Study On Preparation Of Modified Ferrite-montmorillonite Composites For The Removal Of Uranyl Ion

As one of the potential environmental problems,uranium contamination has received considerable attention over recent years.Adsorption is currently the suitable technique for uranium removal of wastewater and various naturally available adsorbents have been used.However,their industrial applications have always been limited by the regeneration and low adsorption capacity of the traditional adsorbents,thereby making it necessary to research new excellent adsorbents with high efficiency and good regeneration.In this paper,Y₂O₃ coated MFe₂O₄（M=Fe,Mn,Zn,Co,Ni）nanoparticles,yttrium-doped MFe₂O₄/montmorillonite（M=Fe,Mn,Zn,Co,Ni）,and amorphous Y（OH）CO₃ modified MFe₂O₄/montmorillonite（M=Fe,Mn,Zn,Co,Ni）were prepared.Particularly,the crystal and chemical structures of the prepared materials were characterized by X-ray diffraction（XRD）,fourier transform infrared spectrophotometer（FT-IR）,Raman spectroscopy（Raman）,scanning electron microscope（SEM）,transmission electron microscopy（TEM）.In addition,based on the discussion on the thermal stability,the structure of amorphous Y（OH）CO₃ was verified with thermal gravimetric analyzer（TGA）.The effect exerted by pH,contact time,and initial concentration of UO₂²⁺on the adsorption properties of the prepared materials was investigated.The pH value of maximum adsorption capacity for prepared materials in the solution with pH of 2⁴ is 4.The adsorption kinetics and adsorption isotherm were employed to describe the adsorption mechanism,with the estimated maximum adsorption capacity of Y₂O₃ coated MFe₂O₄nanoparticles and yttrium-doped MFe₂O₄/montmorillonite as 105.7²27.2 mg/g and194.9⁴50.5 mg/g,respectively.In addition,Y（OH）CO₃ modified MFe₂O₄/montmorillonite exhibited high adsorption capacity of 750⁹22 mg/g.Under the conditions of coexistence of UO₂²⁺,Cr³⁺,Pb²⁺,Ni²⁺,Cd²⁺and Rb⁺,it was found that the prepared materials display a high adsorption selectivity for UO₂²⁺,Cr³⁺,Pb²⁺.Besides,the adsorption mechanism was summarized as the adsorption reaction of surface hydroxyl group with UO₂²⁺,where the adsorbed cations could form an ion monolayer,blocking other cations from being adsorbed.Furthermore,the reusability investigation suggested that all the prepared materials keep60%removal rate of UO₂²⁺after three cycles,indicating that the prepared materials served as potential adsorbents for the removal of UO₂²⁺from solution in industrial wastewater treatment,thus providing references for future researches on magnetic adsorption materials.