DECOLORIZATION OF TEXTILE DYE REACTIVE BLUE 19 IN WATER BY UV/H2O2 PROCESS

摘要

Textile industry is a significant consumer of water and producer of contaminated waste streams. The appearance of color and aromatic compounds in textile wastewater is a very important problem. Advance oxidation processes (AOPs), presented by system UV/oxidizing agent, have been found to be very effective in the degradation of dye pollutants. Decolorization and dye degradation occurs due to the hydroxyl radicals generated in AOP. This study deals with decolorization of textile dye Reactive Blue 19 (RB19) in water by UV/H_2O_2 process. Photochemical decolorization of the dye Reactive Blue 19 has been carried out in the batch mode UV photoreactor, with low pressure mercury lamps (A = 254 nm). The effect of time, pH solution, the UV light dose and acetate anion has been studied, as parameters that strongly influence the decolorization and degradation of the dye RB19. The change of the dye concentration was examined by UV-vis spectrophotometric measurement. The results of spectrum scanning of RB19 show that characteristic absorption peak in the visible region disappeared very fast, in less than 15 min. Decolorization of the RB19 depends of intensity of UV light. The decolorization rate increase with increasing UV light intensity with linear relationship and reached maximal value at the highest applied intensity. At high UV light intensity more hydroxyl radicals are produce upon the photodissociation of H_2O_2, hence decolorization rate increase. The effect of pH at the photodecolorization of the RB19 was investigated in range from 2 up to 12. It was found that pH has specific influence. Obtained result, different of pH effect at other textile dyes, is probably consequence of pH influence at both dye and peroxide, and need detailed investigation. The effect of acetate anion at decolorization efficacy was investigated at pH 7 in wide concentration range. This effect is considered very important, because acetate anion is one of the main UV/H_2O_2 mineralization products of organic compounds. Acetate anions show strong inhibition effect, especially at relatively low concentrations from 1 to 50 mM. With further increase of concentration up to 400 mM inhibition effect decrease photochemical degradation of the dye RB19 by UV/H_2O_2 process proved as an attractive .means for treatment of wastewaters from textile industry. The results of this study clearly demonstrate the importance of choosing the optimum degradation parameters to obtain a high degradation rate, which is essential for any practical application of UV/H_2O_2 process.