Magnetic nanocatalysts of Ni0.5Zn0.5Fe2O4 doped with Cu and performance evaluation in transesterification reaction for biodiesel production

It was proposed in this work to investigate the Cu2+ ions doping influence in the structure, morphology and magnetic properties of nanoferrites Ni0.5Zn0.5Fe2O4 for their application in methyl transesterification of soybean oil to biodiesel production. The nanoferrites with Ni0.5−xCuxZn0.5Fe2O4 composition (0.0 ⩽ x ⩽ 0.4) were synthesized by combustion reaction using a conical reactor with production of 10 g per batch and characterized by X-ray diffraction, textural analysis by N2 adsorption, magnetic measurements, thermal analysis by temperature-programmed desorption, and biodiesel analysis by gas chromatography. All compositions resulted in the single phase of the inverse spinel type B(AB)2O4 and adsorption/desorption isotherms of the same profile, classified as type V, with hysteresis loop type 3 (H3). However, the increase of Cu ions doping from 0.0 to 0.4 mol caused a reduction of 37% in the surface area values and 36.4% in the saturation magnetization value. However, this reduction remained the ferrimagnetic characteristic and that is still strongly attracted by a magnet. The Cu ions presence has also facilitated an increase of 5.5-85% in the conversion values in methyl esters obtained from soybean oil transesterification. These results indicate the potential application of NiZn nanoferrite compositions doped with Cu2+ as heterogeneous nanocatalysts to produce biodiesel.