Rigorous Electrolyte Thermodynamics to Enhance the Accuracy of RO Membrane Models for Industrial Water Treatment

The Mixed Solvent electrolyte model, as developed by OLI Systems, is a recognized leader in process simulation industry for simulating electrolyte chemical systems. OLI technology specializes in the rigorous prediction of multi-phase, multi-component chemical processes. Its temperature and pressure ranges are extreme (-60°C and 4000 bar), and the breadth of chemistry covered include 80+ elements, aqueous and non-aqueous organics, and their behavior in water, vapor, organic, solid, and interfacial environments. The combination of fundamental thermodynamics, property models, numerical algorithms, and databanks enable this unique capability.

This poster will present a novel scientific approach for process engineers to use while simulating and predicting the behavior of reverse osmosis membranes under various conditions. This approach is based on first-principles models to predict membrane permeability using simultaneous electrolyte thermodynamic models, species-transport models, chemical speciation, water coordination and ion hydration (and their respective radii). The poster will consist of three sections.

This poster will illustrate the OLI Mixed Solvent Electrolyte thermodynamic model. Sample chemical systems will be potash, sulfuric acid and lithium double salts. To model the transport mechanism inside the RO membrane, a solution-diffusion approach has been incorporated. In the solution-diffusion model, it is proposed that transfer of ions and water through polymeric membranes occurs via a solution diffusion mechanism because of dissolution of permeates in the membrane materials. In the example case study, the simulation of a desalination plant located in Egypt will be considered with the goal of producing potable water with a TDS (total dissolved solids) less than 100 ppm reduced from a brackish feed water of over 10,000 ppm TDS.