The Study Of Uranium (?) Adsorption Based On Rock Apatite Environmental Function Material And Its Modification

With the development of nuclear power and other relevant field,such as uranium mining and metallurgy,feed plant,nuclear fuel reprocessing process and uranium tailings storage et al,all of these are accompanied with a large amount of radioactive wastewater containing uranium.It would pollute the environment and do harm to human beings if discharging the wastewater without disposing.On the other hand,because of the advantage such as the special crystal structure,low-priced and vast source,apatite has became a prospective environment function material and got more attention by research.This paper used chitosan to modify the rock apatite and studied the effect of uranium adsorption on rock apatite?RA?and uranium adsorption on chitosan modified apatite?CRA?by batch experiments,also,studied the mechanism by the SEM,XRD,FTIR characterization and adsorption models such as adsorption isotherm as well as kinetic models.The results of SEM,XRD,FTIR characterization indicated that the major structure of rock apatite?RA?and chitosan modified rock apatite?RA?were Phlogopite(K2Mg₆[Al₂Si₆O₂₀]?OH,F?₄),Hydroxyapatite?Ca10?PO₄?₆?OH?₂?,Fluorapatite?Ca5F?PO₄?₃?.But the surface morphology had been changed and appeared a new structure of Ammonium Calcium Hydrogen Phosphate?NH4CaHP2O7?accompanying the increased amount of –OH and –NH2 onto the adsorbent surface after rock apatite modified by chitosan.The results of batch experiments showed that the saturated adsorption capacity of natural rock apatite?RA?was 3.2 mg/g and the chitosan modified rock apatite?CRA?is 6.1 mg/g with 5 h equilibrium time.After modification by chitosan,the adsorption capacity and efficiency of chitosan modified rock apatite?CRA?were both enhanced,which means a wider scale of application.The results of SEM,XRD,FTIR characterization indicated that after uranium adsorption,the surface morphology,structure and functional groups of natural rock apatite?RA?and chitosan modified rock apatite?CRA?had been changed.The surface of natural rock apatite?RA?had became smoother and less blade shape as well as a new structure of Phurcalite?Ca₂?UO₂?₃?PO₄?₂?OH?₄·4?H2O??containing UO₂2+ after uranium adsorption.On the other hand,the surface of chitosan modified rock apatite?CRA?also became smoother and generated a new structure of Phurcalite and Uramphite?NH4?UO₂?PO₄·3H2O?containing UO₂2+ on the surface.Both natural rock apatite?RA?and chitosan modified rock apatite?CRA?were fitted well with Langmuir isotherm and pseudo-second order kinetics equation models,which indicated a monolayer coverage chemical adsorption and that both the two adsorbents were favourable uranium adsorbents.