Removal of methanol from water by capacitive deionization system combined with functional nanoporous graphene membrane

• Published in: Chemosphere (Oxford) 2023-01, Vol.311, p.137011-137011, Article 137011
• Main Authors: Han, Yong, Zhao, Jiying, Guo, Xiaoqiang, Jiao, Tifeng
• Format: Article
• Language: English
• Subjects: Capacitive deionization; Graphene membrane; Hydrogen-passivated pores; Methanol removal; Molecular dynamics
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.137011

In this article, molecular dynamics simulations were used to examine the feasibility of capacitive deionization (CDI) system combined with a functionalized nanoporous graphene (NPG) membrane for removing methanol from water. The radial distribution function of electrode-methanol and methanol-water, the self-diffusion coefficient of methanol and water, the water density near the membrane, the interaction energy between methanol and membrane, the hydrogen bond structure between methanol and water, and the 2D density map of methanol molecules near the membrane under different electric field (EF) (to simulate the effect of capacitance) were examined to evaluate the separation performance of NPG membranes with hydrogen-passivated pores for methanol. The findings show that an EF with appropriate strength can decrease the amount of water molecules near methanol, increase the self-diffusion coefficient of methanol and water, increase hydrophobicity of hydrogenated pores, decrease the interaction between the NPG membrane and methanol, and weaken hydrogen bond interaction between water and methanol molecules. All these findings suggest that an appropriate EF can improve the NPG membrane's permeability to methanol, and verify the feasibility of CDI system combined with hydrogenated NPG membrane to remove methanol from water. This study is expected to propose a potential CDI application technology, and also give a novel idea for the removal of small organic molecules in water by functionalized NPG membrane. [Display omitted] •CDI system with hydrogenated NPG membrane can separate methanol from water.•EF increases the hydrophobicity of the hydrogen-passivated pores.•A low EF increases diffusivity of methanol, but a high EF has opposite effect.•EF of appropriate strength enhances the permeability of methanol.•EF changes hydrogen bond network structure in solution.