Selective separation of Pb²⁺ from aqueous solutions by a novel imprinted adsorbent

Abstract

In this research, a selective ion-imprinted adsorbent was synthesized by polymerization of chitosan on the MCM-41 surface. The adsorbent was characterized by FTIR, X-ray diffractometer, and TG/DTG techniques. The surface area, pore size, and pore volume of the adsorbent were calculated by nitrogen adsorption–desorption isotherms. The adsorbent was used for selective separation of Pb²⁺ from aqueous solutions. The effect of different experimental conditions on the adsorption capacity was examined and the optimized conditions were determined: pH 5.5; contact time, 60 min; temperature, 298 K; Pb²⁺ concentration, 250-mg L⁻¹; and adsorbent dose, 0.1-g. The maximum adsorption capacity was 57.7 and 27-mg g⁻¹, respectively, for ion-imprinted and non–ion imprinted adsorbents. The removal efficiency for ion-imprinted sample was 92%. Breakthrough adsorption capacity was measured as 50.75 and close to the static adsorption capacity. The relative selectivity factor for Pb²⁺/Cd²⁺ and Pb²⁺/Ni²⁺ pairs were, respectively, 52.43 and 80.56. The relative standard deviation of the method was 1.12% for 10 replicate samples. The data collected from the adsorption isotherms was fitted to the Langmuir equation.

Keywords:

• Adsorbent
• Selective removal
• Pb²⁺
• Adsorption
• Chitosan
• MCM-41