Efficient Enrichment of 1,3-Propanediol from Fermentation Broths Using Imidazolium Dibutylphosphate Ionic Liquid Based Methacrylate Polymer Membranes

Glycerol, a platform chemical for the production of intermediate bioproducts, can be obtained as a low-value waste feedstock from a wide variety of industrial sources. Its fermentative conversion to bio-renewable chemicals such as 1,3-propanediol (1,3-PD) is an environmentally and economically sustainable recourse to its utilization. 1,3-PD is an important chemical intermediate in manufacturing of polyethers, polyurethanes, and polyesters. It is also widely used in food, cosmetic, and pharmaceutical industries. The principal impediment in the fermentative conversion of glycerol to 1,3-PD lies in the downstream enrichment of 1,3-PD concentration from very low starting concentrations. Conventional processes, like evaporation, chromatography, and reactive extraction have been used but are associated with high-energy usage and process limitations which can be mitigated with pervaporation. The challenge of pervaporative enrichment of 1,3-propanediol (1,3-PD) from dilute aqueous mixtures was addressed by the synthesis of a novel hydrophobic imidazolium alkyl phosphate ionic liquid structure based monomer. Vinylimidazole was “coupled” with mercaptoethanol, converted into an alkylphosphate ionic liquid followed by esterification to the final monomer structure. Characterization and batch pervaporation was carried out on several different polymer chemistry mediated membrane structures based on this monomer, including semi-interpenetrating polymeric network structures with hydrophobic polyglycerol sebacate acrylate (PGSA). The batch pervaporation exhibited high separation factors and fair 1,3-PD fluxes compared to other hydrophobic membranes. The monomer provides recourse to high performing materials by balancing its 1,3-PD affinity with its hydrophobic nature. The excellent cost-performance trade-off makes this an attractive candidate for possible scale-up and industrial applications in multilayer modules.