Solar photocatalytic degradation of metal complex azo dyes and treatment of dye house waste

摘要

In a laboratory study, the effectiveness of zinc oxide-mediated solar photocatalytic degradation of three metal complex azo dyes (Acidol Yellow, Acidol Grey and Acidol Scarlet) and treatment of a woollen textile dye house waste were examined. A 53-86 percent degradation of the dyes was achieved by 15 mm illumination with a sunlight intensity of 0.5-0.8 kW/m and zinc oxide dose of 1.5 g/L. A 67-93 percent decrease in degradation rate was observed for degradation of the dyes in mixture (simultaneous degradation). It was, however, observed that pre-adsorption was not a necessary prerequisite for degradation. Treatment of the dye house waste containing the three dyes, with zinc oxide (3.0 g/L), reduced colour (89 percent) and COD (63 percent) in 2.75 h illumination. BOD_5/COD ratio increased from 0.43 to 0.66. The study has demonstrated that zinc oxide-mediated solar photocatalytic degradation is a potentially useful method of treatment of dye house waste containing metal complex azo dyes.