Effect of environmental conditions on Pb(II) adsorption on β-MnO2

In this study, the adsorption of Pb(II) on β-MnO2 as a function of various environmental conditions such as contact time, pH, ionic strength, humic acid (HA)/fulvic acid (FA), and temperature was investigated using batch techniques. The results indicated that the adsorption of Pb(II) on β-MnO2 was obviously dependent on pH but independent of ionic strength. The presence of HA/FA enhanced the adsorption of Pb(II) on β-MnO2 at low pH, whereas reduced Pb(II) adsorption on β-MnO2 at high pH. The kinetic adsorption of Pb(II) on β-MnO2 can be well fitted by the pseudo-second-order rate equation. The thermodynamic parameters (ΔH°, ΔS°, and ΔG°) were also calculated from the temperature dependent adsorption isotherms, and the results suggested that the adsorption of Pb(II) on β-MnO2 was a spontaneous and endothermic process. The adsorption of Pb(II) on β-MnO2 was attributed to surface complexation rather than ion exchange.