Synthesis and Uranium-adsorption Performance of Phosphoic/Phosphonic Ester Based Functional Materials
In addressing the adsorption issue of low-concentration uranium in nitric acid systems,a chloromethylated styrene-divinylbenzene copolymer was employed as the framework,and phosphoryl-ation was achieved using phosphorus trichloride as the functionalizing reagent.Through Friedel-Crafts alkylation and quenching-hydrolysis/alcoholysis reactions,long-chain hydroxyl and alkyl groups were grafted onto the resin,resulting in uranium adsorbents featuring phosphoric acid and phosphoric ester functional groups,respectively.The resin structural characterization was conducted using infrared spectroscopy,elemental analysis,and thermogravimetric analysis.During the resin preparation,the impact of different process parameters on the phosphorus content and uranium adsorption performance was investigated,leading to the determination of optimal synthesis conditions.Static experiments were performed to assess the influence of pH,equilibrium uranium concentration,and adsorption time on the uranium adsorption properties of the resin.Additionally,a selection of desorption agents and verification of resin reusability were carried out.The results indicate that the prepared phosphoric es-ter-based uranium adsorbent exhibits excellent adsorption performance for low-concentration uranium(＜20 mg/L)in a simulated solution(1 mol/L HNO3+1 mol/L NaNO3).The resin saturation ad-sorption capacity for uranium is 21.9 mg/g dry resin,and the residual uranium concentration in the leachate after adsorption is＜0.05 mg/L.Using 0.4 mol/L NaHCO3 and 0.1 mol/L Na2CO3 as com-posite desorption agents,the desorption efficiency for uranium reaches 98.3％.The synthesized phos-phoric ester-based uranium adsorbent proves effective for the adsorption and separation of low-concen-tration uranium in nitric acid systems.
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