Photolysis of benzotriazole and formation of its polymerised photoproducts in aqueous solutions under UV irradiation

Abstract

Environmental context. Benzotriazole is an anti-corrosion agent that is widely applied in various industrial processes and in household products. It has been found persistent in various aquatic environments. Our investigation found that benzotriazole can be rapidly transformed under UV light to form several photoproducts. Photolysis rates decreased with increasing solution pH, whereas salinity had no significant effect. Metal species Cu 2þ and Fe 3þ , and humic acid in aquatic environment could have inhibitory effects on the photolysis of benzotriazole.Abstract. Benzotriazole (BT) is an anti-corrosion agent used widely in some industrial processes and household products, and it has been detected in surface water and ground water due to its high mobility and low biodegradability. We have investigated the photolysis of benzotriazole in aqueous solutions under UV radiation at 254 nm and the effect of pH, salinity, metal species and dissolved organic matter on the photo-transformation processes. Benzotriazole was found to undergo rapid transformation to form several photoproducts. The half-lives for the photolysis of benzotriazole ranged from 2.8 to 14.3 h in various aqueous solutions containing metal ions and dissolved organic matter. Photolysis rates decreased with increasing solution pH, whereas salinity had no significant effect. Metal species Cu 2þ and Fe 3þ , and especially humic acid had inhibitory effects on the photolysis of benzotriazole under UV light irradiation at 254 nm. We propose the formation of three major photoproducts via instantaneous polymerisation of small intermediates generated during the photolysis of benzotriazole including 2,6-diethylaniline, phenazine and 1,6-dihydroxyphenazine.

Enhancement of Micropollutant Degradation at the Outlet of Small Wastewater Treatment Plants

“…Note that these results were obtained with a higher UV energy than used here. Photolysis of BZT in aqueous solutions was reported by Liu et al [65]. In that study, the degradation rate was much lower (half-life was around 2.3 h) than measured in our study (about 5 min), but with different experimental conditions.…”

Photodegradation of the azole fungicide climbazole by ultraviolet irradiation under different conditions: Kinetics, mechanism and toxicity evaluation

“…Because the absence of HA could cause the damage of the iron cycle involving in the photo-reaction [37]. While HA scavenged radicals as light-absorbing species and result in a quenching effect on the reaction system [33,38], so the higher of the HA concentration, the more evident of the inhibitory effects, which was consistent with the previous reports [19,39]. In contrast, a promoting effect of 10 mg/L NO 3 − on the photodegradation of CZ was discovered, which might be caused by the generation of nitrogen reactive species (NRS) and ROS from NO 3 − under the UV-254 nm [40,41].…”

Photodegradation of the azole fungicide fluconazole in aqueous solution under UV-254: Kinetics, mechanistic investigations and toxicity evaluation

“…UV-254 uses a low-pressure mercury lamp emitting at 254 nm, as the most common light source in the photodegradation process. In fact, UV-254 photodegradation has been investigated for the removal of some emerging contaminants such as PPCPs (Benitez et al, 2013;Canonica et al, 2008;Liu et al, 2011;Marotta et al, 2013). In addition, reactive oxygen species (ROS) including singlet oxygen ( 1 O 2 ), superoxide anion radical ðO À$ 2 Þ and even stronger oxidant hydroxyl radical ( OH) can be photogenerated by certain PPCPs (Agrawal et al, 2007;Chen et al, 2008;Ge et al, 2010;Inbaraj et al, 2002), indicating that photodegradation could be a promising technology for the removal of emerging contaminants like fluconazole.…”