Molecular interlayer intercalation of ethanol-water mixture towards GO laminated membranes

W Zhan and ZJ Xu and XN Yang, SEPARATION AND PURIFICATION TECHNOLOGY, 233, 116029 (2020).

DOI: 10.1016/j.seppur.2019.116029

The practical functions of graphene oxide (GO) layered membranes in liquid phase separation are dependent on the interlayer solvation intercalation, however, it is very challenging to attain the qualitative information on the intercalation kinetics, inserted amount, and composition in the multilayer structures of GO membranes from experiment techniques. In this work, molecular dynamics simulations were conducted to investigate the competitive insertion/adsorption behavior of ethanol- water mixtures into the nanochannels of layered GO structures. Our simulations demonstrate that both water and ethanol can spontaneously intercalate into GO channels and there is no highly selective interlayer intercalation. Two insertion mechanisms have been revealed for GO nanochannels. In general, large ethanol is found to penetrate more significantly than small water. The underlying mechanism can be attributed to the enhanced surface affinity of GO pores with ethanol molecules. However, for smaller pores with high oxidization degree, the insertion of ethanol can be restricted due to pore sieving effect. The mixture concentrations, confined structures, and diffusion dynamics for ethanol-water mixtures confined within GO pores were analyzed. Our results provide new insight into the solvation intercalation of GO layered structures, which is beneficial to the separation application of GO laminated membranes.

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