Kinetic and Thermodynamic Study of 2-Ethylhexyl Oleate Synthesis Catalyzed by Candida antarctica Lipase Immobilized on a
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Kinetic and Thermodynamic Study of 2‑Ethylhexyl Oleate Synthesis Catalyzed by Candida antarctica Lipase Immobilized on a Magnetic Hybrid Support Mateus V. C. da Silva1 · Amanda B. S. Rangel1 · Fellipe P. Dutra1 · Heizir F. de Castro1 · Larissa de Freitas1 Received: 25 June 2020 / Accepted: 4 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract This study investigated the kinetic and thermodynamic parameters of the synthesis of 2-ethylhexyl oleate catalyzed by Candida antarctica lipase (CALB) immobilized on magnetic poly(styrene-co-divinylbenzene) (STY-DVB-M). The influence of acid/alcohol molar ratio and temperature on oleic acid conversion, ester concentration, and productivity was also assessed. Excess of one of the reagents resulted in high conversions, but the highest productivities were obtained at the stoichiometric ratio. Thus, a 1:1 molar ratio was considered optimal. Thermodynamic parameters calculated from the van’t Hoff equation (ΔS = + 850.64 J mol−1 K−1, ΔH = + 273.78 kJ mol−1) revealed that the reaction is endothermic with a positive entropy change. Temperatures below 45 °C negatively affected reaction kinetics, explained by the positive ΔG values. CALB-STYDVB-M showed a hydrolytic activity of 522.97 ± 19.14 U g−1 and was about 1.7 times more thermally stable at 60 °C than the free enzyme. In an operational stability test, conducted for 7 consecutive cycles of 24 h, the biocatalyst had a half-life of 739 h. CALB-STY-DVB-M showed satisfactory performance in the synthesis of 2-ethylhexyl oleate, providing oleic acid conversions close to 100%, ester concentration of 450 g L −1, and productivity of 0.5 mmol g−1 h−1. The biocatalyst holds promise for industrial applications. Graphic Abstract
Keywords Kinetic/thermodynamic studies · Esterification · Operational stability · Immobilized lipase · Magnetic hybrid polymer * Larissa de Freitas [email protected] 1
Department of Chemical Engineering, Engineering School of Lorena, University of São Paulo, Lorena, SP 12602‑810, Brazil
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1 Introduction 2-Ethylhexyl oleate is a long carbon chain molecule widely used as an emollient in cosmetic formulations. The ester also finds application in the pharmaceutical, food, and textile industries. Biodegradability, nontoxicity, low volatility, high spreadability, and chemical stability are some of its main properties [1]. Production of 2-ethylhexyl oleate by conventional chemical processes, characterized by the use of high temperatures and chemical catalysts, may result in low-quality products with components that are aggressive to the skin and harmful to human health [2]. The demand for environmentally friendly products obtained through green chemistry techniques has increased in recent years. Lipase-catalyzed ester synthesis is an attractive alternative, as it affords high-quality products, is carried out under mild pressure and temperature conditions, has high catalytic power, and does not generate byproducts, meeting the requirements of env
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