Insight into the mechanism of persulfate activated by bone char: Unraveling the role of functional structure of biochar

Abstract Recently, biochar was frequently applied in catalysis field, and it has been regarded as an efficient carbon-rich material to degrade organic pollutants in water. Various functional structures of biochar (such as pore structure, oxygen-containing groups and, defects) have been reported to be valid in catalysis. Whereas the complexity of biochar structure and composition hinders the further exploration of specific functions of biochar. To address this problem, selective inactivation experiment was first involved to investigate the role of oxygen-containing groups in catalysis. In this study, swine bone derived biochar (BBC) was adopt as catalyst in persulfate (PS) activation system to degrade acetaminophen (ACT). Both non-radical and radical pathway worked in BBC/PS system. ACT could be completely degraded in 60 min, and the removal rate could reach 0.3111 min-1. The results showed that the ketone groups on the BBC were the primary active sites of PS/BBC system and it played a major role in non-radical pathway (electron transfer pathway), and it might act as the active sites to produce OH in BBC/PS system. Besides, the -COOH and -OH on BBC might be beneficial to radical pathway, which can help to generate OH and SO4-. Interestingly, residual hydroxyapatite and defects in BBC might be able to stimulate PS to produce O2- and 1O2. With the development of increasingly precise biochar synthesis techniques, these verdicts give evidence to further oriented synthesis of biochar.