Magnetic ordered mesoporous copper ferrite as a heterogeneous Fenton catalyst for the degradation of imidacloprid

Abstract

Highly ordered mesoporous copper ferrite (meso-CuFe2O4) with high surface area and large pore size was successfully fabricated and firstly proposed as a heterogeneous Fenton catalyst. It was synthesized through the nanocasting strategy by using KIT-6 as hard template. The morphology and physicochemical properties of meso-CuFe2O4 were characterized by SEM, TEM, XRD, XPS, FT-IR, Raman spectra, etc. The obtained results showed that the surface area and the pore size of meso-CuFe2O4 were 122m2g-1 and 9.2nm, respectively. The meso-CuFe2O4 presented excellent catalytic activity for the degradation of imidacloprid, achieving almost complete removal of 10mgL-1 imidacloprid after 5h at the reaction conditions of 0.3gL-1 catalyst and 40mM H2O2. Kinetic analysis showed that the degradation of imidacloprid follows the pseudo-first order. The apparent rate constant for meso-CuFe2O4 was 1.0445h-1, which was 1.5, 2 and 2.5 times than those of meso-CoFe2O4, con-CuFe2O4 and nano-Fe3O4, respectively. The amount of hydroxyl radical (OH) generated was directly proportional to the degradation efficiency of imidacloprid, suggesting the involvement of OH in oxidizing imidacloprid. The obtained results indicated that meso-CuFe2O4 presented the highest activity, which was not only due to its ordered mesoporous structure with high surface area and large pore size, but also assigned to the redox recycle of Fe2+/Fe3+ and Cu+/Cu2+ in meso-CuFe2O4. The special effect of Cu was discussed in terms of the thermodynamically favorable Fe3+ reduction by Cu+, regenerating the active species Fe2+. The meso-CuFe2O4 presented very low iron leaching (<1ppm) even in acidic condition and retained almost its high catalytic activity after 5 consecutive runs. Besides, meso-CuFe2O4 possessed medium saturation magnetization, which had provided a potential advantage for the recovery and reuse of catalyst. © 2013 Elsevier B.V.