The Enzyme Mimetic Activity Of Copper Sulfide Compounds And Their Application In The Degradation Of Origanic Pollutants

As a biocatalyst, natural enzyme can catalyze a lot of biochemical reactionswhich take place in living organisms. Compared to chemical catalysts, enzymesfrequently exhibit superior performance in terms of:1)rate strengthen,2)reactionspecificity,3)activity at gentle temperatures and pressures, and4)ability forregulation. So, enzymes have wide application in many fields. However, they havesome intrinsic drawbacks including low stability due to denaturation, sensitivity ofcatalytic activity to reaction conditions and difficulty in preparation. Therefore, thestructure of efficient enzyme mimetics has been a particulary important focus forthe researchers. So far, scientists have found that metal oxide nanoparticles, singlemetal nanopaiticles, double inert metal composite nanoparticles and caborn-basednanomaterials all have the properties of peroxidase, and these nanoparticles has alot of application in pollution treatment and analytical detection.In this article, CuS NPs were obtained by a simple solvothermal process inwhich copper chloride and sulfur powder reacted in an ethanolic solvent.Coppersulfide compounds(CuS, Cu7.2S4, Cu9S5) have been synthesized by only adjustingthe molar ratio of Na2S and CuCl2in a hydrothermal process. The crystal structureof as-synthesized products were characterized by X-ray diffraction. Scanningelectron microscopy(SEM) was used to characterize the morphology of theproducts.CuS nanostructures show intrinsic peroxidase-like activity, as they can catalyzeTMB oxidation quickly in the presence of hydrogen peroxide, producing a typicalblue colour for3,3’,5,5’-Tetramethylbenzidine(TMB). We can find that theoptimum pH value is4.0, best temperature is50℃, and best substrate concentrationC(H2O2)=400mmol/L, C(TMB)=2.0mmol/L. The peroxidase-like activity ofCuS NPs depend on nanoparticles, regardless of solution of Cu2+.CuS NPs can catalyze the H2O2for the oxidative removal of RhB. We can findthat the optimum pH value is9.0, best substrate concentration C(CuS)=80mg/L,C(H2O2)=200mmol/L, C(RhB)=10mg/L, and the degradation of RhB increaseswith the temperature addition, has no relationship with the natural light.We alsofind CuS NPs can be reused, the rate of degradation of RhB can reach60%afterrepeated use for ten times.Copper sulfide compounds(CuS, Cu7.2S4, Cu9S5) also show intrinsicperoxidase-like activity, as they can catalyze TMB oxidation quickly in thepresence of hydrogen peroxide, producing a typical blue colour for TMB. The optimum pH value is4.0, and the peroxidase-like activity increase with the additionconcentrations of nanoparticles or TMB. The optimum temperature of CuS is20℃,Cu7.2S4is40℃, Cu9S5is30℃, and the best substrate concentration of hydrogenperoxide is800mmol/L.Copper sulfide compounds(CuS, Cu7.2S4, Cu9S5) also can catalyze thehydrogen peroxide for the oxidative removal of methylene blue(MB). The optimumpH value is9.0, and the degradation of MB increases with the increase oftemperature. CuS and Cu9S5catalyze hydrogen peroxide degradation of MB withoptimal sample concentration of40mg/L, compared to60mg/L of Cu7.2S4. Theoptimum hydrogen peroxide concentration is60mmol/L for CuS and Cu9S5,80mmol/L for Cu7.2S4.