MIRCEA STEFAN, ADRIANA BORS, DANIELA SIMINA STEFAN, IONUT ALEXANDRU SAVU RADU, CICERONE MARINESCU SORPTION OF HEAVY METAL ON NATURAL CLAY Sorption of heavy metals on Na-montmorillonite was studied as a function of solution pH and different concentrations of background electrolyte and also a function of added metal ion at constant pH. Equilibrium isotherms have been measured and analyzed using a Langmuir isotherm model. The metal ions were predominantly adsorbed on the permanent charge sites in a easily replaceable state. There was also evident a substantial involvement of the hydroxyl groups on the edges of Na-montmorillonite in specific adsorption of the cations especially at higher pH.
Keywords: sorption, heavy metals, montmorillonite, Langmuir equation