cd(ii) sorption on iranian nano zeolites: kinetic and thermodynamic studies

An uptake of cd(ii) from aqueous solutions by ion exchange on iranian natural zeolitic (toska) has been studied. experiments were carried out using batch method as a function of the initial concentration of metal ions, contact time, and temperature. the adsorbent is characterized using xrf, ftir, tem, and xrd. the tem images showed that the zeolite particle sizes are reduced into the size range of less than 90 nm by means of ball milling. the characterization of sample indicates that the natural zeolite used in this study was classified into clinoptilolite. equilibrium modelling data were fitted to linear langmuir and freundlich models. thermodynamics parameters such as change in free energy (δg◦), enthalpy (δh◦) and entropy (δs◦) were also calculated. the negative values obtained for δg◦ indicated that the sorption of cd(ii) on natural zeolite was spontaneous at all studied concentrations. these results show that natural zeolites hold great potential to remove cd(ii) from industrial wastewater.