A novel multinuclear zinc complex Zn-Bet-Tf2N for electroplating wastewater treatment using forward osmosis technique

[Display omitted] •A water-soluble multinuclear zinc complex Zn-Bet-Tf2N is developed via a one-pot reaction.•Zn-Bet-Tf2N generates a high water flux with negligible reverse diffusion in the FO process.•The Zn-Bet-Tf2N facilitated FO system reclaims water efficiently from zinc-containing wastewater.•Zn-Bet-Tf2N is readily regenerated through solvent extraction and is reusable in FO. The unavailability of a suitable draw solute constrains the advancement of forward osmosis (FO) technology. Here from a custom-built ionic liquid betainium bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]), a multinuclear zinc complex of [Zn4(bet)10(H2O)2][Tf2N]8 (Zn-Bet-Tf2N) has been synthesized via a one-pot complexation reaction for electroplating wastewater treatment via FO processes. Possessing a large number of hydrophilic groups and an expanded structure, Zn-Bet-Tf2N generates a sufficient osmotic pressure to drive the FO process and minimizes reverse solute diffusion. Zn-Bet-Tf2N produces a water flux of 15.0 LMH even at a dilute concentration (0.2 mol/L) with negligible solute leakage during the FO process. The water permeation rates induced by Zn-Bet-Tf2N increase by up to 50% compared to those of the conventional NaCl, MgCl2 and NH4HCO3 draw solutes in zinc-containing wastewater reclamation. Zn-Bet-Tf2N is readily separated from water after FO through solvent extraction. With no energy input or by-products, the recycling of Zn-Bet-Tf2N is more practical than that of other draw solutes ever reported. Reproducible results are obtained when the recycled Zn-Bet-Tf2N is reused to FO processes. These findings suggest that the Zn-Bet-Tf2N facilitated FO system can achieve high water recovery efficiency, high selectivity and sustainability in zinc-containing wastewater treatment.