(2021) Applied Energy_Independent parallel pyrolysis kinetics of extracted proteins and lipids as well as model carbohydrates in microalgae

Aniza R., Chen W.-H., Lin Y.-Y., Tran K.-Q., Chang J.-S., Lam S.S., Park Y.-K., Kwon E.E., Tabatabaei M.

(Elsevier Ltd) Applied Energy ISSN: 3062619 Vol.300 Issue. Article No.117372 DOI: 10.1016/j.apenergy.2021.117372

Microalgae offer unique potentials for developing advanced biorefineries, including third-generation biofuel production, wastewater treatment, and animal and aquaculture feed production. The thermodegradation of protein, lipid, and carbohydrates plays a vital role in the thermochemical conversion of microalgae for biofuel production. This work aims to investigate the kinetics and the interaction of extracted protein and lipid as well as model carbohydrates from microalgae to assist the development of microalgae conversion techniques, which have not been studied so far. Thermogravimetric analysis is integrated with an independent parallel reaction (IPR) and particle swarm optimization (PSO) method to explore the pyrolysis kinetics of three constituents (protein, lipid, and carbohydrates). The calorific values of the three constituents show that protein (5.33 MJ·kg⁻¹) is not a suitable biofuel feedstock. In contrast, lipid (34.22 MJ·kg⁻¹) and carbohydrates (15.37–15.84 MJ·kg⁻¹) are considered as potential feedstocks for liquid and solid biofuel production, respectively. The pyrolysis processes suggest that the thermodegradation extent follows the order of carbohydrates > protein > lipid. The application of the IPR-PSO method on the pyrolysis kinetics of microalgae in three pseudo-components obtains a high fit quality (>96%) for all cases, indicating that the method is suitable to predict the kinetics parameters of the three constituents of microalgae. The effect analysis reveals that the synergistic effect accounts for about 50% of the total mass of the thermodegradation process of model carbohydrates, occuring at 200–320 °C. Meanwhile, the theoretical and experimental thermogravimetric analysis curve of combination of the three constituents suggests that there are four regions detected, including strong synergistic effect, weak antagonistic effect, weak synergistic effect, and strong antagonistic effect, respectively. © 2021 Elsevier Ltd

The authors acknowledge the financial support of the Ministry of Science and Technology, Taiwan , ROC, under contracts MOST 109-2221-E-006-040-MY3 , MOST 109-3116-F-006-016-CC1 , and MOST 109-2222-E-992-002 for this research. The authors would also like to thank Universiti Malaysia Terengganu under International Partnership Research Grant (UMT/CRIM/2-2/2/23 (23), Vot 55302), and Ministry of Higher Education, Malaysia, under the Higher Institution Centre of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries (AKUATROP) program (Vot. No. 63933 & Vot. No. 56051, UMT/CRIM/2-2/5 Jilid 2 (10) and Vot. No. 56052, UMT/CRIM/2-2/5 Jilid 2 (11)) for supporting Prof Lam and Assoc. Prof. Tabatabaei to perform this joint project. This research was also supported in part by Higher Education Sprout Project, Ministry of Education to the Headquarters of University Advancement at National Chen Kung University (NCKU).