Measuring Liquid-into-Liquid Diffusion Coefficients by Dissolving Microdroplet Electroanalysis
Measuring Liquid-into-Liquid Diffusion Coefficients by Dissolving Microdroplet Electroanalysis
复制标题
通过溶解微滴电分析测量液-液扩散系数
DOI：
10.1021/acs.analchem.3c03256
复制
发表时间：
2023
影响因子：
7.4
通讯作者：
Dick, Jeffrey E.
中科院分区：
文献类型：
--
作者：
Rana, Ashutosh;Renault, Christophe;Dick, Jeffrey E.
扩散是污染控制、药物传递和同位素分离等领域的基本过程。精确测量一种液体到另一种液体的扩散系数(D)经常遇到来自分子间相互作用、液体界面精确观察、对流等方面的挑战。在这里，我们提出了一种创新的电化学方法来确定一种液体到另一种液体的扩散系数。该方法包括精确跟踪非水液滴的寿命。将有机液滴放置在由六氰高铁酸钾（II/III）水溶液包围的超微电极上。液滴最初阻断氧化还原物质的还原或氧化。当液滴溶解，进入导电微电极表面时，在伏安法和安培响应中观察到持续增加的电流。因此，电化学响应直接报告了电极表面氧化还原物质的通量，使我们能够精确地确定液滴的寿命。数值是通过电化学分析和液滴溶解原理的结合直接确定的。我们演示了1,2-二氯乙烷和硝基苯在水中的定量，得到的扩散系数分别为（11.3±1.2）× 10-6cm2 /s和（5.2±1.1）× 10-6cm2 /s。本工作建立了一种可靠的基于液滴寿命分析的扩散系数定量电化学方法。
Diffusion is a fundamental process in various domains, such as pollution control, drug delivery, and isotope separation. Accurately measuring the diffusion coefficients (D) of one liquid into another often encounters challenges stemming from intermolecular interactions, precise observations at the liquid interface, convection, etc. Here, we present an innovative electrochemical methodology for determining the diffusion coefficient of a liquid into another liquid. The method involves precisely tracking the lifetime of a nonaqueous droplet. An organic droplet is placed on an ultramicroelectrode surrounded by an aqueous solution of potassium hexacyanoferrate(II/III). The droplet initially blocks the reduction or oxidation of the redox species. As the droplet dissolves, giving access to the conductive microelectrode surface, a continuously increasing current is observed in voltammetry and the amperometrici–tresponse. The electrochemical response thus directly reports on the flux of redox species on the electrode surface, allowing us to precisely determine the lifetime of the droplet.Dvalues are directly determined through a combination of electrochemical analysis and the principles of droplet dissolution. We demonstrate the quantification of 1,2-dichloroethane and nitrobenzene into water, yielding diffusion coefficients of (11.3 ± 1.2) × 10–6cm2/s and (5.2 ± 1.1) × 10–6cm2/s, respectively. This work establishes a reliable electrochemical approach for quantifying diffusion coefficients based on droplet lifetime analysis.