This study investigates the oxidation of pharmaceuticals during conventional ozonation and advanced processes (AOPs) applied in drinking water treatment. In a first step, second-order rate constants for reactions selected with ozone (kO3) OH radicals (kOH) were determined bench-scale experiments (in brackets apparent kO3 at pH 7 T = 20 °C): bezafibrate (590 ± 50 M-1 s-1), carbamazepine (∼3 × 105 diazepam (0.75 0.15 diclofenac (∼1 106 17α-ethinylestradiol ibuprofen (9.6 1.0 iopromide (<0.8...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransformation Kinetics of Phenols in Water: Photosensitization by Dissolved Natural Organic Material and Aromatic KetonesSilvio. Canonica, Urs. Jans, Konrad. Stemmler, Jurg. HoigneCite this: Environ. Sci. Technol. 1995, 29, 7, 1822–1831Publication Date (Print):July 1, 1995Publication History Published online1 May 2002Published inissue 1 July 1995https://pubs.acs.org/doi/10.1021/es00007a020https://doi.org/10.1021/es00007a020research-articleACS...

Dissolved organic matter (DOM) has recently been shown to reduce the transformation rate of various aqueous contaminants submitted oxidation by excited triplet states, apparently inhibiting intermediates. The main goals present study were evaluate in more detail effect concentration and type DOM on triplet-induced four selected compounds check for an analogous inhibition case induced hydroxyl radical. A marked was observed N,N-dimethylaniline (DMA) two antibiotics sulfamethoxazole (SMX)...

Carbonate radical (CO3•-) is a powerful oxidant that present in sunlit surface waters and treated by advanced oxidation processes. The production of CO3•- aqueous solution through carbonate anion excited triplet states aromatic ketones was investigated this study to provide new methods for the determination rate constants explore possible photoinduced pathway formation aquatic environment. Rate quenching up 3.0 × 107 M-1 s-1 yields approaching unity, determined using laser flash photolysis,...

In water treatment dissolved organic matter (DOM) is typically the major sink for chemical oxidants. The resulting changes in DOM, such as its optical properties have been measured to follow oxidation processes. However, measurements contain only limited information on states of and reactive moieties DOM. this study, we used mediated electrochemical quantify electron donating capacities (EDCs), hence redox states, three different types DOM during with chlorine dioxide (ClO2), (as HOCl/OCl–),...

The photochemical properties of dissolved organic matter (DOM) have been interest to scientists and engineers since the 1970s. Upon light absorption, chromophoric DOM (CDOM) can sensitize formation different short-lived reactive intermediates (RIs), including hydroxyl radical (•OH), singlet oxygen (1O2) superoxide anion (O2•-). In addition, a fraction excited states in CDOM decays into triplet (3CDOM*), which are also important transients environmental systems. These RIs significant impact...

Aromatic ketones efficiently mediate the photo-oxidative degradation of phenols in aerated aqueous solution, a process likely to be relevant sunlit natural waters. Absolute bimolecular rate constants for quenching three model ketone triplets by nine bearing various substituents, from electron-donating alkyl and alkoxy groups electron-withdrawing cyano group, were measured nanosecond laser flash photolysis. Triplet benzophenone (BP) is quenched at nearly diffusion-controlled rates (2.6−5.6 ×...

The phototransformation of the widely used biocide triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) was quantified for surface waters using artificial UV light and sunlight irradiation. pH waters, commonly ranging from 7 to 9, determines speciation (pKa = 8.1) therefore its absorption sunlight. Direct anionic form with a quantum yield 0.31 (laboratory conditions at 313 nm) identified as dominant photochemical degradation pathway triclosan. Combining parameters actual meteorological data...

Recent studies have shown that dissolved organic matter (DOM) may inhibit the excited triplet-induced oxidation of several aromatic water contaminants, in particular those containing an aniline functionality. Such inhibition was ascribed to antioxidant moieties DOM. The present study conducted with aim verifying whether well-defined antioxidants could act as inhibitors analogy Various substituted phenols exhibiting character were able, at micromolar concentration, slow down photoinduced...

Different Swiss freshwater samples spiked with 3,4-dimethoxyphenol (DMOP) or 2,4,6-trimethylphenol (TMP) were irradiated using UV-A and visible light from a medium-pressure mercury lamp. The kinetics of depletion both phenols at pH 8 revealed that in almost all the probe disappeared more rapidly 0.1 microM than 5 initial concentration. Pseudo-first-order rate coefficients on average 2-3 times greater lower phenol A comparable effect was observed buffered solutions Suwannee River fulvic acid,...

UV/H2O2 processes can be applied to improve the quality of effluents from municipal wastewater treatment plants by attenuating trace organic contaminants (micropollutants). This study presents a kinetic model based on UV photolysis parameters, including absorption rate and quantum yield, hydroxyl radical (·OH) oxidation second-order constants for ·OH reactions steady-state concentrations, that used predict micropollutant abatement in wastewater. The successfully predicted efficiencies 16...

The developments of the last fifteen years in field triplet-induced degradation aquatic organic contaminants are reviewed. There is increasing evidence that elusive excited triplet states colored dissolved natural matter (CDOM) initiate oxidative various contaminants. To date, phenols, phenylurea herbicides, and sulfonamide antibiotics have been shown to be affected by such an oxidation. parallel study aqueous oxidation target induced aromatic ketones, taken as model systems, has useful...

Excited triplet states of aromatic ketones and quinones are used as proxies to assess the reactivity excited dissolved organic matter ((3)DOM*) in natural waters. (3)DOM* crucial transients environmental photochemistry responsible for contaminant transformation, production reactive oxygen species, potentially photobleaching DOM. In recent photochemical studies aimed at clarifying role DOM an inhibitor triplet-induced oxidations contaminants, have been presence DOM, question a possible...

Dissolved organic matter (DOM) is both a promoter and an inhibitor of triplet-induced contaminant oxidation. This dual role was systematically investigated through photochemical experiments with three types DOM terrestrial aquatic origins that were preoxidized to varying extents by ozonation. The inhibitory effect assessed determining the 4-carboxybenzophenone photosensitized transformation rate constants two sulfonamide antibiotics (sulfamethoxazole sulfadiazine) in presence untreated or...

For many important classes of pesticides including phenylurea herbicides (PUHs) and triazines, photosensitized transformation may be the only relevant elimination process in surface waters. In this study, dissolved organic matter (DOM) mediated phototransformation PUHs has been investigated laboratory field experiments. The results indicate that, waters, significant occurs primarily by an initial one-electron oxidation most likely involving excited triplet states DOM (3DOM*) constituents....

Excited triplet states of dissolved natural organic matter (DOM) are important players for the transformation chemical contaminants in sunlit waters. The present study focuses on kinetics and mechanistic aspects phenylurea herbicides induced by well-defined excited states, which have been chosen to model DOM having oxidative character. aromatic ketones benzophenone, 3'-methoxyacetophenone, 2-acetonaphthone were used photogenerate their oxidize a series eleven substituted phenylureas....