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.
The adsorption behaviour of Diphenylamine (DPAM), beta napthylamine (beta NAM), alpha napthylamine (alpha NAM) and aniline on pyrolusite and activated carbon has been studied. Pyrolusite shows remarkable sorption capacity for DPAM and beta NAM as compared to aniline; (the adsorption followed the order: Activated Carbon:--> DPAM = beta NAM > alpha Aniline; Pyrolusite: DPAM: --> beta NAM > alpha NAM > Aniline) The maximum adsorption of beta NAM occurred in the concentration range 4-20 microg mL(-1) on pyrolusite (95%) and 4-50 microg mL(-1) on activated carbon (100%). The effect of various doses of activated carbon on the adsorption of beta NAM confirm Langmuir and Freundlich isotherms where as Freundlich isotherm is obeyed by pyrolusite. The adsorption of beta NAM on both the absorbents is not affected in presence of DPAM over a wide range of their initial concentrations (20-60 microg mL(-1)). The desorption studies of beta NAM on pyrolusite was carried out by batch as well as column processes. Excellent results were obtained when a mixture of n-hexane and isopropanol (91:1) was used as eluent.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.