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 m2 g−1 and large pore volume of 0.831 cm3 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 (1O2), hydroxyl radical (•OH) and sulfate radical (SO4•−) were identified to be the reactive oxygen species (ROS), of which 1O2 was the dominant ROS. Besides, the Cu–NCHS/PMS system showed excellent adaptability to pH change (from 3 to 11), common inorganic anions (Cl−, HCO3−, HPO42−, SO42−) 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.