Water desalination using polyelectrolyte hydrogel. Gibbs ensemble modeling

Polyelectrolyte hydrogels possess the remarkable ability to efficiently absorb large volumes of water through an osmotic membrane by exerting swelling pressure. Conversely, the insoluble cross-linked structure of the gel allows for dewatering when triggered by external stimuli such as temperature or mechanical forces. Moreover, from a thermodynamic perspective, polyelectrolyte hydrogels act as osmotic membranes, effectively preventing the passage of ions between external and internal solutions. These unique properties make these gels highly promising for desalination applications, offering an alternative to expensive membranes. In this study, we present our recent investigation into the utilization of polyelectrolyte hydrogels for water desalination. We developed a model to analyze the thermodynamic equilibrium between the gel and the supernatant aqueous salt solution. Our findings demonstrate that as the gel undergoes compression, the salinity of the supernatant phase decreases due to the release of absorbed solution with lower salinity from within the gel matrix. Furthermore, we conducted a series of simulations to replicate the continuous reduction of solution salinity until freshwater concentrations were achieved.