Low-cost CO2-based alkyl carbamate ionic liquids for accelerating enzymatic oil hydrolysis

The enzymatic hydrolysis of vegetable oil is hindered by the prolonged duration required for reaction completion. This study aimed to address this concern by employing low-cost CO₂-based alkyl carbamate ionic liquids (ILs) as additives. First, the verification of the successful synthesis of these ILs was attained through FTIR spectra analysis, revealing distinct C-O stretching peaks at 1,408 and 1,621 cm^-1. Furthermore, the addition of carbamate ILs did not cause enzyme denaturation, as proven by the preservation of the native beta-sheet assignment within the lipase structure. The carbamate ILs also raised the enzyme’s negative zeta potential and reduced the chances of aggregation. Among the carbamate ILs investigated, bis(2-ethylhexyl)-ammonium bis(2-ethylhexyl)carbamate (DBCARB) was determined to be the most effective, owing to its hydrophobic properties and ability to optimize pH levels and expose the enzyme’s active site to the outer surface. Through purification, 8 wt % DBCARB reached a near-optimal equilibrium free fatty acid yield (∼95 wt %) within 8 h with only 0.2 wt % lipase, signifying a notable enhancement compared to the 120 h required in the absence of DBCARB. These results highlight the potential of DBCARB in enhancing enzymatic hydrolysis and shortening reaction times.