Wool graft polyacrylamidoxime as the adsorbent for both cationic and anionic toxic ions from aqueous solutions

Abstract

Wool graft polyacrylamidoxime (W-g-PAO) was synthesized using coarse wool as the raw keratin material and the graft polymerization parameters were optimized. The adsorption properties of W-g-PAO for both cationic and anionic toxic ions from aqueous solutions were investigated. It was found that both cationic and anionic toxic ions can be effectively adsorbed by W-g-PAO. The adsorption followed the pseudo-second-order kinetics model for both cations and anions, and can be well depicted by Langmuir isotherm model. The equilibrium adsorption capacity (Q_e) increases with the rising initial concentration of toxic ions. The adsorption capacity followed the order of Hg²⁺ > Pb²⁺ > AsO₂⁻ > AsO₄³⁻ > Cd²⁺. W-g-PAO can be regenerated after adsorption, and the adsorption capacity slightly decreased with the increase in the regenerated cycles. Besides providing a cheap and excellent adsorbent for the removal of both cationic and anionic toxic ions from waste water, the method can be extended to the modification of other waste raw keratin materials, by which the waste raw keratin materials can be used as a valuable blocks for the fabrication of functional materials.