Multiphysics Modelling and Simulation of Hydrogel Membrane for Water Desalination

A new method to desalinate water by making use of swollen hydrogelsHydrogel under externally applied pressure-difference-driven diffusion is being proposed. The swellingSwelling process of hydrogelHydrogel involves diffusion, polymer–solvent interaction, and mechanical deformation. The present research aims to investigate the use of FEA model to simulate hydrogel as a semi-permeable membrane. Diffusion of water molecules in hydrogelHydrogel is modelled using Fick’s law, polymer–solvent interaction described by the Flory–Huggins mixing theory and mechanical deformation reported with the theory of rubber elasticity. The FEA model yielded a set of partial differential equations with ordinary differential equations for which COMSOL Multiphysics 5.5 is selected as the simulation software. A parametric analysis is conducted to evaluate the overall significance of the model parameters on hydrogel’s behaviour. Reproduction of the hydrogel’s poroviscoelastic behaviour to the exterior incentives and the transport phenomena of species through hydrogelHydrogel has been successfully demonstrated and validated for a new methodology of water desalinationDesalination considering NaCl (salt) as a permeate. The salt rejection ratio has been estimated, and it is found to be 40% with an average salt volume fraction reducing from 0.5 M to 0.3 M. The suggested model may also be explored to designDesign and optimize hydrogelsHydrogel for biological separations.