Efficient Removal of Organic Pollutants by Metal-organic Framework Derived Co/C Yolk-Shell Nanoreactors: Size-Exclusion and Confinement Effect.

Selective removal of organic pollutants from surface water with high efficiency is crucial in water purification. Here, yolk-shell Co/C nanoreactors (YSCCNs) are facilely synthesized via pyrolysis of controllably etched ZIF-67 by tannic acid, and their degradation performance on multiple pollutants is demonstrated. To present the structure-performance relationship between the designed nanocatalyst and the selective removal of organic pollutants, bisphenol A (BPA) was selected as the targeted pollutant with coexistence of humus acid (HA). For comparison, solid and hollow ZIF-67 derived Co/C nanoparticles denoted as SCCNs and HCCNs, were also tested. The results show that YSCCNs exhibit enhanced BPA degradation rate of 0.32 min-1, which is 23.1% and 45.4% higher than that of HCCNs and SCCNs in HA (10 ppm) system. The essential improvement can be ascribed to the synergetic effects from shell layer (size-exclusion) and core/shell (confinement effect). The degradation mechanism and pathway are further confirmed by radical quenching experiments and liquid chromatography-mass spectrograph (LC-MS), respectively. In addition, some influential factors, including reaction temperature, pH value, and peroxymonosulfate (PMS) dosage are investigated in detail. This work provides a possible way to selectively remove target contaminant from multiple pollutants in complex water system.