Ferric ion modified nano-MOF-5 synthesized by direct mixing approach: A highly efficient adsorbent for methylene blue dye

In this study, the adsorption of methylene blue (MB) dye has been studied with modified Fe-MOF-5 and MOF-5, synthesized at room temperature by direct mixing approach. The morphology and physicochemical properties of prepared catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The removal rate of Fe-MOF-5 was considerably greater MOF-5 which shows the adsorption performance of MOF-5 can be improved through the modification. The influences of various parameters on the adsorption interaction of the prepared compounds were considered in pH value, contact time, temperature, adsorbent dosage and concentration of MB. Consequently, the adsorption kinetics, thermodynamics and isotherms were consistently explored. To predict the adsorption isotherms and to specify the characteristic parameters for process design, four isotherm models such as Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) were applied. The experimental isotherm data were found to fit the Langmuir model properly. Additionally, adsorption kinetic data were tested using pseudo-first-order, pseudo-second-order and Elovich model and were found to be fitted into pseudo-second-order model. The thermodynamic parameters illustrated that the adsorption was a spontaneous and endothermic process.