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Lookup NU author(s): Dr Shurooq Al-Humairi, Professor Jonathan LeeORCiD, Professor Adam Harvey
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
© 2022 The Author(s). Microalgae are important biodiesel feedstocks because of their high lipid content and low land requirement for cultivation. One method of harvesting and concentrating algal biomass is by means of a foam column using surfactant CTAB as a collector and foaming agent, however, the downstream treatments for the “foamate” produced have not yet been investigated. Here, the freshwater microalgae strain, Chlorella vulgaris, was harvested by a continuous dispersed air flotation column and the foamate obtained was used as the feedstock for conversion to biodiesel via in situ reactive extraction using KOH as the catalyst. The process variables were methanol: oil molar ratio (100:1 to 1000:1), reaction temperature (40–60 °C) and reaction time (5–10 min). The maximum biodiesel yield from the foamate produced of 97% from C. vulgaris microalgae was accomplished at a molar ratio (methanol to oil) of 1000:1, a 60 °C temperature of reaction and a 10 min time of reaction. Longer reaction times resulted in reduced fatty acid methyl ester (FAME) yield due to saponification, converting the FAME to soap. High FAME yields were obtained despite the presence of significant quantities of free fatty acids (6% lipid) in the C. vulgaris biomass. The method also exhibited greater tolerance to water than that observed in conventional transesterification conditions. At a methanol: oil molar ratio of 1000:1, the method was not adversely affected by the presence of up to 80% level of moisture in the microalgae. Hence, a viable, FFA-tolerant, water-tolerant process has been demonstrated for direct conversion of microalgae foamate to biodiesel, at mild conditions (60 °C and below) in a short residence time (10 min).
Author(s): Al-Humairi ST, Lee JGM, Harvey AP
Publication type: Article
Publication status: Published
Journal: Energy Conversion and Management: X
Year: 2022
Volume: 16
Print publication date: 01/12/2022
Online publication date: 19/08/2022
Acceptance date: 16/08/2022
Date deposited: 20/09/2022
ISSN (electronic): 2590-1745
Publisher: Elsevier Ltd
URL: https://doi.org/10.1016/j.ecmx.2022.100284
DOI: 10.1016/j.ecmx.2022.100284
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