Preparation Of Peroxdase Mimics Copper Sulfide And Its Application In Printing And Dyeing Wastewater Treatment

In 2007,Yan Xiyun the Academician discovered that Fe₃O₄ nanoparticles had horseradish peroxidase activity.The substances with peroxidase activity were collectively called peroxidase mimics.Because of its unique physical and chemical properties,peroxidase mimics have broad application prospect in Fenton-like technology.However,the peroxidase mimics reported still have some problems,such as poor recycling ability and weak catalytic activity.Copper sulfide is often used as a new electrode material and photocatalyst due to its excellent electronic conductivity and wide direct band gap value(1.2?2.0 e V).However,the application of copper sulfide in wastewater treatment is rarely reported.In this paper,flower-like Cu₉S₈ was prepared by sacrificial template method.This material has strong catalytic activity and stable recycling property,and it has potential application in the treatment of simulation wastewater.First,Cu-MOFs was synthesized at room temperature,then porous CuO was obtained by calcination.Finally,flower-like Cu₉S₈ was prepared by Na₂S treatment.The samples were characterized by XRD,EF-SEM and TEM.The results showed that the final product was Cu₉S₈,which formed about 1?m in length and width with 30 nm in thickness.Flower-like microspheres were constructed by the intersection of nanosheets.BET results showed that the specific surface area and average pore size are 6.29 m~2/g and 133.78 nm,respectively.Flower-like Cu₉S₈ had strong catalytic activity,which could make the degradation rate of methylene blue(MB)reach 93.9%and99.4%in 30 min and 40 min,respectively.The results of enzymatic reaction kinetics showed that the K_m value of flower-like Cu₉S₈ was 0.449 m M,which was 2?479 times lower than that of other horseradish peroxidase,and 8 times lower than that of natural horseradish peroxidase(HRP),indicating that the affinity of Cu₉S₈ to H₂O₂ was much higher than HRP.Cu₉S₈ had strong degradation effect on many organic dyes,and the final mineralization rate was as high as 78.2%.The removal of organic dyes from water by Cu₉S₈ mainly used the hydroxyl radicals,and the whole oxidation process belongs to Fenton-like reaction.The catalytic cycle experiment showed that Cu₉S₈had good cyclic stability,and the degradation rate only reduced 2%after ten cycles.In order to further improve the catalytic activity of the Cu₉S₈catalyst,ZVIs@Cu₉S₈ was prepared using a direct reduction method to load ZVIs on the surface of the Cu₉S₈nanosheets.The XRD,EDS and XPS results confirmed the successful loading of ZVIs on Cu₉S₈.The experimental results of catalytic degradation MB showed that ZVI_S@Cu₉S₈ had higher catalytic activity than Cu₉S₈,which can reach 98.7%degradation rate of MB in 30 min.This is because after the Fe²⁺insitu reduction,the specific surface area of the catalyst(77.3 m~2/g)is improved,and the number of effective catalytic sites is improved.It showed that during the entire catalytic cycle process,iron nanoparticles deposited on the copper sulfides nanosheets promoted the Cu(I)/Cu(II)cycle to enhance the rate of production of hydroxyl radicals.While improving the catalytic activity,the cycle stability of the catalyst was not affected,still maintained 96.8%degradation rate of MB after ten catalytic cycles.In the mechanism study,we it found that hydroxy free radicals were the main active oxygen species of oxidative degradation of MB,but there was also a presence of superoxide radicals.In the end,LC-MS was used to study the possible degradation route of MB molecules.