Preparation Of Zirconium Phosphate Adsorbent And Study On Adsorption Properties And Mechanism Of Strontium

With the continuous development of nuclear energy industry,a large number of radioactive pollutants are discharged into the environment due to nuclear accidents.After the Fukushima nuclear accident,many pollutants containing strontium and other radionuclides entered the seawater.How to remove low concentration radionuclides in the complex environment has become a key research issue in recent years.Inorganic ion exchange materials have many advantages,such as strong adsorption capacity,easy to use and recycle,which show a good application prospect in the treatment of radioactive wastewater.Zirconium phosphate has the characteristics of acid resistance and heat resistance,and it contains a lot of hydroxyl groups.In aqueous solution,H⁺and Na⁺in interlayer can exchange with Sr²⁺.Therefore,zirconium phosphate is widely used for the removal of Sr²⁺in the environment.However,the slow adsorption rate seriously limits the applicability of zirconium phosphate adsorbent in real seawater treatment.In this paper,two kinds of zirconium phosphate adsorption materials with different structures were prepared for the purpose of efficiently and directively removing strontium ions(Sr²⁺)from seawater,and their adsorption properties and mechanism for Sr²⁺were studied.Firstly,Zr（HPO₄）₂·n H₂O-MSP composite adsorbent was prepared by liquid phase grafting method with silica microspheres as carrier.Secondly,Zr O₂ aerogels were prepared by dropping epoxy propane and surface phosphorylation was carried out to prepare ZrP aerogel adsorbent.The adsorbents were characterized by SEM-EDS,XRD,FT-IR,BET,XPS and TG-DSC.The ability of the adsorbent to remove Sr²⁺was tested by static adsorption and column experiments.The results are as follows:（1）Zr（HPO₄）₂·n H₂O-MSP and ZrP aerogel adsorbents were successfully prepared.The specific surface area,average pore size and pore volume of the two adsorbents are 293.73 m²/g,2.44 nm,0.42 cm³/g and 98.14 m²/g,17.07 nm,0.41cm³/g,respectively.Its porous properties provide convenience for ion exchange.（2）Zr（HPO₄）₂·n H₂O-MSP adsorbent reaches the adsorption equilibrium at90min with the maximum adsorption capacity of 100.77mg/g,which is 100%and46%higher than that of pure ZrP（180min,68.88mg/g）adsorbent,respectively.The adsorbent can keep the adsorption effect at p H of 5-10.Adsorption experiments show that Zr（HPO₄）₂·n H₂O-MSP has good affinity for Sr²⁺and can catch Sr²⁺in real seawater.（3）ZrP aerogel adsorbent reaches the adsorption equilibrium at 50min with the maximum adsorption capacity of 198.44mg/g,which is 260%and 188%higher than that of pure ZrP（180min,68.88mg/g）adsorbent,respectively.The adsorbent can keep the adsorption effect at p H of 5-10.Adsorption experiments show that ZrP aerogel adsorbent is more suitable for column filling,and its dynamic adsorption capacity is 185.95mg/g by Thomas fitting.In real seawater column experiment(Sr²⁺:5mg/L),ZrP aerogel adsorption can deal with seawater with a volume of about 870 times.（4）The adsorption mechanism of the two adsorbents was studied by Zeta,XPS and FT-IR.The results show that the adsorption mechanism of strontium ions on the two kinds of ZrP adsorbents is completed by electrostatic interaction and ion exchange.