Heavy metal removal from aqueous solution by tannins immobilized on collagen

Different recycled materials, which were derived from leather manufacturing processes, were used as adsorbents for the treatment of synthetic wastewater containing heavy metal ions. Three pelt scraps samples (P-M, P-Z and P-P), one shaving scrap (S) and one trimming scrap (T) were used as recycled adsorbents. Removal efficiency of Cu(II), Cd(II), Zn(II), Pb(II) and Cr(III) was evaluated by a laboratory-scale batch reactor at different solution pH. For all adsorbents except T sample, the adsorption of heavy metal ions begins between pH 2 and 4 and reaches near complete adsorption within the next 3-4 pH units, showing a typical cationictype of adsorption. Removal trend of Cr(III) was quite similar without depending on the kind of adsorbents. From the kinetic experiments of Cu(II) by S adsorbent, adsorption of Cu(II) was better described by second-order reaction than first-order reaction. The initial removal rate of Cu(II) by S adsorbent was 7143 mg/kg^h. Adsorption isotherm of Cu(II) onto S adsorbent was well expressed by Langmuir equation and the maximum adsorption capacity of Cu(II) at pH 4 was calculated as 1667 mg/kg.