Enhanced Activation Of Peroxymonosulfate With ZIF-derived CuCo₂S₄/nitrogen-doped Carbon For Superfast Degradation Of Reactive Brilliant Red K-2G

In view of the technical difficulties of dye wastewater treatment and the restriction effect of traditional activation methods on the application of persulfate advanced oxidation technology.The aim of this study is to prepare an efficient,stable and environmentally friendly catalytic material for the efficient treatment of dye wastewater by activating persulfate（PMS）.In view of zeolite-like metal-organic skeleton materials（ZIFs）have the advantages of structural adjustment,which are ideal precursors for the preparation of porous carbon-based composite catalytic materials,and considering that bimetallic spinel sulfide can effectively promote the catalytic activity of metal ions on the surface with the help of S^2-reduction property,this study used copper and cobalt bimetallic ZIF-9 as precursors and adopted solvothermal method.CuCo₂S₄/nitrogen-doped carbon（CuCo₂S₄/NC）catalyst derived from ZIF was synthesized by sulfurization and pyrolysis under N₂protection.In this study,reactive brilliant red K-2G was used as the target to degrade pollutants,and PMS was used as the oxidant.The optimum preparation conditions were determined by investigating the effects of different sulfur sources,curing solvents,curing time,pyrolysis temperature and pyrolysis time on the catalytic activity of catalysts.The physicochemical properties of CuCo₂S₄/NC catalysts were characterized by various analytical techniques.In addition,the catalytic performance of the catalyst was evaluated by comparison experiments and kinetic and thermodynamic analysis results.On this basis,the effects of various influencing factors,common anions and humic acids in actual wastewater on the degradation performance of CuCo₂S₄/NC/PMS catalytic oxidation system were investigated by single factor experiments.Finally,the reaction mechanism of CuCo₂S₄/NC activated PMS and the degradation mechanism of K-2G were discussed.The main experimental conclusions are as follows:（1）CuCo₂S₄/NC catalysts prepared with thioacetamide as sulfur source,deionized water as curing solvent,curing time of 6 h,pyrolysis temperature and pyrolysis time of 500℃and 3 h,respectively,have the best catalytic performance.The surface of CuCo₂S₄has a rich pore structure,and CuCo₂S₄is uniformly distributed on the surface of nitrogen doped carbon in the form of single crystal.The average pore size is 19 nm,which belongs to mesoporous catalytic materials.CuCo₂S₄/NC catalyst has high catalytic activity and stability.The first order kinetic constant k₁and activation energy（Ea）for the degradation of K-2G dye wastewater by CuCo₂S₄/NC/PMS are 0.3154 min^-1and 21.10 k J/mol respectively.The decolorization rate of K-2G was above 95%in five reuse experiments,and no REDOX peak appeared in the cyclic voltammetry curve.（2）When the dosage of PMS was 200 mg/L,the dosage of CuCo₂S₄/NC catalyst was 60 mg/L,p H was 7,and the initial concentration of K-2G was 50 mg/L,the catalytic oxidation system showed the best degradation effect on K-2G.The three anions（Cl^-,HCO₃^-,NO₃^-）and humic acid inhibited the removal of K-2G in CuCo₂S₄/NC/PMS system to varying degrees,but the degree of inhibition was small,which was suitable for practical application.（3）The SO₄^·-combined with the catalyst surface in aqueous solution plays a dominant role in the degradation of K-2G.The high activation of CuCo₂S₄/NC on PMS was attributed to the promotion of Cu⁺/Cu²⁺and Co²⁺/Co³⁺cycling by S^2-,and the participation of structured nitrogen in nitrogen-doped carbon in catalytic activation.Under the strong oxidation of SO₄^·-,the degradation of K-2G is mainly caused by the break of azo bond leading to decolorization,and then the opening of benzene ring and naphthalene ring to form small molecular organic acids,and then mineralization.