Avaliação da eficiência do processo oxidativo avançado H2O2/UV na fotodegradação do corante têxtil azul reativo 19

Abstract

Textile industries are characterized by high water consumption and a large volume of liquid waste with a high organic load and high levels of coloring. Among the compounds present in wastewater from this industrial sector, dyes stand out. In this work, the efficiency of the advanced oxidative process H2O2/UV in the degradation of a simulated effluent containing 25 mg.L-1 of textile dye Azul Reativo 19 was evaluated. For this, different concentrations of hydrogen peroxide were tested to identify the concentration most viable of the oxidizing agent. Likewise, H2O2 and UV radiation were applied separately to observe the synergistic effect of the advanced oxidative process. Based on the absorbance data obtained, a kinetic study of the reaction was carried out, showing that it was suitable for a pseudo first order equation, and the electrical energy was also evaluated in order (to assess the energy demand), with results observed satisfactory for the advanced oxidative process of the H2O2/UV type. Bearing in mind that there was total discoloration of the sample within 5 minutes of reaction and with the lowest concentration of H2O2, the analyzes to investigate the toxic effects of the effluent were carried out in this condition and at the final treatment time of 90 minutes. The results of the analysis of total phenols and aromatic groups showed a reduction in the concentration of these parameters over the course of treatment, suggesting that in longer periods of exposure, there would be better results. However, the ecotoxicological test revealed less inhibition of A. salina growth at the beginning of the reaction than at the end, suggesting the production of more toxic intermediates for the species with longer exposure time. The mineralization of the organic load verified by the analysis of total organic carbon, was not very significant, with a 32.4% reduction observed in 90 minutes of treatment. Despite the rapid discoloration, the results obtained suggest the need for further studies in order to optimize the efficiency of removing toxic transient species, especially of a phenolic nature.