Use of Modified Zeolites for the Remediation of Waters and Cultivated Soils from Cu(II)

Abstract

The ability of iron oxides (goethite) and natural zeolite (clinoptilolite) to adsorb copper from its aqueous solutions was extensively studied in the past. In this paper, the production of modified zeolites (systems I and II) from raw materials of zeolite and goethite was investigated compared to the initial materials. These two systems presented higher adsorption than goethite or clinoptilolite. Comparing the two systems, system II presented higher adsorption than system I. Isotherm studies showed that the adsorption data from all materials were best described by Freundlich isotherm. According to thermodynamic study, the values of Delta G degrees became more negative with the increase of temperature, indicating that the adsorption process was more favorable to higher temperature. The positive values of Delta H degrees indicated endothermic nature of adsorption. The use of all adsorptive materials as soil improvements was also investigated. Goethite, zeolite, and systems I and II were mixed separately with three different soils (clay loam, sandy loam, and loamy sand). Lettuces were cultivated, and the combination of system II with the loamy sand soil led to the best morphological characteristics of lettuces with the minimum adsorption of copper. Consequently, modified zeolites could be considered as two satisfactory detergents of highly copper concentration in soil and water.