Synthesis, characterization of a metal organic framework: MIL-53 (Fe) and adsorption mechanisms of methyl red onto MIL-53 (Fe)

In this paper, MIL-53 (Fe), was synthesized and the adsorption interaction between this MOF and methyl red (MR) in an aqueous solution was studied. The structural characteristics, surface area, and thermal analysis of the synthesized MIL-53 (Fe) was carried out using XRD, TGA, TEM, and BET methods. The effects of the parameters such as initial concentration, contact time, adsorbent dosage, and temperature on the adsorption capacity were investigated for the determination of the best fit adsorption isotherm, adsorption kinetics, adsorption thermodynamics, and equilibrium time. It was found that the adsorption kinetics obeyed the pseudo-second-order kinetic model and an intraparticle diffusion model was also applied to understand the adsorption mechanism. The Langmuir and Freundlich adsorption isotherm models were also investigated. The results of the adsorption thermodynamics revealed that the adsorption of MR by selected MOF was a spontaneous and exothermic process. MIL-53 (Fe) opens its pores only in the presence of guest molecules. Its flexible structure leads to high adsorption capacities for MR.