Efficient peroxymonosulfate activation by Aurivillius phase Bin+1Fen-3Ti3O3n+3(n = 4, 5, 6) for wastewater purification

Abstract

Aurivillius phase layered perovskites, Bin+1Fen-3Ti3O3n+3(n = 4, 5, 6), have been deemed as promising photocatalysts for degrading organic pollutants in wastewater. However, the inferior photocatalytic performance has greatly limited its application. Here, Bin+1Fen-3Ti3O3n+3 (n = 4, 5, 6) nano-shelves were fabricated and applied as heterogeneous photocatalysts in peroxymonosulfate (PMS) activation for tetracycline hydrochloride degradation. Compared with Bin+1Fen-3Ti3O3n+3(n = 4, 5, 6), the Bin+1Fen-3Ti3O3n+3(n = 4, 5, 6)/PMS system demonstrated an excellent enhancement for tetracycline hydrochloride removal under visible light illumination. Among the synthesized photocatalysts, Bi7Ti3Fe3O21/PMS showed the highest catalytic activity, with the calculated kinetic constant reaching as high as 0.0394 min−1, which was about 78.8 higher than that of Bi7Ti3Fe3O21. The improved tetracycline hydrochloride degradation performance of Bi7Ti3Fe3O21/PMS is attributed to the presence of abundant oxygen vacancies in Bi7Ti3Fe3O21, which can not only boost the separation of electron-hole pairs but also facilitate PMS activation and radical generation. Besides, the scavenging experiments and electron spin resonance analysis showed that sulfate radicals, superoxide radicals, hydroxyl radicals, and holes could effectively degrade tetracycline hydrochloride. Overall, these findings are beneficial for understanding the mechanism of PMS activation by Aurivillius phase layered perovskites-based catalysts and are helpful for the practical application of sulfate-based technology for wastewater purification.