Novel polyelectrolyte-glycol ether ternary phase-separating draw solutions for desalination using forward osmosis

Abstract

This study systematically evaluated the potential of novel organic draw solutions for forward osmosis (FO) desalination. The formulations included 4 binary and 6 ternary systems incorporating sodium carboxymethyl cellulose (NaCMC) and propylene glycol propyl ether (PGPE). Using a custom-built FO laboratory setup, the experimental water and solute fluxes of the new draw solutions were investigated. The ternary 0.5NaCMC-3.75PGPE draw solution demonstrated an osmotic pressure of 33.9942 bars. When tested at 30 °C, this draw solution yielded average experimental water fluxes of 17.487, 15.654, and 12.482 LMH while desalinating 5000 ppm NaCl brackish feed solutions. Furthermore, scaling up to 0.5NaCMC-20PGPE was effective for seawater desalination, with experimental water fluxes averaging 13.975 and 14.284 LMH against a 35,000 ppm NaCl feed solution. A comprehensive morphological analysis was conducted to evaluate the compatibility of the FO membrane with the organic draw solutions following a 21-day immersion period.