Aromatic Polyamide Reverse-Osmosis Membrane: An Atomistic Molecular Dynamics Simulation.
Polyamide (PA) membrane-based reverse-osmosis (RO) serves as one of the most important techniques for water desalination and purification. Fundamental understanding of PA RO membranes at the atomistic level is critical to enhance their separation capabilities, leading to significant societal and commercial benefits. In this paper, a fully atomistic molecular dynamics simulation was performed to investigate PA membrane. Our simulated cross-linked membrane exhibits structural properties similar to those reported in experiments. Our results also reveal the presence of small local two-layer slip structures in PA membrane with 70% cross-linking, primarily due to short-range anisotropic interactions among aromatic benzene rings. Inside the inhomogeneous polymeric structure of the membrane, water molecules show heterogeneous diffusivities and converge adjacent to polar groups. Increased diffusion of water molecules is observed through the less cross-linked pathways. The existence of the fast pathways for water permeation has no effect on membrane's salt rejections.
Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States.
Tao
T
Wei
Key Laboratory of Biomass Chemical Engineering of MOE, Department of Chemical and Biological Engineering, Zhejiang University , Hangzhou, 310027, China.
Lin
L
Zhang
Key Laboratory of Biomass Chemical Engineering of MOE, Department of Chemical and Biological Engineering, Zhejiang University , Hangzhou, 310027, China.
Haiyang
H
Zhao
Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States.
Heng
H
Ma
Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States.
Md Symon Jahan
MS
Sajib
Caerulean Environmental Technology Corporation , Tulsa, Oklahoma 74133, United States.
Hua
H
Jiang
Department of Chemical Engineering, Illinois Institute of Technology , Chicago, Illinois 60616, United States.
Sohail
S
Murad