Wastewaters from textile industry contain organic dyes, which cannot be easily treated by biological methods. Therefore, pretreatment by an advanced oxidation process (AOP) is needed in order to produce more readily biodegradable compounds and to remove color and chemical oxygen demand (COD) simultaneously. In this research, ozone (O3) is combined with hydrogen peroxide (H2O2) for the advanced oxidation of an azo dye solution, namely aqueous solution of Acid Red 151, which is called as &ldquo / Peroxone process&rdquo / . The aim of the study is to enhance the ozonation efficiency in treating the waste dye solution. The effects of pH, initial dye and initial ozone concentrations and the concentration ratio of initial H2O2 to initial O3 on color and COD removals were investigated. Also, the kinetics of O3-dye reaction in the presence of H2O2 was approximately determined. As a result of the experimental study, it was seen that an increase in the initial dye concentration at a constant pH and initial ozone concentration did not change the COD % removal significantly, from a statistical analysis of the data. The results obtained at pH values of 2.5 and 7 gave higher oxidation efficiencies in terms of color and COD removals compared to those at pH of 10. The best initial molar ratio of H2O2 to O3 was found to be 0.5, which yielded highest treatment efficiency for each pH value studied. The results of the excess dye experiments suggest that the ozonation of Acid Red 151 follows an average first order reaction with respect to ozone at pH=2.5 and pH=7 whereas it is around 0.56 at pH=10. By Initial Rate Method, the orders with respect to individual reactants of O3 and dye were determined as one, the total order of the reaction being two for all the studied pH. As a conclusion, a further study of the peroxone process at a pH of 10 can be recommended to determine the reaction kinetics and mechanism at this pH, where radicals play an important role.

Orientador: Ederio Dino Bidoia / Resumo: Os efluentes têxteis têm capacidade de proporcionar cor à água de rios e lagos devido aos corantes presentes em sua composição. Além dos problemas estéticos, outros compostos presentes nestes tipos de efluentes podem ser tóxicos à vida aquática. Os processos oxidativos avançados (POA) vem sendo estudados devido a vantagem de serem mais rápidos, produzirem menos resíduos e não demandarem de grandes áreas de instalação quando se comparado a tratamentos convencionais. Este trabalho teve como objetivo a degradação de efluentes simulados contendo o corante Acid blue 40, o corante Acid red 151 e efluente misto contendo ambos os corantes por tratamento eletrolítico utilizando eletrodo de titânio recoberto por titânio/rutênio (70%TiO2/30%RuO2) com área de 40 cm² em um sistema de recirculação. Foi realizado planejamento experimental e por meio de análise de superfície de resposta, configurações de tratamentos otimizados foram realizadas. Foram realizadas análises de espectrofotometria, DQO, DBO, Cor, pH, cloro residual livre e condutividade durante os processos de tratamento. Análise de espectro de infravermelho com transformada de Fourier (FTIR) foi realizada de todos os tratamentos. Foi também verificada a geração de clorofórmio por meio de análise de cromatografia gasosa e espectrometria de massa (GC-MS). Testes de ecotoxicidade com sementes de alface (Lactuca sativa) e rúcula (Eruca sativa) e com o microcrustáceo Artemia salina foram realizados durante os tratamentos. Teste de mut... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The textile effluents have the capacity to provide color to water from rivers and lakes due to the dyes present in their composition. In addition to aesthetic problems, other compounds present in these types of effluents can be toxic to the aquatic life. The advanced oxidative processes (AOP) have been studied due to the advantage of being faster, producing less waste and not having to spend large areas of installation when compared to conventional treatments. This work aimed at the degradation of simulated textile effluents containing the Acid blue 40 dye, Acid red 151 dye and a mixed effluent containing both dyes by electrolytic treatment using a titanium electrode covered by titanium/ruthenium (70%TiO2/30%RuO2) with an area of 40 cm² in a recirculating system. Experimental design was realized by the response surface the optimized configurations of the treatments were performed. Analysis of spectrophotometry, COD, BOD, color, pH, free residual chlorine and conductivity were performed during the treatment processes. Fourier transformed infrared spectrum analysis (FTIR) were performed in all treatments. The generation of chloroform was investigated by analysis of gas chromatography and mass spectrometry (GC-MS). Ecotoxicity tests with seeds of lettuce (Lactuca sativa) and arugula (Eruca sativa) and with the microcrustacean Artemia salina were performed for during treatments. Mutagenicity test was performed using the D7 strain of the yeast Saccharomyces cerevisiae. The optimiz... (Complete abstract click electronic access below) / Doutor