Degradation of organic contaminants in effluents-synthetic and from the textile industry-by Fenton, photocatalysis, and H2O2 photolysis

Abstract

In this study, the oxidation of the dye rhodamine B (RhB), present in a synthetic effluent, and the degradation of organic matter present in a textile effluent, were assessed by photolysis (H2O2, UV), homogeneous Fenton (Fe2+, H2O2), and photocatalysis (TiO2, UV). The results showed that photolysis and Fenton had an efficiency of 100 % and photocatalysis, 96 %, to discoloration 10 mg L−1 RhB, present in the synthetic effluent. The best experimental conditions determined for these reactions showed that the one performed with 51 mg L−1 H2O2 and UV light had the best results, where 100 % of RhB was discolored in only 6 min of reaction. The optimum conditions determined in the first part of this study for the RhB oxidation did not show satisfactory results for the degradation of organic matter present in the textile effluent sample, and it was necessary to increase the amount of reagents in the three processes. After resizing the concentration of the reagents for the reactions with the textile effluent, the following reductions of color, total organic carbon (TOC), and total soluble solids (SS) were obtained: photocatalysis 29, 25, and 32 %; photolysis 85, 69, and 35 %; Fenton 98, 90, and 23 %; and biological (followed by physicochemical) treatment carried out by the textile industry 96, 48, and 9 %. It is observed that the Fenton reaction showed the best result, followed by photolysis reaction, a treatment carried out by industry and, at last, photocatalysis.