Kinetic and thermodynamic studies of Methylene Blue adsorption process from aqueous solutions by MIL-101(Cr)@ZnO nanostructure
Ali Fathi Hasanbarogh, Nahid Ghasemi, Elham Ezzatzadeh
Abstract
Pollution as a result of coloured compounds has become one of the main concerns in terms of health and environment. Metal-organic frameworks (MOFs) are compounds consisting of metal ions or clusters coordinated with organic ligands, which have proved promising to reduce the relevant environmental challenges. In this research, the MIL-101(Cr)@ZnO as an adsorbent was synthesised by hydrothermal synthesis in order to remove cationic dye Methylene Blue (MB) from aqueous solutions. Then, the MIL-101(Cr)@ZnO was characterised by means of X-ray diffraction (XRD), Fourier transform (FTIR), and scanning electron microscopy (FESEM). In order to assess the efficiency of adsorption, the kinetic and thermodynamic studies on the adsorption process were also conducted. Pseudo-first-order and pseudo-second-order kinetic models were applied with the aim of describing the kinetic behaviour of adsorption and the Langmuir and Freundlich isotherm models were used for analysing laboratory equilibrium data. It was demonstrated with the help of the adsorption kinetics and equilibrium adsorption data that the adsorption process of MB is more consistent with the pseudo-first-order kinetic model and the Freundlich model, respectively. The maximum adsorption capacity of MB obtained for this adsorbent was 285.714 mg/g. Based on the thermodynamic values, the adsorption process of the above mentioned pollutant is an endothermic and spontaneous process. The overall results of the study demonstrate that the MIL-101(Cr)@ZnO adsorbent can be considered as a potential candidate for the removal of coloured pollutants from water.