LAUSR

Abstract Cationic (Malachite Green) and anionic dyes (Indigo carmine) removal by cross-linked chitosan (CSglu) beads has been investigated using experimental and computational approaches. The experimental investigations of the adsorption isotherm, kinetics, and thermodynamics information correlated well with computational studies in term of structures and binding energies (ΔEB). Cross-linked chitosan adsorb Malachite Green better than Indigo carmine using Langmuir adsorption isotherm. The CSglu beads in frozen dried form showed highly adsorption capacity (714.29 mg.g−1) for malachite green (MG) but they are not favorable for indigo carmine (IND). In order to probe the atomistic-level detail between these two dyes and CSglu, molecular dynamics simulations (MDs) have been applied to determine detailed analysis of binding site of the complexes. MG is more preferable to bind with CSglu than IND due to its complementary of the molecular electrostatic potential (MEP) to the CSglu surface. The quantum calculations using density functional theory (DFT) with different levels and basis set super position error (BSSE) were used to calculate ΔEB and to effectively predict the adsorption capabilities of cationic and anionic dyes by cross-linked chitosan.