Enhanced catalytic oxidation via nano Cu_0.5Mg_0.5Fe₂O₄ embedded in CNTs for adsorption-reduction of hexavalent chromium

A catalyst consisting of Cu0.5Mg0.5Fe2O4 (CMF) supported on carbon nanotubes (CNTs) which exhibits great potential as an adsorbent for treating Cr(VI)-contaminated wastewater has been successfully prepared. The ferrite possesses excellent magnetic properties, while CNTs have the advantage of a large surface area. This composite material not only prevents the aggregation of magnetic materials and enhances the exposure of active sites but also effectively solves the recycling problem of CNTs. Our results show that the adsorption capacity of Cu0.5Mg0.5Fe2O4-carbon nanotubes (CMF-CNTs) for Cr(VI) wastewater (45.60 mg/g) is 1.49 times higher than that of Cu0.5Mg0.5Fe2O4 (30.48 mg/g). Compared to a single catalyst, CMF-CNTs not only improve the dispersibility of magnetic materials but also exhibit synergistic effects between the composite materials, enhancing the chemical adsorption capacity. After five consecutive adsorption and desorption experiments, the adsorption capacity of CMF-CNTs remains at 88% of its initial value. Furthermore, the study of the catalyst before and after adsorption by XPS reveals that the valence state transition of Fe3+/Fe2+ and Cu2+/Cu+ plays a crucial role in the adsorption process. The results of this study demonstrate the potential of using waste materials for effective wastewater treatment and provide insights into the development of new adsorbents for pollutant removal.