Degradation and toxicity of bisphenol A and S during cold atmospheric pressure plasma treatment

Bisphenols are widely recognised as toxic compounds that potentially threaten the environment and public health. Here we report the use of cold atmospheric pressure plasma (CAP) to remove bisphenol A (BPA) and bisphenol S (BPS) from aqueous systems. Additionally, methanol was added as a radical scavenger to simulate environmental conditions. After 480 s of plasma treatment, 15–25 % of BPA remained, compared to > 80 % of BPS, with BPA being removed faster (-kt = 3.4 ms−1, half-life = 210 s) than BPS (-kt = 0.15 ms−1, half-life 4700 s). The characterisation of plasma species showed that adding a radical scavenger affects the formation of reactive oxygen and nitrogen species, resulting in a lower amount of ˙OH, H2O2, and NO2- but a similar amount of NO3-. In addition, a non-target approach enabled the elucidation of 11 BPA and five BPS transformation products. From this data, transformation pathways were proposed for both compounds, indicating nitrification with further cleavage, demethylation, and carboxylation, and the coupling of smaller bisphenol intermediates. The toxicological characterisation of the in vitro HepG2 cell model has shown that the mixture of transformation products formed during CAP is less toxic than BPA and BPS, indicating that CAP is effective in safely degrading bisphenols. [Display omitted] •CAP is capable of removing >75% BPA and >48% BPS from water in 480 s.•Addition of a radical scavenger affects BPA/BPS degradation and formation of RONS.•Novel transformation products/pathways of BPA/BPS elucidated.•Transformation products have lower combined toxicity than parent compounds.•CAP has the potential to be an effective water treatment technology.