Sorption of Zinc by Clinoptilolite-Fe(NO3)3 Systems

Abstract

Many factors may affect the zinc (Zn) adsorption and desorption on natural clinoptilolite and iron (Fe) oxides. Among them are ionic strength and pH. In this article, the Zn retention behavior on two clinoptilolite-Fe(NO3)3 systems as a function of ionic strength and pH were evaluated. Two clinoptilolite-Fe(NO3)3 systems were obtained from the mixture of clinoptilolite and iron nitrate in different proportions and conditions and were characterized using Attenuated Total Reflectance (ATR) and X-ray Diffraction (XRD). The clinoptilolite-Fe(NO3)3 systems have specific surface area equal to 151 and 140m2/g respectively and were fully iron exchanged (Fe/Al = 3.17 and 1.23 respectively). The adsorption of Zn and desorption of Zn, magnesium (Mg), and Fe were examined after mixing 1.00g from each of the two systems with five different Zn concentrations, three different pH values, and two different electrolyte concentrations. The Zn adsorption increases as electrolyte concentration decreases and pH increases. The percentage of Zn adsorption decreases as initial Zn concentration increases. Zinc, Mg, and Fe desorption increases as pH decreases and electrolyte concentration increases. The desorption of Mg from the second system is higher than that of the first system, but the desorption of Fe from the first system is higher than that of the second. The statistical analysis reveals a strong relationship between A and B systems concerning the desorption of Mg and Fe. Consequently, the clinoptilolite-Fe(NO3)3 systems could be considered as two satisfactory detergents of high soil Zn concentration.