Construction Of Spinel Composite Peroxymonosulfate Catalysts And Evaluation On Their Catalytic Performance

With the rapid progress of industrialization,the supply of freshwater resources is facing great challenges globally.In order to ensure adequate freshwater to use,it is necessary to develop one efficient and green water remediation technology.In recent year,sulfate radical-based advanced oxidation processes are applied in degradation of organic pollutants due to their superior oxidation ability.Spinel oxides have been widely used as persulfate heterogeneous catalysts because of their stable physicochemical properties,good catalytic performance and easy recycling.However,the capability of pristine spinel catalyst to activate persulfate is limited.Thus,two types of CoMoO₄/CoFe₂O₄（CMO/CFO）and NiCo₂O₄/LaCo_1-xB_xO₃（NCO/B_x）spinel composites were fabricated,and their performances on activation of PMS to degrade typical dyes was investigated.（1）CMO/CFO composite catalyst was prepared by two-step hydrothermal method and employed to activate PMS to degrade methylene blue（MB）.The combination of CMO is beneficial to the increase of oxygen vacancy content of CFO and the improvement in catalytic performance.Therefore,the degradation efficiency of MB by CMO/CFO is significantly improved compared to that of CFO.The reaction rate constant for the MB degradation by CMO/CFO is 1.6 times higher than for CFO.The degradation process of MB by CMO/CFO/PMS is dominated by non-radical pathway,accompanied by the radical pathway.（2）For further avoiding the agglomeration of spinel composite catalysts,boron-doped NCO/B_x（x=0,0.1,0.2,0.3）composite catalysts with heterostructure were prepared by electrospinning and annealing processes.The B-doping increases the content of oxygen vacancies in the composite catalyst,thereby promoting the rapid conversion of Co²⁺/Co³⁺and Ni²⁺/Ni³⁺,meanwhile,accelerating the activation efficiency of PMS.In addition,0.2 is the optimal doping ratio and NCO/B_0.2outperformed other catalysts,the degradation rate of OrgⅡwas increased to 98.7%within 30 min.SO₄^·-,·OH,O₂^·-and ¹O₂are involved in the degradation of OrgⅡ,in which ¹O₂ is the main active species in the NCO/B_0.2/PMS system.The catalytic performances on MB and OrgⅡ by CMO/CFO and NCO/B_0.2 are enhanced with elevated temperature,catalyst dose and PMS concentration.Furthermore,the prepared catalysts could adapt wide pH ranges.