Ketoprofen, 2-(3-benzoylphenyl)-propionic acid, a widely used non-steroidal anti-inflammatory drug, is considered as an important water pollutant. Kinetics and mechanism of its photolytic transformation in aqueous solutions was studied experimentally and partial reaction steps were modelled by means of quantum chemistry methods. While the rate of ketoprofen photolysis was not significantly affected by its acid-base equilibrium, a marked influence of pH on the subsequent degradation reactions was observed. At pH 1.3, two oxygenated primary products were identified, that underwent fast photolysis. Deprotonated form of ketoprofen was transformed preferentially to ethylbenzophenone and further degradation proceeded substantially slower. Oxygen participated on photolytic processes both as a reactant and the triplet state quencher. The active involvement of water molecules in the reaction mechanism was investigated by comparative experiments in acetonitrile. The phototransformation mechanism proposed based on the experimental data corresponded well with the theoretical results.
Over the past decade, the environment has been polluted by a wide spectrum of exogenous chemicals and environmental analysis has become one of the most progressive parts of analytical research. The aim of this work was to determine the kinetics of natural degradation, and to identify the degradation products of the massively used estrogenic drug, 17-α-ethinylestradiol. The photodegradation, oxidation and thermostability conditions were selected according to ICH requirements for pharmaceutical stability testing. A simple 72-h photodegradation study in purified water exhibited significant first-order kinetics with the kinetic constant k = 0.0303 h-1, and degradation halftime 22.8 h. The basic halftime could be reduced to 17.1 h by the addition of sea salt, and increase in temperature. Monohydroxy, dihydroxy and dehydrogenated derivatives of ethinylestradiol with intact steroidal structure were identified as major degradation products resulting from simple photodegradation. The addition of an oxidative agent significantly accelerated the degradation rate; combined with higher temperature, the degradation halftime was reduced to 1.1 h with the first-order kinetic constant k = 0.632 h-1. TOC analysis showed a notable decrease of organic mass (18% in 3 days) during oxidation experiments, and confirmed the degradation of steroidal structure.
- MeSH
- chemické látky znečišťující vodu analýza účinky záření MeSH
- ethinylestradiol analýza účinky záření MeSH
- fotolýza MeSH
- kinetika MeSH
- mořská voda chemie MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí MeSH
- sladká voda chemie MeSH
- světlo * MeSH
- teoretické modely MeSH
- Publikační typ
- časopisecké články MeSH
This study investigated the i) kinetics, and ii) proportion of photolysis of 30 relatively stable active pharmaceutical ingredients (APIs) during artificial UV irradiation for 28 d in ammonium acetate buffer, filtered and unfiltered river water. Buffer was included to control removal kinetics under stable pH conditions and without particulate matter. Dark controls were used to determine removal due to other processes than photolysis and calculate the proportion of photolysis of the total removal. The removal of each API in each matrix was determined using online solid phase extraction/liquid chromatography tandem mass spectrometry (online SPE/LC-MS/MS). Most APIs transformed during the 28 d of UV irradiation and the dark controls showed that photolysis was the major removal process for the majority of the APIs studied. The half-lives ranged from 6 h (amitriptyline) in unfiltered river water to 884 h (37 d, carbamazepine) in buffer. In unfiltered river water, the proportion of APIs with short half-lives (<48 h) was much higher (29%) than in the other matrices (4%), probably due to additional organic carbon, which could have promoted indirect photolysis. Furthermore, two APIs, memantine and fluconazole, were stable in all three matrices, while alprazolam was stable in buffer and unfiltered river water and four additional APIs were stable in buffer. Considering the relatively long-term UV-exposure, this study enabled the investigation of environmentally relevant half-lives in natural waters. Many APIs showed high persistence, which is environmentally concerning and emphasizes the importance of further studies on their environmental fate and effects.
- MeSH
- časové faktory MeSH
- chemické látky znečišťující vodu izolace a purifikace účinky záření MeSH
- extrakce na pevné fázi metody MeSH
- fotolýza účinky záření MeSH
- kinetika MeSH
- léčivé přípravky izolace a purifikace účinky záření MeSH
- poločas MeSH
- regenerace a remediace životního prostředí metody MeSH
- řeky chemie MeSH
- stabilita léku MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- ultrafialové záření * MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
In the present study, the coupling of adsorption capacity and photocatalytic efficiency of two different industrially produced titania catalysts was investigated and compared. The azo dye Reactive Red 195 was selected as a model compound. The tested catalysts, PK-10 and PK-180, exhibited different adsorption capacities due to their significant difference in their specific surface, but both have proven to be effective photocatalysts for photodegradation of the studied dye. PK-10 exhibited strong adsorption of the studied dye due to its high specific surface area, while the second studied catalyst, PK-180, demonstrated negligible adsorption of Reactive Red 195. The effect of the pH, the concentration of the catalyst and the initial concentration of the dye appear to affect the photocatalytic rate. The effect of the presence of humic acids and inorganic ions was also examined, while the contribution of various reactive species was indirectly evaluated through the addition of various scavengers. To evaluate the extent of mineralisation of the studied dye, total organic carbon (TOC) measurements during the experiment were also conducted. Besides total colour removal, evident reduction of TOC was also achieved using both catalysts.
- MeSH
- adsorpce MeSH
- anionty MeSH
- azosloučeniny izolace a purifikace účinky záření MeSH
- chemické látky znečišťující vodu izolace a purifikace účinky záření MeSH
- čištění vody metody MeSH
- fotolýza MeSH
- huminové látky analýza MeSH
- katalýza MeSH
- koncentrace vodíkových iontů MeSH
- naftalensulfonany izolace a purifikace účinky záření MeSH
- nanočástice chemie MeSH
- scavengery volných radikálů chemie MeSH
- titan chemie MeSH
- ultrafialové záření * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The influence of typical *OH radical scavengers as potassium formate and isopropanol on the radiation-induced removal of lead was individually studied. The lead can be completely removed from aqueous solutions containing 1x10(-2) mol/L of formate already at the dose of 2.5 kGy. With increasing concentration of formate (5x10(-5)-1x10(-2) mol/L) increases the amount of Pb(formate)(+) species in the solution before irradiation. The radiation product is metallic lead at low concentration of formate to PbCO(3) at higher concentration of scavenger. In the system with 10% isopropanol dominates the species Pb(2+) and the product of radiation reduction is then metallic lead.
- MeSH
- chemická precipitace MeSH
- chemické látky znečišťující vodu izolace a purifikace účinky záření MeSH
- čištění vody metody MeSH
- formiáty chemie účinky záření MeSH
- olovo chemie izolace a purifikace MeSH
- roztoky chemie účinky záření MeSH
- voda chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
