(593f) Scaling-up, Evaluating, and Modelling the Fabrication of Green Solvent-Based Polymeric Membranes: A Comparison between Blade Casting and Slot Die Coating

Due to increasing clean water insecurity, polymeric membranes are playing a major role as more efficient and scalable filters. A variety of techniques for polymeric membrane fabrication has been studied, with nonsolvent-induced phase separation (NIPS) being one of the most prevalent methods. However, the frequent use of hazardous solvents that are derived from nonrenewable resources hinders the safety and sustainability of NIPS; moreover, new regulations have motivated commercial manufacturers to identify alternative solvents. Two green solvents of great interest for membrane fabrication are Rhodiasolv® PolarClean and gamma-valerolactone (GVL), both of which are biodegradable and nontoxic. While bench-scale studies on green solvent-based polymeric membranes have emerged, the next step of manufacturing scale-up remains largely unstudied.

In this study, the next step is addressed by developing a novel scaled-up manufacturing NIPS method for green solvent-based polysulfone (PSf) membranes via slot die coating (SDC). The SDC setup was configured for continuous processing on a roll-to-roll system. Dope solution properties were analyzed to determine the optimal parameters for fabricating membranes via SDC. A comparison study of filtration characteristics was conducted between PSf-PolarClean-GVL membranes fabricated via bench-scale blade-casting and SDC. A computational model was developed to simulate membrane sheet and defect formation based on a large set of casting parameters.

Under dead-end filtration conditions, PSf-PolarClean-GVL membranes fabricated via SDC exhibited an average permeability of 55.9 ± 3.7 LMH/bar and a maximum bovine serum album (BSA) rejection of 97.0 ± 5.2%, which indicated close agreement with a blade-casted counterpart (69.7 ± 9.7 LMH/bar and 99.2 ± 1.3%, respectively). The complete results highlight the value of green solvents and SDC in bringing sustainable and scaled-up polymeric membranes closer to implementation.