Study of attapulgite on the isotherm adsorption of Zn²⁺, Cu²⁺ and Cd²⁺

Attapulgite is a natural clay mineral with large specific surface and strong adsorption ability.The given paper is aimed to make an exploration of adsorption characteristics of attapulgite on the heavy metal ion Zn²⁺, Cu²⁺and Cd²⁺, the adsorption capacity, removal rate, adsorption selectivity and enrichment coefficients of heavy metal ions Zn²⁺, Cu²⁺and Cd²⁺ by using attapulgite were studied through the adsorption isotherm experiment.The results show that the adsorption capacity of attapulgite to Cu²⁺, Zn²⁺and Cd²⁺ increased with the increase of the initial concentration of the solution, and the characteristics of adsorption selection are Cu²⁺ > Zn²⁺ > Cd²⁺.The removal rate of Cu²⁺ by attapulgite was 97.40%, Zn²⁺ and Cd²⁺ by was 96.76% and 96.22%, respectively, when the initial concentration of attapulgite was 20 mg/L.When the concentration increased to 300 mg/L, the removal rate of Cu²⁺decreased to 73.19%, the removal rate of Zn²⁺ and Cd²⁺ decreased to 48.18% and 38.84%.The enrichment coefficient is consistent with the result of adsorption characteristic, and the adsorption accords with Langmuir and Freundlich equations.The results show that attapulgite can be used for remediation of heavy metal pollution in water and soil.