TY - JOUR
T1 - Comparison of the effects of edge functionalized graphene oxide membranes on monovalent cation selectivity
AU - Qiu, Ruosang
AU - Xiao, Jie
AU - Chen, Xiao Dong
AU - Selomulya, Cordelia
AU - Zhang, Xiwang
AU - Woo, Meng Wai
PY - 2020/2/15
Y1 - 2020/2/15
N2 - Layer-by-layer graphene oxide (GO) membrane in principle has great potential in separating Li+ from monovalent cations, which is achieved by their functionalized interlayer entrance. The edge effects on different monovalent ions, however, are not fully understood. Therefore, molecular dynamics simulations were utilized in this study to separately elucidate the filtration effects of three typical edge functional groups, which were carboxyl (COOH), hydroxyl (OH), and hydrogen (H), on the LiCl, NaCl, and KCl solutions. The results revealed that the water permeance was dominantly influenced by the steric size of edge functional groups. It could also be affected by the ions blocked at the entrance. The drastic dehydration of the hydrated Na+ and K+ caused by the OH edge required more energy that led to higher ion rejection. The compressed-dehydrated hydration shell, which was tuned by the edge functional groups, introduced repulsion from Na+ and attraction from Li+ on Cl− when they were 3–5 Å away from each other. It would be strategic to use all three edge functional groups to retain NaCl in the retentate stream while allowing selective permeance of LiCl and the OH edge could additionally retain KCl.
AB - Layer-by-layer graphene oxide (GO) membrane in principle has great potential in separating Li+ from monovalent cations, which is achieved by their functionalized interlayer entrance. The edge effects on different monovalent ions, however, are not fully understood. Therefore, molecular dynamics simulations were utilized in this study to separately elucidate the filtration effects of three typical edge functional groups, which were carboxyl (COOH), hydroxyl (OH), and hydrogen (H), on the LiCl, NaCl, and KCl solutions. The results revealed that the water permeance was dominantly influenced by the steric size of edge functional groups. It could also be affected by the ions blocked at the entrance. The drastic dehydration of the hydrated Na+ and K+ caused by the OH edge required more energy that led to higher ion rejection. The compressed-dehydrated hydration shell, which was tuned by the edge functional groups, introduced repulsion from Na+ and attraction from Li+ on Cl− when they were 3–5 Å away from each other. It would be strategic to use all three edge functional groups to retain NaCl in the retentate stream while allowing selective permeance of LiCl and the OH edge could additionally retain KCl.
KW - Edge functionalized graphene oxide membrane
KW - Interaction between hydrated ions
KW - Ion dehydration
KW - Ion hydration shell compression
KW - Monovalent cation selectivity
UR - http://www.scopus.com/inward/record.url?scp=85097467325&partnerID=8YFLogxK
U2 - 10.1016/j.memsci.2020.118892
DO - 10.1016/j.memsci.2020.118892
M3 - Article
AN - SCOPUS:85097467325
SN - 0376-7388
VL - 620
JO - Journal of Membrane Science
JF - Journal of Membrane Science
M1 - 118892
ER -