Performance Ang Mechanism Of Uranium(?)Removal By Zero-Valent Aluminum And Hydroxy-Aluminum Impregnated Chitosan

As an important raw material for nuclear industry,uranium has chemical and radiotoxicity.Low concentration uranium-contained wastewater will inevitably enter the environment along with environmental migration and food chain enrichment,which poses a potential threat to the natural ecological environment and human health.How to effectively treat uranium-contained wastewater and recover uranium have become an urgent nuclear environmental problem.In this paper,zero-valent aluminum powder(ZVA1)with strong reducibility was prepared from scrap aluminum can by physical means Hydroxy-Aluminum impregnated Chitosan composite(Al-CTS)with high adsorption capacity was prepared by in-situ hydrolysis-impregnation method.ZVA1 has strong reducibility,and U(?)can be rapidly reduced to U(?)to form UO2 precipitation by ZVAl in aqueous solution.Al-CTS composite not only improves the adsorption capacity and selectivity of chitosan to uranium,but also effectively prevents the agglomeration of nanoparticles.It is an excellent renewable adsorbentIt is a new water treatment technology to treat wastewater containing U(?)by ZVAl with strong reduction performance.Static single factor method is used to study the removal effect of ZVA1 on U(?)in water under different environmental conditions(material dosage,pH value,initial concentration,reaction time,temperature,etc.)and determine the best reaction conditions.The experimental results show that when the initial concentration of U(?)is 10 mg/L,reaction time is 120 min,the dosage of ZVAl is 4.0 g/L and reaction temperature is 303 K,the removal rate of U(?)is 98.2%,which is much better than that of zero-valent iron.Chemical kinetics analysis and XPS characterization show that the removal mechanism of ZVAl for U(?)is mainly reduction precipitation-adsorption coprecipitation,and reduction is the main way for ZVAl to remove U(?).In addition,the hydroxy alumina(AlOOH)nanoparticles were immobilized in chitosan,and the optimal adsorption conditions were determined by investigating the adsorption properties of Al-CTS for U(?).In this experiment,the initial concentrations of U(?)are 10-50 mg/L,the initial pH of solution is 6.0,the dosage is 0.8 g/L,the temperature is 298 K,and the reaction time is 80 min,the adsorption rates of Al-CTS for U(?)are above 95%.Compared with pure chitosan,the adsorption capacity of Al-CTS for U(VI)increases by 23.85 mg/g Kinetics,thermodynamics and isothermal adsorption model of the material are analyzed.The results show that the adsorption of U(?)by Al-CTS is through homogeneous single layer chemical adsorption,and the process is spontaneous endothermic.The consequence revealed that surface complex between Al-O bond,-NH2 group,-OH group and U(VI)may participate in the adsorption processes,and the main mechanism is the surface complexation of the internal sphere.The experiment of interference ion and desorption regeneration proves that Al-CTS is a renewable adsorbent with good application potential and prospects in the treatment of radioactive wastewater.