Degradation of 17 Benzodiazepines by the UV/H2O2 Treatment

Abstract

Benzodiazepines are one group of psychoactive drugs widely detected in water environments, and their persistence during conventional wastewater treatment has raised great concerns. Here we investigated the degradation of 17 benzodiazepines in water by UV/H2O2 treatment. The results showed that the UV/H2O2 treatment significantly increased the degradation of 17 benzodiazepines in phosphate buffer solutions at pH 7.0. This can be attributed to the high reactivity of hydroxyl radicals (·OH) towards benzodiazepines with second-order rate constants of 3.48 × 109 M−1 s−1–2.44 × 1010 M−1 s−1. The degradation of alprazolam, a typical benzodiazepine, during the UV/H2O2 treatment was increased with the increasing H2O2 dosage. The solution pH influenced the alprazolam degradation significantly, with the highest degradation at pH 7.0. Water matrix, such as anions (Cl−, HCO3−, NO3−) and humic acid, decreased the degradation of alprazolam by UV/H2O2 treatment. Based on the degradation products identified using quadrupole time-of-flight mass spectrometer, the degradation mechanisms of alprazolam by UV/H2O2 treatment were proposed, and hydroxylation induced by ·OH was the main reaction pathway. The degradation of 17 benzodiazepines by UV/H2O2 treatment in wastewater treatment plant effluent and river water was lower than that in phosphate buffer solutions. The results showed that the benzodiazepine psychoactive drugs in natural water can be effectively removed by the UV/H2O2 treatment.

Solvothermally Grown Oriented WO3 Nanoflakes for the Photocatalytic Degradation of Pharmaceuticals in a Flow Reactor

“…The possible degradation pathway and photoproduced intermediates are shown in Scheme 3. As reported in other studies[52][53][54], where molecules such as alprazolam, which has similar structural characteristics as OZ and also belongs to the same benzodiazepine class, are inves-…”

“…The possible degradation pathway and photoproduced intermediates are shown in Scheme 3. As reported in other studies [52][53][54], where molecules such as alprazolam, which has similar structural characteristics as OZ and also belongs to the same benzodiazepine class, are inves-tigated, it is hypothesized that the degradation of OZ may be mediated by photoproduced OH radicals as well. From the HPLC/MS analysis, hydroxylated intermediates were, in fact, identified, indicating the attack of OH radicals (pathway A) on the aromatic ring to form the products ia and ib.…”

Degradation of Diazepam with Gamma Radiation, High Frequency Ultrasound and UV Radiation Intensified with H2O2 and Fenton Reagent

“…% M = −9. 24 From the model the response surface and the isoline curves (Figure 4) of the mineralization were constructed as a function of H 2 O 2 and Fe 2+ concentrations. The mineralization reaches a maximum higher than 22.5% for values ranging from 3.6 mmol L −1 to 5.0 mmol L −1 for H 2 O 2 , progressively decreasing with the increase of the catalyst.…”

“…For the degradation of DZP in aqueous medium, some studies report the use of ozone [18], ultraviolet (UV) radiation, and its combination with oxidizing agents [6,[22][23][24]. However, the most studied AOPs for drug degradation in water use gamma radiation and high frequency ultrasound intensified with H 2 O 2 and Fenton reagent [25,26].…”