Solar light promoted degradation of bisphenol s in carbonate/peroxymonosulfate system through accelerating singlet oxygen generation

Abstract

This study investigated for the first time the potential of the novel combination of peroxymonosulfate (PMS) and carbonate (CO32−) toward bisphenol S (BPS) under solar light irradiation. Compared with the Na2CO3/PMS and solar/PMS system, the solar/Na2CO3/PMS system significantly reduces the time required for the degradation of BPS. The excellent removal performance is possible due to the synergistic effect between enhanced light absorption and PMS activation, which accelerated the decomposition of PMS to generate more reactive oxygen species. Scavenging tests and electron paramagnetic resonance analysis revealed that the singlet oxygen (1O2) was the dominant oxidant formed and contributed to BPS elimination with a small proportion of superoxide anion radical (O2•–), rather than sulfate radical (SO4•−) and hydroxyl radical (HO•). The addition of Cl− could promote the degradation of BPS, but the addition of HA and a higher HCO3− concentration inhibited this process. The presence of SO42− and NO3− slightly promote the degradation of BPS. Besides, the solar/Na2CO3/PMS system represented significant degradation efficiency in a wide initial pH range (5.02–10.96). Such a system is favorable for the application in actual water matrices such as domestic wastewater, river water, lake water, and tap water. Meanwhile, based on the intermediates identified, the possible degradation pathways of BPS were proposed. In addition, most of the degradation intermediates of BPS were less toxic to different organisms than the parent compound. Moreover, the highly efficient degradation of several typical organic contaminants was also achieved using the solar/Na2CO3/PMS system under simulated and natural solar light irradiation. This study provides a novel idea and demonstrates the great potential for the elimination of organic pollutants in water.