Adsorption Properties of Nano MnO2 for Cu2+ and Cd2+ in Water

Nano manganese dioxide (nMnO₂) was synthesized by the two-phase method of aqueous phase and organic phase, its adsorption property of Cu²⁺and Cd²⁺ in water, and analyzed the Cu²⁺ and Cd²⁺ adsorption characteristics by Langmuir and Freundlich equation. The results showed that the nMnO2 specific surface area is 141.66 m²/g; the adsorption of Cu2+ and Cd²⁺ respectively reached equilibrium in 500 and 225 min, the adsorption process followed pseudo-second-order kinetics model and Elovich model, the adsorption rate of Cd²⁺ was higher than that of Cu²⁺; the adsorption characteristics of nMnO₂ on Cu²⁺ and Cd²⁺ fit the Langmuir equation, the maximum adsorption amount of Cu²⁺ and Cd²⁺ was 104.5 mg/g and 89.1 mg/g respectively; in the adsorption process of Cu²⁺ and Cd²⁺, ΔG＜0, ΔH＜0 and ΔS＞0, temperature increase favored the adsorption reaction, so the temperature improving would increase the adsorption of nMnO₂ on heavy metal ions; the adsorption ability of nMnO₂ on Cu²⁺ and Cd²⁺ was greatly influenced by pH in the range of 3-6; the improvement of the system pH would increase the adsorption capacity of nMnO₂ on Cu²⁺ and Cd²⁺. The synthesis process of nMnO₂ is simple and it has good adsorption performance on heavy metal Cu²⁺ and Cd²⁺, and it can be used as a good adsorption material.