Purification Of Xanthate Wastewater Via G-C₃N₄ Based Visible Light Photocatalyst

The xanthate reagent is the most effective and commonly used collector of sulfide ore.However,the residue of xanthate medicine in mineral processing wastewater not only seriously affects the ecological environment around the mining area,but also can enter the human body through the biological chain,causing harm to the human nervous system and liver system.Therefore,effective treatment of low concentration and high toxicity of xanthate wastewater is of great significance to the protection of mine and its surrounding environment.In order to solve the environmental pollution problem caused by yellow medicine wastewater,the visible light catalytic material bulk g-C₃N₄ was structurally tailored to prepare two-dimensional g-C₃N₄ nanosheets.Oriented self-assembly by solvent polarity and metal ion doping methods were used to prepare g-C₃N₄ micron spheres and（Mo,K）doped with two-dimensional g-C₃N₄ nano-sheets,respectively.The structure-activity relationship between the morphology and structure of g-C₃N₄photocatalytic material and the photocatalytic quantum efficiency was revealed.After the above modification method,the surface active sites were increased,the absorption range of the spectrum was broadened,and the photogenic charge transmission efficiency was improved.（1）Starting from the morphological regulation and structural synergism of g-C₃N₄,the two-dimensional self-assembly of g-C₃N₄ was carried out in solvents of different polarity by a simple and feasible reflux method.The effect of solvent polarity and carbon chain structure on the self-assembly morphology of g-C₃N₄ was studied systematically.The relationship between the morphology and photoelectric properties of self-assembled g-C₃N₄ is discussed.The formation mechanism and photocatalytic reaction mechanism of self-assembled spherical structure of two-dimensional g-C₃N₄ nanosheets were systematically analyzed.The hydrogen production performance of self-assembled g-C₃N₄ photocatalysts was evaluated.The hydrogen production rate of spherical g-C₃N₄ photocatalysts was 30.67μmol/h,which was about 10 times higher than that of non-self-assembled bulk g-C₃N₄.Moreover,it was applied to the degradation of isobutyl sodium xanthate wastewater.After 6 hours under visible light irradiation,the degradation rate of isobutyl sodium xanthate wastewater was up to 96.08%,showing excellent performance of photocatalytic purification of xanthate wastewater.（2）Starting from the research perspective of regulating the energy band structure of g-C₃N₄,broadening the spectrum response range and improving the quantum efficiency,the photocatalytic materials of two-dimensional g-C₃N₄ nanosheets doped with Mo and K metals were respectively prepared by selecting simple bulk-milling bulk g-C₃N₄ and metal compounds and using air oxidation etching ball-milling mixture.By doping metal ions,metal ion covalent g-C₃N₄ nanosheets were formed,which effectively broadens the spectrum absorption range and improves the transmission capacity of photogenerated charges.The photocatalytic degradation of xanthophora flavescens wastewater by metal ion doped two-dimensional g-C₃N₄nano-sheet photocatalytic materials under visible light irradiation was studied.The effects of concentration,pH value and reaction time of the wastewater on the photocatalytic degradation of xanthophora flavescens wastewater were investigated.The results showed that the optimized parameters were:The initial concentration of xanthocyanin was 50 mg/L,pH=7,and the reaction time was 6 hours.Under this condition,Mo and K doped two-dimensional g-C₃N₄ nanosheets photocatalytic materials were used to degrade the wastewater of mineral processing xanthocyanin,and the degradation rates of isobutyl sodium xanthocyanin were 90.12%and 93.26%,respectively.