Halloysite nanotubes: an eco-friendly adsorbent for the adsorption of Th(IV)/U(VI) ions from aqueous solution
Halloysite nanotubes: an eco-friendly adsorbent for the adsorption of Th(IV)/U(VI) ions from aqueous solution
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DOI：
10.1007/s10967-020-07142-4
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发表时间：
2020-04-18
影响因子：
1.6
通讯作者：
Zhang, Hongxia
中科院分区：
文献类型：
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作者：
Wang, Xinglei;Guo, Hangxu;Zhang, Hongxia
本研究对高岭土纳米管进行了表征，并采用间歇法研究了接触时间、吸附剂用量、pH、离子强度、初始U（VI）浓度和温度对Th（IV）和U（VI）在高岭土纳米管上的吸附作用。同时，探讨了铀和钍在高岭土纳米管上的吸附机理。显微分析结果表明，高岭土纳米管呈管状，多孔性强，比表面积约为55.65 m(2)/g。结果表明，U（VI）和Th（IV）在高岭土纳米管上的吸附符合准二级动力学模型。U（VI）和Th（IV）的吸附表现出与高岭土纳米管表面的强络合作用。Th（IV）和U（VI）的吸附随温度升高而增加，为吸热自发过程。Th（IV）和U（VI）的吸附等温线可以用Freundlich和D-R模型更好地描述。离子强度对钍在高岭土纳米管上吸附的影响远大于对铀的影响（几乎不受影响），说明Th（IV）在高岭土纳米管上的吸附很可能是基于球内配合物的形成，而U（VI）的吸附是基于球外配合物在边缘表面的形成。h（IV）和U（VI）在高岭土纳米管上的吸附-脱附等温线表明吸附过程是不可逆的。高岭土纳米管吸附的选择性顺序为Th(IV) > U（VI）。高岭土纳米管对Th（IV）具有较高的吸附效率，可用于pH为4.1 ~ 4.3的U（VI）水溶液中Th（IV）的选择性分离。这种新型的环境友好型吸附材料对废水溶液中钍的提取是可行的。
In this study, the halloysite nanotubes was characterized and the adsorption of Th(IV) and U(VI) on halloysite nanotubes was investigated as a function of contact time, adsorbent dosage, pH, ionic strength, initial U(VI) concentration and temperature using batch method. Meanwhile, the adsorption mechanism of uranium and thorium on halloysite nanotubes was discussed. The microscopic results displayed that halloysite nanotubes was tubular morphology and highly porous and high specific surface area of ca. 55.65 m(2)/g. The adsorption results showed that the adsorption of U(VI) and Th(IV) on halloysite nanotubes followed pseudo-second-order kinetic model. The strong pH dependent adsorption of U(VI) and Th(IV) displayed their strong surface complexation with the surface of halloysite nanotubes. The adsorption of Th(IV) and U(VI) increased with elevating temperature and was an endothermic and spontaneous process. The adsorption isotherms of Th(IV) and U(VI) can be better described by Freundlich and D-R model. The effect of ionic strength on the adsorption of thorium on halloysite nanotubes was much greater than that on uranium(almost unaffected), which suggested the adsorption of Th(IV) on halloysite nanotubes was most probably based on the formation of inner-sphere complexes, while that of U(VI) was based on the formation of outer-sphere complex on the edge surfaces. Th(IV) and U(VI) adsorption-desorption isotherm on halloysite nanotubes indicated adsorption process was irreversible. The selectivity order of adsorption by the halloysite nanotubes was Th(IV) > U(VI). The higher adsorption efficiency of the halloysite nanotubes for Th(IV) could be utilized for selective separation of Th(IV) from U(VI) aqueous with pH 4.1-4.3. The novel and environmentally friendly adsorption material is feasible to extract thorium from waste aqueous solution.