Computational study on the efficiency of MoS₂ membrane for removing arsenic from contaminated water

Molybdenum disulfide (MoS₂) was used as a new nanostructure membrane for arsenic removal from contaminated aqueous solution. Three types of MoS₂ membrane, with different pore density, were designed to study their permeation properties. The results showed that MoS₂ with pores in its center had both high water permeability and high arsenic rejection. By engineering the pores on the surface of MoS₂, their water permeability was greatly increased, while their arsenic rejection rate maintained high and no arsenic passed through the MoS₂ pore in any of our simulations (100% salt rejection). This property of MoS₂ was due to its fish-bone nanostructure and an hourglass shape nanopore wherein the sulfur atoms were located at the edge pore and molybdenum atoms at the pore center. This arrangement of hydrophobic-hydrophilic atoms in the pore caused the water molecules to permeate through this pore with high flux. This performance of the MoS₂ was clarified by calculating the potential of the mean force for water molecules and arsenic ions. Therefore, MoS₂ with an appropriate pore in its center can be used as a water-pollutant separator.