Enhanced activation of peroxymonosulfate by abundant Co-Nx sites onto hollow N-doped carbon polyhedron for bisphenol A degradation via a nonradical mechanism

Abstract

In this study, novel Co-embedded hollow N-doped carbon polyhedrons, derived from ZIF-8@ZIF-67 core–shell structure, were synthesized and used for activating peroxymonosulfate (PMS) towards efficient bisphenol A (BPA) degradation. The contents of different N species, especially Co-Nx and graphitic N sites, were tuned by different calcination temperatures (800, 900, and 1000 °C). Characterization results demonstrated that hollow polyhedron with high graphitization degree and abundant porosity anchored numerous Co nanoparticles, which could enhance the catalytic performance. Compared to other as-prepared catalysts, Co/HNCP-900 (pyrolyzed at 900 °C) showed a more outstanding performance of PMS activation towards BPA degradation, and 95.1 % of BPA (20 mg/L) could be removed within 3 min. Abundant Co-Nx sites were a critical factor to induce the reaction process. Based on trapping, radical scavenger, and electrochemical analysis experiments, a nonradical process (singlet oxygen and direct electron transfer) was proposed to play the dominant role in BPA degradation. Benefiting from the nonradical process, BPA degradation efficiency almost remained stable either in a wide pH range (2.5–8.0) or in the presence of coexisting ions and natural organic matter. The findings of this study will elucidate a new opportunity for improving environmental remediation.