Abstract
A nanocomposite of multi-walled carbon nanotube (MWCNT) functionalized (f) with chitosan (CS) and poly-2-hydroxyethyl methacrylate (pHEMA) was prepared and characterized. The adsorption of methyl orange (MO) on pHEMA–CS-f-MWCNT composites from an aqueous solution was investigated with respect to the contact time, dosage, pH, temperature and initial MO concentration. Pseudo first-order and pseudo second-order kinetics, as well as intra-particle diffusion were adopted to evaluate the experimental data. Our pseudo second-order model, with a correlation coefficient greater than 0.9986, was found to most accurately describe the adsorption kinetics. Additionally, we used Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms to describe equilibrium adsorption in the nanocomposite system. The best agreement was achieved with the Langmuir model with a correlation coefficient of 0.9991. The standard enthalpy change (ΔH0), the standard free energy change (ΔG0) and the standard entropy (ΔS0) were also calculated. The thermodynamic parameters indicate that the adsorption process is spontaneous and endothermic.
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•pHEMA–CS-f-MWCNT composite as an efficient adsorbent for dyes removal.•The adsorption kinetics followed pseudo second-order kinetic model.•Besides intra-particle diffusion as rate-controlling step the boundary layer diffusion also occurs.•Composite could be used in industrial application and drug delivery as efficient adsorbent.