Co nanoparticles anchored N, B, F codoped carbon as an efficient peroxymonosulfate activator for rapid catalytic degradation of organic pollutants

Abstract

Rational design and exploration of low-cost and robust carbocatalysts with multiple active sites for peroxymonosulfate (PMS) activation towards wastewater purification is challenging. Herein, Co nanoparticles anchored N, B, F-codoped porous carbon (Co@NBFOC) was synthesized and characterized thoroughly, which displayed superior PMS activation ability due to the synergy of multiple active sites. The Co@NBFOC-3/PMS system possessed excellent methylene blue (MB) oxidation capacity over a wide initial pH applicability (4-10) and showed high tolerance for Cl−, NO3−, SO42− and humic acid, while CO32−, HCO3− and HPO42− displayed a considerable inhibiting effect on it. Moreover, the Co@NBFOC-3/PMS system could afford acceptable MB degradation performance in different water matrix and universal applicability in eliminating a variety of organic pollutants. Both free radical pathway and nonradical pathway collectively contributed to MB degradation based on scavenging experiments, EPR measurements and electrochemical analyses. Particularly, ·O2−, 1O2, surface-bonded radicals (·SO4−ads and ·OHads) and catalyst mediated electron transfer were the major contributors, followed by ·SO4−free. Metallic Co, pyridinic-N moieties, graphitic-N moieties, BCO2 moieties, CO groups, the carbon atoms adjacent to graphitic-N, defects and ionic CF moieties on Co@NBFOC-3 surfaces corporately contributed to PMS activation. The main degradation intermediates were analyzed by HPLC-MS and the possible MB degradation pathways were proposed. This work not only improves the fundamental understanding of active sites in multi-heteroatom doped carbocatalysts, but also provides some guidance for future development of high-efficient carbon-based catalysts in PMS-based advanced oxidation processes.