Enhanced activation of peroxymonosulfate by Sr-doped LaFeO3 perovskite for Orange I degradation in the water

A-site doping of perovskite has been considered to be an effective method to simultaneously boost catalytic performance and limit metal release in heterogeneous catalysis. Herein, various Sr-doped LaFeO3 perovskites (La1-xSrxFeO3-delta) were synthesized and evaluated as a heterogeneous catalyst to activate peroxymonosulfate (PMS) for the degradation of Orange I (OI) in water. Specifically, La0.6Sr0.4FeO3-delta (LSFO-40) exhibited a remarkable improvement in catalytic activity with a k constant of 0.0411 min(-1), which was approximately 3 times higher than that of LaFeO3 (0.0142 min(-1)). The superior stability was obtained with less metal leaching after Sr doping. Such enhancement was mainly attributed to the modified surface properties created by Sr doping, such as a rapid transformation of Fe(II)/Fe(III) redox pair, a large number of oxygen vacancies and surface hydroxyl groups, additionally, the strong interaction between PMS and Fe sites and facilitated electron transfer for PMS activation catalyzed by LSFO-40 also stimulated OI degradation. These also promoted the generation of a considerable amount of superoxide radical (O-2(center dot-)) and singlet oxygen (O-1(2)), which was tested as the main reactive oxygen species (ROSs). The synergistic effect of iron and oxygen species ensured a continuous ROSs generation and excellent catalytic performance. Finally, neither a wide pH range of 5.0-9.0 or co-existing anions (Cl and HCO3) showed a negligible inhibitory effect on OI removal, implying a great potential application of the LSFO-40/PMS system in practical wastewater treatment.

Automated summary

A-site doping of perovskite with Sr in LaFeO3 perovskites enhanced catalytic activity and stability, leading to improved PMS activation and Orange I degradation. The modified surface properties resulted in efficient electron transfer and ROS generation, ensuring continuous catalytic performance. LSFO-40 showed great potential for practical wastewater treatment with negligible inhibitory effects under a wide pH range and co-existing anions.