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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Estudo dos par?metros de extra??o de fenol de efluentes aquosos por um tensoativo n?o i?nico / Study of phenol extraction parameters of aqueous effluents by a non-ionic surfactant

Silva, Wanessa Paulino Neves 20 July 2012 (has links)
Made available in DSpace on 2014-12-17T15:01:29Z (GMT). No. of bitstreams: 1 WanessaPNS_DISSERT_PARCIAL.pdf: 561641 bytes, checksum: a77873b2962f7c4cd011f5b8eea3fa7f (MD5) Previous issue date: 2012-07-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Environmental sustainability has become one of the topics of greatest interest in industry, mainly due to effluent generation. Phenols are found in many industries effluents, these industries might be refineries, coal processing, pharmaceutical, plastics, paints and paper and pulp industries. Because phenolic compounds are toxic to humans and aquatic organisms, Federal Resolution CONAMA No. 430 of 13.05.2011 limits the maximum content of phenols, in 0.5 mg.L-1, for release in freshwater bodies. In the effluents treatment, the liquid-liquid extraction process is the most economical for the phenol recovery, because consumes little energy, but in most cases implements an organic solvent, and the use of it can cause some environmental problems due to the high toxicity of this compound. Because of this, exists a need for new methodologies, which aims to replace these solvents for biodegradable ones. Some literature studies demonstrate the feasibility of phenolic compounds removing from aqueous effluents, by biodegradable solvents. In this extraction kind called "Cloud Point Extraction" is used a nonionic surfactant as extracting agent of phenolic compounds. In order to optimize the phenol extraction process, this paper studies the mathematical modeling and optimization of extraction parameters and investigates the effect of the independent variables in the process. A 32 full factorial design has been done with operating temperature and surfactant concentration as independent variables and, parameters extraction: Volumetric fraction of coacervate phase, surfactant and residual concentration of phenol in dilute phase after separation phase and phenol extraction efficiency, as dependent variables. To achieve the objectives presented before, the work was carried out in five steps: (i) selection of some literature data, (ii) use of Box-Behnken model to find out mathematical models that describes the process of phenol extraction, (iii) Data analysis were performed using STATISTICA 7.0 and the analysis of variance was used to assess the model significance and prediction (iv) models optimization using the response surface method (v) Mathematical models validation using additional measures, from samples different from the ones used to construct the model. The results showed that the mathematical models found are able to calculate the effect of the surfactant concentration and the operating temperature in each extraction parameter studied, respecting the boundaries used. The models optimization allowed the achievement of consistent and applicable results in a simple and quick way leading to high efficiency in process operation. / A sustentabilidade ambiental tem se tornado um dos temas de maior interesse nas ind?strias, principalmente devido ? gera??o de efluentes. Os fen?is s?o encontrados em efluentes de v?rias ind?strias, como em refinarias, processamento de carv?o, ind?strias farmac?uticas, de pl?sticos, de tintas e de papel e celulose. Devido os compostos fen?licos serem compostos t?xicos ao ser humano e tamb?m a organismos aqu?ticos, a Resolu??o Federal CONAMA n? 430, de 13/5/2011 limita o teor m?ximo de fen?is, para lan?amento em corpos de ?gua doce, em 0,5 mg.L-1. No processo de tratamento desses efluentes, o processo de extra??o l?quido-l?quido ? o processo mais econ?mico para a recupera??o do fenol, pois consome pouca energia, mas, na maioria das vezes, implementa um solvente org?nico, sendo que o uso deste pode acarretar certos problemas ambientais, decorrentes da alta toxicidade que ele apresenta. Devido a isto, existe a necessidade de desenvolver novas metodologias, as quais visem a substitui??o destes solventes por compostos biodegrad?veis. Alguns trabalhos da literatura comprovam a viabilidade da remo??o de compostos fen?licos de efluentes aquosos, atrav?s de solvente biodegrad?vel. Nesse tipo de extra??o denominada Extra??o Ponto Nuvem ? utilizado um tensoativo n?o i?nico como agente extrator dos compostos fen?licos. Visando otimizar o processo de extra??o de fenol, o presente trabalho aborda a modelagem matem?tica e otimiza??o dos par?metros da extra??o e investiga o efeito das vari?veis independentes no processo. Foi empregando um delineamento fatorial 32 completo que teve como vari?veis independentes a temperatura de opera??o e a concentra??o de tensoativo e, como vari?veis dependentes, os par?metros de extra??o: Fra??o volum?trica da fase coacervato, concentra??o residual de tensoativo e de fenol na fase dilu?da ap?s a separa??o de fases e efici?ncia de extra??o do fenol. Para se alcan?ar os objetivos, o trabalho foi realizado em cinco etapas: (i) sele??o de alguns dados da literatura; (ii)aplica??o do modelo Box-Behnken para encontrar modelos matem?ticos que descrevem o processo de extra??o de fenol; (iii) C?lculo da ANOVA com aux?lio do programa STATISTICA 7.0 para avaliar a signific?ncia e predi??o dos modelos; (iv) Otimiza??o dos modelos atrav?s de superf?cies de respostas; (v) Valida??o dos modelos matem?ticos a partir da tomada de medidas adicionais, com amostras diferentes das utilizadas na obten??o dos modelos. Os resultados obtidos mostraram que os modelos matem?ticos encontrados s?o capazes de calcular o efeito da concentra??o do tensoativo e da temperatura de opera??o em cada par?metro de extra??o estudado, respeitando as faixas trabalhadas. A otimiza??o dos modelos obtidos permitiu de forma simples e r?pida resultados coerentes e aplic?veis na opera??o para se alcan?ar resultados elevados de efici?ncia

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