Decolorization and transformation of anthraquinone dye Reactive Blue 19 by ozonation

The decolorization and transformation of the anthraquinone dye, Reactive Blue 19 (RB-19), by ozonation with a semi-batch reactor were investigated. The effects of different operating parameters, such as the initial RB-19 concentrations, ozone feed rates and initial pH, on the performance of color, dye and total organic carbon (TOC) removal were also evaluated based on their pseudo-first-order rate constants and removal efficiencies. The experimental results indicated that the removal of color and the dye itself was more rapid and complete than that of TOC in all the ozonation tests. However, increasing the initial RB-19 concentration had a significant effect on decreasing the rate constant of RB-19 reduction. In addition, increasing the ozone feed rate had positive effects on the color, dye and TOC removal, particularly on the TOC diminution. The rate constant and efficiency of color removal were highest at initial acidic pH conditions, but the dye and TOC removal were more effective at initial basic pH values, possibly due to the more powerful and non-selective hydroxyl radical oxidation.