T:Toxic;
120-83-2Relevant articles and documents
Electrooxidation of phenol on a Ti/RuO2 anode: Effect of some electrolysis parameters
Dos Santos, Iranildes D.,Afonso, Ju?lio C.,Dutra, Achilles J. B.
, p. 875 - 883 (2011)
The influences of electrolysis time, anodic area, current density and supporting electrolyte on phenol and its byproducts degradation on a Ti/RuO 2 anode were investigated. It was observed that phenol and its byproducts were rapidly broken down in the presence of chloride ions. Gas chromatography/mass spectrometry (GC/MS) data have shown that the presence of chloride ions lead to chlorophenols formation, due to reactions with Cl 2. and/or OCl generated during electrolysis. However, these intermediate products were also degraded later by the oxidizing agents. The standards established by the CONAMA (Brazilian National Council for the Environment) for phenols and chlorophenols in effluents were achieved after 360 min of electrolysis with a current density of 10 mA cm-2. Cyclic voltammograms obtained with the anodes before and after 436 h of electrolysis under severe salinity conditions (2 mol L-1) and current density (800 mA cm-2) showed that Ti/RuO2 did not lose its electrocatalytic properties. This fact indicates that Ti/RuO2 can be used for the treatment of effluents containing phenols in a chloride environment.
Rh-catalyzed direct synthesis of 2,2′-dihydroxybenzophenones and xanthones
Rao, Maddali L. N.,Ramakrishna, Boddu S.
, p. 75505 - 75511 (2016)
An efficient rhodium-catalyzed direct synthesis of 2,2′-dihydroxybenzophenones and xanthones was developed from functionalized salicylaldehydes. This approach provides an easy access to various functionalized 2,2′-dihydroxybenzophenone and xanthone core s
Spectral and GC-MS analysis of phototransformation of herbicides in water
Chaikovskaya,Sokolova,Karetnikova,Mal'Kov,Kuz'Mina
, p. 396 - 401 (2009)
The phototransformation of 2,4-dichlorophenoxyacetic and 2-methyl-4-chlorophenoxyacetic acids in water was studied using the KrCl*(λrad 222 nm) and XeBr*(λrad 283 nm) excilamps as UV radiation source.
Kinetics of heterogeneous photocatalytic decomposition of 2,4-dichlorophenoxyacetic acid over titanium dioxide and zinc oxide in aqueous solution
Djebbar,Sehili
, p. 269 - 276 (1998)
The photocatalytic transformation of 2,4-D in aqueous solution containing a suspension of titanium dioxide or zinc oxide leads to the formation of intermediates which are totally mineralised to carbon dioxide and hydrogen chloride (2,4-dichlorophenol and chlorohydroquinone are the major intermediates). The products at the initial stage of the reaction were 2,4-dichlorophenol (2,4-DCP), chlorohydroquinone, 4-chloropyrocatechol, 2,4-dichloro-pyrocatechol and 1.4-chlorobenzoquinone. The initial rate of photodegradation was studied as a function of the initial concentration of reactants by the linearised form of the Langmuir-Hinshelwood equation, by which rate constants κ and equilibrium adsorption constants K were evaluated. These constants were calculated at different temperatures between 25 and 60°C. The photodegradation rate increased with increase of pH. The photocatalytic transformation of 2,4-D over titanium dioxide or zinc oxide in solution containing hydrogen peroxide was studied. The latter accelerated the reaction rate of 2,4-D significantly. It was found that chloride or bicarbonate ions slowed down the photo-degradation rate of 2,4-D by scavenging hydroxyl radicals. Partial inhibition by ethanol is attributed to scavenging of the OH radicals involved in the first step of the reaction.
Frequent occurrence of triclosan hydroxylation in mammals: A combined theoretical and experimental investigation
Zhang, Hongna,Sanidad, Katherine Z.,Zhu, Lin,Parsonnet, Julie,Haggerty, Thomas D.,Zhang, Guodong,Cai, Zongwei
, (2021)
Triclosan (TCS) is a widespread antimicrobial agent with many adverse health risks. Its hepatoxicity invariably points to the activation of constitutive androstane receptor (CAR), which regulates cytochrome P450 (CYP) genes that are critical for oxidative metabolism. Here, we provide the theoretical and experimental evidences showing that metabolic activation of TCS frequently occurs through aromatic hydroxylation in mammals. CYP-mediated oxidation was predicted to take place at each aromatic C?H bond. Molecular docking and in vitro approaches reveal oxidative reaction could be efficiently catalyzed by CAR-regulated CYP2B6 enzyme. Parallel reaction monitoring (PRM) high-resolution mass spectrometry was utilized to identify and profile TCS oxidative metabolites in paired mouse liver, bile, feces, plasma and urine. We found multiple hydroxylated isomers including the products generated via the NIH shift of chlorine, as well as their subsequent conjugates. These metabolites showed isomer-specific retention in mice. Glucuronide conjugates are more readily excreted than the sulfates. Moreover, for the first time, isomeric hydroxylated metabolites were detected in the urine and stool of human subjects used TCS-contained household and personal care products. Collectively, these findings suggest that hydroxylation is an important, yet often underestimated element that worth considering to fully evaluate the biological fates and health risks of TCS.
Rate enhancement by cations in supercritical water oxidation of 2- chlorophenol
Lin, Kuen-Song,Wang, H. Paul
, p. 3278 - 3280 (1999)
Interactions between cations and Cl species in the supercritical water oxidation (SCWO) of 2.-chlorophenol (2CP) has been investigated in a high- pressure quartz-lined reactor at 673-773 K. Experimentally, we found that the S/D ratio (defined as the amount of 2CP converted to CO2 and H2O/disappearance of 2CP) for SCWO of 2CP was enhanced by cations (such as Li+, Na+, K+, Ca2+, Fe2+, or Fe3+). The S/D ratio increased as the charge density of cations increased (Fe3+> Fe2+ > Li+ > Ca2+ > Na+ > K+). Due to the extremely low solubility of metal salts in the supercritical water, abstraction of Cl in 2CP via an intermediate ((OH)PhCl(δ-)---- M(δ+) was postulated. Formation of these metal chloride (such as KCl, CaCl2, and FeCl3) precipitates in the SCWO of 2CP were identified by X-ray diffraction (XRD) spectroscopy. Since the formation of toxic highly chlorinated phenols and heavy polycyclic aromatic hydrocarbons (PAHs) was notably reduced, abstraction of Cl of 2CP by cations may occur in the early stage of the SCWO process. Interactions between cations and Cl species in the supercritical water oxidation (SCWO) of 2-chlorophenol (2CP) has been investigated in a high-pressure quartz-lined reactor at 673-773 K. Experimentally, we found that the S/D ratio (defined as the amount of 2CP converted to CO2 and H2O/disappearance of 2CP) for SCWO of 2CP was enhanced by cations (such as Li+, Na+, K+, Ca2+, Fe2+, or Fe3+). The S/D ratio increased as the charge density of cations increased (Fe3+>Fe2+>Li+>Ca2+ >Na+>K+). Due to the extremely low solubility of metal salts in the supercritical water, abstraction of Cl in 2CP via an intermediate ((OH)PhClδ-- - - - -Mδ+) was postulated. Formation of these metal chloride (such as KCl, CaCl2, and FeCl3) precipitates in the SCWO of 2CP were identified by X-ray diffraction (XRD) spectroscopy. Since the formation of toxic highly chlorinated phenols and heavy polycyclic aromatic hydrocarbons (PAHs) was notably reduced, abstraction of Cl of 2CP by cations may occur in the early stage of the SCWO process.
Sensitized photooxidation of triclosan pesticide. A kinetic study in presence of vitamin B2
Reynoso, Agustina,Possetto, David,De Gerónimo, Eduardo,Aparicio, Virginia C.,Natera, José,Massad, Walter
, (2021)
Kinetic and mechanistic aspects of Riboflavin (Rf, vitamin B2)-sensitized photochemical degradation of Triclosan (TCS) have been studied by time-resolved and stationary techniques. TCS is a broadly-used biocide, also employed in a series of industrial products as a multifunctional additive. Rf, in the presence of light and oxygen, generates singlet molecular oxygen (O2(1Δg)) and superoxide radical anion (O2[rad]–). Results indicate that TCS quenches the triplet excited state of Rf (3Rf*), O2(1Δg), and O2[rad]–. The reactive rate constant for the interaction TCS-O2(1Δg) is 62-faster in alkaline medium with respect to pH 7. Photosensitized degradation of TCS by Rf was much faster than for phenol, a model pollutant, in similar conditions of pH. Kinetic analysis indicated that the reaction of TCS with 3Rf* and/or O2[rad]– is the prevailing oxidative route. Based on the environmental importance of the TCS, the products were determined by UHPLC-MS / MS analysis.
The role of UV-irradiation pretreatment on the degradation of 2,4-dichlorophenoxyacetic acid in water
Tchaikovskaya,Sokolova,Mayer,Karetnikova,Lipatnikova,Kuzmina,Volostnov
, p. 156 - 161 (2011)
The degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in water by the combination process of UV-irradiation, humic acids and activated sludge treatment has been studied. The photoreaction rate of all irradiated samples was lowest for the sample irradiated at 308 nm (the XeCl excilamp) in the absence and in the presence of humic acids, and highest for the sample irradiated at 222 nm (the KrCl excilamp). Photolysis of 2,4-D has been shown to enhance the subsequent microbial degradation. Copyright
2,4-dichlorophenoxyacetic acid detection using 2,4- dichlorophenoxyacetic acid α-ketoglutarate dioxygenase
Yongxiang Gu,Knaebel,Korus,Crawford
, p. 1622 - 1627 (1995)
2,4-dichlorophenoxyacetic acid (2,4-D) is possibly the most widely used herbicide. Although not very toxic, cleanup of an inadvertant spill is still necessary. This phenoxy herbicide is degraded by several micro-organisms and bioremediation processes have been proposed. Analytical support for these cleanup techniques usually involves gas chromatography or immunoassays, which are moderately (ELISA assays) to very (GC/MS) expensive. Therefore, it is important to develop a quick, inexpensive, and easy-to-use 2,4-D detection method for use in the field by nonspecialists. Reported here is the construction of a detection plasmid, its introduction into Escherichia coli DH5α, and the application of cell-free extracts of this organism to highly specific 2,4-D detection. -from Authors
Synthesis of nitrogen-doped ZnO by sol-gel method: Characterization and its application on visible photocatalytic degradation of 2,4-D and picloram herbicides
Macías-Sánchez,Hinojosa-Reyes,Caballero-Quintero,De La Cruz,Ruiz-Ruiz,Hernández-Ramírez,Guzmán-Mar
, p. 536 - 542 (2015)
In this work, nitrogen-doped ZnO material was synthesized by the sol-gel method using zinc acetate as the precursor and urea as the nitrogen source (15, 20, 25 and 30% wt.). For comparative purposes, bare ZnO was also prepared. The influence of N doping on structural, morphological, optical and photocatalytic properties was investigated. The synthesized catalysts were characterized by XRD, SEM-EDS, diffuse reflectance UV-Vis spectroscopy, BET and XPS analysis. The photocatalytic activity of N-doped ZnO catalysts was evaluated during the degradation of a mixture of herbicides (2,4-D and picloram) under visible radiation ≥400 nm. The photo-absorption wavelength range of the N-doped ZnO samples was shifted to longer wavelength compared to those of the unmodified ZnO. Among different amounts of dopant agent, the 30% N-doped ZnO material showed higher visible-light activity compared with pure ZnO. Several degradation by-products were identified by using HPLC and ESI-MS/MS. The enhancement of visible photocatalytic activity of the N-doped ZnO semiconductor could be mainly due to their capability in reducing the electron-hole pair recombination. This journal is
