CrO42−Ions Adsorption by Fe-Modified Pozzolane

A Fe-modified pozzolane was prepared and employed for the removal of CrO4 2− ions from aqueous solution under batch type experiments as a function of contact time, initial concentration of metal ion and temperature. The adsorption isotherms are described by means of Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) models. The pozzolane was characterized by XRD diffraction analysis. The results showed that the maximum adsorption capacity of Fe-modified pozzolane for CrO4 2− ions was (3.23 ± 0.01)×10−3 mmol g−1. The adsorption was found to be initial concentration and temperature dependent. The thermodynamic parameters values such as ΔH0, ΔG0, and ΔS0 were obtained to predict the nature of adsorption. These values show that the adsorption reaction is endothermic and spontaneous. The results show that the Fe-modified pozzolane, that is an easily available material, can be successfully used as adsorbent of anionic species, such as CrO4 2− ions in aqueous solutions, and can be an alternative for more costly adsorbents used for chromates removal in wastewater treatment processes.