Timmerhuis Nicole A B, Lammertink Rob G H
Soft Matter, Fluidics and Interfaces, MESA+ Institute for Nanotechnology, University of Twente, Post Office Box 217, 7522 NB Enschede, Netherlands.
Langmuir. 2022 Oct 11;38(40):12140-12147. doi: 10.1021/acs.langmuir.2c01577. Epub 2022 Sep 28.
Diffusiophoresis is the movement of particles as a result of a concentration gradient, where the particles can move toward higher concentrations. The magnitude of the movement is largest for the electrolyte solute and depends upon the relative concentration gradient, surface potential, and diffusivity contrast between the cation and anion. Here, diffusiophoresis of ordinary polystyrene particles is studied in a H-shaped channel for different solutes. The experimental results are compared to a numerical model, which is solely based on the concentration gradient, surface potential, and diffusivity contrast. The surface potential of the particles was measured to use as input for the numerical model. The diffusiophoretic movement of the experiments aligns well with the theoretical predicted movement for the inorganic (lithium chloride and sodium bicarbonate) and organic (lithium formate, sodium formate, and potassium formate) salts measured. However, for the carboxylic acids (formic, acetic, and oxalic acids) measured, the theoretical model and experiment do not align because they are weak acids and only partially dissociate, creating a driving force for diffusiophoresis. Overall, the H-shaped channel can be used in the future as a platform to measure diffusiophoretic movement for more complex systems, for example, with mixtures and asymmetric valence electrolytes.
扩散泳是指粒子由于浓度梯度而发生的移动，其中粒子可朝着更高浓度移动。对于电解质溶质而言，这种移动的幅度最大，并且取决于相对浓度梯度、表面电势以及阳离子和阴离子之间的扩散率差异。在此，针对不同溶质，在H形通道中研究了普通聚苯乙烯粒子的扩散泳。将实验结果与一个仅基于浓度梯度、表面电势和扩散率差异的数值模型进行了比较。测量了粒子的表面电势，以用作数值模型的输入。实验的扩散泳移动与所测量的无机（氯化锂和碳酸氢钠）和有机（甲酸锂、甲酸钠和甲酸钾）盐的理论预测移动吻合良好。然而，对于所测量的羧酸（甲酸、乙酸和草酸），理论模型与实验结果不吻合，因为它们是弱酸，仅部分离解，从而产生了扩散泳的驱动力。总体而言，未来H形通道可作为一个平台，用于测量更复杂体系（例如含有混合物和不对称价电解质的体系）的扩散泳移动。
