Controllable Construction Of MOFs Derived Cobalt-based Catalysts And Study Of Tetracycline Degradation Viaactivating PMS

In recent years,tetracycline antibiotics（TCs）,as a class of broad-spectrum antibiotics,have become a new type of pollutant due to their persistence and accumulation in the Yangtze River water.More worrisome is that TCs can induce the growth of drug-resistant bacteria or genes,posing a potential threat to the ecological environment and human health.At present,the advanced oxidation process（AOPs）based on peroxymonosulfate（PMS）are widely used in the treatment of antibiotic wastewater because of their advantages such as environmental friendliness,wide working p H value and low energy consumption.Among them,metal-organic frameworks（MOFs）and their derivatives have become efficient PMS activators due to their high reactivity,stability and adjustable structure.However,the degradation of antibiotic wastewater by heterogeneous cobalt-based catalysts derived from MOFs activated PMS still has some problems,such as insufficient exposure of active sites restrict Co³⁺/Co²⁺redox cycle and low catalytic efficiency.Therefore,it is particularly important to build an efficient and stable heterogeneous catalysis system.This paper takes TC as the research object and constructs a new heterogeneous cobalt-based catalytic system to enhance the treatment capacity of TCs wastewater based on the strategy of shape and structural engineering,defect engineering and co-catalytic effect to control the electron utilization efficiency,PMS activation efficiency and the production/utilization efficiency of reactive oxygen species（ROS）.The main research contents are as follows:1.Controllable construction of ZIF-67 derived hollow Co₃S₄and study of tetracycline degradation via activating PMSIn order to improve the exposure area of active site and electron utilization efficiency,we prepared the hollow Co₃S₄derived from ZIF-67 by one-step solvothermal method via the Kirkendal effect.By optimizing the sulfurization time,compared with other systems,it was found that Co₃S₄-4.0/PMS system（4 h sulfurization time）represented the highest removal rate,with the degradation rate of93%for TC within 10 min and the reaction rate constant was 0.314 min^-1.Quenching experiments,electron spin resonance（ESR）,and electrochemical tests had shown that radicals(SO₄^·-,·OH,O₂^·-)and non-radicals（¹O₂）drove the efficient degradation of TC in Co₃S₄-4.0/PMS system.In the flow-column experiment,the degradation rate exceeded 85%for 12 h and the actual removal efficiency of TC in wastewater exceeded 77%.2.Controllable construction of 3D variable Co species carbon foam and study of tetracycline degradation via activating PMSIn order to accelerate the Co³⁺/Co²⁺redox cycle in the catalytic process and improve the efficiency of ROS production/utilization,we prepared Co_xO_y@CF-1.0with more oxygen vacancies and formed foam porous structure to synergistically accelerate the interface electron transmission and ROS generation efficiency via coupling mechanochemical and thermal reduction strategies by grinding2-methylimidazole and Co（NO₃）₂·6H₂O.The reaction rate constant of optimized Co_xO_y@CF-1.0/PMS system was twice that of ZIFs-500/PMS system(0.155 vs 0.073min^-1).The removal rate of dynamic experiment maintained over 90%within 12 h,which was far better than that of ZIFs-500/PMS system,it was attributed to Co⁰simulating the redox of Co³⁺/Co²⁺in the Co@Co O active centers,ensuring long-term stability in dynamic operation.3.Controllable construction of MoS₂doped cobalt-based carbon foam and study of tetracycline degradation via activating PMSMoS₂as a co-catalyst can break the rate limiting step of metal oxidation to reduction,promoting the activity and stability of cobalt-based catalysts.Here,we prepared ZIFs/MoS₂precursors to synthesize cobalt-based porous catalysts（Co_xO_y@MoS₂/CF）via combining mechanochemical with thermal reduction strategies by grinding 2-methylimidazole,cobalt salt and MoS₂.The reaction rate constant of the optimal Co_xO_y@MoS₂/CF-1.0 activated PMS was 0.4 min^-1,which was 1.74 times of Co_xO_y@MoS₂/CF-0.0.Moreover,the removal rate remained above95%during 12 h of dynamic degradation.Based on ESR testing,quenching experiments,and electrochemical analysis,efficient degradation of TC was achieved through coupling radicals(SO₄^·-,·OH and O₂^·-)and non-radicals（¹O₂）pathways.Most importantly,Compared to Co_xO_y@MoS₂/CF-0.0（0.97-0.43 mg/L）,the cobalt ion leaching Co_xO_y@MoS₂/CF-1.0 of after cycle was significantly decreased（below0.3 mg/L）.The degradation process of TC was simulated using the actual water quality of the Yangtze River,and Co_xO_y@MoS₂/CF-1.0/PMS system exhibited excellent degradation performance,with the removal rate was 90%within 10 min.