Direct and indirect photolysis of triclocarban in the presence of dissolved organic matter

Abstract

Photolysis is an important attenuation pathway for the removal of wastewater effluent organic micropollutants from surface waters. In this work, direct and indirect processes leading to the degradation of the disinfectant, triclocarban were studied. Photo-irradiation experiments were conducted in water collected from Old Woman Creek (OWC) a tributary of Lake Erie near Huron, OH, USA and in solutions of fulvic acids isolated from the Suwannee River, Georgia, USA (SRFA), Old Woman Creek (OWCFA) and Pony Lake, Antarctica (PLFA). Photodegradation of triclocarban proceeded faster in the presence of all three fulvic acids relative to deionized water. PLFA, an autochthonous dissolved organic matter (DOM) was found to be more reactive than the other fulvic acids, while the mostly allochthonous SRFA exhibited the lowest reactivity toward triclocarban. The later observation can be in part explained by anti-oxidant moieties present in SRFA. Photosensitized triclocarban degradation in whole water DOM from OWC was entirely attributable to the fulvic acid fraction and suggests that this component is the most photo-reactive fraction of the DOM. Anoxic and methanol-quenched experiments revealed unexpected results whereby the former suggests oxidation through reaction with triplet DOM, while the later is indicative of reaction with photogenerated hydroxyl radicals. It is possible that methanol can quench excited DOM species, which would shut down the triplet oxidation pathway. Finally, we observed no enhancement of triclocarban-photosensitized degradation through the addition of iron.

Modeling and Experimental Studies on Adsorption and Photocatalytic Performance of Nitrogen-Doped TiO2 Prepared via the Sol–Gel Method

“…In addition to adsorption and photocatalysis, some organic contaminants can undergo direct photolysis under light irradiation without photocatalyst, denoted as path 3 in Figure 1. For example, tricholocarbon (TCC), a disinfectant [23], and β-blocker as a pharmaceutical ingredient [24], can be efficiently degraded via direct photolysis under sunlight. In practice, adsorption, photocatalysis, and direct photolysis occur simultaneously.…”

Photodegradation and photocatalysis of per- and polyfluoroalkyl substances (PFAS): A review of recent progress

“…The reaction rate constant for PFOA degradation was reported as 0.0295 min −1 at pH=10, about 49 times higher than that at pH-5. Thus, initial pH conditions increased the concentration of hydrated electrons and supported the reductive mineralization of PFAS in a homogeneous catalytic system [ 92 ]. This section discusses the role of nanocomposites and microparticle-based photocatalysis.…”

Photolysis- and Dissolved Organic Matter-Induced Toxicity of Triclocarban to Daphnia magna

“…The photolysis of triclosan (TCS), a similar antimicrobial compound, has been extensively studied because it photodegrades into potentially toxic photoproducts, including chlorophenols and dioxin congeners, − TCC has garnered much less attention. Guerard et al and Trouts and Chin reported significant indirect photolysis mediated by dissolved organic matter (DOM), and only one study has identified photochemically derived products (4-chloroaniline, 3,4-dichloroaniline, 4-chlorophenyl isocyanate, and 3,4-dichlorophenyl isocyanate) after photolysis . Nonetheless, to date, there have been no studies that have examined the toxicity of TCC photoproducts on aquatic organisms and only one that we are aware of for triclosan .…”