title: Hydrothermal nitric acid treatment for effectual lipid extraction from wet microalgae biomass.
abstract: Hydrothermal acid (combined with autoclaving and nitric acid) pretreatment was applied to Nannochloropsis salina as a cost-effective yet efficient way of lipid extraction from wet biomass. The optimal conditions for this pretreatment were determined using a statistical approach, and the roles of nitric acid were also determined. The maximum lipid yield (predicted: 24.6%; experimental: 24.4%) was obtained using 0.57% nitric acid at 120°C for 30min through response surface methodology. A relatively lower lipid yield (18.4%) was obtained using 2% nitric acid; however, chlorophyll and unsaturated fatty acids, both of which adversely affect the refinery and oxidative stability of biodiesel, were found to be not co-extracted. Considering its comparable extractability even from wet biomass and ability to reduce chlorophyll and unsaturated fatty acids, the hydrothermal nitric acid pretreatment can serve as one direct and promising route of extracting microalgae oil.
authors.affiliation: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Ilgyu
authors.initials: I
authors.lastname: Lee
authors.affiliation: Clean Fuel Department, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Republic of Korea.
authors.forename: Ji-Yeon
authors.initials: JY
authors.lastname: Park
authors.affiliation: Clean Fuel Department, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Republic of Korea.
authors.forename: Sun-A
authors.initials: SA
authors.lastname: Choi
authors.affiliation: Clean Fuel Department, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Republic of Korea.
authors.forename: You-Kwan
authors.initials: YK
authors.lastname: Oh
authors.affiliation: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea. Electronic address: jihan@kaist.ac.kr.
authors.forename: Jong-In
authors.initials: JI
authors.lastname: Han
mesh_terms: D000704:Analysis of Variance; D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D005227:Fatty Acids / Q000378:metabolism; D008055:Lipids / Q000302:isolation & purification*; D058086:Microalgae / Q000187:drug effects / Q000378:metabolism*; D017942:Nitric Acid / Q000494:pharmacology*; D013223:Statistics as Topic; D013464:Sulfuric Acids / Q000494:pharmacology; D013696:Temperature; D014867:Water / Q000494:pharmacology*
chemical_list: D005227:Fatty Acids; D008055:Lipids; D013464:Sulfuric Acids; D014867:Water; D017942:Nitric Acid; C033158:sulfuric acid
keywords: Cell disruption; Chlorophyll removal; Lipid extraction; Microalgae; Nitric acid