Estudo da fotodegradação da matéria orgânica presente em esgoto doméstico utilizando TiO2, Nb2O5 e WO3

Abstract

The current demand for water supplies faces the diminishing availability of water resources that can be used on a daily basis. In this case, treating domestic sewage is an indispensable task, as it enables the reuse of water for various purposes, as well as avoiding possible contamination of the environment and the population. Since sanitary sewage is composed mainly of organic matter, the present work proposes the use of heterogeneous photocatalysis for the degradation of these substances. To this end, a synthetic sewage solution was fed to a batch photocatalytic reactor under constant agitation and exposure to sunlight in order to define the best operating conditions with regard to the efficiency of the photocatalysts and their respective concentrations. TiO2, WO3 and Nb2O5 at concentrations of 0.25, 0.50, 0.75 and 1.0 mg L-1 and pH set at 3.0 were tested to determine the best conditions for the reaction to occur. Aliquots were collected every 40 min for a total reaction time of 4 hours. The samples were filtered and had their biochemical oxygen demands analyzed. At the lowest concentration in study, Nb2O5 showed the best removal of organic matter, probably due to its higher capacity for contaminant adsorption. At the other concentrations, TiO2 was more efficient, culminating in a removal of 40.93% at a concentration of 1.0 mg L-1. Regarding the kinetic study, a predominance of zero order kinetics was observed, showing that the degradation was not always proportional to the increase in the catalyst concentration.