Simple method for preparation of chitosan/poly(acrylic acid) blending hydrogel beads and adsorption of copper(II) from aqueous solutions

In this paper, poly(acrylic acid) blended chitosan (CS/PAA) hydrogel beads have been prepared by one-step method simply. It was found that glutaraldehyde (GLA) cross-linked CS/PAA beads had better stability in lower pH solutions and higher mechanical strength than CS-GLA beads without PAA. Results from removal of Copper(Cu) ions from aqueous solutions showed that the adsorption capacity of CS/PAA-GLA beads was greater than that of CS-GLA beads. Moreover, the adsorption capacity for two types of beads both showed temperature independent. Furthermore, the adsorption isotherms of various beads at different temperatures were both better fitted for Langmuir equation, while the adsorption kinetics was both better described by the pseudo-second order equation. Furthermore, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy have been employed to investigate the adsorption mechanisms from molecular levels. It indicated that the efficient effects of CS/PAA-GLA beads on removal of Cu(II) resulted from the fact that carboxyl groups were facile to form bidentate carboxylates with metal ions. In addition, Cu(II) ions could be desorbed efficiently from both aforementioned beads at pH below 4.0, and the adsorption capacity of the regenerated beads had no loss until six cycles.