Facile Fabrication Of A Novel Copper Nanozyme For Dye Degradation

Dye wastewater is one of the causes of environmental pollution,so it is urgent to find an efficient and economic wastewater treatment technology.As a biocatalyst,the enzyme showed strong dye degradation performance,including laccase and horseradish peroxidase.However,they can not be used in large-scale industrial production due to their poor stability,high cost and difficult storage.In recent years,the appearance of nanozyme has solved these problems.So far,it has been found that metal oxide nanoparticles,composite metal nanoparticles and single metal nanomaterials have simulated enzyme activity,and can be used for dye degradation and detection analysis.In this study,a novel copper nanoparticle was synthesized by a mild way and characterized by scanning electron microscope(SEM)and fourier transform infrared spectroscopy(FTIR).We have optimized the preparation methods as follows:60?L of tryptophan solution was added into 3 mL of phosphate buffer saline solution(PBS,5mM,pH 7.4)containing 20?L of CuSO₄solution,and then the solution was gently shaken for about 10 min and incubated at 28? for 24 hours.The experimental phenomenon suggested that the as-fabricated copper nanoparticle possess the mimic peroxidase activity.The copper nanoparticle can catalyze the oxidation of ABTS and produce a green solution,We call it copper nanozyme.We ensured the methods of CNZ mimic enzyme activity:8.5?L H₂O₂ with mass fraction of 30%and 0.3 mL ABTS(10 mM)were added in 3 mL of PBS(10 mM,pH 3).Then,2 mg CNZ was added into the mixture to start the reaction,which was monitored at 417 nm.Besides,we excluded that the mimic peroxidase activity of CNZ is due to the overflow of Cu²⁺from the copper nanoparticles.We also measured the like-peroxidase activity of other metal nanoparticles,which was much lower than that of CNZ.Next,we used the prepared CNZ to catalyze the degradation of methyl orange.The optimum reaction conditions for the degradation of methyl orange catalyzed by CNZ were determined:pH=3.0;T=60?;H₂O₂ concentration:200 mM;dosage of CNZ:8 mg;methyl orange concentration:8 mg/L,93%of the degradation rate could be obtained in less than 10 min.The CNZ has better temperature and pH stability,because it can maintain high activity in a wide range of pH(pH 2-9)and temperature(20-90?).The results also showed that the CNZ has good reusability and storage stability,the degradation rate is still above 90%after 10 reaction cycles and the CNZ has almost no loss after a week of storage.To conclude,a novel copper nanozyme with like-peroxidase activity has been synthesized by a simple way.Compared with natural enzyme,copper nanozyme showed high catalytic activity,catalytic stability and good reusability under extreme conditions.