Bisulfite-induced drastic enhancement of bisphenol A degradation in Fe3+-H2O2 Fenton system

The present work aimed at using bisulfites (HSO 3 − ) to enhance the oxidative degradation of bisphenol A (BPA) in a Fenton process based on the Fe 3+ -H 2 O 2 reagents. It was confirmed that both the degradation and mineralization of BPA were drastically enhanced by the addition of HSO 3 − . Typically, the use of 0.1 mmol L −1 Fe 3+ , 0.3 mmol L −1 HSO 3 − and 10 mmol L −1 H 2 O 2 achieved a complete degradation of BPA (0.05 mmol L −1 ) in only 2 min. The addition of HSO 3 − increased the BPA degradation rate constant from 0.045 min −1 in the Fe 3+ -H 2 O 2 system to 2.71 min −1 in the Fe 3+ -HSO 3 − -H 2 O 2 system by 60 times. This drastic enhancement effect of HSO 3 − was attributed to its complexing and reducing abilities. The formation of FeSO 3 + complex prevented the precipitation of Fe 3+ and accelerated the cycling of Fe 3+ /Fe 2+ ; the reducing ability of HSO 3 − further favored the transformation of Fe 3+ to Fe 2+ . Several reactive species, including OH, SO 3 − and SO 4 − were responsible for the degradation of BPA, among which OH was the dominant one. The proposed Fe 3+ -HSO 3 − -H 2 O 2 system is suggested be able to act as the followed stage of a traditional Fe 2+ -H 2 O 2 system in the engineering setting.