Study of heavy metal ion absorbance by amidoxime group introduced to cellulose-graft-polyacrylonitrile

Amidoximated grafted cellulose was obtained by reacting hydroxylamine and cellulose-graft-polyacrylonitrile (C-g-PAN), prepared by KMnO₄/citric acid redox system, and the resultant amidoximated grafted cellulose was characterized by scanning electron microscope (SEM), solid-state NMR, FTIR, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and elemental analysis. The highest value of amidoxime content in the grafted sample was 2.42 mmol/g. The adsorption efficiencies of amidoximated grafted cellulose have been evaluated with studying different adsorption conditions. Amidoximated sample with amidoxime content 2.42 mmol/g showed high ability to adsorb the metal ions from the aqueous solutions as high as 1.7 mmol/g, 1.6 mmol/g, and 0.84 mmol/g for Co²⁺, Cu²⁺, Ni²⁺ ions, respectively, at the highest original metal ion concentration. These values are about three times larger than previous studies.