| At present,the shortage of water resources caused by environmental pollution has been widely concerned by people.Industrial,medical and domestic wastewater has entered the water environment without treatment,which has caused great impact on human production and life.Persulfate-based advanced oxidation technologies(AOPs)have attracted wide attention because of their high mineralization efficiency for organic pollutants.With this technique,sulfate radicals(SO4·-)can be generated by cutting off the O-O bond of peroxy monosulfate(PMS).In general,PMS must be activated before it can be decomposed.From the point of view of economy and operability,it is a good choice to use transition metal to activate PMS without energy.At present,there have been many studies on the efficient activation of PMS for degradation of organic pollutants by transition metal catalysts,and most of the catalysts studied are powders.Due to the addition of additional separation and recovery steps such as high-speed centrifugation,filtration or magnetic separation,the recovery rate of catalysts is inevitably low,which limits the practical application.Choosing suitable substrate materials is a common and effective method to solve the separation problem.Nickel foam(NF)is a kind of sponge-like porous pure nickel,with an average pore size of 100-300 μm.It has good thermal conductivity,high porosity,abundant honeycomb three-dimensional pore structure and excellent chemical stability,and is suitable as a catalyst carrier.Cobalt molybdate(CoMoO4),as a new transition metal oxide,is often used in supercapacitors,high efficiency hydrogen evolution and other electrochemical directions.In this paper,CoMoO4 was supported on NF substrate to construct supported catalyst CoMoO4/NF,which was used to activate PMS to degrade levofloxacin(LVF).The performance of CoMoO4/NF catalyst and CoMoO4/MnO2/NF catalyst to activate PMS to degrade LVF was studied in depth.The specific research contents of this paper are as follows:1.Preparation of CoMoO4/NF Catalyst and Study on Degradation of LVF by Activating PMSCoMoO4/NF catalyst was prepared by hydrothermal method and high temperature calcination method.with cobalt chloride and sodium molybdate as raw materials.The catalytic performance of CoMoO4/NF was evaluated by activating PMS to degrade LVF.The results showed that when the catalyst was 0.1 M Co2+ and the concentration of PMS was 2 mM,the removal rate of LVF at 10 ppm was 72%within 30 min,and the kinetic constant was 0.0698 min-1.XPS analysis showed that there were Co2+ and Co3+ in the mixed valence states,so PMS could be activated effectively.The free radical trapping experiments showed that the main reactive oxygen species(ROSs)produced during the degradation of LVF were SO4-,·OH and ·O2-.The application evaluation of the catalyst showed that CoMoO4/NF catalyst still had high catalytic activity after being reused for five times,and NF was beneficial to recovery.2.Preparation of CoMoO4/MnO2/NF Catalyst and Study on the Performance of Activating PMS to Degrade LVFBased on the preparation of CoMoO4/NF catalyst,the CoMoO4/MnO2/NF catalyst was prepared by compounding MnO2 onto the surface of CoMoO4/NF catalyst by electrodeposition and high temperature calcination.The preparation of CoMoO4/MnO2/NF catalyst was proved by XRD,XPS and TEM.The results of Mapping test show that Ni on Co,Mo,Mn,O and NF substrates exists and distributes uniformly.The catalytic performance of CoMoO4/MnO2/NF was evaluated by the degradation experiment of LVF.The results showed that the catalytic performance of CoMoO4/NF was improved by the introduction of MnO2.When the concentration of PMS was 2 mM and the electrodeposition time of MnO2 was 5 min,80.4%of LVF(15 ppm)could be removed within 30 min.The results of free radical trapping experiments show that·OH,SO4·-and·O2-are the main active species in the degradation of LVF.In addition,the CoMoO4/MnO2/NF catalyst was proved to be highly efficient,stable and easy to recover by five cycle stability experiments. |
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