Adsorption of an anionic azo dye by cross-linked chitosan/bentonite composite

In this study, cross-linked chitosan (CCS)/bentonite (BT) composite was prepared by the intercalation of chitosan in bentonite and the cross-linking reaction between chitosan and glutaraldehyde. CCS/BT composite was characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermal gravimetric analyses (TGA). Their adsorption characteristics were assessed by using an azo dye (Amido Black 10B) as a model adsorbate. The adsorption of Amido Black 10B onto the CCS/BT composite was found to be optimal at pH 2. The adsorption isotherm was well described by the Langmuir model and the maximum adsorption capacity was 323.6 mg/g at 293K and pH 2. Amido Black 10B adsorption kinetics followed a pseudo-second-order kinetic model. The calculated thermodynamic parameters showed that the adsorption of Amido Black 10B by CCS/BT composite was spontaneous and endothermic in nature.