Performance Of Cobalt-based Single Atom Catalyst Activated Peroxymonosulfate For Degradation Of Bisphenol A In Water

Advanced oxidation processes(AOPs)based on peroxymonosulfate(PMS)are considered as potential remediation technologies for refractory organic pollutants.At present,transition metal cobalt-based catalysts have been proved to be promising catalysts for PMS activation.However,traditional transition metal ions are prone to metal ion leaching,low reactivity and low atom utilization.Therefore,it is of great significance to develop a new type of catalyst with high efficiency,stability and high utilization rate of metal atoms for water environmental remediation.In this paper,two single-atom Co-based catalysts(CoSA/NHCS and CoSA@NPC)were constructed using nitrogen-doped nano-hollow carbon spheres(NHCS)as support by different synthesis strategies,and were used to activate PMS to achieve high efficiency and rapid degradation of bisphenol A(BPA).The specific research content is as follows:(1)Through coordination design strategy,single atom cobalt based catalyst(CoSA/NHCS)was prepared by hard template-heat treatment method.Experimental and density functional theory(DFT)studies have shown that the combination of Co-N4 active site and electron transfer mechanism can achieve rapid degradation of BPA,with a degradation rate of up to 98%within 1 min.The main active site of BPA attacked by the electron transfer pathway was predicted by calculating its molecular orbital and Fukui index.LC-MS analysis combined with ecological structure-activity relationship model(ECOSAR)demonstrated that the toxicity of degradation intermediates tended to decrease.In addition,using CoSA/NHCS coupled PVDF membrane,a continuous flow device was constructed,and the BPA removal efficiency remained above 90%after 100 hours.The above studies proved that CoSA/NHCS catalyst has good stability and practical water environment remediation prospects.(2)Phosphorus and nitrogen co-doped single-atom cobalt-based catalyst(CoSA@NPC)was prepared by polymerization-carbonization method through heteroatom doping strategy,and CoSA@NPC inherited the hollow mesoporous structure of nano-hollow carbon sphere.The experimental results show that when only 0.05 g/L catalyst is used,P-doped CoSA@NPC can completely degrade BPA within 5 min,and the degradation rate constant is 3.0 times that of CoSA@NC.Moreover,CoSA@NPC/PMS system is almost unaffected by inorganic anions,humic acid(HA),solution pH and low temperature conditions,showing high stability and reusability.Quenching experiments and EPR techniques have proved that the CoSA@NPC/PMS system is highly selective for the generation of 1O2.