Understanding the interaction in cellulose-chitosan composite and its adsorption ability for Nickel (II): a theoretical investigation

The tight-binding quantum chemical method (GFN2-xTB) was performed to study the nature of the interaction between the two components in a cellulose-chitosan composite (CCS) and its adsorption ability for Ni2+ and NiOH+. The interaction energy, topology of bond paths, frontier molecular orbitals, Fukui functions, and molecular electrostatic potentials were calculated and analysed to figure out the interaction between the components in the CCS. The obtained results show that cellulose and chitosan mainly interact via the formation of hydrogen bonds and van der Waals forces. The CCS shows high adsorption ability for Ni2+ and NiOH+. The preferred adsorption sites of Ni(II) on the CCS were determined and analysed. The improvement in adsorption ability of CCS over pristine cellulose and chitosan was attributed to the changes in structure and electronic properties of the material due to the interaction between the components.