Peroxydisulfate activation by LaNiO nanoparticles with different morphologies for the degradation of organic pollutants.

A series of LaNiO perovskite nanoparticles with different morphologies, such as spheres, rods and cubes, were prepared through co-precipitation and hydrothermal methods, and used as the catalysts for peroxydisulfate (PDS) activation. The physical and chemical characterization of LaNiO perovskites was performed, including X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen isotherm absorption (BET), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The LaNiO with different shapes showed different activities in Acid Orange 7 (AO7) degradation. Sphere-like LaNiO exhibited the highest catalytic activity, which is probably due to the largest specific surface area, higher proportion of reductive Ni and the higher electron transfer ability. The radical scavenging experiments and electron paramagnetic resonance (EPR) revealed the production of massive sulfate radicals (SO) and hydroxyl radicals (OH) during the oxidation. Finally, the possible mechanisms of PDS activation and AO7 degradation were proposed. The prepared LaNiO perovskites also showed excellent reusability and stability.