Oxidative torrefaction performance of microalga Nannochloropsis Oceanica towards an upgraded microalgal solid biofuel

Congyu Zhang; Shih-Hsin Ho; Wei-Hsin Chen; Rupeng Wang; Pau-Loke Show; Hwai Chyuan Ong

doi:10.1016/j.jbiotec.2021.07.009

Oxidative torrefaction performance of microalga Nannochloropsis Oceanica towards an upgraded microalgal solid biofuel

J Biotechnol. 2021 Sep 10:338:81-90. doi: 10.1016/j.jbiotec.2021.07.009. Epub 2021 Jul 21.

Authors

Congyu Zhang¹, Shih-Hsin Ho², Wei-Hsin Chen³, Rupeng Wang¹, Pau-Loke Show⁴, Hwai Chyuan Ong⁵

Affiliations

¹ State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, China.
² State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, China. Electronic address: stephen6949@hit.edu.cn.
³ Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan, 701, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung, 407, Taiwan; Department of Mechanical Engineering, National Chin-Yi University of Technology, Taichung, 411, Taiwan. Electronic address: weihsinchen@gmail.com.
⁴ Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, 43500, Selangor Darul Ehsan, Malaysia.
⁵ School of Information, Systems and Modelling, Faculty of Engineering and Information Technology, University of Technology Sydney, NSW, 2007, Australia.

PMID: 34298023
DOI: 10.1016/j.jbiotec.2021.07.009

Abstract

Microalgae are a promising feedstock for carbon-neutral biofuel production due to their superior cellular composition. Alternatively, oxidative torrefaction has been recognized as a potential thermochemical technique for microalgal solid biofuel upgrading. Herein, by using microalga N. oceanica as a feedstock, several characterizations are adopted for evaluating the potential of oxidative torrefaction towards microalgal solid biofuel production. The oxidatively torrefied microalgae can be upgraded as lignite. After in-depth analysis, significant change in the surface microstructure of oxidatively torrefied microalgae is largely changed (via wrinkle and fragmentation) The hydrophobicity, thermal decomposition, thermal stability, and aromatization of oxidatively torrefied microalgae can be largely enhanced as the oxidative torrefaction severity increase. With the increasing torrefaction temperature, the hydrophobicity of oxidative torrefied microalgae gradually improved. The decomposition of C-2/3/5, and -OCH₃, the CO bonds of CH₃CO-, and the aromatization occurs via oxidative torrefaction according to the NMR analysis. For XPS analysis, torrefaction operation significantly decreases the carbide carbon and enhances the graphitization. As a result, the thermal stability of oxidatively torrefied microalgae is improved. Conclusively, the information obtained in this study can provide insights into the evaluation of oxidative torrefaction performance and fuel properties of microalgal solid biofuel, which may help accelerate the advancement of oxidative torrefaction industrialization.

Keywords: (13)C NMR analysis; Fuel properties; Microalgae and biochar; Oxidative torrefaction; Solid biofuel upgrading; XPS analysis.

MeSH terms

Biofuels
Biomass
Microalgae*
Oxidative Stress
Stramenopiles*
Temperature

Substances

Biofuels