Estudo da Fotodegradação solar do corante azul de metileno e do efluente têxtil por H2O2/UV

Abstract

The color removal of effluents from the textile industry is a major challenge, as conventional treatment is often insufficient to promote satisfactory levels of discoloration. The objective of this work was to evaluate the efficiency of the homogeneous photocatalysis process using hydrogen peroxide (H2O2) in the degradation and discoloration of the methylene blue (MB) dye and a textile effluent. In the first step, factorial design 2³ was used in a simple solution of MB in order to optimizethe interfering variables in the photocatalysis process (pH, H2O2concentration and time). In the second step, the discoloration of the textile effluent (Color Pt Co) and the organic matter removal through COD were verified. In the last step, the elimination of residual peroxide was analyzed through the following processes: a) Partial dosing of H2O2, b) heating and c) use of bisulfite inhibitor (NaHSO3). The results of the first step showed that the MB dye reached maximum removal concentration (100%) in the test performed with [H2O2] = 510 mg.L-1,300 minutes exposure to solar radiation and pH = 9. In the second step, the best condition obtained was 65,64% of color reduction for the textile effluent occurred at pH = 9, with 720 mg.L-1of H2O2 and 300 minutes of reaction. In terms of COD of the textile effluent, a reduction of 62% was achieved with [H2O2] = 720 mg.L-1, 180 minutes reaction and pH = 5. In the last step, it was found that only the process that used inhibitor (NaHSO3) was able to remove the H2O2 residual in the assays tested. The homogeneous photocatalysis process (H2O2/UV) was shown to be a promising technique in reducing the color of the methylene blue dye and the textile effluent. However, as the textile effluent is more complex than methylene blue, it requires analysis of other variables for an effective treatment of the effluent.