Influence of Modification on the Textural Properties of the Natural Zeolite and Its Efficiency for the Heavy Metals Ions Removal from Contaminated Aqueous Solution

The influence of modification on the textural properties of the natural zeolite (NZ) and its efficiency for the heavy metals ions removal from contaminated aqueous solution was investigated. The mineralogical composition of the NZ showed that the dominant mineral is clinoptilolite. The surface of the NZ was modified combining the methods for pure goethite and iron-coated zeolite preparations. After modification, the cation exchange capacities and the specific surface area increased from 30.2 to 52.5 m2/g, i.e., from 141 to 165 meq/100g, respectively. Adsorption experiments were done for different heavy metals initial concentrations (copper(II) 0.8 - 12.6 Cu2+mmol/dm3 or lead(II) 1.9 – 29.0 Pb2+mmol/dm3), for 24h, at pH 4.2, in batch conditions. Results showed positive influence of modification on the heavy metals ions removal. The results were fitted with Langmuir and Freundlich adsorption models, and the best fits were obtained with Freundlich model (R2 > 0.92).