Developing Deep Eutectic Solvent-Resistant Membranes for Efficient Lignin Recovery: A Comparative Study

The paper industry produces ~150 million metric tons of CO2 annually in the US alone. A new manufacturing process has been proposed that would reduce CO2 emissions due to the paper production process by ~65% by utilizing membrane separations rather than lignin recovery boilers. To accomplish this, ultrafiltration membranes must be developed that are 1) >95% effective at lignin filtration and 2) resistant to a novel hydrophobic Deep Eutectic Solvent (DES) used in the new process. Two potential polymers have been identified due to their hydrophobicity and resistance to DES: Polyvinylidene Fluoride (PVDF) and Polybenzimidazole (PBI). The objective of this work was to fabricate PVDF and PBI membranes to compare their permeability, rejection, and long-term DES resistance to make a recommendation on which polymer to further develop and functionalize.