Designing ordered composites with confined Co–N/C layers for efficient pollutant degradation: Structure-dependent performance and PMS activation mechanism
Rational design of ordered catalytic composites with high performance and facile preparation method for environmental remediation still remains a tremendous challenge. For this vision, ordered composites with confined cobalt intercalated N/C layers (Co–N/C) were successfully prepared via carbonizing a mixture of cobalt species, histidine (His) and zirconium-containing SBA-15 (ZS) utilizing a simple non-solvent method. Taking the confinement effect and inherent hydrophilic groups (Si–OH) of mesoporous silica as the foothold, the strong Co 2+ /N or Co 2+ /O coordination (Co 2+ (–COO - or –NH 2 ) 2 and Co 2+ (–O - ) 2 ) and silica/His or His/His adhesive/cohesive interactions endowed the Co-based catalyst with optimal interfacial properties , cycling stability and magnetic separability for degradation of several pollutants (phenol, antibiotics and dyes). The degradation efficiency of Co@NC-ZS-700 for bisphenol A was superior to Co-ZS-700, NC-ZS-700 and Co@NC-SBA-700 due to the flaky structure with confined Co–N/C layers, which could achieve 95.0% within 20 min. In addition, the catalyst could still degrade more than 84.4% bisphenol A after five consecutive reactions. Based on the characterization analysis, tested active species (SO 4 •– , • OH and 1 O 2 ) and degradation products, double-process activation mechanism and degradation pathways were plausibly proposed (radical and non-radical processes). Additionally, various influencing factors, including carbonization temperature, amount of cobalt species, peroxymonosulfate (PMS)/catalyst dosage, pH value, coexisting ions and real water environment, were also systematically studied. This work might pave a feasible way for contaminant treatment utilizing ordered mesoporous silica composites with diffusion promoted channels involved under aqueous systems.
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