Efficient removal of two anionic dyes by a highly robust zirconium based metal organic framework from aqueous medium: Experimental findings with molecular docking study

Abstract

A Zr (IV) based Metal Organic Framework (MOF), UiO-66 has been synthesized by hydrothermal method, and its application for adsorption of two industrially important anionic dyes, Reactive Blue (RB) and Congo Red (CR) was studied. The MOF was thoroughly characterized by Powder X-ray Diffraction (PXRD),UV-vis Diffused Reflectance Spectra (UV-DRS), Fourier-transform Infrared spectroscopy (FT-IR),Thermo Gravimetric Analysis (TGA), N2 adsorption isotherm, 1H Nuclear Magnetic Resonance spectra (1H NMR), Scanning Electronic Microscopy (SEM) and Transmission Electron Microscopy (TEM). From the obtained results, it has been confirmed that our synthesized MOF is mesoporous in nature. The hierarchical adsorption behavior of the MOF has been studied with the dyes, CR and RB by both experimental and molecular docking methods. The binding energy of UiO-66 was found to be -12.82 kcal/mol with CR and -9.42 kcal/mol with RB. Hydrogen bonding and hydrophobic interaction plays a crucial role during adsorption process of both the dyes. Both ligand efficiency and binding energy of CR is found higher as compared to RB. The comprehensive evidences from our experimental as well as molecular docking studies clearly demonstrated that adsorption of CR is higher as compared to RB by the MOF, UiO-66.