Performance of a membrane bioreactor with simultaneous separation in the hydrolysis of residual soybean oil via Pichia pastoris lipase immobilized on graphene oxide

This study evaluates different processes for the hydrolysis of residual soybean oil, comparing the performance of an enzyme immobilized on graphene oxide with that of the free enzyme in membrane and batch reactors. For the free enzyme (45 degrees C, pH 7), in a batch reactor, 39.72 f 1.99 % of FFAs were found in the oil phase and 0.53 f 0.15 % in the aqueous phase, separated by centrifugation. In contrast, using a membrane reactor, the FFA content was 34.63 f 1.35 % in the retentate and 0.56 f 0.03 % in the permeate. For the immobilized enzyme (55 degrees C, pH 7), 38.94 f 0.16 % of FFAs were obtained in the oil phase and 0.67 f 0.08 % in the aqueous phase. Using a membrane reactor, resulted in 35.67 f 1.02 % of FFAs in the retentate and 0.82 f 0.05 % in the permeate, with 100 % oil rejection. The enzyme immobilized in a membrane reactor resulted in a decrease in triacylglycerol and an increase in monoacylglycerol composition in the retentate. This study demonstrates that the use of the immobilized enzyme and its application in a membrane reactor with simultaneous separation is the most suitable process for the hydrolysis of residual soybean oil, allowing for biocatalyst reuse and process optimization.