Removal of Pb²⁺ and Cd²⁺ by adsorption on clay-solidified grouting curtain for waste landfills

Abstract

Pb²⁺ and Cd²⁺ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2:4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb²⁺ and Cd²⁺ are 16.19 mg/g and 1.21 mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb²⁺ is stronger than that for Cd²⁺. The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.

Keywords

adsorption / clay-solidified grouting curtain / Pb²⁺ / Cd²⁺ / Freundlich model / leachate treatment

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