MnFe2O4 nanoparticles as new catalyst for oxidative degradation of phenol by peroxydisulfate.

Manganese ferrite nanopowder was prepared by thermal decomposition at 400°C of the gel synthesized from manganese and iron nitrates and polyvinyl alcohol. X-ray diffractometry evidenced that manganese ferrite was formed as single crystalline phase at this temperature. Scanning electron microscope images evidenced the formation of very fine spherical particles (d<11nm) of manganese ferrite, with specific surface area of 147m2/g. The powder obtained at 400°C was used as a catalyst for the oxidative degradation of phenol in aqueous solutions, in the presence of potassium peroxydisulfate as oxidant. High phenol removal efficiencies above 90% were reached at: pH 3-3.5, phenol initial concentration around 50mg/L, peroxydisulfate:phenol mass ratio 10:1, and catalyst dose 3g/L. Total organic carbon measurements showed that the degradation of phenol goes, under these conditions, to mineralization in an extent of 60%.