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Lookup NU author(s): Professor Lidija SillerORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
In this study, amine-modified multi-walled carbon nanotubes (MWCNTs-APTES) were incorporated into a chitosan hydrogel to develop a robust adsorbent for Cd2+ and Zn2+ ions removal from aqueous solution. The amino-rich CNTs/chitosan hydrogels were designed to enhance surface reactivity, stability, and adsorption capacity. The structural and textural analyses confirmed the homogenous CNT dispersion within the chitosan matrix, accompanied by increasing porosity and improved hydrogel stability. Thermodynamic study revealed that adsorption process is spontaneous and exothermic characteristics of the adsorption process, which refers to the strong affinity between the ions and the hydrogels. Kinetic modelling shows that the adsorption data were best described by the pseudo-second-order (PSO) and Elovich models suggesting a chemisorption-dominated mechanism involving the coordination with amine and hydroxyl groups. The optimised hydrogel exhibited a high maximum adsorption capacity of 216 mg/g for Cd2+ and 187 mg/g for Zn2+ in a single-component system. Also, Zn2+ showed faster adsorption kinetics and higher binding affinity. These experimental findings are consistent with DFT calculations, which predicted shorter equilibrium interaction distances for Zn—N (~2.7 Å) compared to Cd—N (~2.8 Å), supporting the preferential binding of Zn2+ ions. Isotherm analysis indicated adsorption occurring on a heterogeneous surface involving both monolayer and multilayer uptake. Competitive adsorption exhibited preferential Zn2+ uptake due to stronger electrostatic and coordination interactions between Zn2+ and the active sites. Overall, the current study demonstrates that the APTES-CNT/chitosan composite hydrogels exhibited high selectivity, excellent structural stability and strong reusability (˃95% after 5 cycles) highlighting their potential for efficient and simultaneous removal of heavy metal ions from contaminated water.
Author(s): Hassan KT, Madkhali N, Al-Rawi AS, Alzahrani SS, Al-Jobory AA, Siller L, Hunt MRC
Publication type: Article
Publication status: Published
Journal: International Journal of Biological Macromolecules
Year: 2026
Volume: 356
Print publication date: 01/04/2026
Online publication date: 18/03/2026
Acceptance date: 16/03/2026
Date deposited: 24/03/2026
ISSN (print): 0141-8130
ISSN (electronic): 1879-0003
Publisher: Elsevier
URL: https://doi.org/10.1016/j.ijbiomac.2026.151500
DOI: 10.1016/j.ijbiomac.2026.151500
ePrints DOI: 10.57711/ayqa-7411
Data Access Statement: Data will be made available on request.
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