Rapid removal of organic micropollutants by heterogeneous peroxymonosulfate catalysis over a wide pH range: Performance, mechanism and economic analysis

Despite the previous success of MoS 2 /Fe 2+ /PMS process in detoxifying organic micropollutants, the drawback of requiring a narrow range of working pH limits its practical application. In this study, a class of commercial MoS 2 nanoparticles was introduced as a co-catalyst to facilitate the PMS activation by Fe 3+ ion. Results showed that the MoS 2 /Fe 3+ /PMS system over a wide range of pH values (3.0–9.0) achieved above 90% of removal efficiency for seven pollutants (chloramphenicol, tetracycline, ciprofloxacin, benzoic acid , rhodamine B, sulfadiazine, and bisphenol A) within 60 min of reaction time. The addition of MoS 2 greatly accelerated the reduction of Fe 3+ to Fe 2+ and the decomposition of PMS, thereby resulting in increased mineralization efficiency of pollutants. The generation of Mo 6+ ion and Mo 6+ peroxo-complexes also contributed to the promoting effect. Both sulfate (SO 4 − ) and hydroxyl ( OH) radicals were identified in MoS 2 /Fe 3+ /PMS system but SO 4 − was the dominant reactive oxidant. Chloride ion (Cl − ) showed an enhanced effect on degradation, while bicarbonate ion (HCO 3 − ) showed an inhibitory effect. Economic analysis was conducted by using an electrical energy per order (EE/O) approach. The above research findings suggest that the MoS 2 /Fe 3+ /PMS system is a promising oxidation technology owing to its efficient removal of various pollutants over a wide pH range.