Fabrication of multifunction-integrated adsorbent based on zwitterion functionalized cellulose with high adsorption performance for anionic/ cationic dyes and heavy metal ions

A multifunction-integrated adsorbent based on zwitterion functionalized cellulose (MCC@PGMA-IAA) was synthesized by surface grafting polymerization and then modification with polyethyleneimine and sodium chloroacetate in turn. The adsorbent exhibited high functional group contents, switchable surface charge and chelating structure of iminoacetic acid. With the methylene blue, azophloxine, Ni(II) and Cr(VI) as the models of cationic/anionic dyes and heavy metal ions, batch experiments were conducted. The material showed strong adsorption abilities for dyes and heavy metal ions, with maximum adsorption capacities up to 440.5 mg/g, 320.5 mg/g, 59.3 mg/g, and 127.9 mg/g for methylene blue, azophloxine, Ni(II) and Cr(VI), respectively. Especially, the adsorption capacities of methylene blue and Ni(II) after zwitterionic functionalization increased by 50 times and 95.5% than those after polyethyleneimine modification. The adsorption equilibria were achieved within 10-120 min, and the adsorbent exhibited excellent removal efficiency. Furthermore, the adsorbed pollutants were conveniently desorbed by low concentration of HCl or NaOH solution, and the adsorbent had good reusability. Mechanism studies proved that electrostatic attraction and chelation were main driving forces. These results showed that MCC@PGMA-IAA had the characteristics of extensive sources, simple preparation and multifunctional integration, which was poised to develop as universal adsorbent for removing heavy metal ions and dyes.