Mechanistic study of oxidative removal of bisphenol A by pristine nanocatalyst Mn3O4/peroxymonosulfate

Abstract

• Mn 3 O 4 nanocatalyst showed excellent mineralization of BPA. • 1 O 2 was the dominant reactive oxygen species in BPA degradation. • Oxygen vacancy played a vital role in generation of 1 O 2 . • β-scission reaction was the main transformation pathway for the degradation of BPA. • 13 transformation products were decreased while 4 were increased. In recent years, activation of persulfate via Mn-based composites has gained interest due to extraordinary kinetics and performance for the degradation of organic contaminants. However, the potential of pristine manganese oxides (Mn 3 O 4 ) in removing organic compounds and its mechanism has not been comprehensively explored yet. This study systemically investigated the Mn 3 O 4 based peroxymonsulfate (PMS) activation to effectively mitigate bisphenol A (BPA) in different real water matrixes. Substantial mineralization (75.9%) with efficient removal of BPA (96.7%) has been achieved at optimum conditions in 60 min. A long-term performance, eight cycles of reusability, has shown merely an 11% reduction in BPA removal, highlighted the higher stability of Mn 3 O 4 . The oxidizing contributions of reactive oxygen species (ROS) were in the order of 1 O 2 > O 2 •- > SO 4 •- > • OH. The different water matrixes have influenced BPA degradation by<10%. Linear changes in BPA aromatic contents were recorded using log-transformed ultraviolet (UV) spectra and fluorescence excitation-emission matrix (EEM). Total 17 transformation products (TPs) were detected in Mn 3 O 4 /PMS/BPA system, with 13 decreasing concentrations and 4 TPs in increasing concentration with the β-scission reaction as the main pathway for the degradation of BPA. The toxicity of BPA after degradation was also significantly suppressed measured by the activated sludge inhibition method.