Aqueous phototransformation of bisphenol S: the competitive radical-attack pathway to p-hydroxybenzenesulfonic acid.

The kinetics, environmental influencing factors, products and reaction mechanism of aqueous phototransformation of bisphenol S (BPS), as an alternative to bisphenol A, which is of environmental concern, were investigated. p-Hydroxybenzenesulfonic acid, as the major transformation product was confirmed by gas chromatography - mass spectrometry, electrospray ionization, ¹H nuclear magnetic resonance and fluorescence spectrum analysis. A reaction pathway was proposed based on the reactive oxygen species related results by electron paramagnetic resonance and radical traps. The competition of the excited state of BPS between transferring electron to O₂ to •O₂(-) and directly oxidizing H₂O to •OH was revealed.