Novel reusable amine-functionalized cellulose acetate beads impregnated aminated graphene oxide for adsorptive removal of hexavalent chromium ions

Abstract

In this study, a multi-featured adsorbent was developed for the adsorptive removal of hexavalent chromium (Cr6+) ions. Herein, aminated graphene oxide (GO-NH2) was firstly synthetized and incorporated into cellulose acetate beads (CA) which were followed by surface amine-functionalization process. Varies characterization tools such as FT-IR spectroscopy, SEM, TGA, XRD, BET, XPS and zeta potential were employed to ensure the successful fabrication of GO-NH2@CA-NH2 composite beads. An enhancement in the adsorption performance was attained, while the adsorption equilibrium was closely gotten within only 60 min. Therefore, the adsorption capacity was boosted with increasing GO-NH2 ratio in the beads matrix from 10 to 25%. Furthermore, the adsorption process agreed with Freundlich isotherm model with a supreme adsorption capacity of 410.21 mg/g at pH 2, while data followed the pseudo-second-order kinetic model. Besides, thermodynamic studies denoted that the adsorption process was endothermic, randomness and spontaneous. The composite beads retained better adsorption characteristics for seven sequential cycles with ease of separation. The proposed adsorption of Cr6+ onto GO-NH2@CA-NH2 surface occurred via the electrostatic interactions, reduction process and coordinate–covalent bonds. These findings hypothesize that the fabricated GO-NH2@CA-NH2 beads could be act as easy-separable and reusable adsorbent for efficient adsorption of Cr6+ ions.