manganese dioxide;  copper ions;  lead ions;  Adsorption

The adsorption and competitive adsorption properties of δ-type manganese dioxide on Cu2+ and Pb+ were studied, and the effects of pH, temperature, salt concentration, adsorption time and other factors on adsorption were investigated. The results showed that the adsorption capacity increased with the increase of pH value, temperature and salt concentration. The adsorption of Cu2+ and Pb2+ by manganese dioxide in a single system conforms to the Langmiur adsorption isotherm, and the △G° of the adsorption process is negative, and the △H° is greater than zero, indicating that the process is a spontaneous endothermic process. The adsorption process of manganese dioxide to Cu2+ and Pb2+ can be well described by the quasi-secondary reaction kinetic model. The presence of coexisting ions affects the adsorption efficiency of metal ions, and Pb2+ has a great influence on the adsorption of Cu2+. The adsorption order of manganese dioxide on Cu2+ and Pb2+ was Pb2+>Cu2+.