Preparation Of Core-shell Rare Earth Doped Zirconia And Its Arsenic Adsorption Properties

In this study,we use magnetic Fe₃O₄ as the core,double coated it with SiO₂ and ZrO₂ doped with rare earth elements,and a multi-staged core-shell rare earth doped zirconium adsorbent was prepared to treat the arsenic from water,which has a good separation,recovery and regeneration performance.Fe₃O₄ nanoparticles with better dispersibility were prepared by solvothermal method,and then double coated it with sol-gel method.The types and doping ratios of rare earth elements in the shell were determined by adsorption experiments,TEM and BET characterization tests.The influencing factors such as pH,dosage and reaction time during the treatment of arsenic from water were discussed,and isothermal adsorption and reaction kinetic models were constructed.Combined with XPS and FT-IR characterization tests,the mechanism of adsorption and arsenic removal was analyzed.the XPS and FT-IR characterization tests were also carried out to analyze the adsorption and arsenic removal mechanism.The actual arsenic-containing water treatment experiment was carried out by taking the secondary effluent of a smelter as an example,and the regeneration performance of the material was tested.The experimental results were as follows:?1?The zirconium n-butoxide was used as the zirconium source to compare the arsenic removal effects of La and Ce doped materials.The results of TEM,BET and EDS show that the best arsenic removal effect is obtained,when the molar ratio of Ce:Zr was 1:100.?2?A series of adsorption experiments were carried out.The results showed that when the adsorbent dosage was 10 mg,the concentration of arsenic was 5 mg/L,the adsorption time was 60 min,As?III?,As?V?,and mixed As?As?III?:As?V?=1:1?,reaction pH conditions were 7,2,and 2,respectively,the adsorption capacity of adsorbent for As?III?,As?V?and mixed As?As?III?:As?V?=1:1?can reach to 17.19mg/g,32.04mg/g,29.10mg/g,respectively.The effects of SO₄^2-,PO₄^3-,NO₃^-,Cl^-and Ca²⁺as coexisting ions on the adsorption of arsenic on materials were studied,the influence of SO₄^2-and PO₄^3-on the adsorption process were most obvious,while NO₃^-,Cl^-and Ca²⁺have a little effect on the adsorption process.?3?The isothermal adsorption model analysis results showed that the adsorption process of arsenic by adsorbent was more consistent with Langmuir model,which belongs to monolayer adsorption,and its process of arsenic adsorption was spontaneous.The results of reaction kinetics model analysis show that the process of adsorbing arsenic-containing water by adsorbent is more in line with Ho quasi-second-order reaction kinetics model.Energy-dispersive X-ray spectroscopy?EDS?tests showed that the prepared adsorbent can effectively adsorbed arsenic in water to the surface of the material,X-ray photoelectron spectroscopy?XPS?test and Fourier transform infrared spectroscopy?FT-IR?test were indicated that the hydroxyl group on the surface of the adsorbent Fe₃O₄@mSiO₂@mCe-ZrO₂ was an important condition for ensuring the smooth progress of the adsorption process.?4?The adsorption experiment was carried out on the secondary effluent of a smelter.When the dosage is 20 mg and the reaction time is 60 min,the treatment result of the adsorbent Fe₃O₄@mSiO₂@mCe-ZrO₂ to the actual arsenic-containing water can meet the discharge standard of industrial wastewater.The material was regenerated under the conditions of NaOH concentration of 0.1 mol/L,and regeneration time for 6h.After 5 regenerations,the adsorbent Fe₃O₄@mSiO₂@mCe-ZrO₂ could still remove76.64%of arsenic.