Preparation of corn stalk-based adsorbents and their specific application in metal ions adsorption

Corn stalk-based adsorbents modified from corn stalk were prepared by Cu(0)-mediated reversible-deactivation radical polymerization (Cu(0)-mediated RDRP). They were applied to remove metal ions and they exhibited good adsorption capacity, especially for Hg(II). Adsorption properties of corn stalk can be enhanced by introducing cyano, amino, amidoxime, and carboxyl groups onto its surface, which results in efficient adsorbents for different metal ions. TGA, SEM, EA, and FTIR analyses were employed to characterize the structures of corn stalk-graft-polyacrylonitrile (CS-g-PAN), corn stalk-graft-polyacrylamide (CS-g-PAM), amidoxime corn stalk-graft-polyacrylonitrile (AO CS-g-PAN) and carboxyl corn stalk-graft-poly(methyl acrylate) (CO CS-g-PMA). The maximum adsorption capacity for Hg(II) was 8.06 mmol g^?1 of AO CS-g-PAN. Kinetics of the Hg(II) adsorption on AO CS-g-PAN was found to follow the pseudo-second-order model and the adsorption isotherms were well fitted with the Freundlich isotherm model.