Preparation of γ-MnO₂ and Its Properties of Adsorption and Removement of Chromium

γ-MnO2 was prepared by co-precipitation and characterized by SEM, XRD and FTIR. The effects of MnO2 dosage, pH, temperature and shock time on the adsorption capacity of chromium in waste water were investigated. The prepared γ-MnO2 was rich in hydroxyl groups, which was proved to be effective in removing chromium from water. The adsorption could reach equilibrium within 90 minutes. The adsorption kinetics followed the pseudo-secondorder rate equation, and the adsorption equilibrium followed the Freundlich model.