Retention behavior studies for the removal of some hazardous metal ions from waste solutions using polyaniline silicotitanate as composite cation exchanger

Abstract

Polyaniline silicotitanate as “organic–inorganic” composite material has been synthesized and utilized as adsorbent for the removal of Co²⁺, Cu²⁺, Cd²⁺, Cs⁺, and Pb²⁺ ions from aqueous waste solutions. The experimental data were analyzed by Langmuir, Freundlich, and D–R isotherm models of adsorption. The results suggest that the adsorption of the studied metal ions (Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ ions) on polyaniline silicotitanate is favorable for the Freundlich isotherm more than Langmuir and D–R isotherms. The numerical values of (1/n) for the studied metal ions were found to be smaller than one, which implies heterogeneous surface structure with minimum interaction between the adsorbed atoms. The adsorption energies (E) at 25°C were less than 8 kJmol⁻¹ suggesting that the sorption process was dominated by physisorption (physical adsorption). Based on the results obtained, practical separation experiments for the above-mentioned cations on polyaniline silicotitanate column from aqueous waste solutions were carried out.

Keywords:

• Adsorption
• Polyaniline silicotitanate
• Heavy toxic metals
• Sorption isotherm
• Separation