☆ 4.7 Article

Experimental and theoretical study of dyes adsorption process on chitosan-based cryogel

INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES (2021)

Journal

INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES

Volume 169, Issue -, Pages 75-84

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ELSEVIER

DOI: 10.1016/j.ijbiomac.2020.12.100

Keywords

Adsorption; Chitosan-cellulose cryogel; Dyes

Funding

Consejo Nacional de Ciencia y Tecnologia (CONACYT)
Tecnologico Nacional deMexico
Instituto Tecnologico de Toluca

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Abstract

This study compared the adsorption of different synthetic dyes on chitosan cryogel beads and analyzed the impact of solution pH on adsorption capacity. The biosorbent was characterized by SEM, BET method and FTIR. Results showed that the adsorption process is mainly regulated by physisorption and amino groups participate in the adsorption process, with Blue 1 > Red 2 > Yellow 5 being the order of adsorption capacity.

In this research, the adsorption of three synthetic dyes dissolved in an aqueous solution on chitosan cryogel beads (Q-C-EGDE) was compared. The effect of the pH of the solution on the adsorption capacity of each dyes was analyzed. Furthermore, the kinetics and adsorption isotherms were compared, at temperatures of 283.15 K, 303.15 K and 323.15 K, and the kinetic and adsorption equilibrium data were fitted to three mathematical models, respectively. The biosorbent was characterized by scanning electron microscopy (SEM), the nitrogen physisorption BET method and Fourier transform infrared spectroscopy (FTIR). The characterization results show that the cryogel is composed of low-surface, macroporous, porous grooved walls. The functional groups that took part in the adsorption were mainly amino groups (NH3+). When comparing the adsorption capacities, it was found that the dyes adsorb in the following order Blue 1 > Red 2 > Yellow 5 reaching capacities from 1600mg/L to 850mg/L. The results of the adsorption and mathematical modelling suggest that the process is regulated mainly by physisorption and is largely limited by mass transfer mechanisms within the cryogel, where the electrostatic charges present affect adsorption. The latter was corroborated by the Monte Carlo simulation. (C) 2020 Published by Elsevier B.V.

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Removal of anionic and cationic dyes using porous chitosan/carboxymethyl cellulose-PEG hydrogels: Optimization, adsorption kinetics, isotherm and thermodynamics studies

Honglin Zhu, Sunni Chen, Hanyi Duan, Jie He, Yangchao Luo

Summary: Chitosan (CS)/carboxymethyl cellulose (CMC) porous hydrogels crosslinked by epichlorohydrin and with polyethylene glycol (PEG) as a pore-forming agent were synthesized for removal of anionic (Congo red, CR) and cationic (methylene blue, MB) dyes from aqueous solutions. The addition of PEG significantly increased the adsorption of CR and MB, with optimal performance observed for hydrogels prepared with 2% CS and 2% CMC (CS2/CMC2). The adsorption processes followed pseudosecond-order and pseudo-first-order kinetics models for CR and MB, respectively. Freundlich and Langmuir models were suitable for describing the adsorption isotherms of CR and MB, respectively. The thermodynamic study confirmed that the adsorption of CR and MB by the hydrogels was spontaneous, with CR adsorption being endothermic and MB adsorption being exothermic.

INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES (2023)