Removal of congo red from aqueous solution by its sorption onto the metal organic framework MIL-100(Fe): equilibrium, kinetic and thermodynamic studies

Abstract

In this study, an iron based metal organic framework (MIL-100(Fe)) with high surface area and large pore volume has been synthesized by the hydrothermal method and its capability as an efficient sorbent for congo red (CR) removal from aqueous samples has been evaluated. The metal organic framework sorbent was characterized by Fourier transform infrared spectroscopy, scanning tunneling microscopy, thermogravimetric analysis/differential thermal analysis, and X-ray diffraction methods. The sorption capacity of the sorbent for CR was maximized through systematic studies of different factors which affect its sorption, such as contact time, initial concentration, sorbent dosage, pH and temperature. Sorption kinetic was studied in detail by four kinetic models, the pseudo-first-order and second-order equations, the Elovich equation and the intraparticle diffusion equation. The results indicate that the mechanism of the sorption process followed Elovich and pseudo-second-order kinetic. Sorption equilibrium was also studied with Langmuir, Temkin and Freundlich isotherm models. The sorption process followed Langmuir isotherm and the maximum monolayer sorption capacity for CR was found to be 714.3 mg g⁻¹ of MIL-100(Fe).

Keywords:

• Metal organic framework
• Langmuir isotherm
• Congo red removal
• Dye removal