Studies of heavy metal ion adsorption on chitosan/sulfydryl-functionalized graphene oxide composites.

Chitosan/Sulfydryl-functionalized graphene oxide composite (CS/GO-SH) was successfully synthesized via covalent modification and electrostatic self-assembly. A facile diazonium chemical process was developed to fabricate sulfydryl-functionalized graphene oxide (GO-SH) by introducing sulfydryl compounds to the graphene oxide sheets (GO), and the GO-SH was used to self-assemble with chitosan via an electrostatic interaction. The chemical structure and morphology of the CS/GO-SH composite were characterized by Fourier transformed infrared, Raman spectroscopy, scanning electron microscopy, X-ray powder diffraction and thermogravimetric examination. The results indicated that the CS/GO-SH was a new type of with multifunctional groups such as -OH, -COOH, -SH and -NH2. Simultaneously, the self-assembly of chitosan with GO-SH sheets changed the blocky structure of the CS to the loosely packed structure which is analogous to graphene oxide sheets. The resulting CS/GO-SH was used as an adsorbent material for removal of Cu (II), Pb (II) and Cd (II) in single- and multi-metal ions systems. It was found that the CS/GO-SH has potential applications in fields of adsorptive materials due to its superiority of the chemical characteristic and the specific surface area.