Immobilized Candida antarctica lipase B on ZnO nanowires/macroporous silica composites for catalyzing chiral resolution of (R,S)-2-octanol

ZnO nanowires were successfully introduced into a macroporous SiO 2 by in situ hydrothermal growth in 3D pores. The obtained composites were characterized by SEM and XRD, and used as supports to immobilize Candida antarctica lipase B (CALB) through adsorption. The high specific surface area (233   m 2 /g) and strong electrostatic interaction resulted that the average loading amount of the composite supports (196.8   mg/g) was 3–4 times of that of macroporous SiO 2 and approximate to that of a silica-based mesoporous material. Both adsorption capacity and the activity of the CALB immobilized on the composite supports almost kept unchanged as the samples were soaked in buffer solution for 48   h. The chiral resolution of 2-octanol was catalyzed by immobilized CALB. A maximum molar conversion of 49.1% was achieved with 99% enantiomeric excess of ( R )-2-octanol acetate under the optimal condition: a reaction using 1.0   mol/L ( R , S )-2-octanol, 2.0   mol/L vinyl acetate and 4.0   wt.% water content at 60   °C for 8   h. After fifteen recycles the immobilized lipase could retain 96.9% of relative activity and 93.8% of relative enantioselectivity .