Robust Waterborne Polyurethane/Wool Keratin/Silk Sericin Freeze-Drying Composite Membrane for Heavy Metal Ions Adsorption

Wool keratin( WK) and silk sericin( SS) have the ability to interact with metal ions. In order to take advantage of this potential, a novel environmentally friendly waterborne polyurethane ( WPU )/WK/SS membrane named as WPU & WK & SS membrane with crosslinked structure was constructed by freeze-drying via self-assembly style. Surface morphology and chemical structure characterization were investigated by scanning electron microscopy ( SEM ) and Fourier transform infrared spectroscopy ( FT-IR ) . In addition, the adsorption experiments of Cu2+ and Cr6+ were performed to evaluate the adsorption of WPU & WK & SS membrane, including adsorption kinetics, adsorption isotherm models and various factors affecting adsorption. Further investigation indicates that the maximum adsorption capacity of Cu2+ and Cr6+ can reach 54. 21 mg·g-1 and 85. 21 mg·g-1 , respectively, which are higher than most of the reported adsorbents. Through adsorption kinetics and thermodynamic analysis, it is find that the pseudo-second-order kinetic equation and the Langmuir adsorption isotherm model are more suitable for the static adsorption of Cu2+and Cr6+by WPU&WK&SS membrane.