Highly efficient removal of copper ions from water using poly(acrylic acid)-grafted chitosan adsorbent

Biodegradable and ultrahigh content grafted chitosan-g-poly(acrylic acid) powder was successfully synthesized in a homogeneous system and used as adsorbents for the removal of Cu(II) in aqueous solution. The copolymer was characterized by various techniques. The fundamental adsorption behaviors of the material were studied. The adsorption isotherm was well fitted with Langmuir equation, while the adsorption kinetics preferred to be described the pseudo-second order equation. The maximum adsorption capacity obtained from the Langmuir model was 210.13 mg/g, indicating that the adsorption capacity of chitosan was enhanced remarkably after grafting poly(acrylic acid). Moreover, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been used to investigate the adsorption mechanisms at molecular levels, which revealed that carboxyl groups are facile to form bidentate carboxylates with metal ions. Thus, the environment-friendly copolymer will be a promising candidate for application in removal of heavy metal ions.