Atomistic insights into the separation mechanism of multilayer graphene membranes
      for water desalination

Author(s): Jing Zhang ¹ ^, ² ^, ³ ^, ⁴ , Chen Chen ¹ ^, ² ^, ³ ^, ⁴ , Jianuan Pan ¹ ^, ² ^, ³ ^, ⁴ , Li Zhang ¹ ^, ² ^, ³ ^, ⁴ , Lijun Liang ⁵ ^, ⁶ ^, ³ ^, ⁴ , Zhe Kong ⁷ ^, ³ ^, ⁴ , Xinping Wang ¹ ^, ² ^, ³ ^, ⁴ , Wei Zhang ¹ ^, ² ^, ³ ^, ⁴ , Jia-Wei Shen ⁸ ^, ⁹ ^, ¹⁰ ^, ⁴

Publication date (Electronic): 2020

Journal: Physical Chemistry Chemical Physics

Publisher: Royal Society of Chemistry (RSC)

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Abstract

Multiple influencing factors on desalination and the separation mechanism of graphene membranes for water desalination have been investigated on a molecular level.

Abstract

Graphene-based membranes have been extensively explored owing to their excellent separation properties. In this paper, multiple factors regarding desalination performance were investigated by molecular dynamics (MD) simulations. These factors include the interlayer spacing distance ( H), the gap width (dG), offset ( O), and the number of gaps and layers in a multilayer graphene membrane (MGM). It is found that salt rejection is influenced significantly by the interlayer spacing distance owing to the largest free energy between ions and graphene sheets as well as the relatively larger size of the hydration layer around the ions. The optimal desalting parameter (dG = 1 nm, H = 0.8 nm) was selected; MGM systems based on the optimized parameter exhibited excellent salt rejection for NaCl, MgCl ₂ and CaCl ₂ solutions. These results can provide some ideas for the future design of graphene-based membranes.