基于单颗粒碰撞电化学的液/液界面加速离子转移反应研究  

Analysis of Facilitated Ion Transfer Across Liquid-Liquid Interfaces Using Collision Electrochemisty

作　　者：孟遥 张建伟 岳云沛 何俊辉 李延 MENG Yao;ZHANG Jian-Wei;YUE Yun-Pei;HE Jun-Hui;LI Yan(School of Chemistry and Chemical Engineering,Northwestern Polytechnical University,Xi′an 710072,China;Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education,College of Chemistry and Materials Science,Northwest University,Xi′an 710127,China)

机构地区：[1]西北工业大学化学与化工学院,西安710072 [2]西北大学化学与材料科学学院合成与天然功能分子化学教育部重点实验室,西安710127

出　　处：《分析化学》2020年第11期1535-1541,共7页Chinese Journal of Analytical Chemistry

基　　金：国家自然科学基金项目(Nos.21705128,21675124);陕西省自然科学基金项目(No.2018JQ2006)资助。

摘　　要：利用乳滴颗粒的碰撞电化学行为研究了二苯并-18-冠-6-醚(DB18C6)加速碱金属离子在水/1,2-二氯乙烷界面上的转移反应。通过高能超声分散技术制备出亚微米级油包水型乳化液滴,采用1-丁基-3-甲基咪唑双(三氟甲基磺酰)酰亚胺作为乳化剂,实现乳滴颗粒的长时间稳定。当在铂微电极上施加0.6 V的电压(相对于银伪参比电极)时,分散于油相的乳滴颗粒可通过与微电极的碰撞产生电导通,进而促发颗粒内部K 4Fe(CN)6的氧化反应。然而,仅在添加DB18C6的条件下可观察到与颗粒碰撞过程相对应的尖峰型电流响应,表明DB18C6可加速K+从水相到油相的转移,从而维持颗粒内外的电荷平衡,保证固/液界面电化学反应的持续进行。当DB18C6浓度增至0.05 mol/L时,乳滴颗粒内0.05 mol/L K 4Fe(CN)6由不完全电解转变为完全电解,提示加速K+转移反应伴随着离子:载体(1∶1,n/n)的界面络合反应过程。在不同偏置电压下,测定了含K 4Fe(CN)6或Na 4 Fe(CN)6的乳滴颗粒的碰撞电化学响应,构建出平均反应电量与偏置电压的关系。相比于Na+,DB18C6更易于络合K+进行液/液界面离子转移,此结果与传统四电极方法的结论类似。因而,单颗粒碰撞电化学可用于液/液界面加速离子转移反应的定性研究,具有简便、快捷、低成本等优点。An electrochemical method was developed to analyze the alkali metal ion transfer across the water/1,2-dichloroethane interfaces facilitated by dibenzo-18-crown-6 ether(DB18 C6)by observing the collisions of single emulsion droplets on an ultramicroelectrode(UME).The water-in-oil emulsion droplets were stabilized by an ionic liquid of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides,in which a highly hydrophilic redox probe of K3Fe(CN)6/K4Fe(CN)6 was used.When the droplets collided with the UME that was biased at a potential to drive the oxidation reaction of 0.05 mol/L[Fe(CN)6]4-,the current spikes could be observed only with the addition of DB18 C6.It was suggested that the DB18 C6 as K+ionophore facilitated the K+transfer from the water to the oil to maintain charge balance during droplet electrolysis.As more K+ionophores were added,the integrated charge of the current spikes showed a rising trend in general because of the ionophore to lower the Gibbs energy of ion transfer.Further collision experiments were conducted to investigate transfer of Na+and K+cations facilitated by the DB18 C6.The order in which the‘voltammetric’oxidation waves appeared indicated that the ionophore of DB18 C6 was more efficient in carrying K+across the water/1,2-dichloroethane interface.Thereby,the collision electrochemistry is a convenient and effective mean to study the ion selectivity of ionophore.

关 键 词：加速离子转移 离子载体 油包水型乳化液滴 单颗粒碰撞电化学 

分 类 号：O657.1[理学—分析化学]