Effect of Ion Size on Pressure-Induced Infiltration of a Zeolite-Based Nanofluidic System

A nanofluidic system consists of a nano-porous medium and functional liquid, which demonstrates a higher energy absorption density compared to conventional systems for energy absorption. Alterations in the composition of the functional liquid can significantly impact the properties of a nanofluidic system. In this paper, the widely used zeolite ZSM-5 was chosen as the porous medium to establish a nanofluidic system. Three distinct electrolyte solutions, namely KCl aqueous solutions, NaCl aqueous solutions and MgCl₂ aqueous solutions were employed as functional liquids while pure water served as the reference condition for configuring four kinds of nanofluidic systems. Pressure-induced percolation experiments were performed on the four zeolite-based systems. The difference in the infiltration process between the electrolyte solution systems and the deionized water system has been ascertained. The effect of the ion size on the infiltration and defiltration process has been determined. The results show that the introduction of ions induces a hydration effect, resulting in a higher critical infiltration pressure of the electrolyte solution system compared to an aqueous solution system. The magnitude of cation charge directly correlates with the strength of the hydration effect and the corresponding increase in critical infiltration pressure. Upon entering the nanochannel, the liquid infiltrates primarily in the form of ions rather than a cation hydration form. The larger the ion size, the shallower the penetration depth after entering the nanopore channel and the larger the corresponding relative outflow rate. The present work will provide valuable theoretical complementary and experimental data support for nanofluidic system applications.