aper title: Computer simulations of water flux and salt permeability of the reverse osmosis FT-30 aromatic polyamide membrane

Journal: Journal of Membrane Science. Volume 384, Issues 1-2, 15 November 2011, Pages 1-9

Author/s: Yun Luo (a), Edward Harder (a), Ron S. Faibish (b), Benoit Roux (a,b)
 

 

a) Department of Biochemistry and Molecular Biology, The University of Chicago, Gordon Center for Integrative Science, 929 East 57th Street, Chicago, IL 60637, USA
b) Argonne National Laboratory, Argonne, IL 60439, USA

Summary: 
In this paper, the permeability of salt relative to water across a constructed model of the FT-30 RO membrane was investigated using nonequilibrium molecular dynamics (MD) simulations.

Details of the simulation of polymerization were presented in the paper: number of monomers, temperature, simulation time, etc. The atomistic model assembled was in good accordance with the experimental characteristics of the membrane: membrane density, water solubility and water flux. Afterwards, the procedure and requirements for the simulation of hydrated membrane system were also discussed thoroughly. In following the pathways of ions across the membrane, targeted molecular dynamics (TMD) method was employed.

The electrostatic free energy for moving ions along the TMD pathways was determined by using the Poisson-Boltzmann (PB) equation. The relative free energies involved in transferring ions from the bulk phase to a point inside the membrane were also calculated using the free energy perturbation (FEP) method to validate the results of the PB calculations.

Finally, water and salt permeability of the model membrane were determined. The estimated salt rejection for the FT-30 model was 99.9%.

Contribution and application:
This study confirms that MD simulations may be used for membrane development: to study the properties of membranes as well as to improve the current membranes and develop new ones.



By: Hannah Ebro
hannah@gist.ac.kr