An efficient approach for Pb(II) and Cd(II) removal using manganese dioxide formed in situ

An efficient method for Pb(II) and Cd(II) removal from aqueous solution was proposed, which is characterized by adsorbing heavy metals by manganese dioxide formed in situ (MOF) prepared by reacting MnSO4 with KMnO4. Results indicated that the adsorption capacity of MOF was found to be significantly more than the several adsorbents reported in the literatures. The maximum adsorption capacity estimated with the Langmuir model was 917 mg/g for Pb(II) and 176 mg/g for Cd(II). The uptake of Pb(II) and Cd(II) onto MOF approached to equilibrium quickly. The removal of Pb(II) and Cd(II) increased with increasing MOF dose and solution pH. The presence of Ca2+ and Mg2+ in the concentration more than 5 mmol/L had no significant influence on Pb(II) and Cd(II) removal. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis indicated that Pb(II) and Cd(II) uptake onto MOF might be related to inner-sphere complex formation. Finally, the elimination of Pb(II) and Cd(II) in simulated water demonstrated that this approach for heavy metal removal has a great potential application in environmental protection, especially in accidental pollution event.

► Manganese dioxide formed in situ (MOF) showed a good efficiency in Pb(II) and Cd(II) removal from aqueous solution.
► The removal of Pb(II) and Cd(II) increased with increasing solution pH.
► The presence of Ca2+ and Mg2+ in metal solution had no significant influence on the removal efficiency.
► Pb(II) and Cd(II) uptake onto MOF might be driven mainly by inner-sphere complex formation.