Fabrication of Au(III) ion-imprinted polymer based on thiol-modified chitosan

Au(III) ions were selectively extracted from aqueous media using Au(III) ion-imprinted bio-adsorbent based on modified chitosan (Au-CMB). First, 2-mercaptobenzaldehyde-chitosan Schiff base was prepared and interacted with Au(III) ions. The obtained polymeric Au(III) complex was then cross-linked by epichlorohydrin (ECH) before leaching the template Au(III) ions out of the cross-linked matrix. During the synthetic procedures, the obtained chitosan derivatives were characterized by Elemental analysis, FTIR and NMR spectra. Moreover, the crystalline structures along with surface morphology of the fabricated polymeric materials were investigated using X-ray diffraction (XRD) spectra and scanning electron microscope (SEM), respectively. The Au(III) ions uptake studies indicated that the adsorption process was greatly influenced by pH and followed the pseudo-second-order kinetic mechanism. Furthermore, the adsorption was endothermic and the isotherms showed the best fit with Langmuir model with qm 370 ± 0.5 and 195 ± 0.5 mg g−1 in case of Au-CMB and NI-CMB, respectively.