Removal of Bisphenol A via peroxymonosulfate activation over graphite carbon nitride supported NiCx nanoclusters catalyst: Synergistic oxidation of high-valent nickel-oxo species and singlet oxygen

In this work, a g-C3N4 supported NiCx nanoclusters catalyst (NiCx-CN) was developed, and its performance in activating peroxymonosulfate (PMS) was evaluated. Mechanism investigation stated that although singlet oxygen (1O2) was formed in the catalytic process, its contribution to BPA elimination was weeny. Interestingly, through the experiment with dimethyl sulfoxide as the probe, it was considered that the high-valent nickel-oxo species (Ni&+=O), generated after the interaction of NiCx-CN and PMS, was the dominating reactive oxygen species (ROS). Theoretical calculations (DFT) implied that NiCx-CN might lose electrons to generate high-valent Ni, which was consistent with the detection of Ni3+ on the surface of the used NiCx-CN. Besides, the prepared NiCx-CN showed advantages in resisting the interference of inorganic anions. Meanwhile, three BPA degradation routes had been proposed based on the transformation intermediates. This study will establish a new protocol for PMS activation using heterogeneous Ni-based catalysts to efficiently degrade organic pollutants via a nonradical mechanism.

Automated summary

In this study, a g-C3N4 supported NiCx nanoclusters catalyst (NiCx-CN) was developed and its capability in activating peroxymonosulfate (PMS) was investigated. The mechanism investigation revealed that singlet oxygen (1O2) formed during the catalytic process had limited contribution to BPA elimination. Interestingly, high-valent nickel-oxo species (Ni&+=O) generated after the interaction of NiCx-CN and PMS were identified as the dominant reactive oxygen species (ROS). The prepared NiCx-CN also exhibited excellent resistance to interference from inorganic anions. Three BPA degradation routes were proposed based on the transformation intermediates. This study provides a new approach for the efficient degradation of organic pollutants using heterogeneous Ni-based catalysts through PMS activation via a nonradical mechanism.