Abstract
In this work, a chitosan/ZSM-5 composite was prepared as an adsorbent to remove methyl orange (MO) from aqueous solutions. The material’s morphological features and surface functional groups were examined using scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy. Batch experiments were carried out to investigate the effect of adsorption time, adsorption isotherms, pH effect and thermodynamics. Adsorption kinetics indicated a fast adsorption rate and reached an equilibrium within 60 min; Adsorption capacity was maximum at pH=4.0; The experimental data fitted better to Langmuir than to Freundlich isotherm equation, while the sorption process was described by pseudo-second-order model. The thermodynamic analysis of the removal reaction carried out at three temperatures: 293K, 303K,313K and 323K gave following values (ΔH°=−44.75 kJ mol−1). The values for ΔG° were between –1.06 and –5.12 kJ·mol-1 while ΔS° was equal to –135.26 J·mol-1·K-1. Thermodynamic analysis shows spontaneous adsorption process at the given conditions that are feasible and exothermic in nature. These results indicate that chitosan/ZSM-5 composite materials hold promising potential for the removal of MO from aqueous environments.