화학공학소재연구정보센터
Applied Surface Science, Vol.324, 877-889, 2015
Mn substituted cobalt ferrites (CoMnxFe2-xO4 (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0)): As magnetically separable heterogeneous nanocatalyst for the reduction of nitrophenols
Manganese substituted cobalt ferrite nanoparticles with composition CoMnxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized using sol-gel technology and characterized using the Fourier transform infrared spectroscopy, high resolution transmission electron microscopy and X-ray diffraction techniques to confirm their formation. The prepared ferrite samples were explored as catalysts for the reduction of nitrophenols in the presence of NaBH4 as reducing agent. Pure cobalt ferrite was found to be inactive. However, catalytic efficiency enhanced dramatically with the introduction of Mn ions into the catalytically active surface sites (octahedral sites) of the cobalt ferrite lattice. This could be due to the presence of synergistic effect between the Co3+, Mn3+ and Fe3+ ions present in the octahedral sites. CoMn02Fe1.8O4 ferrite was observed to have the best catalytic activity for the reduction of nitrophenols because of the highest Fe3+/Mn3+ and Co3+/Mn3+ ionic ratio at the catalytically active octahedral sites. The kinetics of reduction was studied and the reduction reaction followed pseudo first order kinetics. The rates of reduction of the three isomers of nitrophenols followed the order - 2-nitrophenol > 4-nitrophenol > 3-nitrophenol.