季胺盐阳离子插层蒙脱土对铀吸附性能的研究

Adsorption of Uranium from Aqueous Solution Using CTMA^+-Pillared Montmorillonite

通过十六烷基三甲基溴化铵(CTMAB)与钠基蒙脱土离子交换制备出季胺盐阳离子插层蒙脱土(CTMA+-M),采用小角X射线衍射仪、傅里叶变换红外光谱仪和高分辨透射电镜表征微观结构,研究CTMA+的插层量、溶液的初始pH值、初始浓度和其他共存离子对吸附铀性能的影响,考察了CTMA+-M处理铀矿水冶废水的应用性能。结果表明:CTMA+插层后蒙脱土的层间距由1.21 nm增加到4.09 nm,但仍保持钠基蒙脱土原有的晶体结构。随CTMAB用量的增加,插层到蒙脱土层间的CTMA+量增加,对铀离子的吸附容量逐渐增大,当CTMAB的用量超过阳离子交换容量的1.4倍时,铀吸附容量基本保持不变。溶液pH和接触时间对铀离子吸附性能影响较大,CTMA+-M最佳吸附pH值为6.0,平衡吸附时间为80 min,CTMA+插层能够改善蒙脱土对铀离子的选择性吸附。在1 L含有15 mg/L铀的废水中加入1.5 g CTMA+-M时,铀的去除率达到98%以上。

The ability of hexadecyltrimethylammonium cation pillared montmorillonite （CTMA ~ -M） has been ex- plored for the removal and recovery of uranium from aqueous solutions. The adsorbent was characterized using small-angle XRD, FTIR and HRTEM. The influences of different experimental parameters such as CTMA ＋ pil- lared amount, solution pH, initial uranium concentration and contact time on adsorption were investigated. The interlayer spacing rose from 1.21 nm to 4.09 ran, and still remained the original crystal structure. The CTMA ＋ - M exhibited the highest uranium sorption capacity at initial pH of 6.0 and at 80 rain. With the increasement of CTMA ＋ , the uranium sorption capacity enhanced, and kept steady when the CTMAB used exceed 1.4 time of the cation exchange capacity. Selective adsorption studies showed that the CTMA＋ -M could selectively remove U （VI）, and the selectivity coefficients were improved after pillaring in the presence of co-existing ions, Na（I）, Ni （ Ⅱ）, Sr（ Ⅱ）, Mn（ Ⅱ）, Mg（Ⅱ） and Zn（II）. Complete removal （ - 100% ） of U（VI） from 1.0 L simulated nu- clear industry wastewater containing 15.0 mg U（VI） ions was possible with 1.5 g CTMA＋ -M.