Adsorptive removal of cationic methylene blue and anionic Congo red dyes using wet-torrefied microalgal biochar: Equilibrium, kinetic and mechanism modeling

Yu, Kai Ling and Lee, Xin Jiat and Ong, Hwai Chyuan and Chen, Wei-Hsin and Chang, Jo-Shu and Lin, Chih-Sheng and Show, Pau Loke and Ling, Tau Chuan (2021) Adsorptive removal of cationic methylene blue and anionic Congo red dyes using wet-torrefied microalgal biochar: Equilibrium, kinetic and mechanism modeling. Environmental Pollution, 272. ISSN 0269-7491, DOI https://doi.org/10.1016/j.envpol.2020.115986.

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Abstract

This study aims to investigate the adsorption behavior of cationic and anionic dyes of methylene blue (MB) and Congo red (CR) onto wet-torrefied Chlorella sp. microalgal biochar respectively, as an approach to generate a waste-derived and low-cost adsorbent. The wet-torrefied microalgal biochar possessed microporous properties with pore diameter less than 2 nm. The optimum adsorbent dosage of wet-torrefied microalgal biochar for MB and CR dyes removal were determined at 1 g/L and 2 g/L, respectively, with their natural pHs as the optimum adsorption pHs. The determined equilibrium contact times for MB and CR were 120 h and 4 h, respectively. Based on the equilibrium modeling, the results revealed that Langmuir isotherm showed the best model fit, based on the highest R-2 coefficient, for both the adsorption processes of MB and CR using the wet-torrefied microalgal biochar, indicating that the monolayer adsorption was the dominant process. From the modeling, the maximum adsorption capacities for MB and CR were 113.00 mg/g and 164.35 mg/g, respectively. The kinetic modeling indicated the adsorption rate and mechanism of the dyes adsorption processes, which could be crucial for future modeling and application of wet-torrefied microalgal biochar. From the results, it suggests that the valorization of microalgae by utilizing wet-torrefied microalgal biochar as the effective adsorbent for the removal of toxic dyes with an approach of microalgal biorefinery and value-added application to the environment is feasible. (C) 2020 Elsevier Ltd. All rights reserved.

Item Type: Article
Funders: Ministry of Science and Technology, Taiwan [MOST 106-2923-E-006-002-MY3], Ministry of Science and Technology, Taiwan [MOST 109-2221-E-006-040-MY3], Ministry of Science and Technology, Taiwan [MOST 109-3116-F-006-016-CC1]
Uncontrolled Keywords: Microalgae; Biochar; Dye adsorption; Wet torrefaction; Environmental sustainability; Equilibrium and kinetic modeling
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Q Science > QH Natural history
Divisions: Faculty of Engineering > Department of Mechanical Engineering
Faculty of Science > Institute of Biological Sciences
Depositing User: Ms Zaharah Ramly
Date Deposited: 08 Jul 2022 03:48
Last Modified: 08 Jul 2022 03:48
URI: http://eprints.um.edu.my/id/eprint/33949

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