Enzymatic hydrolysis of used cooking oil and palm olein using a Starbon-immobilized Candida Antarctica lipase B

Abstract

This study investigated the enzymatic hydrolysis of UCOs and refined palm olein using Candida Antarctica lipase B (CALB) immobilized on a mesoporous carbon (Starbon A800), and commercial immobilized lipases (Lipozyme TLIM and Novozyme 435). Various immobilization techniques were assessed, with physisorption onto an amino-functionalized surface followed by crosslinking (CALBAC3) providing the best results, achieving the highest enzyme loading (11.3 wt. %), anchoring efficiency (56.36 %), and hydrolytic activity (136.5 LU/g). Activity remained stable at pH 6–7.3, with optimal performance at 45–50 °C. The best hydrolytic activity was achieved at 45 °C, pH 7, 7.0 wt. % enzyme loading, ultrasonic mixing during initial 120 min at 100 W and 37 kHz, a 1:30 oil-to-water ratio, and mechanical stirring at 300 rpm. Under these conditions, conversion reached 91.04 ± 3.92 %. The obtained data were used to correlate kinetic expressions using the Michaelis-Menten-type and water-inhibition models, and they agreed reasonably well with experiments showing relative errors below 2 %. Despite high initial activity comparable to Novozyme 435, CALBAC3 exhibited a significant drop in performance after reuse, likely due to mechanical instability of the support and enzyme immobilization strength. Future work should focus on enhancing the support strength, optimizing mesoporous pore distribution, and exploring alternative crosslinking strategies.