微波对吸附氨氮饱和沸石的再生

以吸附氨氮饱和的斜发沸石为研究对象,分别采用单独微波辐射及微波辅助溶剂法对其进行再生研究.研究发现,单独微波辐射再生效果较差,功率462 W, 微波辐射12 min,饱和沸石再次去除率为32.31%,再生率仅为44.88%;添加NaCl和NaOH混合液可以大大增强饱和沸石的再生效果,在NaCl和NaOH混合液浓度均为0.01 mol/L,固液比1∶50,功率700 W,微波辐射4 min时,最佳去除率为71.92%,再生率接近100%. 通过FTIR, SEM, EDS等测试手段对改性、吸附、再生前后的沸石分析发现, 沸石在改性、吸附、再生过程中主要发生的是不同阳离子间交换过程. 微波辐射加速了NH4+与Na+交换过程且加深了离子交换平衡程度,因此微波辅助溶剂法具有再生迅速、完全,多次再生效果基本不衰减的优点.
Modified clinoptilolite saturated with ammonia nitrogen was regenerated by microwave radiation alone and microwave-assisted regeneration solution, respectively. The study showed that the poor regeneration effect was obtained by microwave alone. The adsorption removal efficiency of ammonia onto spent zeolite after regeneration restored to 32.31% under the conditions of the power of 462 W and microwave radiation of 12 min， and the regeneration rate was only 44.88 %. The regeneration effect of the saturated zeolite was highly enhanced by adding mixed solution of NaCl and NaOH. The saturated zeolite achieved the maximum removal rate of about 71.92%, and the regeneration rate was close to 100%, when it was treated in NaCl and NaOH mixed solution concentration of 0.01 mol/L, the ratio of solid to liquid as 1∶50, the power of 700 W, and the microwave radiation of 4 min. For all the zeolites before and after modification, adsorption and regeneration were fully characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) technique. The results demonstrated that zeolites mainly exhibited cation exchange in the process of modification, adsorption and regeneration. Microwave radiation accelerated the exchange process and deepened the ion exchange equilibrium degree between NH4+ and Na+, which contributes to the NH4+ desorption from zeolite framework fast and completely.