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A novel hierarchically structured γ-MnO has been synthesized using a simple chemical reaction between MnSO and KMnO in aqueous solution without using any templates, surfactants, catalysts, calcination and hydrothermal processes. As an example of potential applications, hierarchically structured γ-MnO was used as adsorbent in radionuclide Ni(II) treatment, and showed an excellent ability. The effects of pH, ionic strength, temperature, humic acid (HA) and fulvic acid (FA) on the sorption of radionuclide Ni(II) to hierarchically structured γ-MnO have been investigated by using batch techniques. The results indicated that the sorption of Ni(II) on γ-MnO is obviously dependent on pH values but independent of ionic strength. The presence of HA/FA strongly enhances the sorption of Ni(II) on γ-MnO at low pH values, whereas reduces Ni(II) sorption at high pH values. The sorption of Ni(II) on γ-MnO is attributed to inner-sphere surface complexation rather than outer-sphere surface complexation or ion exchange. The thermodynamic parameters (Δ H, Δ S, Δ G) are also calculated from the temperature dependent sorption isotherms, and the results suggest that the sorption of Ni(II) on γ-MnO is a spontaneous and endothermic process. [ABSTRACT FROM AUTHOR]

A novel γ-MnO hollow structure has been synthesized using a simple chemical reaction between MnSO and KMnO in aqueous solution without using any templates, surfactants, catalysts, calcination and hydrothermal processes. As an example of potential applications, γ-MnO hollow structure was used as adsorbent in radionuclide Co(II) treatment, and showed an excellent ability. The effect of pH, contact time, ionic strength, humic acid (HA)/fulvic acid (FA), and temperature was investigated using batch techniques. The results indicated that the sorption of Co(II) on γ-MnO was obviously dependent on pH values but independent of ionic strength. The presence of HA/FA enhanced the sorption of Co(II) on γ-MnO at low pH, whereas reduced Co(II) sorption on γ-MnO at high pH. The kinetic sorption of Co(II) on γ-MnO can be well fitted by the pseudo-second-order rate equation. The thermodynamic parameters (Δ H, Δ S, Δ G) were also calculated from the temperature dependent sorption isotherms, and the results suggested that the sorption of Co(II) on γ-MnO was a spontaneous and endothermic process. The sorption of Co(II) on γ-MnO was attributed to surface complexation rather than ion exchange. [ABSTRACT FROM AUTHOR]