First Exploration on a Poly(vinyl chloride) Ultrafiltration Membrane Prepared by Using the Sustainable Green Solvent PolarClean

Large-scale membrane fabrication currently relies on the use of traditional solvents, such as N,N-dimethylacetamide, 1-methyl-2-pyrrolidinone, and dimethylformamide. These solvents are toxic, slowly biodegradable, and combustible, posing risks to human health and the environment, and requiring careful safety procedures. Replacing traditional solvents with green solvents while maintaining or improving the membrane performance is a challenging task at the forefront of research and development in the field of membrane technology. We employed a novel green solvent, methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (Rhodiasolv PolarClean), to prepare high-performance poly(vinyl chloride) ultrafiltration membranes. This green solvent was used to completely replace toxic solvents during membrane fabrication, for the first time. The effects of polymer concentration, addition of amphiphilic copolymer poly(vinyl chloride)-graft-poly(ethylene glycol) methyl ether methacrylate concentration, and use of a nonwoven polyethylene terephthalate fabric as support layer were investigated systematically. The membrane fabricated with 8% PVC, 5% PVC-g-PEGMA, and nonwoven PET fabrics as support layer showed the best overall performance, presenting small and narrowly distributed membrane pores, high surface porosity, smooth surface, ultrahigh pure water permeability coefficients of >5000 L m-2 h-1 bar-1, high sodium alginate rejection of nearly 98%, and flux recovery ratio of 57%. This study demonstrates the feasibility of using green solvent to increase the sustainability and effectiveness of membrane processes.