Preparation and Characterization of a Novel Amidoxime-Modified Polyacrylonitrile/Fly Ash Composite Adsorbent and Its Application to Metal Wastewater Treatment

The polyacrylonitrile/fly ash composite was synthesized through solution polymerization and was modified with NH(2)OH·HCl. The amidoxime-modified polyacrylonitrile/fly ash composite demonstrated excellent adsorption capacity for Zn(2+) in an aqueous medium. Fourier transform-Infrared spectroscopy, thermogravimetric analysis, nitrogen adsorption, X-ray diffraction, and scanning electron microscopy were used to characterize the prepared materials. The results showed that the resulting amidoxime-modified polyacrylonitrile/fly ash composite was able to effectively remove Zn(2+) at pH 4–6. Adsorption of Zn(2+) was hindered by the coexisting cations. The adsorption kinetics of Zn(2+) by Zn(2+) followed the pseudo-second order kinetic model. The adsorption process also satisfactorily fit the Langmuir model, and the adsorption process was mainly single layer. The Gibbs free energy ΔG(0), ΔH(0), and ΔS(0) were negative, indicating the adsorption was a spontaneous, exothermic, and high degree of order in solution system.