Optimising molecular simulations of reverse osmosis based concentration processes using molecular replication

BJ Bashmmakh and K Hinkle and CJ Jameson and S Murad, MOLECULAR SIMULATION, 51, 899-908 (2025).

DOI: 10.1080/08927022.2025.2545245

Reverse-osmosis (RO) plays an important role in many natural and industrial processes such as water purification, wastewater treatment, and food and beverage processing. Molecular dynamics (MD) simulation of extremely dilute (ppm concentrations) RO systems are generally impractical due to the high computational cost associated with the large number of particles that must be included in the MD system. These systems are nevertheless of great industrial importance. Here, we propose a new method of MD simulations for reverse-osmosis using molecular replication (MR-RO) for concentrating very dilute solutions in a fraction of the computational time required by 'direct reverse- osmosis' (D-RO). In this study, we demonstrate the application of this method to concentrate a dilute LiCl solution ($x_LiCl = 1.22 \times 10<^>-3$xLiCl=1.22x10-3) by these two methods MR-RO and D-RO. We validated the optimised method by comparing a wide range of properties obtained from the 'rigorous' D-RO method. In this preliminary study we saw a saving of over an order of magnitude in computational time. Even larger savings are possible by increasing the frequency of replication and compression steps. The proposed method thus opens the possibility of using MD for screening studies of potential RO membranes in extremely dilute solutions.

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