Simultaneous removal of 2,4,6-tribromophenol from water and bromate ion minimization by ozonation

Abstract

The study investigates the degradation of 2,4,6-tribromophenol (2,4,6-TBP) and the influence of solution pH, alkalinity, H2O2 and O3 dosage. Debromination efficiency of 2,4,6-TBP was the highest in basic water (pH = 10.61). The extent of TOC removal compared favourably with the amount of substrate converted, suggesting favourable mineralization of oxygenated by-products (OBPs). Ozonation in basic water favoured the formation of toxic BrO3-, while in acidic water (pH = 2.27) BrO3- yield was lowest. In acidic water the presence of CO32- showed negligible effect on conversion, TOC and BrO3- yield compared to ozonation alone. In basic water both 2,4,6-TBP conversion and TOC removal decreased with an increase in CO32-, hence minimizing BrO3- formation. The O3/H2O2 process showed an improvement in the debromination efficiency and TOC data revealed that total mineralization of OBP’s was achieved. However, only 10% H2O2 was able to effectively decrease BrO3- formation. Increasing the ozone concentration from 20 to 100 ppm enhanced the conversion of 2,4,6-TBP and TOC removal. At low ozone concentrations poor mineralization of OBP’s occurred, while complete mineralization was achieved at higher ozone dose. The reaction pathways for ozone degradation of 2,4,6-TBP in acidic and basic waters is proposed.