title: Extractive-transesterification of algal lipids under microwave irradiation with hexane as solvent.
abstract: This study describes the use of microwaves (MW) for enhanced extractive-transesterification of algal lipids from dry algal biomass (Chlorella sp.). Two different single-step extractive-transesterification methods under MW irradiation were evaluated: (1) with ethanol as solvent/reactant and sodium hydroxide catalyst; and (2) with ethanol as reactant and hexane as solvent (sodium hydroxide catalyst). Biodiesel (fatty-acid-ethyl-esters, FAEE) yields from these two methods were compared with the conventional Bligh and Dyer (BD) method which followed a two-step extraction-transesterification process. The maximum lipid yields for MW, MW with hexane and BD methods were 20.1%, 20.1%, and 13.9%, respectively; while the FAEE conversion of the algal lipids were 96.2%, 94.3%, and 78.1%, respectively. The algae-biomass:ethanol molar ratio of 1:250-500 and 2.0-2.5% catalyst with reaction times around 6min were determined as optimum conditions for both methods. This study confers that the single-step non-conventional methods can contribute to higher algal lipid and FAEE yields.
authors: Civil & Environmental Engineering, Mississippi State University, Mississippi State, MS 39762, United States.
authors: Edith
authors: E
authors: Martinez-Guerra
authors: Civil & Environmental Engineering, Mississippi State University, Mississippi State, MS 39762, United States. Electronic address: gude@cee.msstate.edu.
authors: Veera Gnaneswar
authors: VG
authors: Gude
authors: Chemical and Paper Engineering, Western Michigan University, Kalamazoo, MI 49008, United States.
authors: Andro
authors: A
authors: Mondala
authors: Chemical Engineering, University of Louisiana at Lafayette, Lafayette, LA 70504, United States.
authors: William
authors: W
authors: Holmes
authors: Chemical Engineering, University of Louisiana at Lafayette, Lafayette, LA 70504, United States.
authors: Rafael
authors: R
authors: Hernandez
mesh_terms: D002384:Catalysis / Q000187:drug effects; D002708:Chlorella / Q000187:drug effects / Q000378:metabolism; D004951:Esterification / Q000187:drug effects; D006586:Hexanes / Q000494:pharmacology*; D008055:Lipids / Q000302:isolation & purification*; D008872:Microwaves; D012997:Solvents / Q000494:pharmacology*; D013696:Temperature; D013997:Time Factors
chemical_list: D006586:Hexanes; D008055:Lipids; D012997:Solvents; C026385:n-hexane
keywords: Algal biodiesel; Chlorella sp.; Extractive-transesterification; Hexane; Microwave extraction