Adsorption studies and the removal of dissolved metals using pyrolusite as adsorbent

The adsorption of metals from aqueous solutions of Pb(2+), Zn(2+) and Mg(2+) on naturally occurring pyrolusite have been studied. The chemical stability of the pyrolusite has been determined in NaOH, H2SO4, HNO3, HCl, NaCl and NK4Cl solutions of various concentrations. Adsorption of the metal ions followed the order Pb(2+)>Zn(2+)>Cd(2+).The maximum adsorption of Pb(2+) (100%) occurred at pH 7. the relation between the amount of Pb(2+) adsorbed per unit weight of pyrolusite and the concentration of Pb(2+) at equilibrium follows the Freundlich adsorption isotherm.The efficiency of pyrolusite has been demonstrated by removing lead from synthetic waste water. 100% and 96% removal of lead have been achieved from synthetic waste water containing 5 mg l(-1) and 120 mg l(-1) of Pb(2+) respectively at pH 7. The results of these studies suggest that pyrolusite might provide an economical method for the removal of lead from industrial waste water.