A Bifunctional Zwitterion That Serves as Both a Membrane Modifier and a Draw Solute for Forward Osmosis Wastewater Treatment

Abstract

Producing clean water and simultaneously recovering valuable compounds are a big challenge in wastewater treatment. Here we designed a bifunctional zwitterion of (1-(3-aminopropyl)imidazole) propanesulfonate (APIS) for membrane modification and being a draw solute as well for water production and protein enrichment via forward osmosis (FO). Immobilized to the membrane surface by a fast amidation reaction, APIS endows the membrane with favorable properties benefiting the FO process. The APIS-modified sulfonated poly(ether sulfone) (APIS− sPES) membrane produces a water flux 101% higher than that of the nascent membrane (from 9.3 to 18.7 LMH) with 0.5 M NaCl as the draw solution. The APIS− sPES membrane also exhibits higher fouling resistance with a much smaller decline in water permeation and stronger renewability with the flux restored to 88% of the original value compared to a 59% recovery rate of the nascent membrane after 20-h experiments against a 200 ppm ovalbumin solution. APIS produces a fair good water flux coupled with negligible reverse diffusion when used as a draw solute and can be readily regenerated via pH regulation. Unlike the conventional NaCl draw solute, APIS does not contaminate or damage protein structure. The APIS−sPES membrane and APIS draw solute prove a perfect match in protein-containing wastewater treatment and protein enrichment.

Membrane Surface Functionalization with Imidazole Derivatives to Benefit Dye Removal and Fouling Resistance in Forward Osmosis

“…There was a red-shift in the absorption of the imidazole ring from 620 cm −1 in IM-NH 2 to 580 cm −1 in IL-NH 2 resulting from the reduced electron cloud density in the imidazole ring of the latter due to quaternization. 20 We also observed peaks centered at 3400 cm −1 that corresponded to the amine functional group in both compounds synthesized here. These amine groups were crucial for the subsequent covalently grafting of these compounds on to the PA surface via an amidation reaction for membrane modification.…”

pH-Responsive Polyoxometalates that Achieve Efficient Wastewater Reclamation and Source Recovery via Forward Osmosis

“…Forward osmosis (FO) can be a potential choice for simultaneous GSH recovery and wastewater remediation because of its high selectivity, low membrane fouling tendency, and high energy efficiency when an efficient and recyclable draw solute is available. , In the FO process, water in the feed flows to the draw solution side driven by the osmotic pressure gradient across the membrane. − Therefore, draw solutes are crucial elements, which determine the FO separation efficiency. A wide range of draw solutes have been applied to FO over the past few decades. − Commercial salts, such as NaCl, NH 4 HCO 3 , and sodium/magnesium carboxylates, have been the first to be used for FO separation. , These compounds generally produce a sufficient osmotic pressure to extract water from various feed solutions.…”

Application of Zwitterions in Forward Osmosis: A Short Review

“…Chen et al designed a zwitterionic amine monomer, (1-(3-aminopropyl) imidazole) propane sulfonate (APIS) and grew it on a PA layer. The surface hydrophilicity decreased significantly from ~70° (PA-PES) to ~40°; meanwhile, 101% higher water flux than the unmodified membrane [76]. Figure 4 schematically presents the inclusion of zwitterionic moieties by 2 nd interfacial polymerization.…”

“…Figure 4 schematically presents the inclusion of zwitterionic moieties by 2 nd interfacial polymerization. [76]).…”