Preparation Of CeO₂ And Fe₃O₄/CeO₂ Composite And Their Application In Treatment Of Dye Wastewater

The development of new materials with high economic benefits is extremely important in the field of dye wastewater treatment.In the past few decades,in-depth research in the field of materials science has promoted the development of new nanomaterials.Cerium oxide(CeO₂)is one of the most studied oxides in the field of catalysis and environmental chemistry due to its excellent performance as a catalyst carrier and pollutant adsorbent.Although many synthetic methods to prepare CeO₂ nanomaterials have appeared,there are few studies on the adsorption and photocatalytic degradation of dye wastewater pollutants by CeO₂ hollow spheres.In this paper,CeO₂ hollow spheres and magnetic CeO₂ composite materials were synthesized based on CeO₂ materials,and experiments on photocatalysis and adsorption of dye wastewater were carried out.Compared with other research results,this study improved the degradation amount of dye molecules in wastewater,and solved the difficulty of adsorbent/catalyst recovery.That is,CeO₂ was coated on the surface of Fe₃O₄ nanosphere,and magnetic field was applied to facilitate the recovery of adsorbent/catalyst after the degradation of dye wastewater was completed.This research provides a better idea for the research on the degradation of dye wastewater.The research content of this topic is as follows:(1)CeO₂ hollow spheres were synthesized by solvothermal method,and the micro morphology and crystal structure of the synthesized materials were characterized by SEM,XRD,BET,FT-IR and other characterization methods.The adsorption experiment of anionic dye Acid Black(AB210)on CeO₂ hollow spheres was carried out under the conditions of temperature(30-60?),solution pH(2-11)and initial dye concentration(20-80 mg/L).The photocatalytic experiment of the cationic dye Rhodamine B(Rh B)on Ce O2 hollow spheres was carried out under the conditions of pH(2-11)and initial dye concentration(10-40 mg/L).The adsorption capacity of AB210 increases with the increase of the initial dye concentration and temperature,and decreases with the increase of the pH value of the AB210 solution.The maximum adsorption capacity of CeO₂ hollow spheres for AB210 dye reached 130.51mg/g.The quasi-first-order and quasi-second-order kinetic models are used to describe the adsorption behavior.The latter fits the adsorption process well,and the adsorption process also conforms to the intraparticle diffusion model.Langmuir,Freundlich and Temkin models are used to describe the isotherm adsorption behavior.The data show that the adsorption behavior is highly consistent with the Langmuir model.The photocatalytic degradation efficiency of Rh B dyes increases with the increase of the pH value of the dyes,and increases first and then decreases with the increase of the amount of CeO₂ hollow spheres.The photocatalytic degradation of Rh B dye by CeO₂ hollow spheres is consistent with the first-order kinetic model.Compared with the first degradation effect of the dye,even after four cycles,the CeO₂ hollow sphere still maintains90%of the photocatalytic and adsorption degradation efficiency for the dye,which proves the effectiveness of the CeO₂ hollow sphere as an adsorption/catalyst.(2)The magnetically separable Fe₃O₄/CeO₂ composite material was synthesized by solvothermal method and sol-precipitation method,and characterized by SEM-EDS,XRD,BET,FT-IR and VSM techniques.Under the conditions of temperature(30-60?),solution pH(1-11),Fe-Ce molar ratio(1:2.5-4)and pH(30-60?),the AB210 dye on Fe₃O₄/CeO₂composite material Adsorption experiment.The photocatalytic experiment of Rh B dye on Fe₃O₄/CeO₂composite material was carried out under the conditions of solution pH(2-11)and initial dye concentration(10-40 mg/L).The adsorption capacity of AB210 dye increases with the increase of the initial dye concentration and temperature,and decreases with the increase of the pH value of the solution.When the Fe-Ce molar ratio is 1:3,the maximum adsorption capacity of Fe₃O₄/CeO₂ to AB210 dye reaches 124.5mg/g.The quasi-first-order and quasi-second-order kinetic models are used to describe the adsorption behavior.The quasi-second-order kinetic model fits the adsorption process well,and the adsorption process also conforms to the intra-particle diffusion model.The adsorption isotherm is described by Langmuir,Freundlich and Temkin models,and its adsorption behavior is highly consistent with the Langmuir model.The photocatalytic efficiency of Rh B dyes increases with the increase of the pH value of the dyes,and keeps increasing and then decreases with the increase of the amount of Fe₃O₄/CeO₂composite material.The photocatalytic behavior of Fe₃O₄/CeO₂ composite material is consistent with the first-order kinetic model.FT-IR and Zeta potential measurement proved the physical adsorption process of AB210 dye on Fe₃O₄/CeO₂.The magnetic saturation of Fe₃O₄nanospheres and Fe₃O₄/CeO₂ are 69.1 emu/g and 22.9 emu/g,respectively,which indicates that the CeO₂ coating reduces the magnetization of Fe₃O₄ nanospheres,but it has high separability and is still easy to separate Fe₃O₄/CeO₂ by applying a magnetic field.