Highly-charged EDTA-2Na salt as a novel draw solution in pressure-retarded Osmosis process

Abstract

The need for using sustainable green energy to fulfill the more and more energy demands is essential because of many problems like changes in climate, environmental pollution, and global warming and their effects on the health of humans. A process of closed-loop pressure retarded osmosis (CL-PRO) is a renewable technology producing green energy with no deleterious impacts on nature. For the first time, Ethylene-diamine tetra-acetic acid disodium (EDTA-2Na) salt is estimated for its possibility as a draw solution in the PRO process, while its performance is put to comparison with inorganic sodium chloride (NaCl) draw solution. The impact of various operational variables including the concentration of draw solution (0.1M-0.5M) and applied pressure difference (0-8bar) was estimated via laboratory-based investigation related to the CL-PRO. The impact of such operational parameters was examined on power density, reverse salt flux, water flux, and specific salt flux. Based on the experimental results, the EDTA-2Na salt is showing as an effective draw solution in CL-PRO as a result of its elevated osmotic pressure and reduced reverse salt flux. With regard to the same molar concentrations, the EDTA-2Na draw solution created high water flux and significantly less reverse salt flux in comparison with NaCl. Furthermore, the maximum power density which is reached for EDTA-2Na draw solution is 1.6 W/m2, while the corresponding water flux is 7.209 LMH at an applied pressure of 8 bars. According to the results of this work, elevated production of power and low reversal salt flux made EDTA-2Na salt as possible draw solution for future studies in CL-PRO.