Metya Atanu K, Das Chandan K
Department of Chemical and Biochemical Engineering, Indian Institute of Technology Patna, Patna 801106, India.
Department of Chemical Engineering, National Institute of Technology Raurkela, Rourkela, Odisha 769008, India.
Langmuir. 2024 Feb 6. doi: 10.1021/acs.langmuir.3c03184.
Molybdenum disulfide (MoS) is a two-dimensional (2D) material that offers molecular transport and sieving properties and might be a potential candidate for membrane technologies for energy and environmental applications. To facilitate the separation application, understanding the structural and dynamic properties of water near the substrate-aqueous solution is essential. Employing the molecular dynamics simulation, we investigate the density, local water network at the solid-liquid interface, and water dynamics in aqueous electrolyte solutions with various chloride salts confined in MoS nanochannels with different pore sizes and electrolyte concentrations. Our simulation results confirm that the layering of interfacial water at the hydrophilic MoS surface and the water density variation depends on the nature of the ions. The simulation results imply a strong attraction of cations to the surface-liquid interfaces, whereas anions are expelled from the surface due to electrostatic interaction. An examination of the dynamical property of water reveals that the confinement effect is more pronounced on water mobility when the pore width is less than 3 nm, and the salt concentration is below 1 M, whereas the electrolyte concentration greater than 1 M, ions predominantly drive the water mobility as compared to confinement one. These simulation results enhance experimental observations and provide molecular insights into the local ordering mechanism that can be crucial in controlling water dynamics in nanofiltration applications.
二硫化钼（MoS）是一种二维（2D）材料，具有分子传输和筛分特性，可能是用于能源和环境应用的膜技术的潜在候选材料。为了促进分离应用，了解基底 - 水溶液附近水的结构和动力学性质至关重要。我们采用分子动力学模拟，研究了不同孔径和电解质浓度的MoS纳米通道中，含有各种氯化物盐的电解质水溶液中，固 - 液界面处的密度、局部水网络以及水的动力学。我们的模拟结果证实，亲水性MoS表面的界面水层和水密度变化取决于离子的性质。模拟结果表明阳离子对表面 - 液体界面有强烈的吸引力，而阴离子由于静电相互作用被排斥在表面之外。对水的动力学性质的研究表明，当孔径小于3 nm且盐浓度低于1 M时，限制效应在水的迁移率上更为明显，而当电解质浓度大于1 M时，与限制效应相比，离子主要驱动水的迁移率。这些模拟结果增强了实验观察，并为局部有序机制提供了分子见解，这在控制纳滤应用中的水动力学方面可能至关重要。
