Preparation And Uranium (Ⅵ) Biosorption For Polydigital Amidoxime-modified Marine Fungus Materials

With the modern society is developing constantly,global’s energy demand continues to increase,and industrial wastewater discharged from mining development is also growth,which leads to more serious contaminate sources of environmental.Since the 21st century,how to abbreviate ecological damage and treat industrial wastewater have become a front-burner issue.Various advanced processes have been tried for the treatment of radioactive U（Ⅵ）wastewater,such as chemical precipitation,ion exchange,solvent extraction,evaporation and concentration,and adsorption.However,there are still many loopholes such as large amount of sludge,secondary pollution,high cost and complex follow-up treatment,so the researchers gradually turned their attention to biosorption methods,which are of the advantages of a high adsorption efficiency,material safety,low price and so on.The amidoxime group has high selectivity and affinity for uranium ions,which is considered to be one of the most effective ligands for the adsorption of uranium ions.Therefore,amidoxime-modified adsorbents are the most widely used in adsorption of uranium in wastewater.According to the anterior research fruits of the laboratory,this research keep trying to synthesis claw-shaped fungus materials containing tri-amoxime and tetra-amoxime groups by chemical modification.This functional material is based on endogenous fungus Fusarium sp.#ZZF51as the synthetic substrate,which were made in the mangrove forest of the South China Sea.The results was characterized by SEM,FT-IR,N₂-BET and TGA.In order to improve the material’s adsorbability to uranium（Ⅵ）,the effects of sorbent dose,uranium ion concentration,initial pH value,and reaction time on uranium adsorption were investigated from single factor experiments.On the basis of its experimental results,the adsorption conditions were further optimized by orthogonal experimentation to offer scientific reference for industrial processing of uranium-containing wastewater.The experimental process is as follows:probe into the influence of material dosage,initial uranium ion concentration,reaction time on the uranium adsorption performance of modified materials under the condition of pH=5±3.Meanwhile,the isothermal adsorption model and adsorption kinetic model were used to study its adsorption behavior and adsorption mechanism,and the stability,reusability and economic efficiency of biomaterials were discussed through desorption regeneration experiments.The SEM analysis was found that the surface gradually became rough and dense with the progress of chemical modification and the surface of the modified material changed significantly after loaded uranium.FT-IR analysis showed that the grafted cyano group was successfully converted to amidoxime group,and a complexation with uranium ions occurred after the adsorption reaction.From N₂-BET analysis,the specific surface area,pore volume and average pore diameter of ZGEA were calculated to be 10.6907 m² g^-1,0.012839 cm³ g^-1,and 29.13 nm,respectively.In addition,TGA analysis results showed that the modified fungal material had good thermal stability and loaded U3O8successfully.The coefficients of the fitting curves of the quasi-first-order and quasi-second-order kinetic models（R²>0.999）indicated that the adsorption process of ZGEA involved both chemical and physical adsorption.The Langmuir and Freundlich models fit the adsorption process well,which declared the adsorption process had both single-molecule adsorption and bi-molecular adsorption.In addition,the adsorption rate decreased only 10.92%after five desorption-regeneration cycles using 0.1 mol L^-1 HCl solution as the desorbent,and adsorption capacity of ZGEA for uranium ions was still as high as 511.31 mg g^-1.Therefore,ZGEA has potential application prospect in uranium extraction field.The last chapter summarizes the paper in detail,and look beyond to the development of uranium containing wastewater treatment methods.