Hydrated electron-based degradation of atenolol in aqueous solution

• eaq− reacted with ATL at a rate constant of 2.3 × 1010 M−1 s−1.
• Effective SO32− concentration was vital for degradation efficiency.
• UV/SO32− process can’t reduce ATL toxicity to a satisfactory level.
• Two attacking ways were involved in the degradation mechanisms.

Photoactivation of SO32− with UV254 irradiation (UV/SO32−) was used to generate hydrated electron (eaq−)-based process to degrade atenolol (ATL) in drinking water. The decontamination mechanism of UV/SO32− process was investigated by means of competitive kinetic analysis and identification of transformation products, followed by the assessment of potential for drinking water treatment through evaluating the influence of operational parameters (dosage of SO32−, solution pH, HCO3−, dissolved organic matters (DOM), and temperature), detoxification efficiency, and technical economy. The kinetic and transformant observations lead to the suggestion that eaq−-induced dissociative electron capture and addition reactions be involved in the ATL degradation mechanism. The results show a positive correlation between the ATL removal efficiency and dosage of SO32− (0.5–2.0 mM). The process is also pH-dependant. Increasing solution pH from 5 to 9 promoted the elimination of ATL due to the pH-dependent SO32− photoactivity. For the pH increase from 9 to 11, deprotonation of ATL caused further enhancement of ATL destruction. 1–4 mM HCO3− exerted little inhibition effect on the ATL destruction, while the presence of 1 and 4 mg L−1 L DOM deteriorate the ATL degradation due to the effective UV fluence decrease. In addition, for every 10 °C the solution temperature rose, the reaction rate increased 1.3–1.6 times. The toxicity evaluation further suggests that ATL degradation and detoxification do not occur simultaneously. Compared to UV/H2O2 or UV/OXONE process, UV/SO32− process was more energy-consuming.