Efficient removal of bisphenol S by non-radical activation of peroxydisulfate in the presence of nano-graphite.

An environmentally friendly and efficient catalyst is important for the persulfate activation and pollutants removal from water. In this study, nano-graphite (NG) prepared by detonation method, was firstly applied as the superb carbon catalyst to activate peroxydisulfate (PDS) for the degradation of bisphenol S (BPS) via a non-radical pathway. Results showed that NG had a very high catalytic performance and degraded most of BPS within 20.0 min, out-performing many popular metal-based catalysts. The doped N atoms (i.e. graphitic N and pyridinic N) in NG were identified as the possible reactive sites for the PDS activation. It is proposed that PDS could form the metastable surface-bound PDS complexes on the NG surface, which promoted the BPS degradation. The NG/PDS system had a strong anti-interference ability for the environmental background substances and a wide operative pH range, so it had a good application prospect in the actual wastewater environment. This study not only provides an efficient method for the removal of bisphenol pollutants, but also deepens the insight into the reaction mechanisms.