(496c) Exploiting Deep Eutectic Solvents for Porous Polysulfone Membrane Synthesis

In the quest for advanced water treatment technologies, amidst escalating water scarcity challenges, this study propels the development of Polysulfone (PSF) membranes via Non-Solvent Induced Phase Separation (NIPS) with an innovative twist—modification using Deep Eutectic Solvent (DES) comprised of Choline Chloride (ChCl) and Malic Acid (MA). This DES integration strives to bolster the membrane's hydrophilicity, porosity, and pure water permeability (PWP), while also evaluating the trade-offs in mechanical robustness. A key aspect of our research is the assessment of fouling behaviors, utilizing proteins and dyes with varying molecular weights to simulate the stringent demands of actual service conditions.

The results depict a notable improvement in the PWP of DES-modified membranes compared to the pristine PSF variant (Figure 1). Specifically, the 1% DES membrane exhibits a remarkable rise in permeability, affirming the positive role of DES in enhancing filtration properties. Conversely, the 3% SOLO MA HBD membrane demonstrates constricted permeability, likely a consequence of its smaller pore size, inherent to MA's function as the Hydrogen Bond Donor (HBD). In stark contrast, the 3% SOLO ChCl HBA membrane, infused with ChCl as the HBA, significantly escalates the PWP to 121.62 LMH/bar, indicative of ChCl's predominant influence in enlarging pore dimensions and thereby amplifying permeability.

Interestingly, BSA rejection shown in Figure 1 test further expound on the tailored filtration efficacy achieved through DES modification. The 3% SOLO MA HBD membrane could not be tested for BSA rejection due to its impermeability, highlighting the restrictive nature of its pore structure. However, the 3% SOLO ChCl HBA membrane displayed discerning rejection performance, effectively filtering out larger molecules such as BSA despite facilitating the transit of smaller ones, demonstrating the potential to selectively block molecules based on size.

SEM analysis corroborates these findings as presented in Figure 2, revealing that the 3% SOLO ChCl HBA membrane possesses significantly larger pores, measuring up to 42.72 nm. This enhancement in pore size evidences the profound effect of DES on the membrane structure, with implications for permeability and molecular sieving capabilities.

This comprehensive investigation elucidates the dynamic effects of DES components on PSF membrane morphology, permeability, and separation efficiency. The synergy between ChCl as the HBA and MA as the HBD in DES-modified membranes emerges as a promising strategy for achieving sustainable water filtration solutions. These insights serve as a foundation for future endeavors to refine these membranes for specific industrial applications, leveraging the versatility of DES to optimize water treatment processes.