Synthesis and Characterization of Magnetic Poly(STY-EGDMA) Particles for Application as Biocatalyst Support in Octyl Oleate Ester Synthesis: Kinetic and Thermodynamic Parameters and Mathematical Modeling

This study aimed to (i) synthesize and characterize magnetic poly(styrene- co -ethylene glycol dimethacrylate) particles (STY-EGDMA-M) as immobilization support for Candida antarctica lipase B (CALB), (ii) determine kinetic and thermodynamic parameters of the immobilized biocatalyst in emollient ester synthesis, and (iii) develop a mathematical model for the bioprocess. The enzyme support was characterized by optical microscopy, hysteresis analysis, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Magnetic copolymer particles were found to have spherical shape, ideal for use as immobilization support. The results confirmed that magnetic particles were incorporated into the polymer matrix, whose saturation magnetization was about 7 emu g −1 . Immobilized CALB showed an activity of 570 ± 48 U g −1 in the hydrolysis of butyl butyrate. The derivative was used to synthesize octyl oleate by esterification of oleic acid with octanol. The influence of temperature on the esterification reaction was analyzed, and a mathematical model was developed to determine apparent kinetic and thermodynamic parameters. The highest ester conversion (56%) was obtained at 55 °C, and chemical equilibrium was achieved in 12 h of reaction. Under these conditions, the reaction was spontaneous, with negative Gibbs energy (− 4.73 kJ mol −1 K −1 ), positive entropy (+ 0.463 kJ mol −1 K −1 ), endothermic nature (+ 147.53 kJ mol −1 ), and low activation energy (61.71 kJ mol −1 ). A second-order reversible kinetic model provided a satisfactory fit to the data ( R 2 = 0.9965), within the 95% confidence interval. In an operational stability test, conducted for five consecutive cycles of 24 h, the biocatalyst had a half-life of 315.07 h. Graphical Abstract