Investigation of doped carbon nanotubes on desalination process using molecular dynamics simulations

•The effects of Ag, Si, N, and B doping in nanotube on desalination were investigated.•The BN and SiC tubes have the most water flux and ion rejection, respectively.•Ag-doped CNT and SiC at first part of a hetero-junction BN tube increases salt rejection.•The B-doping of CNT increases the water flux. Carbon nanotubes (CNTs) with their natural nanoscale pores are excellent candidates for the reverse osmosis and ion-selection processes. Previous works also showed that the doping of CNTs is an important way to improve the different properties of the carbon materials. In this research, we have investigated the effects of silver (Ag), silicone (Si), nitrogen (N), and boron (B) doping in (10,10) CNT on desalination process using molecular dynamics (MD) simulation. The results have been also compared with the silicon carbide (SiC), and boron nitride (BN) nanotubes. We have also examined the possible use of heterojunction nanotubes (HNTs) including doped, SiC, and BN nanotubes as new membranes in the desalination process. The different properties including water and ion flux, radial distribution function, potential of mean force, and the water-nanotube interaction energy have been investigated. Our results indicated that the BN and SiC nanotubes have the most water flux and ion rejection, respectively. Also, positioning of Ag-doped CNT and SiC tube at the first part of a hetero-junction system decreases the water and ion fluxes whereas positioning of BN at the last part increases the ion flux.