Degradation of Metal Complex Dyes in Neutral Aqueous Solution by UV/H2O2 Process

In this paper, the possibility of treatment for metal complex dyes (Neutral Bordeaux GRL, Neutral Pink BL and Neutral Blue BNL) using UV/H₂O₂ process in neutral aqueous solution was monitored. Based on pseudo-first-order kinetic model, the effect of UV intensity on decolorization rate constants was studied. The results showed that the decolorization rate constants were obviously enhanced with the increase of UV intensity. In UV (254 nm)/H₂O₂ system, 89.2% decolorization of neutral bordeaux GRL, 96.4% decolorization of neutral pink BL and 64.2% decolorization of neutral blue BNL were obtained after 20 min reaction. The TOC removal rates of metal complex dyes in UV (254 nm)/H₂O₂ system could also be described well by the pseudo-first-order equation. Although the TOC removal rates were all slower than the decolorization rates of these dyes in UV (254 nm)/H₂O₂ system, 66.3%, 77.2% and 74.4% TOC removals were achieved after 60 min reaction for neutral bordeaux GRL, neutral pink BL, neutral blue BNL, respectively. The experimental results indicated that the UV (254 nm)/H₂O₂ process was a promise pretreatment method for degradation of metal complex dyes in neutral aqueous solution.