Salt separation from water using graphene oxide nanochannels: A molecular dynamics simulation study

• Type: Article in International Scientific Journal
• Date: 2019

Authors

Giri, AK (Author) Other; Teixeira, F (Author) Other; Natalia N D S Cordeiro (Author) FCUP

Journal

Title: Desalination

Vol. 460

Pages: 1-14

ISSN: 0011-9164

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 44 Citations

Scopus - 45 Citations

Other information

Authenticus ID: P-00Q-EVR

DOI: 10.1016/j.desal.2019.02.014

Abstract (EN): Recently, water transport through graphene oxide (GO) nanochannels has gained much attention because of its potential applications in desalination and water filtration. In this work, molecular dynamics (MD) simulations were carried out to elucidate the filtration efficiency and water structure in GO nanochannels of varying oxidation degree (from 0% to 40%) and interlayer spacing (from 0.6 nm to 1.0 nm). The results from these simulations show that ion permeation is observed in 1.0 nm channels, but ion rejection is close to complete for the narrower channels, irrespective of the degree of oxidation. Furthermore, water permeation increases with increasing interlayer separation and decreases with increasing oxidation degree. In general, water molecules prefer flowing through unoxidized regions of the narrower channels, but show no preferential path when flowing through the wider ones. Moreover, the analysis of the interaction between water molecules and the hydroxyl groups inside the GO channel shows that OH groups play a vital role disrupting the solvation sphere of the salt ions. However, with increasing oxidation of the GO wall, the formation of intra-layer hydrogen bonds becomes relevant, decreasing the overall number of hydrogen bonds involving water molecules, and thus preventing further decrease of the water permeance. To sum up, our results indicate that the best GO channel for the desalination is the one with interlayer spacing 0.8 nm and oxidation degree of 10% or lower.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14