Hexavalent Chromium Adsorption by Tannin Immobilized Goat Hair

Biomaterial based sorbents have been increasingly interesting for heavy metal removal in aqueous solutions. Waste goat hair from tanneries was utilized as matrix for immobilizing tannins, and a sorbent based on mimosa tannins and goat hair was prepared. The adsorption behavior of the sorbent to hexavalent chromium was investigated. The experimental results indicated that the optimal pH for the adsorption of Cr(VI) was found to be 2.0~3.0. The time for attaining adsorption equilibrium was 200 min. The adsorption isotherms of the sorbent to Cr(VI) could be well described by the Freundlich model, indicating the adsorption can processed easily. The adsorption capacity of Cr(VI) on the sorbents was 117.3 mg/g at 313 K. The adsorption kinetic data of Cr(VI) fitted the pseudo- second-order model, illustrating that the Cr(VI) can diffuse into the interior of the sorbents during the adsorption process. Competitive adsorption studies revealed that the sorbent exhibits ability of selective adsorption to Cr(VI) in mixture solutions of metal ions, and proved that Cr(VI) could be well removed by adjusting the solution pH from 2.0 to 6.0.