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

Abstract

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% degradation of the dyes was achieved by 15 min illumination with a sunlight intensity of 0.5-0.8 kW/m² and zinc oxide dose of 1.5 g/L<i>. </i>A 67-93% 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)<i>, </i>reduced colour (89%) and COD (63%) in 2.75 h illumination. BOD₅/COD<i> </i>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 ho use waste containing metal complex azo dyes.