Removal of Lead and Cadmium Ions from Aqueous Solutions by Using Natural and Modified Zeolite

Abstract

In this paper, immobilization of the natural (NZ) and Fe(III)-modified zeolite (FeZ) by Na-alginate was performed in order to improve their properties. Obtained results showed that alginate could be used for encapsulation of the natural and Fe(III)-modified zeolite in order to solve problem with water turbidity. Heavy metal cations (lead and cadmium) removal from water solutions by the natural and Fe(III)-modified zeolite with particle size: LT 0.043 mm (NZ and FeZ) and -0.8 + 0.6 mm (NZ1 and FeZ1) and NZ or FeZ after encapsulation with alginate (NZA and FeA) was preliminarily tested. Obtained results showed that adsorbed amounts of lead as well as cadmium increased after modification of the natural zeolite with Fe(III) ions but decreased with increasing of the particle size. Adsorbed amounts for lead were: 63, 57, 133 and 101 mg/g, while for cadmium: 11, 6, 19 and 14 for NZ, NZ1, FeZ and FeZ1, respectively. After immobilization of the NZ and FeZ with alginate, adsorbed amounts of lead were 101 and 134 mg/g and for cadmium 20 and 28 mg/g for NZA and FeA, respectively indicating that modification had no negative influence on adsorption. Besides positive effect on adsorption of heavy metal cations, easy modification with alginate could solve problems with water turbidity and separation, thus these materials may be suitable for column experiments. These results suggest that encapsulated samples could find practical application in purification of water contaminated with lead and cadmium.