Efficient peroxymonosulfate activation through a simple physical mixture of FeS2 and WS2 for carbamazepine degradation

Abstract

In this study, carbamazepine (CBZ) degradation was evaluated by peroxymonosulfate (PMS) activation after the simultaneous introduction of FeS2 and WS2. For FeS2/WS2/PMS system, 99% of CBZ was removed within 40 min under the conditions of 100 mg/L FeS2, 150 mg/L WS2, 0.2 mM PMS, and initial pH 6.7. The apparent rate constant (kobs) of CBZ degradation in the FeS2/WS2/PMS system (0.108 min−1) was about 3.0- and 13.5-folds of that in FeS2/PMS system (0.036 min−1) and WS2/PMS system (0.008 min−1). Quenching experiments and electron paramagnetic resonance (EPR) experiments indicated that hydroxyl radical, sulfate radical, superoxide radical, and singlet oxygen participated in the CBZ degradation. The catalytic reaction mechanism was proposed, and W on the surface of WS2 was the main reactive site to accelerate the regeneration of Fe(II) in the FeS2, which played a dominant role in PMS activation. The degradation pathways of CBZ in the FeS2/WS2/PMS system were put forward, and the ecotoxicity of CBZ and its degradation by-products was evaluated. A distinguishing performance of CBZ degradation in the successive six runs was shown. The work indicated the FeS2/WS2/PMS system was an efficient advanced oxidation process with promising engineering application due to its simple operation, high efficiency, and stability for the degradation of the organics from water.