Lavabre Dominique, Pradines Vincent, Micheau Jean-Claude, Pimienta Véronique
Laboratoire des IMRCP, UMR au CNRS No. 5623, Université Paul Sabatier, 118 Route de Narbonne, F-31062 Toulouse Cedex, France.
J Phys Chem B. 2005 Apr 21;109(15):7582-6. doi: 10.1021/jp045197m.
Periodic Marangoni convective instability has been observed in a biphasic system during the mass transfer of cetyltrimethylammonium bromide (CTAB) from an aqueous to a dichloromethane organic phase. Visualization of the convective fluxes was possible thanks to the CTAB crystals that are formed in the aqueous phase at a temperature below the Krafft point. Surface tension and electrical potential oscillations have been shown to be correlated with the fluid motion. Surface tension measurements, representative of the adsorption state, showed fast adsorption during the convective stage, followed by a slower desorption process in the quiet stage. To account for the electrical potential data, two components need to be taken into account. In the quiet stage, the signal was comparable to surface tension, and the main contribution would result from the electrical double layer formed at the interface by charged surfactants. In the convective stage, the electrical potential was furthermore related to the velocity of the fluid in the aqueous layer. Perturbations of the charge distribution in the Gouy-Chapman layer due to tangential flows could be at the origin of the phenomenon.
在十六烷基三甲基溴化铵（CTAB）从水相转移至二氯甲烷有机相的传质过程中，在双相体系中观察到了周期性的马兰戈尼对流不稳定性。由于在低于克拉夫特点的温度下在水相中形成的CTAB晶体，对流通量的可视化成为可能。表面张力和电势振荡已被证明与流体运动相关。代表吸附状态的表面张力测量表明，在对流阶段吸附迅速，随后在平静阶段解吸过程较慢。为了解释电势数据，需要考虑两个因素。在平静阶段，信号与表面张力相当，主要贡献来自带电表面活性剂在界面处形成的双电层。在对流阶段，电势还与水层中流体的速度有关。切向流引起的古依-查普曼层中电荷分布的扰动可能是该现象的起源。
