Removal of Cr(VI) ions using Fe-loaded chitosan carbonized rice husk composite beads (Fe-CCRCB): Experiment and quantum chemical calculations

This investigation deals with the preparation of cross-linked Fe-loaded chitosan rice husk carbon composite (Fe-CRHCB) for the adsorption of Cr (VI) ions. The surface properties of Fe-CRHCB were characterized by Brauner, Emmett and Teller (BET) analyser, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX), and Fourier Transform Infrared Spectroscopy (FTIR). The chemical processes occurred during the synthesis of adsorbent and the adsorption process involving the adsorbent and adsorbate were studied through quantum chemical method, which elucidates the reactivity and stability of the interacting system via the highest occupied molecular orbital and the lowest unoccupied molecular orbital energies with its energy gap. Quantum chemical studies were carried out for each stage of adsorbent synthesis, as well as for the interaction of adsorbent with Cr (VI) ions. The interaction of molecules is described by global scalar properties such as chemical potential (mu), electronegativity (chi), chemical hardness (eta), chemical softness (S) and electrophilicity index (omega). From these global scalar properties, it was observed that the interaction occurred at each stage of reaction during the adsorption process. Hence, it can be concluded that Fe-CRHCB is an efficient adsorbent for the adsorption of Cr (VI) ions. (C) 2015 Elsevier B.V. All rights reserved.