Hydrothermal temperature effect on microstructure evolution and Fenton-like catalytic performance of spinel ferrite (Mg,Ni)(Fe,Al)2O4 synthesized from saprolitic nickel laterite

Abstract

Metal-doped magnesium ferrites (Mg, Ni)(Fe, Al)2O4 were prepared by a hydrothermal method from saprolitic nickel laterite leaching solution. The effects of the hydrothermal reaction temperature (140–220 °C) and post calcination on the microstructure and catalytic performance of the as-prepared samples were investigated in detail. It is shown that higher hydrothermal temperature combined with calcination could promote the migration of Fe3+ from tetrahedral to octahedral sites almost exclusively located at the surface of the solid spinel ferrites, which was beneficial to improve the activity of formed MgFe2O4 catalysts. In addition, the calcined samples (hydrothermal synthesized at 180, 200 and 220 °C, then calcined at 500 °C (H180C, H200C and H220C)) exhibited excellent heterogeneous Fenton-like catalytic activity for decomposing Rhodamine B (about 97.0% degradation efficiency in 120 min). Moreover, reusability test results show that the reduction of degradation efficiency was less than 1.0% for the sample H200C, implying the as-prepared catalyst had good catalytic activity and excellent reusability. This study may provide a better understanding of relationships between microstructure and heterogeneous Fenton-like catalytic performance of spinel ferrites synthesized from natural minerals containing transition metals.