Preparation Of Hydroxyapatite And Composite Materials And Efficacy And Mechanism Study Of Uranium(?) Adsorption

The exploitation and smelting of uranium resources,the operation of nuclear facilities and nuclear accidents,the utilization of associated radionuclides and nuclear scientific experiments all produce waste water contaminated with radionuclides.The harm of uranium is both radioactive toxicity and chemical toxicity as a heavy metal.At present,China is the country with the fastest development of nuclear power in the world,and also a major country in the development of rare earth.Therefore,whether from the perspective of green and sustainable development of energy,or from the perspective of human health and environmental protection,the rapid removal of uranium from the environment is an urgent problem facing mankind.In this paper,uranium containing radionuclide wastewater as the research object.New environmental functional materials were prepared by biomimetic synthesis of hydroxyapatite,composite hydroxyapatite and graphene oxide.Both adsorbents were synthesized by simple one-step hydrothermal method.The biomimetic hydroxyapatite was synthesized with polyaspartic acid as the template.The synthesized hydroxyapatite had the special morphology of graded hollow microspheres with nanorods.The GO/HAP complex was synthesized by template-free one-step hydrothermal method,and a large number of HAP particles grew uniformly on the surface of GO nanometer sheets.The synthesis conditions were optimized to further improve the adsorption capacity,adsorption rate and environmental compatibility of the materials.The adsorption capacity of the bionic hydroxyapatite microspheres was 199mg/g,and the removal rate was as high as 99.5%?the concentration of 40 mg/L uranium solution was 50 mL,and the dosage was 0.01 g?.The adsorption capacity of GO/HAP complex was 373 mg/g,and the removal rate of uranium was 93%?the concentration of40mg/L uranium solution was 100 mL,and the dosage was 0.01 g?.The changes in the phase,composition,morphology and properties of the synthesized crystals were observed by infrared spectra?FTIR?,X-ray diffraction spectra?XRD?,transmission electron microscope analysis?TEM?,laser Raman spectroscopy?Raman?,scanning electron microscope?FESEM?,and X-ray photoelectron Spectra?XPS?.And establish isotherms,kinetics and thermodynamics models to explore the adsorption mechanism.Then identified the adsorption behavior and adsorption mechanism of the prepared material for uranium.The removal mechanism is the rapid adsorption of uranium by the active site on the surface of the adsorbent,followed by chemical reaction with the adsorbent and in-situ mineralization on the adsorbent to form a stable mineral,uranyl phosphate.The mineralized products of uranium on the hydroxyapatite microsphere and the GO/HAP complex are Ca?UO₂?₂?PO₄?₂·3H₂O and H₃OUO₂PO₄·3H₂O respectively.This removal mechanism provides an effective strategy for the rapid and effective treatment of uranium-containing wastewater.The prepared materials show great potential for use as nuclear emergency treatment materials.