Adsorption characteristics of reactive black 5 onto chitosan-intercalated montmorillonite

The adsorption behavior of reactive black 5 (RB5) on a biocomposite (chitosan-intercalated montmorillonite: CTS/MMT) was studied in batch operation. The precursor and the CTS/MMT were characterized by X-ray diffraction and scanning electron microscopy. The effects of contact time, initial solution pH, initial dye concentration, and temperature on adsorption capacity were investigated. The optimum conditions were found as the following: contact time 1 h, initial solution pH 2.0, initial dye concentration 200 mg L−1, and temperature 60°C. The kinetic data followed the pseudo-second-order model. The Langmuir and Freundlich models were applied to describe the isotherm data, of which Langmuir and Freundlich models proved good correlation. Various thermodynamic parameters, such as ΔG°, ΔH°, and ΔS°, were also evaluated, which indicated a spontaneous and endothermic process. Finally, desorption experiments revealed that the adsorbent can be reutilized by regeneration with dilute NaOH solution.