Dual role of bromide in the degradation of phenolic compounds in peracetic acid process: Promotion of degradation and formation of disinfection byproducts

Abstract

Peracetic acid (PAA) is a potential disinfectant for water treatment due to its high efficiency and the limited formation of disinfection byproducts (DBPs). In PAA process of this study, bromide (Br−) significantly enhanced the degradation of phenolic compounds, including bisphenol A (BPA), phenol, p-aminophenol, and hydroquinone. The promotion is mainly due to the formation of hypobromous acid (HOBr), which comes from the oxidation of Br− by PAA. A kinetic model of PAA treatment in the presence of Br− was established to explore the degradation mechanism of phenolic compounds with good accuracy. The removal of phenolic compounds is positively related to Br− concentration. The degradation process was pH-dependent and favored at acidic conditions. In the real water matrix, the presence of multiple water matrix components may inhibit the degradation of phenolic compounds by consuming PAA and HOBr. Further, the transformation of BPA mainly involves bromination, hydroxylation, oxidation, bond cleavage, and ring opening, resulting in the formation of organic bromines. Brominated DBPs, such as dibromoacetic acid and tribromomethane were found, suggesting the potential adverse health effects of PAA treatment in the presence of Br−. The acute toxicity of phenolic compounds initially increased and then decreased with the increase of reaction time, indicating that prolonging the reaction time may reduce the environmental risk.