Preparation of a Novel Magnetic Nanocomposite Hydrogel Based on Carboxymethyl Chitosan for the Adsorption of Crystal Violet as Cationic Dye

Abstract

The novel magnetic carboxymethyl chitosan/poly (acrylic amide) hydrogel (m-CMC-PAMH) was prepared using magnetic montmorillonite (m-MMT) and characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) techniques. Results showed that m-CMC-PAMH has been prepared successfully properties without damaging the crystal structure of Fe₃O₄. Adsorption capacity of Crystal Violet (CV) on the m-CMC-PAMH was 72.4 mg/g. The CV adsorption well described by the pseudo-second-order kinetics and Langmuir isotherm equations. The positive value of the enthalpy change ΔH° (23.5 kJ/mol) showed that the adsorption was endothermic and physical in nature. The value of Gibbs free energy change ΔG° was found to be -9.7 kJ/mol at 295 K for m-CMC-PAMH, which shows spontaneity of the CV adsorption. So, m-CMC-PAMH can be used as a low-cost alternative to other adsorbents for the removal of dyes from aqueous solutions.