Performance of magnetite/layered double hydroxide composite for dye removal via adsorption, Fenton and photo-Fenton processes

Abstract

In order to investigate the effect of the addition of magnetite in layered double hydroxide (LDH) from a structural and catalytic point of view, the synthesis of LDH containing cobalt and chromium (CoCr-LDH) was performed with or without Fe3O4. These materials were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption Isotherms, Fourier transform infrared spectroscopy (FTIR), and evaluated as adsorbents and heterogeneous catalysts in Fenton-like and photo-Fenton-like reactions. The results showed that the magnetite was prepared and incorporated to the LDH with success, forming a composite providing magnetic properties and promoting alteration in the morphology, quantity and size of the LDH pores. The evaluation of the adsorption and oxidation processes utilizing the Fe3O4/LDH composite showed to be more efficient than for pure LDH. This better performance can be explained by higher surface area and larger pores for Fe3O4/LDH which allow a more effective contact with the dye solution and more proximity of large molecules like those of Reactive Black with the sites where the OH• radicals are formed.