Co-hydrothermal carbonization of rape straw and microalgae: pH-enhanced carbonization process to obtain clean hydrochar

Xiangmin Liu, Yuwei Fan, Yunbo Zhai, Xiaoping Liu, Zhexian Wang, Ya Zhu, Haoran Shi, Caiting Li and Yun Zhu

Energy, 2022, vol. 257, issue C

Abstract: In this study, co-hydrothermal carbonization of rape straw and microalgae was conducted for clean hydrochar. The effect of different feedwater pH values (pH = 1, 3, 5, 7, 9, 12) on co-HTC and the mechanism of enhanced N, S, and O removal were revealed. The acidic and alkaline environment of the feedwater exacerbates the carbonization process. The higher heating value (HHV) of the hydrochar formed at pH = 1 reach 22.30 MJ/kg but the value of feedstock is only 13.87 MJ/kg. Deamination and deoxidation were the main method for protein degradation to remove N, S, and O from hydrochar. O/C, N/C, and S/C ratios of hydrochar reduced and the removal fraction of N, S, and O was 84.61%, 79.84%, and 81.80% of the hydrochar formed at pH = 1, respectively. Results showed that the acidic enhanced the content of aromatic clusters in aqueous increases, and the deoxidized hydrochar with high HHV was obtained. GC-MS analysis indicates that the aromatic clusters were formed in acidic and neutral conditions, while long-chain alkanes in alkaline. N-containing organic substances existing in the aqueous product were removed from the hydrochar by solid-liquid separation.

Keywords: Deoxidation; Hydrochar; Microalgae; pH-enhanced carbonization; Rape straw (search for similar items in EconPapers)
Date: 2022
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Citations: View citations in EconPapers (4)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:257:y:2022:i:c:s036054422201636x

DOI: 10.1016/j.energy.2022.124733

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