Levulinic Acid Separation Using Hollow Fibers Supported Liquid Membrane: Effects of Impregnation Time and Coagulation Bath Temperature

In the production of levulinic acid (LA) from biomass, creating an efficient separation method is essential to isolate LA from unreacted reactants and unwanted byproducts. One promising approach is the use of a supported liquid membrane (SLM). This study examined the performance of LA separation using a hybrid graphene/polyethersulfone hollow fiber SLM by varying the liquid membrane impregnation time from 1 to 24 h. Additionally, the hollow fiber membranes used in the SLM were fabricated at different coagulation bath temperatures (CBT), ranging from 32°C (room temperature) to 60°C, under high relative humidity (86%). The optimal impregnation time of 24 h resulted in 11.1% LA extraction and 36.6% recovery in the stripping phase without any liquid membrane leakage. Increasing the CBT promoted the formation of a dense outer layer in the fiber while reducing overall thickness and porosity. The hollow fiber membrane prepared at a CBT of 50°C exhibited a well-balanced porosity and thickness, achieving 10.1% LA extraction from a 10 g/L aqueous LA solution and the highest LA recovery in the stripping phase at 70.9%. Optimizing hollow fiber membrane properties for SLM is essential for enhancing LA extraction in biorefineries, as it improves membrane stability, increases separation efficiency, and extends operational lifespan.