Preparation Of Cu₂S/Cu₂O Modified Nano-iron And Its Application In The Treatment Of Organically Polluted Wastewater

With the development of science and technology and the progress of society,chlorophenol pollutants have gradually entered people’s lives.Chlorophenol pollutants have the characteristics of carcinogenic,teratogenic,mutagenic,strong persistence and bioaccumulation,so it is urgent to remove them.In recent years,nano-zero-valent iron has been widely concerned in the treatment of organic pollutants,but because of its easy agglomeration and easy formation of oxide layers,it has limitations in practical applications that cannot be ignored.At the same time,advanced oxidation technology（AOPs）is well-known because it can generate free radicals with strong oxidizing ability,and AOPs are also considered as one of the effective ways to remove chlorophenol pollutants.How to improve the stability of nano-zero valent iron so that it can be used and promoted in actual production and life is an important research problem at present.This research is aimed at the problem of nano-zero valent iron and modified it.In the research of this thesis,a new type of nano-zero-valent iron material（Cu₂S/Cu₂O@nZVI-B）was prepared by using the liquid-phase reduction method to synthesize nano-zero-valent iron,which was loaded on bentonite,loaded with metallic copper and subjected to sulfide treatment.The results showed that nZVI,copper and its sulfides were successfully supported on bentonite.Through the design and comparison experiment,it clearly showed the obvious advantages of the modified nano-zero valent iron compared with other materials in removing 2,4-dichlorophenol（2,4-DCP）,and through the demonstration of the degradation efficiency of 2,4-DCP,when the ratio of Cu₂S:Cu₂O is 1:1,the synthesized Cu₂S/Cu₂O@nZVI-B material had the best treatment effect on 2,4-DCP.In order to further study the difference in the removal efficiency of2,4-DCP under different environmental conditions,the degradation experimented of 2,4-DCP were carried out.In this regard,we set a series of variables such as sulfurization degree,dosage of Cu₂S/Cu₂O@nZVI-B,initial pH value,initial concentration of 2,4-DCP,dosage of hydrogen peroxide,coexisting anions,and light irradiation experiments to further explain Cu₂S/Cu₂O@nZVI-B on 2,4-DCP removal efficiency.The experimental results show that the initial concentration of 2,4-DCP is 30 mg/L,the vulcanization ratio was 1:1,the dosage was 2.0 g/L,the initial pH was 4.0,the dosage of H₂O₂ was 0.65 m M,and the reaction time was Under the initial condition of 120 min,the removal efficiency of 2,4-DCP can reach almost 100%.There were significant differences in the effect of coexisting anions on the removal efficiency of 2,4-DCP.Bicarbonate ions promoted the degradation efficiency of 2,4-DCP.Nitrate ions,sulfate ions and superphosphate ions the degradation efficiency of DCP exhibited an inhibitory effect.The Cu₂S/Cu₂O@nZVI-B was characterized by X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy,transmission electron microscopy,UV-Vis diffuse reflectance,photochemical properties and specific surface area.The crystal structure,binding energy,surface morphology,light absorption properties,impedance,electron resonance spin,specific surface area,and pore size distribution of Cu₂S/Cu₂O@nZVI-B were tested by the above characterizations.The test results showed that the as-prepared material allowed copper to be deposited on nano-iron and supported on bentonite,and there were diffraction peaks of cuprous sulfide and cuprous oxide on the surface of Cu₂S/Cu₂O@nZVI-B,test results were consistent with predictions.The deposition of copper and the addition of bentonite made the nano-zero-valent iron material more uniformly distributed and the agglomeration phenomenon was not obvious,and the addition of copper increased the specific surface area,and proved that Cu₂S/Cu₂O@nZVI-B had photocatalytic performance,and by from the test of free radicals,it can be concluded that h⁺,·OH,·O₂^-free radicals with strong oxidizing ability generated during the degradation reaction.In the system of VL/H₂O₂/Cu₂S/Cu₂O@nZVI-B,there were strong oxidants such as hydroxyl radicals and peroxy anions with strong oxidizing properties.At the same time,the electrons in the conduction band of Cu₂O were excited and transferred to Cu₂S under illumination.In the conduction band,the recombination of photo-induced electrons and holes is effectively inhibited,h⁺transfers from the valence band of Cu₂S to the opposite direction of Cu₂O,and the accumulated h⁺directly participates in the decomposition process of organic pollutants,and further generates hydroxyl radicals,thereby significantly promoting the removal of 2,4-DCP,the whole reaction process is accompanied by the occurrence of adsorption.Finally,the preparation mechanism of the novel nano-zero valent iron and the degradation mechanism of 2,4-DCP were analyzed and summarized.