Adsorption behavior of Cr(VI) on activated hazelnut shell ash and activated bentonite

The possible use of activated hazelnut shell ash and activated bentonite as the adsorbents of Cr(VI) from synthetic solutions and the effect of operating parameters were investigated. The activated hazelnut shell ash was prepared thermally in two sizes 0.5 and 1.0 mm. The maximum removal of Cr(VI) occurred at pH 3 by activated hazelnut shell ash and at pH 5 by activated bentonite. The amounts of Cr(VI) adsorbed increased with increase in dose of both adsorbents and their contact time. The equilibrium data was analysed using the Langmuir and Freundlich isotherms. The characteristics parameters for each isotherm were determined. The Freundlich adsorption model was applied to describe the equilibrium isotherms and the isotherm constants were determined. The Freundlich model agrees very well with experimental data.