The mechanism of adsorption of zinc and cadmium ions onto bentonite clay

Abstract

Adsorption of zinc and cadmium ions onto bentonite clays from the Zyryanskoe deposit (Kurgan region, Russia) was studied as a function of contact duration, pH, and temperature. Silanol and aluminol groups of the clay were found to participate in ion exchange and in complex formation with zinc and cadmium ions; a certain process prevails depending on pH. Adsorption of zinc and cadmium ions from equimolar binary solutions was studied. Adsorption of ions onto clay increases with temperature increasing from 293 to 333 K. Adsorption mechanisms of Zn(II) and Cd(II) ions were proposed.