Improving the performance of heavy metal separation from water using MoS₂ membrane: Molecular dynamics simulation

Molecular dynamics simulations were used to study the separation of mercury ions from water by molybdenum disulphide (MoS₂) membrane. The systems comprised of a MoS₂ membrane which was located in the aqueous ionic solution. An external pressure was applied to separate the ions from aqueous solution. Various pores of MoS₂ were designed to investigate their selectively to heavy metal ions. The ions were rejected by the pore of membrane when the pore size became equal to the size of ion hydration shell. The results indicated that the application of external pressure caused the water molecules pass through the molybdenum pore (pore 3) of MoS₂ with high permeability due to fish-bone structure of this pore. This selective behaviour of the MoS₂ was confirmed by calculating the potential of the mean force (PMF) for each ion and water molecules. The PMFs revealed that Hg²⁺ ions faced a high energy barrier and could not pass through some of the designed pores in MoS₂. Our findings showed that the rejection of mercury ions through the MoS₂ pores was a function of type and size of pores.