Oil-water separation performance of aligned single walled carbon nanotubes membrane: A reactive molecular dynamics simulation study

Abstract

Carbon nanotubes (CNTs) have played pivoting role in water remediation owing to peculiar features such as high porosity and desirable chemical and mechanical properties. This research is dedicated to separation of oil–water systems by using aligned armchair SWCNTs–based membrane via reactive molecular dynamic (MD) simulation and density functional theory (DFT) calculations. It was found that no water molecules transmitted through CNT with 5.7 Å diameter, but CNTs with diameters of 7 Å and 8.5 Å were both able to transfer water molecules, although CNT with diameter of 7 Å was more efficient for water permeation. The incorporation of hexane was observed into CNTs with diameters of 7 Å and 8.5 Å and also toluene into latter one. Moreover, the determination of interaction energy, electronic structures and barrier energy with DFT-D3 calculation for hexane molecule incorporating into the nanotube cavity confirms our reactive MD simulation outcomes. It was revealed that armchair CNTs membrane with diameter of 7 Å has more efficacy for the separation of oil–water mixture compared to other counterparts though it could not avoid the permeance of small oil components such as linear hydrocarbons. Our reactive MD simulations findings provided a novel strategy for the application of aligned CNTs membranes in water treatments with voluntarily viable motivations, high efficiency and stability as well as long lifetime.