ABSTRACT
Chitosan (CTS) biopolymer was modified by commercial activated charcoal (AC) as a source of carbon to fabricate a hybrid chitosan-activated charcoal (CTS-AC) composite biosorbent to remove thionine (TH), acationic dye, from aqueous solution. The key factors affecting adsorption process, i.e. CTS-AC mass (0.04–0.4 g), initial pH (4–11), initial dye concentrations (10–100 mg/L) and contact time (0–570 min) on TH removal efficiency were tested and optimised. The optimum conditions for TH removal were obtained at CTS-AC dosage = 0.16 g, solution pH = 10, and contact time = 60 min. The experimental data indicated that the adsorption process is in line with the pseudo-second-order (PSO) kinetic and the Freundlich isotherm models. The maximum adsorption capacity of 56.7 mg/g was recorded for CTS-AC composite at 303 K. The calculated thermodynamic functions show that the TH adsorption process was endothermic and spontaneous. Besides, the adsorption mechanism of TH onto the CTS-AC may include electrostatic interactions, hydrogen bonding, and π-π interactions. This study suggests that CTS-AC composite has a great potential as an eco-friendly and effective biosorbent for the removal of cationic dyes from aqueous environment.
Acknowledgments
The authors would like to thank the Ministry of Education, Malaysia, for supporting this research project under Fundamental Research Grant Scheme (600-IRMI/FRGS 5/3 (433/2019); (FRGS/1/2019/TK02/UITM/02/15).
Disclosure statement
No potential conflict of interest was reported by the author(s).