U(VI) adsorption onto cetyltrimethylammonium bromide modified bentonite in the presence of U(VI)-CO3 complexes
U(VI) adsorption onto cetyltrimethylammonium bromide modified bentonite in the presence of U(VI)-CO3 complexes
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DOI：
10.1016/j.clay.2016.09.005
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发表时间：
2017
影响因子：
5.6
通讯作者：
Jun Liu;Changsong Zhao;H. Tu;Jijun Yang;Feize Li;Dongmei Li;J. Liao;Yuanyou Yang;Jun Tang;Ning Liu
中科院分区：
文献类型：
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作者：
Jun Liu;Changsong Zhao;H. Tu;Jijun Yang;Feize Li;Dongmei Li;J. Liao;Yuanyou Yang;Jun Tang;Ning Liu
为模拟十六烷基三甲基溴化铵（CTAB）改性膨润土作为铀资源回收吸附剂的可行性，采用静态吸附实验研究了U（VI）-CO 3络合物对CTAB改性膨润土吸附U（VI）的影响。吸附容量（qe）随pH值从8.9增加到9.5和溶解碳酸盐浓度下降，但阳离子表面活性剂改性后显着提高。吸附动力学符合准二级动力学方程，其中非线性的Langmuir和Freundlich模型与CTAB-膨润土的数据拟合较好。计算的热力学参数表明，U（VI）在材料上的吸附是一个自发的吸热过程。特别是，我们确定UO 2（CO 3）34 −，UO 2（CO 3）22 −，（UO 2）2CO 3（OH）3−，UO 2（OH）3−阴离子可能是通过与溴离子的阴离子交换从CTAB分子中吸附的，根据铀酰形态计算，而U（VI）-CO 3复合物的吸附容量与含水U（VI）物种的比例以及CO 32-之间的竞争吸附相关阴离子和U（VI）-CO 3络合物。脱附实验表明，1.0 mol/L HNO 3溶液脱附效果最好。本研究报告的结果有助于促进使用CTAB-膨润土和其他可能的粘土从水，特别是从盐湖卤水或海水中提取铀资源，并考虑自然环境中的实际U（VI）物种。
The influence of U(VI)-CO3complexes on U(VI) adsorption onto cetyltrimethylammonium bromide (CTAB) modified bentonite was investigated using batch adsorption experiments to simulate the feasibility of CTAB-bentonite as an adsorbent for the uranium resources recovery. The adsorption capacity (qe) decreased with increasing pH from 8.9 to 9.5 and dissolved carbonate concentrations, but was significantly improved after cation surfactant modification. The adsorption kinetics was depicted by the pseudo-second-order kinetic equation, where the nonlinear Langmuir and Freundlich models fitted well with the data of CTAB-bentonite. The calculated thermodynamic parameters suggested that the adsorption of U(VI) on material was a spontaneous and endothermic process. In particular, we determined that UO2(CO3)34 −, UO2(CO3)22 −, (UO2)2CO3(OH)3−, UO2(OH)3−anions may have been adsorbed by anion exchange with bromide ion from the CTAB molecule at high CTAB loading levels according to the uranyl speciation calculations, whereas U(VI)-CO3complexes adsorption capacity correlated with the proportion of aqueous U(VI) species and the competitive adsorption between CO32–anions and U(VI)-CO3complexes. Additionally, desorption results revealed that the most effective desorption agent was 1.0 mol/L HNO3solution. The findings reported in this study aid in facilitating the extraction of uranium resources from aqueous using CTAB-bentonite and other possible clays, especially from salt lake brines or seawater and the consideration of practical U(VI) species in the natural environment.