Desalination Performance of Nano porous Mos$_2$ Membrane on Different Salts of Saline Water: A Molecular Dynamics Study

Abstract: The freshwater crisis is a growing concern and a pressing problem for the world because of the increasing population, civilization, and rapid industrial growth. The water treatment facilities are able to supply less than 1% of the total water demand. Water desalination can be a potential solution to deal with this alarming issue. Researchers have been exploring for quite some time to find novel nano-enhanced membranes and manufacturing techniques to increase the efficiency of the desalination process. Graphene and graphene modified membranes showed huge potential as desalination membranes for comparatively easier synthesis process and higher ion rejection rate than conventional filter materials. Currently, single-layer Mos$_2$ has been discovered to have the same potential of water permeability and ion rejection rate as graphene membrane in a more energy-efficient way. For almost analogous nano porous structure of the graphene membrane, almost 70% of the higher water flux is obtained from the Mos$_2$ membrane. In this work, it has been shown that nano porous Mos$_2$ membranes provide a promising result for desalinating other salts of seawater alongside NaCl. We have also observed the effect of variations in ions, pore size, and pressure on water permeation and ion rejection rates in the water desalination process. In this study, water permeation increased significantly by increasing the pore area from 20{\AA} to 80{\AA}. The rate of water filtration increases in proportion to both applied pressure and pore size, sacrificing the ion rejection rate for the type of ions studied. A combination of salt ions in the saline water for desalination has also been studied, where the rejection rates for the different ions are separately represented for various applied pressures. For seawater, the Mos$_2$ membrane has showed quite promising performance in the study of ion variation.