Modeling of a continuous water desalination process using directional solvent extraction

Directional Solvent Extraction (DSE) is a novel alternative desalination technology to the traditional evaporation and membrane based desalination processes. This new process takes advantage of the fact that water is soluble in some solvents and its solubility increases with temperature. Furthermore, these solvents are insoluble in water and salts do not dissolve in them. These special characteristics of some directional solvents have been utilized in this new process to extract fresh water from seawater. The objective of this paper is to investigate the technical feasibility of a continuous water desalination process using decanoic and octanoic acid as directional solvents. Process modeling was used to predict thermal and electrical energy consumptions for two DSE processes, with and without heat recovery. The effects of highest process temperature, recovery ratio and heat exchanger effectiveness on the thermal energy consumption were studied. The results show that heat recovery significantly reduces the thermal energy consumption. The results also show that octanoic acid has lower thermal and electrical energy consumptions than decanoic acid. Compared to the Multi Stage Flashing (MSF) and Multi Effect Distillation (MED), DSE water desalination process results in higher energy consumption. In conclusion, the results reveal the need to identify more suitable directional solvents with higher product water yield and lower water solubility in order to facilitate the application of DSE as a potential water desalination process.