A copper-loaded N-doped carbon catalyst with mesoporous hollow sphere structure for bisphenol A removing via peroxymonosulfate activation

In this study a copper-loaded N-doped carbon catalyst with mesoporous hollow sphere structure characteristic (Cu–NCHS) was prepared by in-situ synthesis followed with calcination and hydrothermal etching. Its catalytic performance for peroxymonosulfate (PMS) activation was evaluated using bisphenol A (BPA) as target pollutant. Owing to the coordination of more active sites provided by copper-loading and the mesoporous hollow structure characterized with high specific surface area (SSA) of 282.2 m 2  g −1 and large pore volume of 0.831 cm 3  g −1 , Cu–NCHS showed significantly better catalytic performance in BPA degradation (96.8% within 120 min) than those of NCHS (16.4%) and Cu-NC (19.6%) under the same initial conditions of BPA (20 mg L −1 ), PMS (100 mg L −1 ) and catalyst dosage (50 mg L −1 ). The possible mechanism of PMS activation by Cu–NCHS was also explored by ESR analysis and quenching experiments, and both radical and non-radical pathways were confirmed to be involved in BPA degradation process in Cu–NCHS/PMS system. Singlet oxygen ( 1 O 2 ), hydroxyl radical (•OH) and sulfate radical (SO 4 •− ) were identified to be the reactive oxygen species (ROS), of which 1 O 2 was the dominant ROS. Besides, the Cu–NCHS/PMS system showed excellent adaptability to pH change (from 3 to 11), common inorganic anions (Cl − , HCO 3 − , HPO 4 2− , SO 4 2− ) and natural organic matter (humic acid) in water. Meanwhile, the Cu–NCHS catalyst also showed good stability (with low Cu leaching of 0.14 mg L −1 ) and well reusability in recycling tests (the removal rate of BPA dropped by 14.0% after four successive runs). Combined with the experimental results in actual water (river water and wastewater), we demonstrated this study might provide a new insight for developing copper-loaded catalyst with high effect toward water treatment.