FeS2/NC composite with Fe−Nx and Fe−Cx reactive sites to efficiently activate peroxymonosulfate for the degradation of carbamazepine under visible light

Iron-based catalysts have been widely used to activate peroxymonosulfate (PMS) for the treatment of carbamazepine (CBZ) wastewater. However, the development of efficient and stable pyrite (FeS 2 )-based catalysts to mitigate the consumption of Fe 3 + /Fe 2+ and S 2 2– is still challenging. Herein, FeS 2 /nitrogen-doped carbon (FeS 2 /NC) composite was synthesized using hydrothermal combined with pyrolytic strategy, wherein FeS 2 and NC connected by Fe−N x and Fe−C x bonds. In the photo-PMS system, FeS 2 /NC achieved a removal rate of 98.2 % for CBZ within 6 min, and the total organic carbon (TOC) removal was 83.4 %, which exceeded FeS 2 and most of the results reported in the previous literature. The electron paramagnetic resonance results and quenching experiments confirmed that 1 O 2 played a critical role in the FeS 2 /NC + PMS + visible light system, while h + , SO 4 • − , and •O 2 − were secondary. The excellent performance stemmed from that the Fe−N x and Fe−C x bonds between FeS 2 and NC enhanced the photogenerated electron transport efficiency, resulting in efficiently circulating Fe 3+ to Fe 2+ and minimizing the S 2 2– consumption. Meanwhile, the electron-deficient graphitic-N could facilitate the 1 O 2 generation. Moreover, FeS 2 /NC exhibited good stability and satisfactory universality, providing the potential for actual wastewater treatment. This work offers a novel strategy for enhancing the Fe 3+ /Fe 2+ cycle and reducing the S 2 2– consumption of FeS 2 -based catalyst for the effective treatment of CBZ wastewater.