Kou Xin, Ma Yutian, Pan Congming, Huang Yong, Duan Yulai, Yang Ying
The Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province; School of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China.
Jinchuan Group Co., Ltd., Jinchang 737100, P. R. China.
Langmuir. 2022 May 17;38(19):6116-6127. doi: 10.1021/acs.langmuir.2c00482. Epub 2022 May 5.
Ionic polymers have been proven to be promising adsorbents in recovering Au(III) due to their advantages of simple synthesis and high adsorption efficiency. However, the unclarity of the relationship between the adsorption ability of ionic polymers and their cationic structures hinders further optimization of their adsorption performance. This study synthesized a series of ionic polymers with pyridinium, imidazolium, piperidinium, pyrrolidinium, and triethylammonium cations to discover the effects of the cationic structure on their adsorption properties. Experimental results show that the existence of anion-π interaction between aromatic cations and [AuCl] makes the aromatic cations-anion interaction stronger, which does not enhance the adsorption performance of the aromatic-based ionic polymer. This is due to the charge delocalization in the aromatic ring, resulting in a lower electrostatic potential (ESP) of aromatic cations than that of aliphatic cations with a localized charge. The higher the ESP of cations, the better the adsorption performance of the corresponding ionic polymer. This study serves as a deep understanding of the cationic structure-adsorptive performance relationship of the ionic polymer at the molecular level and further provides a theoretical guidance to optimize the adsorption performance of ionic polymers.
离子聚合物因其合成简单、吸附效率高的优点，已被证明是回收金（III）的有前景的吸附剂。然而，离子聚合物的吸附能力与其阳离子结构之间关系不明确，阻碍了其吸附性能的进一步优化。本研究合成了一系列含有吡啶鎓、咪唑鎓、哌啶鎓、吡咯烷鎓和三乙铵阳离子的离子聚合物，以发现阳离子结构对其吸附性能的影响。实验结果表明，芳香族阳离子与[AuCl]之间存在阴离子-π相互作用，使得芳香族阳离子-阴离子相互作用更强，但这并没有提高基于芳香族的离子聚合物的吸附性能。这是由于芳香环中的电荷离域，导致芳香族阳离子的静电势（ESP）低于具有局域电荷的脂肪族阳离子。阳离子的ESP越高，相应离子聚合物的吸附性能越好。本研究有助于在分子水平上深入理解离子聚合物的阳离子结构-吸附性能关系，并进一步为优化离子聚合物的吸附性能提供理论指导。
