Employment of Magnetic Poly(Styrene-co-Triethylene Gycol Dimethacrylate) as an Immobilization Matrix for Lipase G: Application of Hexyl Oleate Synthesis and Kinetic Study

This study aimed to synthesize the emollient ester hexyl oleate by enzymatic catalysis using lipase G from Penicillium camemberti immobilized on the magnetic copolymer poly(styrene-co-triethylene glycol dimethacrylate) (STY-TEGDMA-M). For this, an experimental study was carried out on esterification reactions conducted in solvent-free medium, and the collected data were used to construct a mathematical model. The physical properties of the immobilized derivative were evaluated by scanning electron microscopy and Fourier-transform infrared spectroscopy. The results confirmed that lipase G was successfully immobilized onto the support, with a catalytic activity of 564.63 U g⁻¹. The biocatalyst showed optimum performance at 45 °C, reaching 82% conversion after 48 h of reaction. A chromatographic method was used to confirm the formation of hexyl oleate. A thermal stability assay was conducted, showing that the biocatalyst retained 87% of its initial activity after 4 h of incubation at 60 °C. Mathematical modeling was based on the ping-pong bi-bi kinetic mechanism. The best model was selected according to the lowest value of the corrected Akaike information criterion (AIC_C = 124.776). The model revealed equilibrium constant values (K_eq) ranging from 0.87 to 14.57, maximum rates of the forward reaction ranging from 0.088 to 0.090 mol L⁻¹ min⁻¹, and a maximum rate of the reverse reaction of 0.021 mol L⁻¹ min⁻¹.