Preparation of Tannin Immobilized Goat Hair and its Adsorption of Hexavalent Chromium from Aqueous Solution

Mimosa tannins were immobilized on goat hair to prepare a sorbent for the adsorption of hexavalent chromium (Cr⁶⁺) in aqueous solution. The results indicate that the redox reaction occurs during the adsorption process. Cr⁶⁺ is firstly reduced to Cr³⁺ and then adsorbed on the sorbent. The adsorption capacity is 117.3 mg/g at pH 2.0 and 313 K with the initial Cr⁶⁺ concentration of 300 mg/L. Increasing temperature can promote the adsorption capacity. The solution pH can affect the adsorption capacity significantly because the redox reaction is dependent on pH value, and the optimal pH for the adsorption is 2.0. The adsorption isotherms of the sorbent to Cr⁶⁺ can be well described by the Freundlich model, and the adsorption kinetic data of Cr⁶⁺ fit the pseudo-second-order model. The results of adsorption experiments for the simulated electroplating wastewater indicate that Cr⁶⁺ can be effectively removed using the sorbent when adjusting pH of the solution.