Dynamic interfacial tension measurement under electric fields allows detection of charge carriers in nonpolar liquids
Dynamic interfacial tension measurement under electric fields allows detection of charge carriers in nonpolar liquids
复制标题
电场下的动态界面张力测量可以检测非极性液体中的电荷载流子
DOI：
10.1016/j.jcis.2020.01.081
复制
发表时间：
2020
影响因子：
9.9
通讯作者：
Walker, Lynn M.
中科院分区：
文献类型：
--
作者：
Sengupta, Rajarshi;Khair, Aditya S.;Walker, Lynn M.
假设当表面活性剂在油相中形成带电聚集体时，电场增强了表面活性剂向油-水界面的迁移。因此，电场下的传输可以用于检测非极性介质中带电的表面活性剂聚集体。实验将两种具有不同结构的表面活性剂分散在Isopar-M中。使用定制的通电微张力计平台，在恒定电场下，表面活性剂到油-水界面的运输被量化。电导率的油与表面活性剂浓度也进行了测量，以确定存在的电荷carriers.FindingsThe充电机制的油相，和现场增强运输是不同的两种表面活性剂。在表面活性剂的电导率难以区分的低浓度下，电场下的动态界面张力测量可以确定Isopar-M中电荷载流子的存在。离子表面活性剂在水相中的运输不受电场的影响，证实了油相表面活性剂的电场增强运输是由于电荷载体的电泳。此外，平衡界面张力没有发现改变下的电场，表明吸附等温线是独立的电场强度。我们证明了在电场下的动态界面张力的测量是一种灵敏的技术来检测非极性流体中的电荷载流子。
HypothesisElectric fields enhance surfactant transport to oil-water interfaces when the surfactant forms charged aggregates in the oil phase. Hence, transport under electric fields could be used to detect charged surfactant aggregates in nonpolar media.ExperimentsTwo surfactants with different architecture were dispersed in Isopar-M. The transport of surfactants to an oil-water interface under a constant electric field was quantified using a custom-built electrified microtensiometer platform. Electrical conductivity of the oil with surfactant concentration was also measured to determine the presence of charge carriers.FindingsThe charging mechanism of the oil phase, and field-enhanced transport was different for the two surfactants. At low concentrations where the electrical conductivity of the surfactants is indistinguishable, dynamic interfacial tension measurements under electric fields can ascertain the presence of charge carriers in Isopar-M. The transport of ionic surfactants in the aqueous phase was unaffected by the field, confirming that the field-enhanced transport of oil-phase surfactants is due to electrophoresis of charge carriers. Moreover, the equilibrium interfacial tension was not found to change under an electric field, suggesting the adsorption isotherm is independent of the field strength. We demonstrate that dynamic interfacial tension measurements under electric fields is a sensitive technique to detect charge carriers in nonpolar fluids.