果胶/AMP-Zn微球的制备及对Cs^+的吸附性能

Preparation and Adsorption Properties of Pectin/AMP-Zn Microspheres for Cesium Ions

采用溶胶-凝胶法,以Zn2＋为交联剂,将磷钼酸铵（AMP）通过静电注射装置包埋于果胶中,制备了果胶/AMP-Zn微球吸附剂,用于放射性废水中Cs^＋的去除。系统探讨了不同pH、吸附剂质量、接触时间、Cs^＋质量浓度、温度及共存离子对果胶/AMP-Zn去除Cs^＋的影响,并利用SEM、FTIR和XPS分析了吸附机理。结果表明：果胶/AMP-Zn可在pH=3-11内使用,耐酸碱性能良好,且在25℃、pH=5、Cs^＋质量浓度为120 mg/L、吸附剂质量为0.05 g、接触时间为330 min的条件下,吸附剂的吸附量为41.837 mg/g;共存离子K＋、Na^＋、Li^＋、Ca^2＋和Mg2＋对Cs^＋的吸附影响不大,说明该吸附剂具有较好的吸附选择性;热力学和动力学研究结果表明：此吸附过程符合Freundlich等温吸附模型和准二级动力学模型,且是一个自发放热的过程。果胶/AMP-Zn吸附Cs^＋的吸附机理可能是Cs^＋与AMP上的NH4＋发生离子交换作用。

Pectin/AMP-Zn microspheres were prepared by embedding ammonium phosphomolybdate （AMP） in pectin by electrostatic-injecting device via gel-sol method and using Zn^2＋ as cross-linking agent, which was evaluated for its potential for the removal of Cs^＋ in radioactive waste water.The factors affecting the adsorption of Cs^＋ on pectin/AMP-Zn microspheres such as pH, mass of adsorbent, contact time, mass concentration of Cs^＋, temperature and competing ions were systematically investigated. In addition, the adsorption mechanism of Cs＋ on pectin/AMP-Zn microspheres was analyzed by means of SEM, FTIR and XPS. The results showed that the pectin/AMP-Zn microspheres could be applied in a range of pH=3-11 with good acid resistance and alkali resistance. The adsorption capacity of adsorbent reached 41.837 mg/g under the conditions of 25℃, pH=5, 120 mg/L mass concentration of Cs^＋, 0.05 g adsorbent, and 330 min contact time. Competing ions （K^＋, Na^＋, Li^＋, Ca^2＋ and Mg^2＋） had little effect on the adsorption of Cs^＋, indicating that pectin/AMP-Zn had excellent adsorption selectivity. Thermodynamic and kinetic studies demonstrated that the adsorption of Cs^＋ on pectin/AMP-Zn microspheres was fitted well with Freundlich model and pseudo-second-order kinetic model, respectively.Besides, the adsorption process was a spontaneous exothermic process, and the adsorption mechanism was ion exchange reaction between NH4^＋ and Cs^＋.