Ozonation for the removal of bisphenol A.

Abstract

The mechanism of byproduct formation and oxidation pathway of bisphenol A (BPA) during ozonation process have been compared under acidic, neutral and alkaline conditions at an applied ozone dose of 5.3 mg·L-1 min-1. Alkaline conditions promoted the fastest removal and the pseudo first-order reaction rate constant was calculated as 0.15 min-1. Complete removal under alkaline conditions (after 30 minutes of reaction time) was achieved with 1.59 mg ozone per mg BPA and 52% mineralization was achieved at 6.04 mg ozone application per mg total organic carbon (after 90 minutes of reaction time). Hydroxyl radical dominated degradation pathway (pH 10) resulted with opening of ring-structured products into Heptanoic acid, methyl ester. Sixty per cent BPA removal occurred under acidic conditions where the ozone was dominant and formation of Cyclohexene-1-carboxylic acid, ethyl ester, Benzaldehyde, 4-hydroxy-3,5-dimethyl- and 2-Phenylbenzoquinone were evidenced. Despite the fact that complete removal was achieved under neutral conditions, mineralization was not remarkable and both hydroxyl radical and ozone-based degradation pattern was evidenced after the treatment.