Biocatalysts based on nanozeolite-enzyme complexes: Effects of alkoxysilane surface functionalization and biofuel production using microalgae lipids feedstock

• Published in: Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2018-05, Vol.165, p.150-157
• Main Authors: de Vasconcellos, Adriano, Miller, Alex Henrique, Aranda, Donato A.G., Nery, José Geraldo
• Format: Article
• Language: English
• Subjects: Biocatalysis; Biofuels; Biofuels - microbiology; Biomass; Lipids - chemistry; Microalgae - metabolism; Nanoparticles - chemistry; Nanoparticles - ultrastructure; Nanozeolite surface chemical modulation; Non-edible lipid feedstocks; Silanes - chemistry; Spectroscopy, Fourier Transform Infrared; Static Electricity; Surface Properties; X-Ray Diffraction; Zeolite-enzyme surface interaction; Zeolites - chemistry
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2018.02.029

[Display omitted] •Nanozeolites functionalized with APTMS and cross linking GA for enzyme immobilization.•Thermomyces lanuginosus lipases physically or covalently immobilized on nanozeolites.•Nanozeolite-enzymes complexes used as catalysts for the production of biodiesel.•High yield of FAEEs were obtained with zeolitic support treated with nickel.•T. lanuginosus immobilized covalently bonded on GA-Nanozeolite is much more stable. Nanozeolites with different crystallographic structures (Nano/TS1, Nano/GIS, Nano/LTA, Nano/BEA, Nano/X, and Nano-X/Ni), functionalized with (3-aminopropyl)trimethoxysilane (APTMS) and crosslinked with glutaraldehyde (GA), were studied as solid supports for Thermomyces lanuginosus lipase (TLL) immobilization. Physicochemical characterizations of the surface-functionalized nanozeolites and nanozeolite-enzyme complexes were performed using XRD, SEM, AFM, ATR-FTIR, and zeta potential measurements. The experimental enzymatic activity results indicated that the nanozeolitic supports functionalized with APTMS and GA immobilized larger amounts of enzymes and provided higher enzymatic activities, compared to unfunctionalized supports. Correlations were observed among the nanozeolite surface charges, the enzyme immobilization efficiencies, and the biocatalyst activities. The catalytic performance and reusability of these enzyme-nanozeolite complexes were evaluated in the ethanolysis transesterification of microalgae oil to fatty acid ethyl esters (FAEEs). TLL immobilized on the nanozeolite supports functionalized with APTMS and GA provided the most efficient biocatalysis, with FAEEs yields above 93% and stability during five reaction cycles. Lower FAEEs yields and poorer catalytic stability were found for nanozeolite-enzyme complexes prepared only by physical adsorption. The findings indicated the viability of designing highly efficient biocatalysts for biofuel production by means of chemical modulation of nanozeolite surfaces. The high biocatalyst catalytic efficiency observed in ethanolysis reactions using a lipid feedstock that does not compete with food production is an advantage that should encourage the industrial application of these biocatalysts.