Study On Preparation Of Copper Selenide-based Photocatal Lytic Material And Degradation Of Organic Pollutants

Solar energy can be converted into chemical energy through photocatalytic oxidation technology.Photocatalytic oxidation technology has the characteristics of clean and pollution-free,low energy acquisition cost,convenient recycling and good treatment effect of wastewater,and is a green environmental protection technology with broad prospects.Copper selenide is an excellent p-type semiconductor material and can be used as a good photocatalyst.The preparation of copper selenide and its complexes and their photocatalytic effect on methylene blue simulated wastewater?MB?were studied.In addition,the properties of CuSe-like peroxidases were also studied,the details are as follows:?1?CuSe and CuSe-Polydopamine?PDA?were prepared by liquid phase co-precipitation method,and CuSe-PDA/Graphite carbon nitride?g-C3N4?composite samples were prepared by hydrothermal method.The morphology,structure,optical properties and adsorption properties of the samples were characterized by Scanning Electron Microscopy?SEM?,Transmission Electron Microscopy?TEM?,Powder X-ray Diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,Fourier transform infrared spectroscopy?FTIR?and other methods.The experimental conditions of photodegradation of CuSe-PDA/g-C₃N₄ sample to the methylene blue simulated wastewater were optimized.The result shows:when the volume ratio of Sodium selenite?Na2SeSO3?solution to Copper hydroxide?Cu?NH3?4?OH?2?solution is 3:1and the molar ratio of CuSe-PDA to g-C₃N₄ is 1:1,the prepared sample has the strongest photocatalytic performance;The dosage of hydrogen peroxide?H2O2?is0.1mL,the dosage of catalyst is 0.05g,the initial concentration of MB is 50mg/L,and the optical power is 500W,which is the optimal condition for the photocatalytic degradation of MB by CuSe-PDA/g-C₃N₄ sample.The degradation rate is 99.0%.In addition,the MB removal rate exceeded 85%through 6 cycles of experiments,indicating that the CuSe-PDA/g-C₃N₄ composite sample has good stability and reusability.?2?CuSeCo-PDA composite sample was prepared by hydrothermal method.The morphology and structure of the samples were characterized by SEM,XRD,XPS and other methods.The characterization of the optical properties of the sample shows that the band gap energy of CuSeCo-PDA is significantly reduced compared to CuSe,and the band gap energy is calculated to be 1.6 eV.The preparation conditions of CuSeCo-PDA composites were optimized and the best photocatalytic conditions for MB degradation were explored.The result shows:the CuSeCo-PDA material prepared with the molar ratio of Cu to Co of 1:1 has the best photocatalytic performance;H₂O₂ dosage is 0.5mL,catalyst dosage is 0.05g,MB initial concentration is 60mg/L,and optical power is 500W,the degradation rate at this time is 98.8%.In addition,the MB removal rate of CuSeCo-PDA composite samples through the circulation experiment is greater than 85%,indicating that its recycling is better.?3?CuSe was prepared by hydrothermal method,and its structure was characterized by SEM,TEM,XRD and XPS.The experiment proved that CuSe had peroxidase-like properties,and its catalytic reaction kinetics and influencing factors were studied.The result shows:compared with Horseradish peroxidase?HRP?,CuSe mimic peroxidase has poor affinity for H2O2 and slightly better affinity for3,3,5,5-Teramethylbenzidine?TMB?;the optimal pH for enzyme activity is 4.5,and the optimal temperature is 15?.The CuSe/TMB colorimetric method for the detection of H₂O₂ was constructed.Experimental results show that:The detection limit of the system for H2O2 is 2.94?M,the detection precision and accuracy are good,the H₂O₂ has good selectivity,and it is not interfered by other ions in the water sample during the test.In addition,a CuSe/TMB/H2O2 detection L-cysteine system was constructed,and the detection limit of L-cysteine was 0.21?m.