Effect of Temperature and Time on the Conversion of Defatted Microalgae Biomass into Bio-Oil through Hydrothermal Liquefaction
Muhammad Khairul Hilmi MOHD ZAKI, Shafirah SAMSURI, Usman BELLO, Nor Adilla RASHIDI
Abstract. The growing demand for renewable energy has increased interest in bio-oil production from microalgae biomass using hydrothermal liquefaction (HTL). However, limited research has focused on the utilization of defatted microalgae biomass (DMB), the residual biomass remaining after lipid extraction. Therefore, this study investigated the effect of varying operating conditions on the conversion of DMB derived from Chlorella sp. into bio-oil via HTL. Experiments were conducted at reaction temperatures ranging from 210–270 °C and reaction times between 30 and 90 min. The resulting bio-oils contained a range of compounds, including aliphatic acids, amines, amides, pyrazine, pyridine, and phenolic compounds. The highest yields of desirable aliphatic acids were obtained at 250–260 °C and 45 min, indicating these as optimal conditions for maximizing fuel-relevant components. While higher temperatures and longer reaction times promoted the formation of nitrogenous and aromatic compounds, they also introduced instability in the product composition. Hence, this work highlights the importance of optimizing HTL parameters to enhance bio-oil recovery from DMB.
Keywords
Bio-Oil, Biorefining, Microalgae, Thermochemical Process, Defatted Microalgae Biomass
Published online 1/15/2026, 7 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Muhammad Khairul Hilmi MOHD ZAKI, Shafirah SAMSURI, Usman BELLO, Nor Adilla RASHIDI, Effect of Temperature and Time on the Conversion of Defatted Microalgae Biomass into Bio-Oil through Hydrothermal Liquefaction, Materials Research Proceedings, Vol. 59, pp 10-16, 2026
DOI: https://doi.org/10.21741/9781644903957-2
The article was published as article 2 of the book Separation Technology
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
References
[1] C. Xia, A. Pathy, B. Paramasivan, P. Ganeshan, K. Dhamodharan, A. Juneja, D. Kumar, K. Brindhadevi, S. Kim, and K. Rajendran, Comparative study of pyrolysis and hydrothermal liquefaction of microalgal species: Analysis of product yields with reaction temperature. Fuel, 311, (2021) 121932. https://doi.org/10.1016/j.fuel.2021.121932
[2] Y. Guo, T. Yeh, W. Song, D. Xu, and S. Wang, A review of bio-oil production from hydrothermal liquefaction of algae. Renewable and Sustainable Energy Reviews, 48, (2015) 776–790. https://doi.org/10.1016/j.rser.2015.04.049
[3] K. Brindhadevi, S. Anto, E. R. Rene, M. Sekar, T. Mathimani, N. T. L. Chi, and A. Pugazhendhi, Effect of reaction temperature on the conversion of algal biomass to bio-oil and biochar through pyrolysis and hydrothermal liquefaction. Fuel, 285, (2021) 119106. https://doi.org/10.1016/j.fuel.2020.119106
[4] L. Brennan, and P. Owende, Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products. Renewable and Sustainable Energy Reviews, 14(2), (2009) 557–577. https://doi.org/10.1016/j.rser.2009.10.009
[5] D. R. Vardon, B. K. Sharma, G. V. Blazina, K. Rajagopalan, and T. J. Strathmann, Thermochemical conversion of raw and defatted algal biomass via hydrothermal liquefaction and slow pyrolysis. Bioresource Technology, 109, (2012) 178–187. https://doi.org/10.1016/j.biortech.2012.01.008
[6] J. Yang, H. Shin, Y. Ryu, and C. Lee, Hydrothermal liquefaction of Chlorella vulgaris: Effect of reaction temperature and time on energy recovery and nutrient recovery. Journal of Industrial and Engineering Chemistry, 68, (2018) 267–273. https://doi.org/10.1016/j.jiec.2018.07.053
[7] S. I. Mustapha, U. A. Mohammed, F. Bux, and Y. M. Isa, Catalytic hydrothermal liquefaction of nutrient-stressed microalgae for production of high-quality bio-oil over Zr-doped HZSM-5 catalyst. Biomass and Bioenergy, 163, (2022) 106497. https://doi.org/10.1016/j.biombioe.2022.106497
[8] J. Zhou, M. Wang, J. A. Saraiva, A. P. Martins, C. A. Pinto, M. A. Prieto, J. Simal-Gandara, H. Cao, J. Xiao, and F. J. Barba, Extraction of lipids from microalgae using classical and innovative approaches. Food Chemistry, 384, (2022) 132236. https://doi.org/10.1016/j.foodchem.2022.132236
[9] C. Yuan, S. Zhao, J. Ni, Y. He, B. Cao, Y. Hu, S. Wang, L. Qian, and A. Abomohra, Integrated route of fast hydrothermal liquefaction of microalgae and sludge by recycling the waste aqueous phase for microalgal growth. Fuel, 334, (2022) 126488. https://doi.org/10.1016/j.fuel.2022.126488
[10] J. Arun, P. Varshini, P. K. Prithvinath, V. Priyadarshini, and K. P. Gopinath, Enrichment of bio-oil after hydrothermal liquefaction (HTL) of microalgae C. vulgaris grown in wastewater: Bio-char and post-HTL wastewater utilization studies. Bioresource Technology, 261, (2018) 182–187. https://doi.org/10.1016/j.biortech.2018.04.029
[11] Y. Huang, Y. Chen, J. Xie, H. Liu, X. Yin, and C. Wu, Bio-oil production from hydrothermal liquefaction of high-protein high-ash microalgae including wild Cyanobacteria sp. and cultivated Bacillariophyta sp. Fuel, 183, (2016) 9–19. https://doi.org/10.1016/j.fuel.2016.06.013
[12] I. Nava-Bravo, S. Velasquez-Orta, I. Monje-Ramírez, L. Güereca, A. Harvey, A. Cuevas-García, L. Yáñez-Noguez, and M. Orta-Ledesma, Catalytic hydrothermal liquefaction of microalgae cultivated in wastewater: Influence of ozone-air flotation on products, energy balance, and carbon footprint. Energy Conversion and Management, 249, (2021) 114806. https://doi.org/10.1016/j.enconman.2021.114806
[13] S. Chaudry, P. A. Bahri, N. R., and Moheimani, Pathways of processing of wet microalgae for liquid fuel production: A critical review. Renewable and Sustainable Energy Reviews, 52, (2015) 1240–1250. https://doi.org/10.1016/j.rser.2015.08.005
[14] S. Kandasamy, B. Zhang, Z. He, H. Chen, H. Feng, Q. Wang, B. Wang, V. Ashokkumar, S. Siva, N. Bhuvanendran, and M. Krishnamoorthi, Effect of low-temperature catalytic hydrothermal liquefaction of Spirulina platensis. Energy, 190, (2019)116236. https://doi.org/10.1016/j.energy.2019.116236
