Ideal desalination through graphyne-4 membrane: Nanopores for quantized water transport
Chongqin Zhu1, Hui Li1, Xiao Cheng Zeng2, Sheng Meng1
1Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
2Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
This is an unpublished yet revolutionary and impactful study on an emerging graphene-derived material called graphyne which exhibits interesting transport and electronic properties. Graphyne is a carbon allotrope consisting of triple- and double-bonded carbons arranged in an orderly mesh. Unlike graphene, which has a honeycomb structure, graphyne can assume various geometries i.e. differently-shaped pores due to the presence of the triple-bond groups. In this study, the focus was on γ-graphyne; a graphyne variant having triangular pores.
Based on the first principles method, molecular dynamics (MD) simulation was applied to model the structure of γ-graphyne. In this study, γ-graphyne membranes were named according to the edge length of their triangular pores, i.e. graphyne-i, where i refers to the number of acetylene groups forming the edge of the pore. Different graphyne membranes were subjected to reverse osmosis simulations, but it was determined that graphyne-4 delivered the optimal performance. 100% salt rejection was achieved along with an impressive water permeability of 13L/cm2/day/MPa. This translates to much less energy required compared to current RO technology.
Although research into the properties of graphyne and its possible applications is still in its infancy, graphyne possesses great potential of being an ideal reverse osmosis membrane capable of delivering both high water flux and high salt rejection; a truly unprecedented feat in membrane desalination. Graphyne-1 and graphdiyne (graphyne-2) have already been synthesized; it's only a matter of time for graphyne-4 and other variants of graphyne to emerge and be put into use for various applications. MD simulations can be used to further studies on graphyne and its properties.
John Matthew V. Cajudo