Chitosan/montmorillonite composites for fast removal of methylene blue from aqueous solutions

New modified chitosan nano-montmorillonite composites were synthesized for efficient removal of Methylene Blue (MB) pollutant. The composites' structure and morphology were confirmed by H-1 NMR, FTIR, TGA, SEM, XRD, XPS, water regain, stability in acidic medium, and pH(pzc). Factors influencing dye adsorption; nano-montmorillonite ratio, initial dye concentration, composite dose, pH, temperature, contact time, and desorption were investigated. The new modified composites showed very fast adsorption performance and equilibrium occurred after 8 min with adsorption capacity 248.9, 276.03, 204.39, and 180 mg/g for R0, RI, RII, and RIII respectively. MB adsorption is a multilayer process preceded via electrostatic attraction in alkaline medium and/or cation exchange in acidic medium. Adsorption data is well-fitting to Freundlich isotherm and pseudo-second-order kinetics. The composites prepared showed high desorption ability amounting to 77.13, 84.28, 88.47, and 97% for R0, RI, RII, and RIII respectively by using 0.5 M HCl eluent.