Adsorptive Removal of Heavy Metal Ions by Waste Wool

Abstract

Raw and waste wool were studied for the removal of heavy metal ions such as Zn(II) and Cu (II) from wastewater. Characterization of both wool samples was done by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and zeta potential analysis. The sorption kinetics of metal ions on wool samples was also studied, and compared with different models for adsorption kinetics and adsorption isotherms. The maximum Zn(II) sorption efficiency of 95.5% was achieved on raw wool at a contact time of 3 h and a Zn(II) concentration of 6.25 mg/l. An efficiency above 94% was obtained for Cu(II) sorption at initial concentrations of 6.25 mg/l and 12.5 mg/l after 3 h. In the case of waste wool, the maximum efficiency of Zn(II) and Cu(II) sorption was reached after 24 h at 34.4%, and after 3 h at 60.4%, respectively. The best fit for the sorption kinetics was obtained with a pseudo-second-order model, and the Redlich-Peterson isotherm represents the sorption results very well. The regeneration of raw wool and waste wool regarding Zn(II) was successful, while that of Cu(II) failed from either of the wool fibers.

Keywords

• wool
• zinc
• copper
• heavy metal removal
• waste wool