Degradation of β2-adrenoceptor agonists salbutamol and terbutaline by UV-activated persulfate

Abstract

SSCI-VIDE+ATARI+LZO:CFE:JMCInternational audienceThis work investigated the degradation reactivity and mechanisms of salbutamol (SAL) and terbutaline (TBL), two typical β2-adrenoceptor agonists by using persulfate (PS) activated bysimulated solar light. Our results indicated that UV/PS could remove these two target compounds efficiently, more than 94% of SAL and TBL could be decomposed within 2h. The quenching experiment suggested that SO4•− was the dominant reactive species in the oxidation process. The second-order rate constant of sulfate radical with SAL and TBL was calculated as (3.7 ± 0.3) × 109 and (4.2 ± 0.3) × 109 M-1 s-1 by using laser flasher photolysis (LFP), respectively. The results also revealed that basic conditions inhibited the decomposition of SAL and TBL, while, increasing PS dose enhanced the degradation. Reaction pathways and mechanisms were proposed based on products identification using high resolution HPLC-ESI-MS, LFP and molecular orbital calculations. For both of the target compounds, phenoxyl radicals were found to play key roles in the orientation of the primary pathways. For SAL, a benzophenone derivative was generated by oxidation of the phenoxyl radical. However, the transformation of the phenoxyl radical into benzoquinone was impossible for TBL. Instead, the addition of –OSO3H on the aromatic ring was the major pathway. The same reactivity pattern was observed in TBL structural analogs resorcinol and 3,5-dihydroxybenzyl alcohol. The present work indicated that UV/PS oxidation method could be a promising approach in the removal of β2-adrenoceptor agonists and related pharmaceuticals. Moreover, it could also help for a better understanding of the difference in oxidation reactivity of substituted phenols widely present in natural waters