State Key Laboratory for Nuclear Resources and Environment, East China University of Technology, 418 Guanglan Road, 330013 Nanchang, PR China.
State Key Laboratory for Nuclear Resources and Environment, East China University of Technology, 418 Guanglan Road, 330013 Nanchang, PR China; Reactor Engineering & Technology Group, School of Chemical Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
Int J Biol Macromol. 2020 Oct 1;160:1000-1008. doi: 10.1016/j.ijbiomac.2020.05.179. Epub 2020 May 25.
The porous chitosan/carboxylated carbon nanotubes composite aerogels (CS-CCN) with different CCN contents were prepared for the efficient removal of U(VI) from aqueous solution. The successful formation of CS-CCN aerogels with highly porous structure was confirmed by different characterizations (such as SEM, TEM, XRD, etc.). The sorption capacity of the aerogels depends on CCN content, which has significant impact on the porous structure and the sorption ability of the aerogels. The CS-CCN aerogels were found to be very effective for U(VI) sorption: the maximum mono-layer sorption capacity for CS-CCN2 aerogel reached 307.5 mg/g at pH 5.0 and 298 K. The chemisorption or surface complexation through sharing of O/N lone pair electrons on the active sites (carboxylic and amine groups) was responsible for U(VI) sorption, which is confirmed by the IR and XPS analysis. Meanwhile, the good-fitting of both sorption kinetics by pseudo-second-order model and sorption isotherms by Langmuir model also indicates chemisorption mechanism. The thermodynamic data suggest that U(VI) sorption on CS-CCN aerogel is endothermic and spontaneous. The unique characteristics such as high sorption capacity, fast kinetic, and easy recovery from solution make CS-CCN aerogels be very efficient sorbents for the treatment of radioactive wastewater.
不同 CCN 含量的多孔壳聚糖/羧化碳纳米管复合气凝胶（CS-CCN）被制备用于从水溶液中高效去除 U(VI)。通过不同的表征（如 SEM、TEM、XRD 等）证实了 CS-CCN 气凝胶具有高度多孔结构的成功形成。气凝胶的吸附能力取决于 CCN 含量，这对气凝胶的多孔结构和吸附能力有重大影响。CS-CCN 气凝胶被发现对 U(VI)的吸附非常有效：在 pH 5.0 和 298 K 时，CS-CCN2 气凝胶的最大单层吸附容量达到 307.5 mg/g。通过在活性位点（羧基和氨基）上共享 O/N 孤对电子的化学吸附或表面络合负责 U(VI)的吸附，这通过 IR 和 XPS 分析得到证实。同时，吸附动力学的准二级模型拟合和吸附等温线的 Langmuir 模型拟合都表明了化学吸附机制。热力学数据表明，CS-CCN 气凝胶上 U(VI)的吸附是吸热和自发的。CS-CCN 气凝胶具有高吸附容量、快速动力学和易于从溶液中回收等独特特性，使其成为处理放射性废水的非常有效的吸附剂。
