(619b) Utilizing Greener Solvents for Membrane Fabrication

Commercial microfiltration (MF) and ultrafiltration (UF) membrane fabrication methods utilize toxic, petroleum-based solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylformamide (DMF). Greener solvents are inherently less toxic, more environmentally friendly, and/or derived from renewable materials. By developing strategies to incorporate greener solvents into membrane fabrication, further societal and environmental impacts can be mitigated while maintaining the separation performance of current commercial membranes. This study investigates the structure-property-performance relationship of solvents and how they impact fundamental properties of polyethersulfone (PES) membranes prepared using nonsolvent-induced phase separation (NIPS). Solvents were selected based on the evaluation of their Hansen solubility parameters, toxicity, and partition coefficient (LogP). The membranes were prepared by the NIPS method using PES in two categories of solvents: conventional and greener. N,N-dimethylacetamide (DMAc) was used as the conventional solvent while dimethyl sulfoxide (DMSO), 2-methylpyrazine (2MP), and glycerol-derived compounds were used as the greener solvents. Cloud point titration was used to determine the thermodynamic stability of polymer solutions. Dead-end filtration was used to evaluate the pure water permeance and solute rejection of the membranes. Physical characterization of each membrane’s cross-section and surface morphology were accomplished via scanning electron microscopy. Analysis of SEM images found that 2MP lead to an increased top surface pore size and a denser cross-sectional morphology, which may be attributed to the hydrophobic character of the solvent. This denser cross-sectional morphology resulted in less compaction and lower permeances.