Solvothermal synthesis of MnxFe3 - xO4 nanoparticles with interesting physicochemical characteristics and good catalytic degradation activity

In this work, composition-adjusted manganese ferrites (MnxFe3 (-) O-x(4)) were synthesized by a simple one-step solvothermal route and characterized by ICP-AES, XRD, SEM, N-2 adsorption/desorption, and VSM. It was identified that the chemical composition had a significant influence on the physicochemical characteristics of MnxFe3 (-) O-x(4) samples. The specimen with value of x = 1.07 (Mn1.07Fe1.93O4) exhibited a unique combination of good monodispersity, regular morphology (sphere-like), abundant porosity, uniform size, distinct crystalline structure, satisfactory water dispersability, and high magnetic responsivity. Activities of these magnetically recoverable MnxFe3 (-) O-x(4) samples were evaluated by employing them as Fenton catalysts for the degradation of highly concentrated methylene blue (MB, 400 mg.L-1). Exceptionally high activity for the catalytic degradation of MB without any external energy input was achieved, being 1-2 orders of magnitudes greater than that over other Fe-based or Mn-based heterogeneous catalysts. We demonstrated that the large surface area of MnxFe3 (-) O-x(4) as well as the high activity and favorable regeneration of the Mn2+ sites were responsible for the excellent performance. Overall, this study provides not only a practical strategy for rational design of targeted spinel-type ferrite nanomaterials, but also a new physical insight on catalytic activity of manganese ferrite and its application to organic pollutant removal. (C) 2016 Elsevier Ltd. All rights reserved.