Highly efficient removal of Congo red by MIL-101 Fe @PDopa@Fe3O4

A magnetic metal-organic framework MOF composite, MIL-101Fe @PDopa@Fe3O4, was synthesized as the stable adsorbent for removal of Congo red CR from water. A very thin film of 3,4-dihydroxy-L-phenylalanine L-Dopa was used as an efficient and environmentally friendly binder between Fe3O4 nanoparticles and MIL-101Fe. The synthesized nanocomposite was investigated by SEM, TEM, FT-IR, XRD and TGA analyzes. Magnetic properties of the composite were studied by vibrating sample magnetometer VSM. Zeta potential analysis was also performed to determine the surface charge of the nanocomposite. Influencing factors such as pH, contact time, adsorbent dosage, temperature, and initial dye concentration on the adsorption ability of the MIL-101Fe @PDopa@Fe3O4 were investigated. The very excellent adsorption capacity about 909 mg/g for CR was achieved. Adsorption kinetics and isotherms studies indicated that CR adsorption followed Langmuir isotherm model and pseudo second-order kinetic model. Studies have also shown that The MIL-101Fe @ PDopa@Fe3O4 was found to be recyclable for removal of CR.