obtained six distinct sugar esters: 5-0-lauroyl L-arabinose, 6-0-lauroyl D-glucose, 1'-O-lauroyl sucrose, 5-0-vinyladipoyl L-arabinose, 6-0-vinyladipoyl D-glucose and 1 '-O-vinyladipoyl sucrose, being lhe last three polymerizable. The progress of lhe reaction was monitored by HPLC analysis, through lhe decrease of sugar concentration in comparison to lhe blank. Qualitative analysis by TLC confirmed lhe formation of lhe products. In lhe purification step, two methodologies were adopted: (1) chromatographic column and (2) extraction with hot acetone. The acylation position and lhe chemical structure were determined by 13C-RMN. The polymerization of lhe three vinyl sugar esters was possible, through chemical catalysis, using H2O2 and K2S2O8 as initiators, at 60°C, for 24 hours. IR spectra of lhe monomers and respective polymers were compared revealing lhe disappearance of lhe vinyl group in lhe polymer spectra. The molar weights of lhe polymers were determined by GPC and presented lhe following results: poly (5-0-vinyladipoyl L-arabinose): Mw = 7.2 X 104; PD = 2.48; poly (6-0-vinyladipoyl D-glucose): Mw = 2.7 X 103; PD = 1.75 and poly (1'-O-vinyladipoyl sucrose): Mw = 4.2 X 104; PD = 6.57. The six sugar esters were submitted to superficial tension tests for determination of the critical micelle concentrations (CMC), which varied from 122 to 167 ppm. Finally, a study of applicability of these sugar esters, as lubricants for completion fluids of petroleum wells was' accomplished through comparative analysis of lhe efficiency of these sugar esters, in relation to three commercial lubricants. The products synthesized in this thesis presented equivalent or superior action to lhe tested commercial products

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Biodiesel is an alternative fuel, renewable, biodegradable and nontoxic. The transesterification of vegetable oils or animal fat with alcohol is most common form of production of this fuel. The procedure for production of biodiesel occurs most commonly through the transesterification reaction in which catalysts are used to accelerate and increase their income and may be basic, acid or enzyme. The use of homogeneous catalysis requires specific conditions and purification steps of the reaction products (alkyl ester and glycerol) and removal of the catalyst at the end of the reaction. As an alternative to improve the yield of the transesterification reaction, minimize the cost of production is that many studies are being conducted with the application of heterogeneous catalysis. The use of nano-structured materials as catalysts in the production of biodiesel is a biofuel alternative for a similar to mineral diesel. Although slower, can esterify transesterified triglycerides and free fatty acids and suffer little influence of water, which may be present in the raw material. This study aimed at the synthesis, characterization and application of nano-structured materials as catalysts in the transesterification reaction of soybean oil to produce biodiesel by ethylic route. The type material containing SBA-15 mesoporous lanthanum embedded within rightly Si / La = 50 was used catalyst. Solid samples were characterized by X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, nitrogen adsorption and desorption. For the transesterification process, we used a molar ratio of 20:1 alcohol and oil with 0.250 g of catalyst at 60°C and times of 6 hours of reaction. It was determined the content of ethyl esters by H-NMR analysis and gas chromatography. It was found that the variable of conversion obtained was 80%, showing a good catalytic activity LaSBA-15 in the transesterification of vegetable oils via ethylic route

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Molecular, 2016.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação (mestrado)—Universidade de Brasília, Faculdade UnB Planaltina, Mestrado em Ciências de Materias, 2016.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tese (doutorado)–Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2015.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Since the beginning of the National Program for Production and Use of Biodiesel in Brazil, in 2004, different raw materials were evaluated for biodiesel production, trying to combine the agricultural diversity of the country to the desire to reduce production coasts. To determine the chemical composition of biodiesel produced from common vegetables oils, international methods have been used widely in Brazil. However, for analyzing biodiesel samples produced from some alternative raw materials analytical problems have been detected. That was the case of biodiesel from castor oil. Due the need to overcome these problems, new methodologies were developed using different chromatographic columns, standards and quantitative methods. The priority was simplifying the equipment configuration, realizing faster analyses, reducing the costs and facilitating the routine of biodiesel research and production laboratories. For quantifying free glycerin, the ethylene glycol was used in instead of 1,2,4-butanetriol, without loss of quality results. The ethylene glycol is a cheaper and easier standard. For methanol analyses the headspace was not used and the cost of the equipment used was lower. A detailed determination of the esters helped the deeper knowledge of the biodiesel composition. The report of the experiments and conclusions of the research that resulted in the development of alternative methods for quality control of the composition of the biodiesel produced in Brazil, a country with considerable variability of species in agriculture, are the goals of this thesis and are reported in the following pages

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Uma vez que as técnicas cromatográficas permitem a separação, quantificação e identificação dos compostos organicos parentais e dos produtos de degradação e, considerando-se que a maioria dos fungicidas benzimidazois absorvem fortemente a luz ultra-violeta, testou-se o método de Cromatografia Liquida de Alta Eficiência (CLAE), para quantificar a biodegradabilidade do fungicida carbendazim. Neste experimento foi utilizada uma linhagem de Alternaria alternata isolada de solos agrícolas suplementados com benomil. Os frascos com os microorganismos crescidos foram repicados para frascos contendo meios de cultura batata-dextrose (50%) + carbendazim (100mg/ml). Estes foram incubados sob agitacao a 28oC mais ou menos 1oC por períodos de 2,4,7,15 e 30 dias. Apos extração e purificação das amostras procedeu-se a analise cromatográfica. Para tanto utilizou-se uma coluna de troca cationica nas seguintes condições: temperatura da coluna: 40oC, fase móvel: fosfato de amônio 0,0125M com fluxo de 0,2ml por minuto e detector de absorbância operando a 280nm. Sob estas condições, o tempo de retenção de carbendazim e 2 amino-benzimidazol foi de aproximadamente 4,5 e 6,3 minutos, respectivamente. A quantificação foi feita utilizando-se regressão linear de curvas de calibração obtidas em soluções padrões de carbendazim versus a resposta (altura ou área do pico), obtida no cromatograma. A confirmação da identidade do pico com alto grau de confiança foi possível pela comparação do tempo de retenção e o espectro de absorbância em ultra-violeta do carbendazim. Este espectro, em diferentes condições de cultivo de A alternata, indicou índices de similaridade da molécula variando de 0,99 a 1 entre as diferentes amostras. Por este método foram obtidas recuperações acima de 70% da concentração inicial de carbendazim. A degradação de carbendazim foi de 66,4% aos dois dias de incubação.