Process Biochemistry, Vol.47, No.3, 435-445, 2012
Surface functionalized mesoporous activated carbon for the immobilization of acidic lipase and their application to hydrolysis of waste cooked oil: Isotherm and kinetic studies
This study deals with the surface functionalization of mesoporous activated carbon, using ethylenediamine and glutaraldehyde to facilitate the strong immobilization of acidic lipase (AL) onto MAC. The AL was produced from Pseudomonas gessardii by using slaughterhouse lipid waste as the substrate. The AL immobilized on functionalized mesoporous activated carbon (ALFMAC) was applied for the hydrolysis of waste cooked oil (WCO). The optimum conditions for the immobilization of AL onto functionalized mesoporous activated carbon (FMAC) were 90 min; pH 3.5; and 35 degrees C: which resulted at the maximum immobilization of 5440 U/g of FMAC (3.693 mg of AL/g of FMAC or the yield 2.7% or the expressed activity 103.7% or the activity per unit area of FMAC 1.08 mg of AL/m(2)). The ALFMAC showed better thermal and storage stabilities than the free AL The ALFMAC retained a 98% and a 92% initial activity at 40 degrees C and 50 degrees C. respectively, while the AL showed the thermal stability (residual activities) 65% and 38%, respectively. The storage stability of ALFMAC at 4 degrees C showed 100% initial activity up to 15 days from the initial day of the storage, whereas AL showed only 88% initial activity up to 15 days. The FMAC and ALFMAC were characterized by using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD) analysis. The K-m values of the ALFMAC and AL were 0.112 mM and 0.411 mM, respectively. The v(max) values of the ALFMAC and AL were 1.26 mM/min and 0.53 mM/min, respectively. Immobilization of AL onto FMAC obeyed the Freundlich and Redlich-Peterson isotherm models. The non-linear models of pseudo first, and second order, intra-particle diffusion, Bangham, and Boyd plot were also performed to understand the dynamic mechanism of immobilization. ALFMAC showed a 100% hydrolysis of WCO up to 21 cycles of reuse, and 60% up to 45 cycles. The hydrolysis of WCO was confirmed by using FT-IR spectra. (C) 2011 Elsevier Ltd. All rights reserved.
Keywords:Surface functionalized mesoporous activated carbon;Immobilization;Acidic lipase;Pseudomonas gessardii;Biocatalyst;Waste cooked oil hydrolysis