Selective adsorption of chromium(VI) from zinc(II) and other metal ions using persimmon waste gel

An adsorption gel was prepared from persimmon waste, a cellulosic material, rich in polyphenolic compounds, which exhibits a high affinity for chromium(VI). It was prepared by cross-linking persimmon waste with concentrated sulphuric acid. Adsorption tests for different metal ions such as Cr(VI), Cr(III), Fe(III), Zn(II), Cd(II) and Pb(II) from aqueous solution at pH values ranging from (pH 1 to 5) found Cr(VI) to be selectively adsorbed on the cross-linked gel over the other metal ions studied. The adsorption isotherm of Cr(VI) followed the Langmuir type of adsorption and exhibited a maximum loading capacity of 7.18 mol kg− 1 at pH 1. Selective removal of Cr(VI) from Zn(II) was successfully demonstrated by using a column packed with the persimmon waste gel.