Reactivity of novel Ceria–Perovskite composites CeO2- LaMO3 (MCu, Fe) in the catalytic wet peroxidative oxidation of the new emergent pollutant ‘Bisphenol F’: Characterization, kinetic and mechanism studies

Abstract

In the present study, ceria, pristine perovskites LaMO3 (Cu, Fe) and novel ceria-perovskite composites CeO2-LaMO3 were successfully prepared and applied as heterogeneous Fenton like- catalysts for the degradation and mineralization of a new emergent compound- bisphenol F (BPF) in aqueous solution. The catalysts were characterized by X-ray diffraction spectrometer (XRD), BET surface area determination, scanning electron microscopy (SEM), Energy Dispersive X-ray (EDS) and X-ray photoelectron spectroscopy (XPS) techniques. Catalytic bisphenol F behavior shows that the activity of pristine perovskites was improved due to the introduction of cerium. Catalytic activity in terms of TOC removal followed the order of CeO2-LaCuO3>CeO2-LaFeO3>LaCuO3>LaFeO3>CeO2 with about 83, 79, 68, 64 and 28% respectively. Only the novel composite oxide CeO2-LaCuO3 was found to be effective for Bisphenol F degradation at neutral conditions. EPR analyses and scavenging experiments revealed that BPF was mainly decomposed by the attack of OH, especially the surface-bounded OH. BPF decay followed pseudo-first-order reaction kinetics. The absolute rate constant for BPF oxidation by OH was found to 2.09109M−1s−1, as determined by the competition kinetic method. Six stable organics intermediates were observed and five of them were identified p-benzoquinone, hydroquinone, 4-hydroxybenzaldehyde and Bis (4-hyroxyphenyl) methanol. Subsequent attack of these intermediates by OH radicals led to the formation of short chain acids: malonic, succinic, acetic, formic and oxalic acids. On the basis of the analytical results for the intermediate products and the assumption that hydroxyls radicals are the major reactive species, a plausible pathway of BPF mineralization during the heterogeneous Fenton process was proposed. Furthermore, the CeO2-LaCuO3 composite exhibited excellent long-term stability in the heterogeneous Fenton-like process. These results suggested that the novel ceria perovskite material would be a promising candidate for practical wastewater treatment.