Enhancing forward osmosis performance via an oligomeric deep eutectic solvent as a draw solute

Abstract

The development of forward osmosis (FO) as a new technology for water desalination faces limitations mainly due to the selection and regeneration of the appropriate draw solution. In this study, the concept of using an oligo- deep eutectic solvent (DES) based on itaconic acid-choline chloride (IA-CC) as a draw solute in the sustainable FO process was introduced. The moderate molecular weight of oligomers can overcome the trade-off relationship of the water flux and reverse solute flux in the FO process. The average water flux of 1 g mL−1 oligo (IA1-CC1.5) solution was found to be 32.8 L m−2 h−1 (LMH) with the reverse solute flux of 1.4 g m−2 h−1 (gMH). The water regeneration from DES draw solutions was then carried out through the phase separation at 5 °C. To analyze the capability of the synthesized material as draw solution in desalination process, FO tests were performed using 0.6 and 1.0 M NaCl and also Caspian Seawater as the feed solutions, and 1 g mL−1 oligo (IA1-CC1.5 DES) as the draw solution, which the average water flux was found to be 14.5, 9.7, and 13.8 LMH, respectively.