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1

The plasma discharges in the anodic and cathodic regimes of plasma driven solution electrolysis for hydrogen production

Bespalko Sergii, Mizeraczyk Jerzy

Przegląd Elektrotechniczny

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2022

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R. 98, nr 9

122--125

EN

This paper presents results of the experimental study of the plasma discharges in the anodic and cathodic regimes of plasma-driven solution electrolysis (PDSE) in 10 wt% Na2CO3 aqueous solution. The study revealed features of the plasma discharge formation at the smaller electrode and values of the breakdown and discharge onset voltages for the anodic and cathodic regimes of PDSE. By applying the fast Fourier transformation analysis, the frequency characteristics of both plasma discharges were found. In the anodic regime of PDSE, the electrical discharge occurred at much higher frequencies (dozens of kHz), while in the cathodic regime at much lower frequencies (hundreds of Hz) but at higher amplitudes of the discharge current and voltage, resulting in higher electrical power dissipation. The applied optical emission spectroscopy (OES) showed emission lines of the hydroxyl (OH*), hydrogen (H*), and oxygen (O*) radicals formed as a result of the dissociation of the water molecules. The obtained results were discussed in terms of the hydrogen production efficiency by the PDSE method.

PL

W pracy przedstawiono wyniki badań eksperymentalnych wyładowań plazmowych w anodowym i katodowym reżimie plazmowej elektrolizy (PDSE) wodnego roztworu Na2CO3 (10% wag.). Badania ujawniły cechy powstawania wyładowań plazmowych na mniejszej elektrodzie. Wyznaczone zostały wartości napięć przebicia i początku wyładowania dla obu reżimów pracy PDSE. Stosując szybką analizę transformacji Fouriera, przebadano charakterystyki częstotliwościowe wyładowań plazmowych. W reżimie anodowym PDSE wyładowania elektryczne występują przy znacznie wyższych częstotliwościach (kilkadziesiąt kHz), natomiast w reżimie katodowym przy dużo niższych częstotliwościach (setki Hz), ale przy wyższych amplitudach prądu i napięcia wyładowania, co skutkuje wyższą rozpraszaną mocą elektryczną. Za pomocą optycznej spektroskopii emisyjnej (OES) zarejestrowano linie emisyjne wzbudzonych rodników hydroksylowych (OH*), wodorowych (H*) i tlenowych (O*) powstałych w wyniku dysocjacji cząsteczek wody. Przedyskutowano otrzymane rezultaty pod kątem skuteczności produkcji wodoru metodą PDSE.

2

Wpływ struktury leków sulfonamidowych na mechanizm inicjacji ich fotokatalitycznej degradacji

Baran Wojciech, Adamek Ewa, Cholewiński Mateusz, Krumpholz Laura, Kulej Barbara, Łazarczyk Antoni, Ledwoń Szymon

Proceedings of ECOpole

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2020

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Vol. 14, No. 1

69--87

PL

Sulfonamidy, pochodne sulfanilamidu, stanowią dużą grupę leków o właściwościach bakteriostatycznych. Część z nich jest powszechnie wykorzystywana w hodowli zwierząt w celach profilaktycznych i leczniczych. Następnie ich pozostałości trafiają do środowiska, gdzie stanowią uciążliwe i trwałe zanieczyszczenie. Leki te znacznie różnią się podatnością na fotokatalityczną degradację. Prowadzone badania pozwoliły na wyznaczenie związku pomiędzy strukturą sulfonamidów a drogą inicjacji ich rozkładu podczas naświetlania w obecności TiO2. Pozwoliły również na prognozowanie zastosowania procesu fotokatalitycznego do usuwania farmaceutyków z odpadów pohodowlanych.

EN

Sulfonamides, sulfanilamide derivatives, are a large group of drugs with bacteriostatic properties. Some of them are widely used in breeding for prophylactic and therapeutic purposes. Their residues get into the environment (soil, surface waters, and ground waters) where they are regarded as persistent organic pollutant. These drugs differ significantly in susceptibility to photocatalytic degradation. Sulfonamides differ significantly in susceptibility to the photocatalytic degradation. The study allowed to determine the relationship between the sulfonamides structure and the mechanism of initiation of their degradation during UV-A irradiation in the presence of TiO2 as a photocatalyst. Additionally, the results allowed us to develop a project involving the application of the photocatalytic process to the removal of pharmaceuticals from post-culture waste.

3

Metody in-vivo badania właściwości antyoksydacyjnych związków kompleksowych

Malinowski Jacek, Drzeżdżon Joanna, Chmurzyński Lech, Jacewicz Dagmara

Wiadomości Chemiczne

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2019

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[Z] 73, 7-8

523--538

EN

This article describes the in-vivo methods of studying the antioxidant properties of complex compounds. The reduced glutathione (GSH) method, which uses the reactivity of the reduced form of GSH with free radicals, is among the described methods. Further the in-vivo methods are based on the use of antioxidant enzymes such as glutathione peroxidase, glutathione S-transferase, superoxide dismutase, catalase. These types of enzymes occur naturally in the human body and they are responsible for the inactivation of free radicals, e. g. superoxide dismutase catalyzes the reaction of disproportionation of superoxide anion radical to water and oxygen. The next in-vivo methods described in this article use y-glutamyl transpeptidase and glutathione reductase, which are components of the antioxidant mechanism occurring in an organism. The last method described in this work relates to the lipid peroxidation, which is determined by the concentration of dimalonic aldehyde.

4

Hydroxyl radicals as an indicator of knocking combustion in the dual-fuel compression-ignition engine

Lasocki J., Orliński P., Wojs M. K., Owczuk M., Matuszewska A.

Combustion Engines

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2017

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R. 56, nr 1

178--185

EN

The occurrence of knocking combustion is one of the basic problems of dual-fuel compression-ignition engines supplied with diesel oil and gaseous fuel. In order to detect this phenomenon and evaluate its intensity, several methods are commonly used, including the analysis of pressure of working medium in the combustion chamber of the engine or vibrations of certain engine components. This paper discusses the concept of using mass fraction of hydroxyl radicals as the indicator of the occurrence of knocking combustion. Current knowledge on the conditions of hydroxyl radical formation in the engine combustion chamber has been systematized and the results of research on this subject have been presented. Theoretical considerations are illustrated by exemplary results of simulation studies of the combustion process in a dual-fuel compression-ignition engine supplied with diesel oil and methane. The conclusions drawn may be useful for the development of dual-fuel engine control systems.

5

The acid-catalyzed interaction of melanin with nitrite ions : an EPR investigation

Matuszak Z., Chignell C. F., Reszka K. J.

Nukleonika

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2015

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Vol. 60, No. 3, part 1

475--481

EN

The interaction of synthetic dihydroxyphenylalanine (DOPA) melanin (DM) with nitrite ions, NO2 –, in the pH 3.6–7.0 range, has been investigated using electron paramagnetic resonance (EPR). We found that especially at pH <5.5 (from ca. 5.5 to 3.6) the reaction of DM with nitrite generated large quantities of new melanin radicals, which implies the involvement of nitrous acid, HNO2, in the radical formation process. Measurements carried out at constant pH of 3.6 showed that the melanin signal increased together with nitrite concentration, reaching a plateau level which was more than fourfold larger compared to the initial signal amplitude observed in a nitrite-free buffer of the same pH. The effects of nitrite and DM concentrations on the melanin-free radical content were also investigated. It is proposed that the radicals are generated by one electron oxidation of melanin ortho-hydroquinone groups to ortho-semiquinones by HNO2 or related nitrogen oxides such as NO2 • radicals. The possible involvement of nitric oxide (•NO) and peroxynitrite (ONOO–) in DM oxidation was also examined. In air-free solutions, nitric oxide per se did not generate melanin radicals; however, in the presence of oxygen a marked increase in the melanin EPR signal intensity was observed. This result is interpreted in terms of the generation of radicals via the oxidation of DM by peroxynitrite. Our fi ndings suggest that melanin can function as a natural scavenger of nitrous acid and some nitrous acid-derived species. This property may be relevant to physiological functions of melanin pigments in vivo.

6

Multifrequency EPR study on radiation induced centers in calcium carbonates labeled with 13C

Sadło J., Bugaj A., Strzelczak G., Sterniczuk M., Jaegermann Z.

Nukleonika

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2015

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Vol. 60, No. 3, part 1

429--434

EN

In calcite and aragonite, γ-irradiated at 77 K, several paramagnetic centers were generated and detected by EPR spectroscopy; in calcite, CO3 – (orthorhombic symmetry, bulk and bonded to surface), CO3 3–, NO3 2–, O3 –, and in aragonite CO2 – (isotropic and orthorhombic symmetry) depending on the type of calcium carbonate used. For calcium carbonates enriched with 13C more detailed information about the formed radicals was possible to be obtained. In both natural (white coral) and synthetic aragonite the same radicals were identifi ed with main differences in the properties of CO2 – radicals. An application of Q-band EPR allowed to avoid the signals overlap giving the characteristics of radical anisotropy.

7

EPR study of γ-irradiated feather keratin and human fingernails concerning retrospective dose assessment

Strzelczak G., Sterniczuk M., Sadło J., Kowalska M., Michalik J.

Nukleonika

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2013

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Vol. 58, No. 4

505--509

EN

In this paper we report the results of comparative EPR studies on free radicals generated in γ-irradiated powder samples of feather keratin powder and human fingernails. In degassed samples of both materials irradiated at 77 K the major component of EPR spectrum represents sulphur-centred radicals in cysteine residues. It quickly decays after air admission at room temperature while a singlet assigned to semiquinone melanin radicals remains the only one seen. The singlet recorded with fingernails decays slowly at room temperature and might be potentially useful for dose assessment by EPR. The advantages and limitations of fingernails EPR dosimetry are discussed.

8

Research on betanidin oxidation by ABTS radicals

Starzak K., Skopińska A., Wybraniec S.

Challenges of Modern Technology

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2012

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Vol. 3, no. 4

39--43

EN

Betanidin is a basic betacyanin with 5,6-dihydroxyl moiety which causes its high antioxidant activity. It belongs to betalains, a group of natural, water-soluble plant pigments, which elicit a red-violet coloration of fruits and fl owers. One of the most popular sources of betanidin is red beet root (Beta vulgaris L.). Recent studies have shown importance of betalains oxidation, because of their high natural, antiradical and antioxidant activity and potential benefi ts for human health [1]. An eff ect of oxidation of betanidin using ABTS radicals was investigated in aqueous solutions at pH 3–8 and compared to activity of horseradish peroxidase. Products of the biomimetic betanidin oxidation were monitored by high performance liquid chromatography (HPLC) coupled to optical detection and mass spectrometry (LC-DAD-ESI-MS/MS). The presence of two main oxidation products: 2-decarboxy-2,3-dehydro-betanidin and 2,17-didecarboxy-2,3-dehydro- -betanidin at pH 3 indicates their generation through two possible reaction ways with two diff erent quinonoid intermediates: dopachrome derivative and quinone methide. Both reaction paths lead to the decarboxylative dehydrogenation of betanidin.

9

Autooxidation of leuco-Methylene Blue – the Role of the Methylene Blue Radicals and Reactive Oxygen Species

Katafias A., Koter S.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 6

1139-1146

EN

Autooxidation of leuco-Methylene Blue to the dye, Methylene Blue, was studied in the 1.9–7.8 pH range under a large molar excess of dioxygen dissolved in the reaction solution using electronic spectroscopy. The synproportionation of the substrate and the reaction product, yielding Methylene Blue radical, plays a key role in the over all redox process. Numerical simulation of the complicated kinetic curves shows that presence of this radical opens an effective reaction path for the autooxidation process and results in coupling of the reaction steps. Reactive oxygen species (HO2 ź /O2 ź - / and H2O2) formed in the examined system are not effective oxidants and do not affect the autooxidation kinetics under applied conditions.

10

X- and Q-band EPR study on dosimetric biomaterials

Strzelczak G., Sadło J., Michalik J.

Nukleonika

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2009

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Vol. 54, No. 4

247-250

EN

Electron paramagnetic resonance (EPR) spectroscopy (X- and Q-band) was used for identification of stable radicals in: compact bone powder, shell of arcidae mollusc and crystalline alanine. The aim of our investigation was to analyze the complex EPR spectra of these materials and to identify paramagnetic species contributing to it. The most successful results were obtained in the EPR study (X- and Q-band) on deproteinized and irradiated bone powder and arcidae shell at room temperature.

11

Knockdetection using spectral emission of flames

Piernikarski D.

Journal of KONES

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2009

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Vol. 16, No. 2

383-392

EN

Introduction of spectrophotometric methods into engine research considerably expands diagnostic possibilities of the work cycle in the internal combustion engine. Spectral analysis enables to determine concentrations of chemically active compounds - radicals, which are temporary present in the flame and do not constitute finał products of the combustion. The aim of the presented research was to investigate spectral properties of the combustion flame with special regard to the detection and estimation of intensity of knocking combustion. Research was made using modifled single cylinder si test engine equipped with an optical sensor having direct access to the combustion chamber. The sensor enabled on-line transmission of the transient optical signal during the combustion through the bundle of optical wave-guides. Measurements were based on the chemiluminescence phenomena occurring in the combustion flame under the influence of high temperature and pressure. Gathered signal was passed to the monochromator. Spectral recordings were done for wavelengths typical of emission of intermediate products, covering the range from 250 nm to 625 nm, including investigated radicals like C2, CH, CN, OH. Obtained results confirmed, that occurrence of knock can be precisely detected on the basis of signal analysis which was recorded for chemiluminescence traces of different radicals. Comparison with in parallel recorded indicated pressure have shown that characteristics of emitted spectra remain in good conformity and are more sensitive to the changing of engine operating conditions.

12

Study of low temperature inactivation of spores using microwave excited air plasma

Nagatsu M., Singh M. K., Zhao Y., Fujioka Y., Ogino A.

Journal of Automation Mobile Robotics and Intelligent Systems

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2009

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Vol. 3, No. 4

108-111

EN

In the present study, we investigated the inactivation characteristics and contribution of different inactivating factors generated in a low temperature and low pressure nitrogen, oxygen and air-simulated plasma for the inactivation of Geobacillus stearothermophilus spores. We used three optical filters i.e. thin quartz (lambda>180 nm), lithium fluorine (LiF, lambda>120 nm) and Pyrex glass (lambda>300 nm) plates to identify the most efficient wavelength range. The effect of optical radiations alone was studied through placing a small isolated and evacuated chamber with spore sample inside the plasma chamber.

13

Functionalization of polymer surfaces by radiation-induced grafting

Przybytniak G., Kornacka E. M., Mirkowski K., Walo M., Zimek Z.

Nukleonika

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2008

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Vol. 53, No. 3

89-95

EN

The mutual radiation grafting of acrylic acid (AAc) onto polyethylene (PE), polypropylene (PP) and polystyrene (PS) films was performed. At first stage of investigations, the influence of ionizing radiation on the trunk polymers was studied, i.e. the level of radicals stable at room temperature and radiation yield of evolved hydrogen were estimated for each polymer. The measurements were carried out using electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC), respectively. Radiation yields of radicals as well as hydrogen emission increased in the following order PS < PP < PE. Under comparable conditions, the same relationship was found for the yield of radiation-induced grafting of AAc. A distinct correlation between content of radicals generated by ionizing radiation in polymeric matrices and grafting degree was confirmed for the studied materials. The effect of monomer and inhibitor concentrations on the efficiency of processes were studied as well.

14

Tautomeric Equilibria and pi-Electron Delocalization for the Substrate (Pyruvate) and Inhibitor (Oxamate) of Lactate Dehydrogenase - DFT Studies

Raczyńska E. D., Duczmal K., Hallmann M.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 9

1655-1666

EN

Keto-enol tautomerism for the substrate (pyruvate) of lactate dehydrogenase (LDH) and amideiminol tautomerism for its inhibitor (oxamate) were studied at the DFT(B3LYP)/6-31++G(d,p) level. Both anions (and also both radicals) prefer the C=O forms, i.e. the keto and amide form, respectively. The OH forms (enolpyruvate and iminoloxamate) have higher Gibbs free energies. Their amounts in the tautomeric mixtures are larger than 0.01% for anions and lower than 0.001% for radicals. pi-Electron delocalization for OCO fragments is greater than that for XCO fragments for both anions and radicals.

15

Metody oznaczania oraz identyfikacji związków przeciwutleniających

Tarko T., Duda-Chodak A.

Laboratorium - Przegląd Ogólnopolski

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2007

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nr 3

32--37

PL

Przeciwutleniacz to substancja, która obecna w niskim stężeniu, opóźnia bądź eliminuje reakcje utleniania. Zewzględu na duże zróżnicowanie w budowie i funkcji tych związków istnieje wiele metod ich oznaczania i identyfikacji. Większość badań opiera się na ocenie aktywności antyoksydacyjnej, będącej sumą właściwości poszczególnych składników zawartych w badanym materiale. Najczęściej wykorzystuje się metody spektrofometryczne i kolorometryczne, ale także elektrochemiczne. Do identyfikacji związków o charakterze przeciwutleniającym służą techniki chromatograficzne, głównie HPLC.

EN

Antioxidant is a substance that in low concentration delays or inhibits oxidation. There are many methods of antioxidants determination and identyfication due to the diversification of their structure and function. Majority of investigations are based on evaluation of antioxidant activity, which equals the sum of the particular components properties in a sample. Spectrophotometric and colorometric methods are used most often, as well as electrochemical ones. The chromatograohis techniques , mainly HPLC, are used for identification of antioxidants.

16

Intramolecularly Sn-N Coordinated Organotin Hydrides

Komsta Z., Cmoch C., Stalinski K.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 8

1259-1292

EN

In recent years, internally Sn-N coordinated organotin hydrides have found an application in organic syntheses, which involve radical chain reactions. Unique reactivity of such hydrides suggests the potential of intramolecular coordination for the control of radical reactions. When the tin hydrides are used in the presence of Lewis acids single- enatiomer outcomes are accessible. This opens a new aspect of free radical chemistry. The intramolecular Sn-N coordination enhances also nucleophilic character of the tin hydrides in reduction of ketones under mild reaction conditions. The occurrence of intramolecular interaction between the nitrogen and tin atoms can be additionally based on the changes in the characteristic values of the 1H, 13C, 15N and117/119Sn NMR parameters and their interrelations.

17

Understanding the reactivity of photoinitiating systems for photopolymerization

Allonas X., Lalevée J., Morlet-Savary F., Fouassier J. P.

Polimery

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2006

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T. 51, nr 7-8

491-498

EN

The reactivity of photoinitiating systems (PIS) of polymerization reactions is the subject of many research works. Investigation of primary processes involved in PIS is largely based on time resolved laser spectroscopy techniques, mainly through the well known transient absorption spectroscopy (TRAS). Recently, transient infra-red spectroscopy, laser induced photoacoustic calorimetry, photoconductivity were introduced in order to collect useful information on the excited states which were not easily accessible by TRAS. By now, molecular modelling calculations performed at high level of theory are shown to provide unique thermodynamical data on the processes that govern the overall efficiency of PIS. A new approach that combines both experimental and theoretical aspects was found very promising for the understanding of the photochemical and chemical processes involved in photopolymerization reactions.

PL

W artykule o charakterze monograficznym przedstawiono przegląd publikacji (w istotnym stopniu - prac własnych z ostatnich kilku lat) poświęconych metodom i wynikom badania mechanizmu reakcji elementarnych w procesie inicjowania fotopolimeryzacji przez układy fotoinicjujące (PIS). Omówiono wybrane wyniki uzyskiwane metodami TRAS (Time-resolved absorption spectroscopy), z uwzględnieniem nowej metody indukowanej laserem kalorymetrii fotoakustycznej (LIPAC). Sporo uwagi poświęcono zagadnieniu zależności reaktywności rodników od ich budowy oraz własnemu sposobowi bezpośredniej obserwacji rodników (na przykładzie rodników akrylanowych), a także ocenie ich reaktywności na podstawie metody TRAS (rys. 6-8).

18

Free Radical Addition and Cyclization Reactions of [2-(4-(S)-Isopropyl-2-oxazoline)-5-phenyl]dialkyltin Hydrides

Stępień A., Petrosyan A., Wilk M., Cmoch P., Rupnicki L., Staliński K.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 6

1015-1024

EN

Radical addition reactions of [2-(4-(S)-isopropyl-2-oxazoline)-5-phenyl]dibutyl and dimethyl hydrides to activated double/triple bonds took place in good yields. Triethylborane in presence of oxygen can serve as a radical initiator. Addition of stannyl radicals to N,N-(2-methoxycarbonyl-allyl)benzyl glycinate results in formation of the corresponding piperidine derivatives. The intramolecular tandem radical addition/ cyclization process can be performed in high yields and good diastereoselectivity.

19

Stereoselection at the Steady State within radicals - How far can we go ?

Staliński K.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 5

611-622

EN

Stereoselection at the steady state is a process, which results from a complex interplay of reaction pathways that diverge and reconverge at various points. Therefore, it can be considered as a manipulation of stereocontrol mainly by reaction topography. The advantages of this process are at least twofold: First, stereoconvergence allows the system to exceed the yield of the initial stereoconvergent event, where stereomeric transition states compete. Second, a successive resolution of the reactive intermediates by chemoselective events allows the system to generate high stereomeric excess, practically without any stereoselective competition. While illustrated with radicals, the process may prove useful in other fields of chemistry.

20

Zastosowanie wysokoefektywnych procesów utleniania do oczyszczania ścieków z produkcji maści Efudix

Naumczyk J., Piotrowska A.

Chemia i Inżynieria Ekologiczna

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2004

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Vol. 11, nr S2

199-207

PL

Przedstawiono wyniki badań nad utlenianiem 5-fluorouracylu oraz nad oczyszczaniem ścieków powstałych przy produkcji maści Efudix - 5%, zawierającej ten związek jako składnik aktywny. Utlenianie 5-fluorouracylu prowadzono metodą ozonowania przy pH = 12 i 13 oraz metodą O3/H2O2. Ponieważ najbardziej efektywna okazała się metoda ozonowania przy pH = 13, do badań nad oczyszczaniem ścieków zastosowano tylko tę metodę. Osiągnięto wysoki stopień redukcji wartości ChZT oraz pełny i szybki rozkład 5-fluorouracylu, rozpoczynający się od oderwania atomu fluoru od molekuły.

EN

The process of oxidation of 5-flurouracil and the treatment of wastewater from Efudix ointment production were investigated. 5-fluorouracil was oxidized by ozonation at pH = 12 and 13 and by O3/H2O2 method. Because the ozonation at pH = 13 proved to be the most effective method, this method was applied to the wastewater treatment. The high degree of COD reduction was achieved and 5-fluorouracil was completely and quickly destroyed. The process was initiated by fluorine detachment.