Degradation of UV filters 2-ethylhexyl-4-methoxycinnamate and 4-tert-butyl-4'-methoxydibenzoylmethane in chlorinated water

2013 ◽  
Vol 10 (2) ◽  
pp. 127 ◽  
Author(s):  
A. Joel M. Santos ◽  
Diana M. A. Crista ◽  
Margarida S. Miranda ◽  
Isabel F. Almeida ◽  
José P. Sousa e Silva ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Rate Constant ◽  
Half Life ◽  
Chlorine Concentration ◽  
Solar Irradiation ◽  
Uv Filters ◽  
Tert Butyl ◽  
The Stability ◽  
By Products

Environmental context The increasing use of sun-creams containing UV-filtering chemicals has led to increased inputs of these compounds to the aquatic environment. Chlorinated waters can convert these chemicals into chlorinated products whose toxic effects are of primary concern. To better understand the environmental fate of sun-cream chemicals, we studied the stability of two UV-filtering compounds under varying conditions of pH, chlorine concentration, temperature, dissolved organic matter and solar irradiation. Abstract The stability of the UV filters 2-ethylhexyl-4-methoxycinnamate (EHMC) and 4-tert-butyl-4′-methoxydibenzoylmethane (BDM) in chlorinated water was studied. High-performance liquid chromatography (HPLC)-UV-diode array detection (DAD) was used to follow the reaction kinetics of both UV filters and HPLC-tandem mass spectrometry (MS/MS) was used to tentatively identify the major transformation by-products. Under the experimental conditions used in this work both UV filters reacted with chlorine following pseudo-first order kinetics: rate constant k=0.0095±0.0007min–1 and half-life t1/2=73±4min for EHMC and rate constant k=0.006±0.001min–1 and half-life t1/2=119±14min for BDM (mean±standard deviation). The chemical transformation of the UV filters in chlorinated water led to the formation of chlorinated by-products that were tentatively identified as mono- and dichloro-substituted compounds that resulted from substitution of the hydrogen atoms in the benzene rings by one or two chlorine atoms. Experimental Box–Behnken designs were used to assess the effect of experimental factors: pH, temperature, chlorine concentration, dissolved organic matter and artificial sunlight irradiation on the transformation of the UV filters.

Characterization and Source of Trihalomethane Formation in the Secondary Effluent by Sequencing Batch Reactors

2013 ◽  
Vol 316-317 ◽  
pp. 323-326
Author(s):  
Chao Jie Zhang ◽  
Si Bo Li ◽  
Qian Chen ◽  
Qi Zhou
Keyword(s):  
Organic Matter ◽  
Activated Carbon ◽  
Dissolved Organic Matter ◽  
Secondary Effluent ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Human Beings ◽  
By Products

Dissolved organic matter (DOM) may do harms to human beings. After disinfected by chlorine (amine), DOM can form disinfection by-products (DBPs) which can be mutagenic, teratogenic and carcinogenic. Characterization and source of trihalomethane precursors in the secondary effluent by sequencing batch reactors were investigated. CHCl3 was the primary DBPs. The results showed that the precursors of CHCl3 were mainly strongly hydrophobic DOM, while CHCl2Br and CHClBr2 were mainly formed from hydrophilic DOM. The effects of different powder media (activated carbon, zeolite) on removal of DOM were compared. The results showed that the dosing of powder media can promote the removal of DOM and the DBPs precursors.

scholarly journals The chemodiversity of algal dissolved organic matter from lysed Microcystis aeruginosa cells and its ability to form disinfection by-products during chlorination

2019 ◽  
Vol 155 ◽  
pp. 300-309 ◽  
Author(s):  
Michael Gonsior ◽  
Leanne C. Powers ◽  
Ernest Williams ◽  
Allen Place ◽  
Feng Chen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Microcystis Aeruginosa ◽  
By Products

Photodegradation of UV filters oxybenzone and sulisobenzone in wastewater effluent and by dissolved organic matter

2017 ◽  
Vol 83 ◽  
pp. 150-157 ◽  
Author(s):  
Molly C. Semones ◽  
Charles M. Sharpless ◽  
Allison A. MacKay ◽  
Yu-Ping Chin
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Wastewater Effluent ◽  
Uv Filters

Resolution of photo chemically induced changes of dissolved organic matter as function of cumulated radiation in a sample of a humic-rich and forested stream

2020 ◽  
Author(s):  
Peter Herzsprung ◽  
Christin Wilske ◽  
Wolf von Tümpling ◽  
Norbert Kamjunke ◽  
Oliver J. Lechtenfeld
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Fluorescence Intensity ◽  
Solar Irradiation ◽  
Large Reservoir ◽  
Photo Degradation ◽  
Peak Intensity ◽  
Ft Icr Ms ◽  
Ft Icr

<p>Photochemical processing is a major transformation pathway for allochthonous and autochthonous dissolved organic matter (DOM). DOM consists of thousands or even millions of different molecules and the isomer-resolved identification molecular structures is still far from any analytical realization. The highest analytical resolution of DOM can be achieved on a molecular mass basis via Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). With this technique, the molecular elemental compositions of thousands of DOM components can be assessed, given that they are extractable from water (via e.g. solid phase extraction, SPE-DOM) and ionizable (e.g. via electrospray ionization).</p><p>Increasing levels of DOC in drinking water reservoirs pose serious challenges for drinking water processing. Photochemical processes potentially influence the DOM quality in the reservoir water. The photo degradation and / or the photo production of DOM components in surface freshwater as function of cumulated radiation was rarely investigated. In order to fill this gap we performed an irradiation experiment with water from a shaded forest stream flowing into a large reservoir (Muldenberg, Germany). DOC concentration, UV absorption, excitation-emission-matrices (EEMs) including calculated PARAFAC components and fluorescence indices, and FT-ICR MS derived molecular formulas of SPE-DOM were recorded at 13 different time points. The cumulated radiation was recorded during six days of solar irradiation (sunny days in August at 50.401847 deg. latitude and 12.380528 deg. longitude). Changes in relative peak intensity of DOM components as function of cumulated radiation were evaluated both by Spearman`s rank correlation and linear regression.</p><p>We found components with different types of photo reaction behavior. Relative aliphatic components like C<sub>9</sub>H<sub>12</sub>O<sub>5</sub> were identified as photo products showing a monotonous mass peak intensity increase with irradiation time. Highly unsaturated and oxygen-rich components like C<sub>15</sub>H<sub>6</sub>O<sub>8</sub> showed a more or less monotonous intensity decrease indicating photo degradation. Many similar components were positively correlated to the humic-like fluorescence intensity and the humification index (HIX). The strong degradation of these components can explain the high loss of fluorescence intensity and the drop of the HIX in our experiment. As a result of the high temporal resolution in our experiment (i.e. intensity change as function of cumulated irradiation) we found another type of photo reaction. Components like C<sub>15</sub>H<sub>16</sub>O<sub>8</sub> showed first increasing and then decreasing intensity indicating the formation of intermediate products.</p><p>In general, the river DOM from the forested catchment area showed high potential for photochemical transformations which probably occur in the sunlight exposed predam of the drinking water reservoir.</p>

THE DECOMPOSITION OF SILYL PEROXIDES

1964 ◽  
Vol 42 (5) ◽  
pp. 985-989 ◽  
Author(s):  
Richard R. Hiatt
Keyword(s):  
Thermal Decomposition ◽  
Rate Constant ◽  
Half Life ◽  
Order Rate Constant ◽  
Butyl Alcohol ◽  
Base Catalysis ◽  
First Order ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Acid And Base

The thermal decomposition of tert-butyl trimethylsilyl peroxide has been investigated and found to be sensitive to acid and base catalysis and to the nature of the solvent. In heptane and iso-octane the first-order rate constant could be expressed as 1.09 × 1015e−41200/RT and in 1-octene as 3.90 × 1015e−41200/RT (sec−1). The half life at 203 °C was about 1 hour. The reaction was faster in aromatic solvents; in chlorobenzene it was complicated by formation of HCl from the solvent.Products of the reaction were acetone, tert-butyl alcohol and hexamethyldisiloxane.

Photodegradation of dissolved organic matter in ice under solar irradiation

Chemosphere ◽  
2016 ◽  
Vol 144 ◽  
pp. 816-826 ◽  
Author(s):  
Shuang Xue ◽  
Chao Wang ◽  
Zhaohong Zhang ◽  
Youtao Song ◽  
Qiang Liu
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Solar Irradiation

Tracking the formation of new brominated disinfection by-products during the seawater desalination process

2020 ◽  
Vol 6 (9) ◽  
pp. 2521-2541 ◽  
Author(s):  
Leanne C. Powers ◽  
Annaleise Conway ◽  
Carys L. Mitchelmore ◽  
Stephen J. Fleischacker ◽  
Mourad Harir ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Seawater Desalination ◽  
Ultrahigh Resolution ◽  
By Products ◽  
Resolution Mass

Ultrahigh resolution mass spectrometry revealed substantial dissolved organic matter changes and the formation of numerous bromine-containing disinfection by-products during the seawater desalination process.

scholarly journals Effect of prescribed fires on the export of dissolved organic matter, precursors of disinfection by-products, and water treatability

2020 ◽  
Vol 187 ◽  
pp. 116385
Author(s):  
Habibullah Uzun ◽  
Wenbo Zhang ◽  
Christopher I. Olivares ◽  
Cagri Utku Erdem ◽  
T Adam Coates ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Prescribed Fires ◽  
By Products

Stability of nano-sized titanium dioxide in an aqueous environment: effects of pH, dissolved organic matter and divalent cations

2013 ◽  
Vol 68 (2) ◽  
pp. 276-282 ◽  
Author(s):  
X. N. Yang ◽  
F. Y. Cui
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Organic Matter ◽  
Zeta Potential ◽  
Dissolved Organic Matter ◽  
Ph Value ◽  
Divalent Cations ◽  
Aqueous Environment ◽  
Nano Tio2 ◽  
The Stability

Nano-sized titanium dioxide in the aquatic environment has a potential impact on the environment and human health. In this study, the impact of pH value, dissolved organic matter (DOM) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles (nano-TiO2) in an aqueous environment was investigated in batch tests. The results showed that the particle size of nano-TiO2 was not sensitive to pH value but was inversely proportional to zeta potential. The nano-TiO2 becomes more stable with surface zeta potential, accompanied by small particle size and high dispersion. In the presence of DOM, the particle size was smaller and the stability of nano-TiO2 could be enhanced. This might be a synergistic effect of the ligand exchange and electrostatic force. Particle size increased with the addition of Ca2+ and the stability decreased.

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