Removal Of As(Ⅲ) By Mn-oxide-coated Cu Oxides Hollow Spheres From Water:Performance And Mechanism

With the rapid economic development,human life and production activities have intensified,and arsenic pollution in the water environment has become increasingly serious.In addition to the ion exchange method and membrane separation method,the removal method,adsorption method,chemical precipitation method and electro-flocculation method are also widely used.The adsorption method has been well-respected due to its simple and efficient operation.It is especially important to develop a new type of adsorbent with high adsorption capacity and good stability.In this study,arsenic（As）is used as the target pollutant,and Mn-oxide-coated Cu oxides hollow spheres are studied to remove target pollutants.Using a new method,the influencing factors of the adsorption process are analyzed,the mechanism of pollutant removal by adsorption is explored,and new ideas are provided for the repair and treatment of arsenic pollution source water.The main conclusions are as follows:（1）The CuOx hollow sphere was prepared by a low-temperature liquid phase method,and a layer of manganese oxide was supported on the surface.By optimizing the preparation conditions,Mn-oxide-coated Cu Oxides Hollow Spheres（MCOHS）with a copper-manganese molar ratio of 7:1 and a loading system pH of 7 were selected.SEM,TEM,XRD,XPS,FT-IR,Zeta potential and other characterization methods were used to observe the surface morphology and structural characteristics of the MCOHS adsorbent.The study found that the MCOHS adsorbent has a hollow sphere structure with a diameter of about 1μm and manganese oxidation The objects are uniformly loaded on the surface of the sphere.Combining characterization methods such as XRD and XPS,it is found that the main elements in the MCOHS adsorbent are Cu,Mn,and O,etc.The main forms of copper are Cu₂O and CuO,and the main forms of manganese are Mn O₂.（2）Based on the above studies,the adsorption kinetic experimental results showed that the the pseudo-second-order kinetic curve model provided the best correlation of the experimental data.The adsorption isotherm experimental results showed that Freundlich model fitted As（Ⅲ）adsorption data much better.The maximum adsorption capacity of As（Ⅲ）is 81.45 mg/g.At lower concentrations,the adsorbent still has a good adsorption effect.The pH value will affect the adsorption of As（Ⅲ）to a certain extent,and the main manifestation is that as the pH value increases,the adsorption amount decreases.Interfering ion experiments show that SiO₃^2-,CO₃^2-,and PO₄^3-have a greater effect on As（Ⅲ）,of which PO₄^3-has the greatest effect;Ca²⁺and Mg²⁺can promote the adsorption of As（Ⅲ）by MCOHS.（3）By investigating the mechanism of adsorption,it was found that the As-O vibration peak appeared in the FT-IR analysis,the newly appeared As-O peak in the XPS O1s peak,the new appearance of the As3d peak,and the reduced Me-OH peak after MCOHS adsorbed As（Ⅲ）,Reduced Mn（Ⅳ）,etc.can prove that during the adsorption process,the hydroxyl complexation reaction between the surface of the MCOHS adsorbent and As（Ⅲ）pollutants was accompanied by the process of As（Ⅲ）to As（Ⅴ）conversion.