In this work the preparation and characterization of a supported catalyst intended for degradation of reactive dyes by Fenton-like processes is described. The photocatalyst was prepared by immobilization of Fe3+ into the molecular sieve (4A type) surface and characterized by x-ray diffractometry and infrared, Mössbauer and EPR spectroscopy. The solid containing 0.94% (w/w) of ferric ions was used in degradation studies of aqueous reactive-dyes samples with really promissory results. Generally, Vis-assisted photochemical processes leads to almost total decolorization of all tested dyes at reaction times lower than 30 min. It was also observed that the iron-molecular sieve matrix can be reused.

Neste trabalho, a potencialidade de processos fotoeletroquímicos frente ao tratamento de líquidos lixiviados de aterro sanitário foi avaliada. Em primeiro lugar, foi observado que a forte coloração e elevada carga orgânica apresentada pela matriz dificultam significativamente a ocorrência de processos fotoquímicos. Neste caso, a capacidade degradativa do sistema é devida fundamentalmente à componente eletroquímica, provavelmente processos indiretos viabilizados pela geração de elevadas quantidades de hipoclorito. Em geral, a aplicação de processos de precipitação preliminares permite uma redução da cor e da carga orgânica, o que viabiliza o tratamento fotoeletroquímico posterior. Quando substâncias húmicas são previamente eliminadas por precipitação em meio ácido, o tratamento fotoeletroquímico posterior permite descolorações superiores a 95% e remoções de DQO da ordem de 70%, em tempos de reação de 300 min. Trata-se de um resultado bastante promissor, levando-se em consideração a elevada resistência da matriz em questão.

In this work the potentiality of photoelectrochemical processes toward the treatment of landfill leachates was evaluated. Firstly, was observed that the dark coloration and high organic content of the samples hinder in a significant way the occurrence of photochemical processes. At these conditions, the degrading capacity of the system is a function of the electrochemical process, provably indirect mechanisms mediating by the observed high amount of hipochlorite. Generally, the application of a preliminary precipitation processes induces significant reduction on the color and organic content, fact that improves the further photoelectrochemical treatment. When humic substances are previously eliminated by acid precipitation the further photoelectrochemical treatment permit almost total elimination of the color and COD removal of about 70% at reaction time of 300 min. That is a very promissory result, mainly taking into account the high recalcitrant character of the landfill leachates.