纳米银负载型阳离子交换树脂的制备及其对水中碘离子的吸附去除

Preparation of nano-silver loaded cation exchange resin and adsorption of iodide ion in water

以大孔型磺酸基聚苯乙烯阳离子树脂为载体,采用硝酸银溶液浸渍、硼氢化钠溶液还原制备了纳米银负载型阳离子交换树脂,并对其吸附去除水中碘离子的性能进行了研究。结果表明:最佳硝酸银浸渍浓度为10 mmol/L,对应载银量19.3 mg/g;25℃中性水溶液中,该材料对碘离子的饱和吸附量为74.7 mg/g;吸附量受溶液离子强度的影响较小,但当溶液pH从11降至3时吸附量降低了23%。根据吸附前后材料的XPS谱图变化推测碘离子的去除机理可能为:树脂载体上负载的纳米银活性组分首先与水中溶解氧发生氧化反应产生银离子,随后与溶液中的碘离子结合形成AgI沉淀,从而将碘离子从溶液中去除。

Using macroporous sulfonic polystyrene cationic resin as the carrier,the nano-silver loaded cation exchange resin was prepared by impregnation with silver nitrate solution and reduction with sodium borohydride solution,and its adsorption performance to iodide ions in water was studied.Results show that:The optimal silver nitrate concentration is 10 mmol/L,corresponding to a silver loading of 19.3 mg/g;The saturated adsorption capacity of the material to iodide ions in 25℃and neutral solution is 74.7 mg/g;Ionic strength shows less impact on the material’s adsorption quantity,but when the solution pH decreases from 11 to 3,the adsorption quantity decreases by 23%.Basing on the changes of XPS spectra of the material before and after adsorption,the mechanism for iodide ions removal is extrapolated that the nano-silver active component loaded on the resin carrier first undergoes an oxidation reaction with dissolved oxygen in water to generate silver ions,and then combines with iodide ions in solution to form AgI precipitation,thereby iodide ions are removing from the solution.