A cage-like supramolecular draw solute that promotes forward osmosis for wastewater remediation and source recovery

Draw solute is a key element of forward osmosis (FO) technology. Here we design a cage-like supramolecular material of N-(hexamethylenetetramine) propane-1-sulfonate (HMTA(+) - SO3-) for the simultaneous wastewater remediation and protein enrichment via FO processes. HMTA(+) - SO3- reclaims water efficiently with a transfer rate of 36.0 LMH at 1.0 M without reverse solute diffusion, outperforming the conventional NaCl draw solute that produces a smaller water flux coupled with severe solute leakage. The good performance originates from the innate nature of HMTA(+) - SO3- that can create a sufficiently high osmotic pressure to drive the FO process and form a supramolecular network with H2O via hydrogen-bonding to prevent solute leakage. Protein enriched by HMTA(+) - SO3- remains intact in structure but those concentrated by typical NH4HCO3 or NaCl draw solutes are either contaminated or denatured resulting from the severe reverse solute diffusion in the FO process. HMTA(+) - SO3- can be readily collected quantitatively via precipitation purification and reused with reproducible results. The HMTA(+) - SO3- facilitated FO process for protein-containing wastewater treatment reported here may ultimately find use in processing other high-value-added compounds.