Produção de ésteres industriais empregando biocatalisadores heterogêneos preparados por imobilização de lipase em partículas de biossílica funcionalizadas

Abstract

The objective of this study consisted in the preparation and characterization of a renewable and hydrophobic support from rice husk silica functionzalized with triethoxy(phenyl)silane (PheTES) to imobilize a microbial lipase from Thermomyces lanuginosus (TLL) via interfacial activation to be used as biocatalyst in ester production. The introduction of phenyl groups on its surface has been confirmed by microscopy (SEM, TEM and AFM), N 2 physisorption (B.E.T. method) and elementar analysis. This support had a maximum immobilized TLL concentration of 27.7 ± 2.3 mg/g using an initial protein loading of 40 mg/g. The biocatalyst prepared was used to produce cetyl oleate by esterification in a solvent-free system and maximum conversion of 92% was attained after seven successive batches of 330 min each. This biocatalyst was also used to catalyze biolubricants production via esterification of free fatty acids (FFA) from refined and frying soybean oils with decanol in solvent- free systems. Its catalytic activity has been compared with TLL immobilized via interfacial activation on rice husk silica chemically modified containing octyl groups (Octyl–SiO 2 ), a heterogeneous biocatalyst with a maximum immobilized TLL concentration of 21.9 ± 0.1 mg/g and active in the production of cetyl esters (cosmetic esters) and biosurfactants (solketal palmitate). According to results, maximum conversion percentage of ≈85% has been attained within 120 min (FFA from frying oil) and 150 min (FFA from refined soybean oil) using TLL immobilized on Octyl–SiO 2 . Reuse tests revealed that this biocatalyst retained 88% of its original activity after 16 consecutive batches of reaction for both reaction systems. The ester production has been confirmed by nuclear magnetic resonance (NMR) analysis. Viscosity index (VI from 190 to 204) and specific mass (0.865–0.867 g/cm 3 ) values of these esters were similar to other synthetic esters, thus suggesting their promising application as alternative biolubrificants.