Bisphenol S (BPS), as a main alternative of bisphenol A for the production of industrial and consumer products, is now frequently detected in aquatic environments. In this work, it was found that free chlorine could effectively degrade BPS over a wide pH range from 5-10 with apparent second-order rate constants of 7.6–435.3 M⁻¹s⁻¹. A total of eleven products including chlorinated BPS (i.e., mono/di/tri/tetrachloro-BPS), 4-hydroxybenzenesulfonic acid (BSA), chlorinated BSA (mono/dichloro-BSA), 4-chlorophenol (4CP), and two polymeric products were detected by high performance liquid chromatography and electrospray ionization-tandem quadrupole time-of-flight mass spectrometry. Two parallel transformation pathways were tentatively proposed: (i) BPS was attacked by stepwise chlorine electrophilic substitution with the formation of chlorinated BPS. (ii) BPS was oxidized by chlorine via electron transfer leading to the formation of BSA, 4CP and polymeric products. Humic acid (HA) significantly suppressed the degradation rates of BPS even taking chlorine consumption into account, while negligibly affected the products species. The inhibitory effect of HA was reasonably explained by a two-channel kinetic model. It was proposed that HA negligibly influenced pathway i while appreciably inhibited the degradation of BPS through pathway ii, where HA reversed BPS phenoxyl radical (formed via pathway ii) back to parent BPS.

双酚S（BPS）作为生产工业产品和消费品的双酚A的主要替代品，现在经常在水生环境中被检测到。在这项工作中，发现游离氯可以在5-10的宽pH范围内有效降解BPS，表观二级速率常数为7.6-435.3 M ^-1 s ^-1。总共有11种产品，包括氯化BPS（即一/二/三/四氯BPS），4-羟基苯磺酸（BSA），氯化BSA（一/二氯-BSA），4-氯苯酚（4CP）和两种聚合物产品通过高效液相色谱和电喷雾串联四极杆飞行时间质谱进行检测。初步提出了两个平行的转化途径：（i）BPS受到逐步氯亲电取代并形成氯化BPS的攻击。（ii）BPS通过电子转移被氯氧化，导致形成BSA，4CP和聚合物产品。腐殖酸（HA）即使考虑了氯的消耗，也能显着抑制BPS的降解速率，而对产品种类的影响可忽略不计。通过两通道动力学模型合理地解释了HA的抑制作用。有人提出，HA对途径i的影响可忽略不计，而通过途径ii则明显抑制了BPS的降解，其中HA使BPS苯氧基（通过途径ii形成）逆转回到了母体BPS。