Carbon nanotube: Possible candidate for forward osmosis

In this study, the transport phenomena of water molecules and ions through the membranes incorporating the neutral “armchair” (R,R) carbon nanotubes (CNTs) with indices R = 6–11, in forward osmosis (FO) process are studied by means of the molecular dynamic simulation. Particularly, the membrane properties, including water permeation and the cross-contamination of ions between the feed solution and the draw solution, are investigated. The simulation results indicate the great suitability of the CNT membranes for seawater desalination using FO. Thereinto, the membrane incorporating CNT(8,8) can achieve not only the optimum salt rejection property but also the largest water flux, which break the limit of trade-off effect between selectivity and permeability existing in the traditional liquid separation membrane. Together with other potential properties endowed by CNTs, such as the anti-fouling ability, good mechanical property and so on, it is reasonable to think that there must be plenty of room to develop for the carbon nanotubes in FO process.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ This study indicates the great suitability of the CNT membranes for water desalination using FO. ▶ The simulation results show that the CNT membranes can achieve a higher water flux far in excess of the existing commercial FO membranes. ▶ A rough estimation on flux and rejection indicates the FO membrane comprising the specifically sized CNTs possesses anti-trade-off property. ▶ It is reasonable to think that there must be plenty of room to develop for the carbon nanotubes in the field of membrane separation, especially in FO process.