Abstract
The immobilization of Candida antarctica lipase B (CALB) was performed by physical adsorption on both neat and organo-modified forms of sepiolite and montmorillonite. The influence of different parameters, e.g., solvent, enzyme loading, cross-linking, and type of clay support, on immobilization efficiency and catalyst hydrolytic activity has been investigated. The highest hydrolytic activities were obtained for CALB immobilized on organo-modified clay minerals, highlighting the beneficial effect of organo-modification. The esterification activity of these CALB/organoclay catalysts was also tested in the ring-opening polymerization of ε-caprolactone. The polymerization kinetics observed for clay-immobilized catalysts confirmed that CALB adsorbed on organo-modified montmorillonite (CALB/MMTMOD) was the highest-performing catalytic system.
Highlights
Lipases (E.C 3.1.1.3), members of the hydrolase family, are esterases that can hydrolyze triglycerides to glycerol and fatty acids at the water-oil interface [1]
The letter L stands for Candida antarctica lipase B (CALB) immobilized on the different types of clay, the number 1, 2 or 3 stands for the corresponding amount of enzyme loading and the last letter (a, b) denotes the catalysts resulting from different batches of immobilization
The resulting CALB/clay catalysts were tested for both their hydrolytic activity and esterification potential for ε-caprolactone enzymatic ring-opening polymerization (eROP)
Summary
Lipases (E.C 3.1.1.3), members of the hydrolase family, are esterases that can hydrolyze triglycerides (or esters) to glycerol and fatty acids at the water-oil interface [1]. In certain cases, lipase-catalyzed hydrolysis in water can be reversed in non-aqueous media to ester synthesis or transesterification [2]. This specific behavior paved the way for the development of lipase-catalyzed ring-opening polymerization (ROP) of lactones, cyclic diesters (lactides), and cyclic carbonates to produce aliphatic polyesters or polycarbonates [3,4]. The immobilization of enzymes is often carried out to increase their activity and stability and to allow easier separation from the reaction mixture [5,6]. Immobilization can be performed either by simple physical adsorption on the support or by covalent bonding between the enzyme proteins and the carrier surface. Covalent anchoring may affect the enzyme activity due to possible difficulties for the enzyme to change its structure to accommodate the specific organic substrate [6]
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