Mg-Co-Zn magnetic nanoferrites: Characterization and their use for remediation of textile wastewater

Highly active and magnetically separable Mg substituted cobalt zinc nanoferrites having formula (Co0.6Zn0.4MgxFe2-xO4, x = 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized using sol-gel auto combustion method. The photo-catalytic activity of all the nanoferrites samples annealed at 1000 degrees C under visible light was evaluated by the degradation of Methyl orange (MO) dye. All the heterogeneous catalysts were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction patterns and vibrating sample magnetometer. FT-IR absorption spectra exhibited two absorption bands in the range of 400-600 cm(-1) which were characteristic feature of spinel ferrites. Powder X-ray diffraction patterns at room temperature confirmed the formation of single-phase cubic spinel (FCC) structure with Fd(3)m space group in all the nanoferrites. Lattice parameter was found to decrease from 8.390 to 8.360 angstrom with increase in Mg concentration. Semiconductor behavior of all the prepared samples was confirmed by performing electrical measurements. Saturation magnetization (M-s) was observed to decrease from 55.13 to 24.14 (emu/g) with increase in magnesium concentration. All the samples were catalytically active and photo catalytic efficiency was enhanced as the concentration of magnesium ion increased from 0.2 to 1.0. Complete degradation of the MO dye was achieved along with easy magnetic separation of the catalyst from the solution, thereby exhibiting its potential use in organic pollutant removal from wastewater. (C) 2014 Elsevier Ltd. All rights reserved.