Effects of the Cationic Structure on the Adsorption Performance of Ionic Polymers toward Au(III): an Experimental and DFT Study

Abstract

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 4 ] − 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.

Selective and Efficient Gold Extraction from E-Waste by Pyrrolidinium-Based Ionic Liquids with Various N-Substituents

“…In other words, the positive charges of pyrrolidinium cations increase and the maximum ESP increases. It can be speculated that the extraction performance roughly follows the order of ESP. , As expected, [Pyr-EA]­[NTf 2 ] has the largest ESP and the highest extraction efficiency. However, the ESP of [Pyr-C 2 OC 2 ]­[NTf 2 ] is higher than that of [Pyr-Bu]­[NTf 2 ], but the extraction performance is worse than that of [Pyr-Bu]­[NTf 2 ], which does not conform to the order of ESP.…”

“…20 Kou et al reported that the adsorption performances of poly(ionic liquid)s (PILs) toward Pd(II) and Au(III) were affected by various N-substituents due to the changes of electrostatic potential (ESP). 21,22 As far as we know, no one has explained the influences of N-substituents on the extraction performances of pyrrolidinium-based ILs.…”

“…In addition, substituents can significantly affect the physicochemical properties of ILs and then affect their application performances. − For example, Zheng et al revealed that the antibacterial activities of both ILs and PILs increased with the increase of alkyl chains and higher charge densities . Kou et al reported that the adsorption performances of poly­(ionic liquid)­s (PILs) toward Pd­(II) and Au­(III) were affected by various N-substituents due to the changes of electrostatic potential (ESP). , As far as we know, no one has explained the influences of N-substituents on the extraction performances of pyrrolidinium-based ILs. Therefore, in order to optimize the extraction performances of pyrrolidinium-based ILs, it is necessary to further explore the relationships between the structures and the extraction performances of ILs.…”

Anion Coordination into Ligand Clefts

“…In particular, the pyrimidine inserted into the receptor was chosen precisely for this reason: being highly electron-poor, it has a marked tendency to form anion-π interactions, a characteristic confirmed by the crystal structures of several anion complexes with receptors containing this group [13][14][15][16][17]. Moreover, protonated pyridine groups have a non-negligible ability to form anion-π interactions [18][19][20][21][22][23][24][25][26][27][28].…”

Molecular Insights into Curvature Effects on the Capacitance of Electrical Double Layers in Tricationic Ionic Liquids with Carbon Nanotube Electrodes

“…Ionic liquids (ILs) have been demonstrated to be superior candidates for supercapacitor electrolytes due to their beneficial electrochemical and physicochemical qualities of a wider working voltage window (3–5 V), better thermostability, lower volatility, and inflammability compared with organic or water electrolytes. − Extensive investigations of the properties of EDLs in ILs with CNT electrodes have been carried out. Honda et al found that the tunable curvature of CNT may noticeably influence the EDL capacitance during experiments.…”