Single-layer graphyne membranes for super-excellent brine separation in forward osmosis

Abstract

Forward osmosis (FO) technology has shown great promise in sea water desalinization and in power generation from the mixing of fresh water and seawater in estuaries. However, the desalination efficiency and the power density level of the present FO system are very low owing to the low water flux of the commercial FO membranes. In this study, we report the brine separation performance of single-layer graphyne-N (N=3, 4, 5, 6) membranes in forward osmosis system by molecular dynamic simulation. Our calculations show that graphyne-3 not only can achieve a high water flux up to about 39.15 L/(cm 2 ·h), which is 3 to 4 orders of magnitude higher than that of the conventional osmotic membranes, but also can achieve a perfect salt rejection rate. Results indicate that structural characteristics and charge properties of these membranes as well as the distribution pattern of both water molecules and salt ions in each system are the main factors that affect the brine separation performance of graphyne membranes. Besides, we find that the formation of hydrated salt ions is the basic reason of brine separation in salt solutions. Graphyne membranes have good prospects in brine separation, regeneration-free applications * Corresponding authors.

Layered double hydroxide/graphene oxide hybrid incorporated polysulfone substrate for thin-film nanocomposite forward osmosis membranes

“…7). 29,45 . Meanwhile, the corresponding AFM images exhibited a ''ridge-valley'' structure throughout the plane 24,54 .…”

The nano gold rush: Graphynes as atomic sieves for coinage and Pt-group transition metals

“…More fruitful has been the study of graphynes on water desalination. Diverse working groups reported, by Molecular Dynamics (MD) simulations employing a variety of Force Fields (FFs) and conditions, the same picture; graphtriyne, also known as graphyne-3, as well as graphyne-4, feature both a permeability to water -of the order of 40 L cm -2 h -1 -several times higher than the conventional reverse of forward osmosis membranes [26], even an order of magnitude higher than nanoporous graphene [27], with an essentially perfect 100% salt rejection [ 28 ]. Along this line, the rejection of nearly all ions in seawater seem to be achievable, including as well organic or inorganic contaminants [29,30], implying suitable trespassing energy barriers for H 2 O yet not for ions and molecules.…”

Graphynes: indispensable nanoporous architectures in carbon flatland

“…Employing molecular dynamics (MD) simulations, Zhang et al demonstrated that γ-GY membranes could be used as FO membranes to purify water. 70 Water fluxes through a series of GY- N membranes ( N = 3, 4, 5 and 6) were studied and they were all found to be of the same order of magnitude. In the simulation, no linear correlation between structural properties like pore size and water flux during FO was observed.…”

“…68 ILJ force eld (FF) optimization curves serve as a good approximation for water-graphyne interactions (Fig. 4b) 70 Water uxes through a series of GY-N membranes (N ¼ 3, 4, 5 and 6) were studied and they were all found to be of the same order of magnitude. In the simulation, no linear correlation between structural properties like pore size and water ux during FO was observed.…”