Preparation Of Chitosan/Hydroxyapatite Microspheres And Study On The Adsorption Mechanism Of U(Ⅵ)

Uranium is an important raw material for the nuclear industry,and it is both chemically and radioactively toxic.With the migration of the environment and the enrichment of the food chain,low-concentration uranium-containing wastewater will inevitably enter the environment,posing a potential threat to the natural environment and human health.Efficiently treating uranium-containing wastewater and recovering the uranium in it has become an urgent nuclear environmental problem that needs to be solved urgently.In this study,waste pig bones from food factories were used as raw materials,and pig bone-based hydroxyapatite（HAP）was first successfully prepared by high-temperature carbonization.On this basis,in order to prepare a shaped adsorbent with certain mechanical strength,chitosan/hydroxyapatite microspheres were prepared by inverse emulsification method using pig bone-based hydroxyapatite and chitosan as raw materials（CS/HAP）.HAP has strong adsorption to a variety of metal ions.The Ca²⁺in its crystal lattice can be ion-exchanged with uranyl ions,and the phosphoric acid group can form complexes with uranyl ions to remove them;CS/HAP The microspheres combine the characteristics of hydroxyapatite and chitosan,which solves the problem that the powdery adsorbent is easy to agglomerate in the solution and is not easy to be recovered after the reaction.At the same time,it has a good adsorption effect on uranium in water,which is an excellent Renewable adsorbent.Hydroxyapatite（HAP）was prepared from pig bone as raw material,and its adsorption performance for heavy metal ions U（Ⅵ）was investigated.The p H of the system,the initial concentration of uranium-containing wastewater,the amount of hydroxyapatite,the adsorption time,and the temperature of the system were investigated.The effect of adsorption performance was characterized by FT-IR,XRD,EDS and SEM to characterize the morphology,structure and composition of hydroxyapatite,and to study its mechanism of action.The results showed that the main composition of the adsorbent was hydroxyapatite Ca₁₀（PO₄）₆（OH）₂,and its crystal structure changed from a short rod-like structure to a lamellar structure.When the temperature is 25℃and the p H is 4,the uranium in the hydroxyapatite adsorption solution reaches equilibrium within 80 minutes,and the maximum adsorption capacity reaches 483.10 mg/g.The adsorption capacity gradually increases with the increase of the system temperature,and the temperature rise is beneficial to adsorption;the pseudo-second-order kinetic equation can better fit the adsorption process,and the adsorption behavior is more in line with the Langmuir model.Characterization and adsorption experiments show that the adsorption mechanism is the surface complexation reaction of U（Ⅵ）and HAP active groups and ion exchange reaction.Using chitosan（CS）and pig bone-based hydroxyapatite（HAP）as raw materials,on the basis of the successful preparation of pig bone-based hydroxyapatite（HAP）,chitosan/hydroxyapatite was prepared by inverse emulsification method Greystone（CS/HAP）microspheres.The material was characterized by scanning electron microscopy（SEM）,X-ray energy spectroscopy（EDS）,Fourier infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,and the adsorption performance of CS/HAP on uranium was explored.The reaction products and mechanism were analyzed,and the material’s desorption and regeneration characteristics were tested at the same time.The results showed that:CS and HAP were successfully cross-linked by inverse emulsification method;it is inferred that the adsorption of uranium by CS/HAP is dominated by chemical adsorption.This process is consistent with the quasi-second-order kinetic model（R²>0.999）and the Langmuir isothermal model（R²>0.998）It can fit well;CS/HAP is a kind of adsorbent with good reproducibility.