title: Enhancing trimethylolpropane esters synthesis through lipase immobilized on surface hydrophobic modified support and appropriate substrate feeding methods.
abstract: Candida sp. 99-125 lipase immobilized on surface hydrophobic modified support and appropriate substrate feeding methods were used to improve the synthesis of tri-substituted trimethylolpropane (TMP) esters, which can be used as raw materials for biodegradable lubricants. The proposed novel production method is environmentally friendly. Lipase was adsorbed on surface hydrophobic silk fibers that were pretreated by amino-modified polydimethylsiloxane. A 5-level-4-factors central composite model, including reaction time, temperature, enzyme amount, and molar ratio of fatty acid to TMP, was designed to evaluate the interaction of process variables in the enzymatic esterification. The water activity was kept constant using a LiCl-saturated salt solution. Under the optimum conditions with 30% enzyme amount and substrates molar ratio 8.4 at 45°C for 47h, the total conversion of caprylic acid is 97.3% and the yield of tri-substituted TMP esters is 95.5%. The surface hydrophobic treatment resulted in less cluster water accumulated on the surface immobilized lipase, which was demonstrated by near-infrared spectra. Consequently, the optimum temperature and water tolerance of immobilized lipase were increased. Two TMP-feeding methods were used to maintain high molar ratio of fatty acid to TMP, and increase the final tri-substituted TMP esters content exceeding 85% (w/w) in reactant.
authors.affiliation: Beijing Key Lab of Bioprocess, The Biorefinery Research and Engineering Center of the Ministry of Education, Beijing University of Chemical Technology, East Road No 15 of North Third Ring, Chaoyang District, Beijing, China.
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Tao
authors.affiliation: Beijing Key Lab of Bioprocess, The Biorefinery Research and Engineering Center of the Ministry of Education, Beijing University of Chemical Technology, East Road No 15 of North Third Ring, Chaoyang District, Beijing, China.
authors.forename: Caixia
authors.initials: C
authors.lastname: Cui
authors.affiliation: Beijing Key Lab of Bioprocess, The Biorefinery Research and Engineering Center of the Ministry of Education, Beijing University of Chemical Technology, East Road No 15 of North Third Ring, Chaoyang District, Beijing, China.
authors.forename: Huaqing
authors.initials: H
authors.lastname: Shen
authors.affiliation: Beijing Key Lab of Bioprocess, The Biorefinery Research and Engineering Center of the Ministry of Education, Beijing University of Chemical Technology, East Road No 15 of North Third Ring, Chaoyang District, Beijing, China.
authors.forename: Luo
authors.initials: L
authors.lastname: Liu
authors.affiliation: Beijing Key Lab of Bioprocess, The Biorefinery Research and Engineering Center of the Ministry of Education, Beijing University of Chemical Technology, East Road No 15 of North Third Ring, Chaoyang District, Beijing, China. Electronic address: chenbiqiang@gmail.com.
authors.forename: Biqiang
authors.initials: B
authors.lastname: Chen
authors.affiliation: Beijing Key Lab of Bioprocess, The Biorefinery Research and Engineering Center of the Ministry of Education, Beijing University of Chemical Technology, East Road No 15 of North Third Ring, Chaoyang District, Beijing, China. Electronic address: twtan@mail.buct.edu.cn.
authors.forename: Tianwei
authors.initials: T
authors.lastname: Tan
mesh_terms: D000327:Adsorption; D019149:Bioreactors; D002175:Candida / Q000201:enzymology; D002210:Caprylates / Q000378:metabolism*; D004129:Dimethylpolysiloxanes; D004800:Enzymes, Immobilized / Q000378:metabolism*; D004867:Equipment Design; D004952:Esters; D005656:Fungal Proteins / Q000378:metabolism*; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D008049:Lipase / Q000378:metabolism*; D054327:Lubricants / Q000302:isolation & purification* / Q000378:metabolism; D011409:Propylene Glycols / Q000302:isolation & purification* / Q000378:metabolism; D047011:Silk; D019265:Spectroscopy, Near-Infrared; D013499:Surface Properties; D013696:Temperature; D013784:Textiles; D014867:Water
chemical_list: D002210:Caprylates; D004129:Dimethylpolysiloxanes; D004800:Enzymes, Immobilized; D004952:Esters; D005656:Fungal Proteins; D054327:Lubricants; D011409:Propylene Glycols; D047011:Silk; D014867:Water; C018163:trimethylolpropane; C013830:baysilon; D008049:Lipase; C031492:octanoic acid
keywords: Biodegradable lubricants; Esterification; Immobilized lipase; Substrate feeding; Surface hydrophobic treatment