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

Kai Ling Yu; Xin Jiat Lee; Hwai Chyuan Ong; Wei-Hsin Chen; Jo-Shu Chang; Chih-Sheng Lin; Pau Loke Show; Tau Chuan Ling

doi:10.1016/j.envpol.2020.115986

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

Environ Pollut. 2021 Mar 1:272:115986. doi: 10.1016/j.envpol.2020.115986. Epub 2020 Nov 3.

Authors

Kai Ling Yu¹, Xin Jiat Lee², Hwai Chyuan Ong³, Wei-Hsin Chen⁴, Jo-Shu Chang⁵, Chih-Sheng Lin⁶, Pau Loke Show⁷, Tau Chuan Ling⁸

Affiliations

¹ Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia; Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan, 701, Taiwan.
² Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603, Kuala Lumpur, Malaysia; Centre of Research in Energy Sciences (ENERGY), Faculty of Engineering, University of Malaya, 50603, Kuala Lumpur, Malaysia.
³ School of Information, Systems and Modelling, Faculty of Engineering and Information Technology, University of Technology Sydney, NSW, 2007, Australia.
⁴ 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; Department of Chemical and Materials Engineering, College of Engineering, Tunghai University, Taichung, 407, Taiwan. Electronic address: weihsinchen@gmail.com.
⁵ Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung, 407, Taiwan; Department of Chemical and Materials Engineering, College of Engineering, Tunghai University, Taichung, 407, Taiwan; Department of Chemical Engineering, National Cheng Kung University, Tainan, 701, Taiwan.
⁶ Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan.
⁷ Bioseparation Research Group, Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.
⁸ Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.

PMID: 33187841
DOI: 10.1016/j.envpol.2020.115986

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 R² 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.

Keywords: Biochar; Dye adsorption; Environmental sustainability; Equilibrium and kinetic modeling; Microalgae; Wet torrefaction.

MeSH terms

Adsorption
Charcoal
Chlorella*
Coloring Agents
Congo Red
Hydrogen-Ion Concentration
Kinetics
Methylene Blue
Microalgae*
Water Pollutants, Chemical*

Substances

Coloring Agents
Water Pollutants, Chemical
biochar
Charcoal
Congo Red
Methylene Blue