Features of Sorption and Proton-Desorption of Heavy Metals (M2+) from Aqueous Solutions by Biopolymers

Abstract

Several features of the sorption and proton-desorption mechanisms of heavy metals (M²⁺) from aqueous solutions of acids and native salts (cellulose, chitosan, keratin) by modified biopolymers with acidic (Cell–COOH), salt (^–OOC–W–NH₃⁺), amine (CS–NH₂), and other sorption sites were examined. Sorption isotherms of metal cations from their aqueous salt solutions (pH < 7) by biopolymers were described well in terms of the Langmuir model. The distributions of Cu²⁺, Fe²⁺, Ni²⁺, Zn²⁺, and Cd²⁺ in the heterophasic system H₂O–H₂SO₄–MSO₄–biopolymer were linear functions of the solution acidity in logarithmic coordinates log \( \left({K}_{D{\mathrm{M}}^{2+}}\right) \) vs. pH with tan α ≈ 0.5.