title: Efficient solvothermal wet in situ transesterification of Nannochloropsis gaditana for biodiesel production.
abstract: In situ transesterification of wet microalgae is a promising, simplified alternative biodiesel production process that replaces multiple operations of cell drying, extraction, and transesterification reaction. This study addresses enhanced biodiesel production from Nannochloropsis gaditana at elevated temperatures. Compared with the previously reported in situ transesterification process of conducting the reaction at a temperature ranging from 95 to 125 °C, the present work employs higher temperatures of at least 150 °C. This relatively harsh condition allows much less acid catalyst with or without co-solvent to be used during this single extraction-conversion process. Without any co-solvent, 0.58% (v/v) of H2SO4in the reaction medium can achieve 90 wt% of the total lipid conversion to biodiesel at 170 °C when the moisture content of wet algal paste is 80 wt%. Here, the effects of temperature, acid catalyst, and co-solvent on the FAEE yield and specification were scrutinized, and the reaction kinetic was investigated to understand the solvothermal in situ transesterification reaction at the high temperature. Having a biphasic system (water/chloroform) during the reaction also helped to meet biodiesel quality standard EN 14214, as Na+, K+, Ca2+, Mg2+cations and phosphorus were detected only below 5 ppm. With highlights on the economic feasibility, wet in situ transesterification at the high temperature can contribute to sustainable production of biodiesel from microalgae by reducing the chemical input and relieve the burden of extensive post purification process, therefore a step towards green process.
authors.affiliation: Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea.
authors.forename: Bora
authors.initials: B
authors.lastname: Kim
authors.affiliation: Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea.|ABC Biomass R&D Center, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea.
authors.forename: Yong Keun
authors.initials: YK
authors.lastname: Chang
authors.affiliation: Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea. jaewlee@kaist.ac.kr.
authors.forename: Jae W
authors.initials: JW
authors.lastname: Lee
mesh_terms: D056804:Biofuels; D004951:Esterification; D006358:Hot Temperature; D008055:Lipids / Q000737:chemistry*; D058009:Stramenopiles / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry
chemical_list: D056804:Biofuels; D008055:Lipids; D013464:Sulfuric Acids; C033158:sulfuric acid
keywords: Fatty acid ethyl ester (FAEE); High temperature; In situ transesterification; Microalgae; Sulfuric acid