Development of a magnetically stabilized fluidized bed bioreactor for enzymatic synthesis of 2-ethylhexyl oleate.

This study aimed to develop and investigate the synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on magnetic poly(styrene-co-divinylbenzene) (STY-DVB-M) particles in a magnetically stabilized fluidized bed reactor (MSFBR) operated in continuous mode. The physical properties of the copolymer were characterized by Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The glass transition temperature was 85.68 °C, and the onset of thermal degradation occurred at 406.66 °C. Syntheses were performed at 50 °C using a space time of 12 h and a bed porosity of 0.892. Assays were conducted to assess the influence of magnetic field intensity (5 to 15 mT) on reaction yield, ester concentration, and productivity. The highest productivity was 0.850 ± 0.023 mmol g-1 h-1, obtained with a magnetic field intensity of 15 mT. An operational stability test was performed under these conditions, revealing a biocatalyst half-life of 2148 h (179 operation cycles) and a thermal deactivation constant of 3.23 × 10-4 h-1 (R2 = 0.9446). Computational simulations and mathematical modeling were performed using Scilab based on ping-pong bi-bi kinetics and molar balances of reaction species. The model provided consistent results of interstitial velocity and good prediction of reaction yields, with R2 = 0.926. These findings demonstrate that the studied technique can provide improvements in biocatalytic processes, representing a promising strategy for the enzymatic synthesis of 2-ethylhexyl oleate.

Synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on a magnetic polymer support in continuous flow.

This study investigated the synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase immobilized on magnetic poly(styrene-co-divinylbenzene) particles in a continuous packed-bed bioreactor. Runs were carried out in a solvent-free system at 50 °C. The performance of the reactor was evaluated for substrates composed by oleic acid and 2-ethylhexanol at five molar ratios (1:4-4:1), determining its operation limits in terms of substrate flow rate. The system performance was quantified for three different flow rates corresponding to space-time between 3 and 12 h. For each condition, the influence of the space-time in the ester formation, esterification yield and productivity was determined. The molar ratio of acid-to-alcohol interfered, in a remarkable way, in the formation of 2-ethylhexyl oleate and the best performance was attained for substrate at equimolar ratio running at 12 h space-time. Under this condition, average 2-ethylhexyl oleate concentration was 471.65 ± 2.98 g L-1 which corresponded to ester productivity of 23.16 ± 0.49 mmol g-1 L-1 h-1. This strategy also gave high biocatalyst operational stability, revealing a half-life time of 2063 h. A model based on the ping-pong Bi-Bi mechanism was developed to describe the kinetics of the esterification reaction and validated using experimental data. The goodness of fit of the model was satisfactory (R2 = 0.9310-0.9952).