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Published on: August 23, 2024
Thermo-responsive draw solute for forward osmosis process; poly(ionic liquid) having lower critical solution
Changha Ju1, Chanhyuk Park1, Taehyung Kim1
1Department of Chemical Engineering, Dong-A University 37 Nakdong-Daero 550beon-gil, Saha-gu Busan 49315 Republic of Korea hkang@dau.ac.kr +82 51 200 7728 +82 51 200 7720.
Abstract:
We synthesized poly(4-vinylbenzyltributylammonium hexanesulfonate) (P[VBTBA][HS]), a poly(ionic liquid) that shows lower critical solution temperature (LCST), via the anion exchange reaction of poly(4-vinylbenzyltributylammonium chloride) (P[VBTBA][Cl]) with sodium hexanesulfonate in order to investigate its suitability as a draw solute for the forward osmosis (FO) process. P[VBTBA][Cl] was obtained by the free radical polymerization of (4-vinylbenzyltributylammonium chloride [VBTBA][Cl]) monomer acquired by the Menshutkin reaction. The FO performance and recovery properties of the synthesized materials were systematically investigated. For example, the LCST of P[VBTBA][HS] was observed to be ∼17 °C at 20 wt%, while no LCST was observed for [VBTBA][Cl] monomer and P[VBTBA][Cl] polymer before the anion exchange reaction, indicating that P[VBTBA][HS] can be recovered from the aqueous solution by heating it to above its LCST. Moreover, in an active layer facing the feed solution (AL-FS) system containing 20 wt% aqueous P[VBTBA][HS] solution at 15 °C, the water flux and reverse solute flux of P[VBTBA][HS] were found to be ∼5.85 L m-2 h-1 and 1.13 g m-2 h-1, respectively. Therefore, we studied the feasibility of using the poly(ionic liquid), a homopolymer having LCST characteristics, as a draw solute in the FO process.
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