Effective mineralization of p-nitrophenol by catalytic ozonation using Ce-substituted La1-xCexFeO3 catalyst

In this study, cerium-doped lanthanum ferrite perovskite oxides (La1-xCexFeO3) with different A-site were synthesized using a sol-gel method and they were used as ozonation catalyst for p-nitrophenol (PNP) mineralization for the first time. Catalytic activity in terms of total organic carbon (TOC) removal followed the order of La0.8Ce0.2FeO3 > La0.4Ce0.6FeO3 > La0.6Ce0.4FeO3 > La0.2Ce0.8FeO3 > LaFeO3 with 77, 66, 61, 60 and 56% respectively. The synthesized catalysts were characterized by diffraction of X-ray (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) and scanning electronic microscopy (SEM). Moreover, electron spin resonance (ESR) and radicals quenching experiments showed that the active oxygen species in the ozone decomposition process are mainly hydroxyl radical (center dot OH), and also include superoxide radical (O-2(-)) and singlet oxygen (O-1(2)). Furthermore, the superior activity of La0.8Ce0.2FeO3 could be attributed to the higher surface area, the richer lattice oxygen, richer surface -OH groups and the facilitated redox Ce3+/Ce4+ and Fe2+/Fe3+ cycling. In addition, this study provides an insight to use metal-doped perovskite catalysts for catalytic ozonation.