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Influence of lipid extraction and processing conditions on hydrothermal conversion of microalgae feedstocks - Effect on hydrochar composition, secondary char formation and phytotoxicity

Benavente, Veronica and Lage, Sandra and Gentili, Francesco and Jansson, Stina (2022). Influence of lipid extraction and processing conditions on hydrothermal conversion of microalgae feedstocks - Effect on hydrochar composition, secondary char formation and phytotoxicity. Chemical Engineering Journal. 428 , 129559
[Research article]

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Abstract

This study investigated the effect of lipid extraction of microalgae feedstocks subjected to hydrothermal carbonization (HTC) with regard to the carbonization degree, chemical composition and phytotoxicity of hydrochars produced under different reaction temperatures and residence times. Special attention was given to the formation and composition of secondary char, as this part of the hydrochar may be of particular importance for environmental and technical applications. A microalgae polyculture grown in municipal wastewater was extracted to retrieve lipids, and both unextracted (MA) and extracted microalgae (EMA) were used to produce hydrochars at 180-240 degrees C for 1-4 h. The composition of the hydrochars was thoroughly characterized by elemental analysis, thermogravimetric analysis and pyrolysis-gas chromatography/mass spectrometry analysis. MA exhibited a greater carbonization degree than EMA and contained higher amounts of secondary char under the same processing conditions. During the carbonization of EMA, more decomposition products remained in the liquid phase and less polymerization occurred than for MA, which explained the lower solid yield of EMA-derived hydrochars in comparison to MA hydrochars. Consequently, although they contained potentially toxic substances (i.e., carboxylic acids, aldehydes and ketones), the EMA-derived hydrochars exhibited a lower phytotoxic potential. This indicates that low-temperature hydrochars containing less than 10% of extractives might be suitable as soil amendments, whereas extractive-rich hydrochars would be more appropriate for other long-term applications, such as adsorbents for contaminant removal, energy storage and composite materials. Detailed characterization of microalgae-derived hydrochars is required to enable the most suitable application areas to be identified for these materials, and thereby make full use of their function as carbon sinks.

Authors/Creators:Benavente, Veronica and Lage, Sandra and Gentili, Francesco and Jansson, Stina
Title:Influence of lipid extraction and processing conditions on hydrothermal conversion of microalgae feedstocks - Effect on hydrochar composition, secondary char formation and phytotoxicity
Series Name/Journal:Chemical Engineering Journal
Year of publishing :2022
Volume:428
Article number:129559
Number of Pages:11
Publisher:ELSEVIER SCIENCE SA
ISSN:1385-8947
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 204 Chemical Engineering > Polymer Technologies
Keywords:CO2 capture systems, Hydrochar applications, Thermogravimetric analysis, Pyrolysis-gas chromatography/mass, spectrometry analysis, Secondary char, Toxicity
URN:NBN:urn:nbn:se:slu:epsilon-p-114351
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-114351
Additional ID:
Type of IDID
DOI10.1016/j.cej.2021.129559
Web of Science (WoS)000713692800004
ID Code:26126
Faculty:S - Faculty of Forest Sciences
Department:(S) > Department of Forest Biomaterials and Technology
Deposited By: SLUpub Connector
Deposited On:18 Nov 2021 12:25
Metadata Last Modified:18 Nov 2021 12:31

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