Study on the catalytic performance of LaMnO3 for the RhB degradation

LaMnO3 nanoparticles were synthesized by citric acid complex sol-gel method and used to degrade rhodamine B (RhB) in water. The effects of initial pH value, LaMnO3 dosage, RhB concentration and disrupter agents on the degradation of RhB were investigated. We found that LaMnO3 exhibits an excellent degradation ability of RhB in high acidic conditions without additional oxidants or light irradiation and can achieve 99.7% degradation efficiency for RhB and 65.8% for total organic carbon. This result showed that LaMnO3 itself provides an effective oxidative system to degrade RhB. Furthermore, a reasonable degradation pathway of RhB was proposed, including N-de-ethylation, chromophore cleavage, opening-ring, and mineralization. Finally, LaMnO3 samples before and after the reaction were characterized by X-ray diffraction and X-ray photoelectron spectroscopy. It is found that LaMnO3 can maintain perovskite structure in the degradation of RhB. Mn ions in LaMnO3 provides active center and plays a role of electron transfer during RhB degradation.