Non-radical activation of peroxymonosulfate by iron–chitosan carbonization composites for selective bisphenol A degradation: Focusing on singlet oxygen and iron–oxo species

The contamination of emerging organic contaminants (EOCs) in natural waters poses a serious threat to environmental and public health. Advanced oxidation processes (AOPs) based on non-radical reactive species are considered the mainstream methods for degrading EOCs. However, the catalysts used for oxidant activation often suffer from elaborate synthesis, poor stability and low selectivity. Herein, a one-pot carbonization of chitosan–FeCl 3 complexes was designed to yield Fe/Fe 3 O 4 -embedded graphitic carbon (FC900) catalyst. This catalyst was capable of activating peroxymonosulfate (PMS) for selective degradation of bisphenol A (BPA). The FC900/PMS system removed 97.8 % BPA within 40 min with a rate constant k of 0.09 min −1 , which was nine times faster than that by nano-Fe 3 O 4 /PMS. Singlet oxygen and high-valent iron-oxo species were identified as the primary reactive species with negligible •OH/SO 4 - • contribution, demonstrating a non-radical reactive species-dominated degradation process. The system showed excellent tolerance to interference from common anions and natural organic matter, and could be reused for five cycles. It achieved an oxidant utilization efficiency of 0.33 mg BPA per mg PMS, among the best surveyed PMS activator systems to date. The results provide insight into developing simple, stable and efficient catalysts for the treatment of EOCs in complex environment.