The research on adsorption efficiency of toxic nickel ion using synthetic α-MnO2.

We discuss the adsorption efficiency of α-MnO2 for Ni2+ in water under various conditions. The adsorption kinetics of α-MnO2 fitted the pseudo-second-order model better than the pseudo-first-order model. The adsorption efficiency increased rapidly at 0-30 minutes, although after 90 minutes, the rate of adsorption efficiency was almost 0. The pH affected the adsorption efficiency significantly. From pH 2 to 4, the adsorption efficiency increased sharply as the pH increased. At pH≥4, the adsorption efficiency was high, and at pH 8, it reached a maximum of 63%. Increasing the temperature also increased the adsorption efficiency, suggesting that the adsorption reaction is endothermic. For reaction systems containing more than 10 mmol α-MnO2, the adsorption efficiency for Ni2+ was nearly 100%. [ABSTRACT FROM AUTHOR]