PL
 |
EN
Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl
Ograniczanie wyników
Czasopisma help
  1. 92 Przemysł Chemiczny
  2. 54 Ochrona przed Korozją
  3. 35 Polish Journal of Chemistry
  4. 22 Polish Journal of Chemical Technology
  5. 21 Inżynieria Materiałowa
Więcej...
Lata help
  1. 3 2023
  2. 1 2022
  3. 13 2021
  4. 12 2020
  5. 9 2019
Więcej...
Autorzy help
  1. 22 Żurek Z.
  2. 16 Jaroń A.
  3. 15 Małecka J.
  4. 11 Dąbek L.
  5. 11 Przeliorz R.
Więcej...
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 694

Liczba wyników na stronie
first rewind previous Strona / 35 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  oxidation
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 35 next fast forward last
1
Content available A facile and effective method for preparation of 2.5-furandicarboxylic acid via hydrogen peroxide direct oxidation of 5-hydroxymethylfurfural
100%
Zhang S. , Zhang L.
Polish Journal of Chemical Technology
|
2017
|
tom Vol. 19, nr 1
11--16
EN
In this paper, 2,5-furandicarboxylic acid (FDCA) was efficiently prepared by the direct oxidation of 5-hydroxymethylfurfural (5-HMF) using hydrogen peroxide (H2O2) in alkaline conditions without any catalysts. The effects of reaction parameters on the process were systematically investigated and the optimal parameters were obtained as follows: molar ratio of 5-HMF:KOH: H2O2  was 1:4:8, reaction temperature and reaction time were determined as 70°C and 15 minutes, respectively. Under these conditions, the yield of FDCA was 55.6% and the purity of FDCA could reach 99%. Moreover, we have speculated the detailed oxidation mechanism of 5-HMF assisted by hydrogen peroxide in alkaline condition to synthesize FDCA.
2
Content available remote Catalytic synthesis of 2-methyl-1,4- naphthoquinone in 1%Au/HPS presence
100%
Shimanskaya E. I. , Sulman E. M. , Doluda V. Y.
Catalysis for Sustainable Energy
|
2014
|
tom 2
|
nr 1
EN
In this paper, theoxidation process of 2 -methylnaphthalene to vitamin K3, using a gold catalyst systems will be discussed. This catalysis process is based on the hypercrosslinked polystyrene, synthesized by the impregnation with solutions of precursors − HAuCl4·2H2O and Ph3PAuCl. The use of gold catalyst system, which has been synthesized using Ph3PAuCl, allows to obtain the main product − 2-methyl-1,4-naphthoquinone − with 72% yield.
3
Content available remote Properties of atmospheric pressure plasma oxidized layers on silicon wafers
100%
Skácelová D. , Sládek P. , Sťahel P. , Pawera L. , Haničinec M. , Meichsner J. , Černák M.
Open Chemistry
|
2015
|
tom 13
|
nr 1
EN
In this research a new process of plasma oxidation of crystalline silicon at room temperature is studied. The plasma oxidation was carried out using Diffuse Coplanar Surface Barrier Discharge (DCSBD) operating in ambient air and oxygen at atmospheric pressure. The influence of exposition time, plasma parameters and crystallographic orientation of silicon on oxidized layers and their dielectric properties were investigated. Thickness, structure and morphology of these layers were studied by ellipsometry, infrared absorption spectroscopy and scanning electron microscopy. During the treatment time, from 1 to 30 minutes, oxidized layers were obtained with thickness from 1 to 10 nm. Their roughness depends on the crystallographic orientation of silicon surface and exposure time. Electrical parameters of the prepared layers indicate the presence of an intermediate layer between silicon substrate and the oxidized layer.
4
Content available Properties of TiN protective coatings on steel
100%
Fornal P. , Stanek J. , Jaglarz J. , Dąbrowski M.
Nukleonika
|
2003
|
tom Vol. 48,suppl.1
21-24
EN
The properties of fast cutting steel SW7M, stainless steel 1H18N9T, and tool steel NC11 coated with a TiN protective layer were studied using 57Fe Conversion Electron Mössbauer Spectroscopy. The adhesion of the coatings is determined by the thickness of Fe-N and Fe-Ti interface. The model of the abrasion of the protected tools, based on fast diffusion of Fe ions to the surface though the TiN layer and further oxidation is proposed.
5
Oxidation of Hexacyanoferrate(II) by Peroxynitrite. A Mechanistic and Kinetic Study
100%
Martinez E. , Mucientes A. , Poblete F. , Rodriguez A.
Polish Journal of Chemistry
|
2004
|
tom Vol. 78 / nr 2
261-271
EN
Akinetic study of the oxidation of hexacyanoferrate(II) by peroxynitrite has been carried out, using a stopped-flow technique. The variation of the experimental rate constant over a wide concentration range of Fe(CN)6 4 has been investigated under different experimental conditions in terms of pH, ionic strength and temperature. Acorrelation between kexp and the substrate concentration has been obtained and this shows first-order behavior in substrate at high concentrations of Fe(CN)6 4 .Areaction mechanism is proposed, in which the hexacyanoferrate(II) reacts in competitive pathways with the peroxynitrous acid (direct oxidation) and with HOź and źNO2 radicals formed in the homolysis of the peroxide bond ofHOONO(indirect oxidation). Moreover, two individual constants, kc (the formation constant of the germinated radical pair [HOź źNO2]) and k7 (direct oxidation constant), have been evaluated together with the thermodynamic parameters of these elementary steps.
6
Content available remote Oczyszczanie ścieków przemysłowych metodą utleniania
100%
Tic W. J.
Chemik
|
2005
|
tom Vol.58, nr 11-12
598-600
PL
Przedstawiono wyniki badań nad oczyszczaniem ścieku wodnego z procesu kondensacji aldolowej 2-metylopropanalu. W reakcji rozkładu zawartych w ścieku soli sodowych kwasów organicznych kwasem siarkowym(VI) mieszanina po reakcji uległa rozdziałowi na dwie fazy. Wydzieloną fazę organiczna można spalić w zakładowej kotłowni. Zanieczyszczenia organiczne zawarte w fazie wodnej utleniano nadtlenkiem wodoru do dwutlenku węgla i wody.
EN
The results of investigations on the purification of aqueous sewage from the condensations 2-methylpropanal are presented. The decomposition of the organic acid salt contained in the sewage with sulfuric acid makes the mixture divide into two phases. The organic phase would be burned for instance boiler room. While contained the aqueous phase with organic contained can be treated with hydrogen peroxide to give carbon divide and water.
7
Silica Gel Supported gamma-Picolonium Chloromate ; A New and Efficient Reagent for Selective Conversion of Alcohols and Oximes into Carbonyl Compounds under Mild and Non-Aqueous Conditions
100%
Salehi P. , Khodaei M. M. , Yazdanipoor A.
Polish Journal of Chemistry
|
2003
|
tom Vol. 77 / nr 10
1281-1286
EN
The preparation of silica gel supported _-picolinium chlorochromate and its application as an efficient reagent for selective oxidation of oximes and alcohols into carbonyl compounds is reported. The trimethylsilyloxy and ester groups survived under the reaction conditions.
8
Content available remote High temperature corrosion of the cobalt base clad layers
100%
Smoleńska H.
Advances in Materials Science
|
2007
|
tom Vol. 7, nr 2(12)
254-263
EN
Cobalt base clad layer underwent oxidation at 650° C and 750° C and corrosion in exhaust gases. The oxidation processes were run in two different ways; isothermal oxidation for 100 hours and cyc1ic oxidation for 200 hours. Corrosion in exhaust gases were run in a cyclic way for two month and about 200 hours at 6500 C. This clads were produced both laser and PTA cladding techniques. Thermal stability and oxidation behavior of the c1ads at different temperatures and environment were investigated. It appeared that exhaust gases were less harmful for this alloys than oxidizing atmosphere. The influence of the oxidation conditions (isothermal or cyclic oxidation) was established. Generally, the clad layers demonstrated good corrosion property in both atmospheres. The morphology changes of the clads were insignificant and the tiny oxide layer on the surface were noticed. The clads hardness changes were observed.
9
Content available remote Influence of linear rate constant on parabolic process of oxidation of low-carbon steel
100%
Adamaszek K. , Jurasz Z.
Advances in Materials Science
|
2007
|
tom Vol. 7, nr 2(12)
236-241
EN
In this paper we give a presentation of the recently developed approaches concerned of the rate of oxidation the Arema steel at high-temperature in first stage of this process. The comparison analysis was performed on the basis of the experimental results of oxidation of cylindrical specimens made of above steel. The experiment was carried out in chamber furnace on series of specimens with dimension '" = 20 . 1=30 mm. The specimens were oxidised at 1000°C for 10 - 2280 minutes in air and then quenched in silica sand, afterwards were measured both with and without of scale.
10
Quinolinium fluorochromate oxidation of alpha-hydroxy acids in perchloric acid medium
100%
Meenakshisundaram S. , Sathiyendiran V.
Polish Journal of Chemistry
|
1998
|
tom Vol. 72, nr 10
2261-2266
EN
The kinetics of oxidation of alpha-hydroxy acids (mandelic, lactic and glycolic) with a recently developed new mild Cr(VI) regent quinolinium fluorochromate (QFC) has been investigated in perchloric acid medium. First-order depedence with respect to [oxidant] is observed. Increase in [substrate] increases the rate proportionally. The acidity dependence is fractional order throughout the entire range of acidities studied. Decrease in dielectric constant of the medium increases the oxidation rate considerably. Kinetic solvent isotope effect studies indicate a pre-equilibrium fast proton transfer. Absence of polymerization with acrylonitrile rules out a free radical mechanism. An intermediate formed between protonated oxidant and substrate decomposes in a slow rate-limiting step giving the products.
11
A cyclic voltammetric and coulometric study of a modified electrode prepared by electrooxidative polymerization of nickel complex of 1,5-diaminonaphthalene in acetonitrile
100%
Yousef U. S. , Abdel-Azzem M.
Polish Journal of Chemistry
|
1998
|
tom Vol. 72, nr 12
2583-2597
EN
The electrooxydative polymerization of nickel complex of 1,5-diaminonaphthalene was performed in acetonitrile containing lithium perchlorate, using cyclic voltammetry and controlled potencial electrolysis. The film coated electrode showed an electroactive redox response in acidic solutions only. The stability of the redox response towards repetitive cyclic voltammetry was studied. The formal redox potential of the resulting film electrode was about 0.28 V vs. Ag/Ag(+) in 1.0 M acid chloride aqueous solution (ph=0). The electrical conductivity of the film was measured in 0,01 M KCl aqueous solution and was found as (2.2 (+/-) 0.02) 10(-4) S cm(-1). The morphology of the film and the factors affecting its electroactivity were studied in detail.
12
Pyridinium chlorochromate oxidation of arsenic(III) in hydrochloric acid
100%
Virkar D. D. , Gokavi G. S.
Polish Journal of Chemistry
|
1998
|
tom Vol. 72, nr 10
2267-2271
EN
The reaction between pyridinium chlorochromate and As(III) was studied in hydrochloric acid medium. The reaction was found to be overall second order the added product As(V) was found to decrease the rate. The hydrogen ion was found to catalyse the reaction and it was predicted that both protonated and free pyridinium chlorochromate are active to a different extent. The active species of the reductant was H3AsO3 and the mechanism is discussed in terms of these species. The retardation by the added product is predicted to be due to a competitive ester formation.
13
Phosphorus losses in VPO catalysts
100%
Stoch J. , Stoch A. , Mikołajczyk M. , Brożek A.
Polish Journal of Chemistry
|
1998
|
tom Vol. 72, nr 12
2606-2609
EN
During oxidation of n-butane to maleic anhydride on VPO catalysts phosphorus is carried out from the catalyst by gas phase. The transport medium is likely an organic compound of phosphorus. An active role of phosphorus in the n-butane transformation is suggested.
14
Content available remote Capacitive behavior of highly-oxidized graphite
100%
Ciszewski M. , Mianowski A.
Materials Science Poland
|
2014
|
tom Vol. 32, No. 3
307--314
EN
Capacitive behavior of a highly-oxidized graphite is presented in this paper. The graphite oxide was synthesized using an oxidizing mixture of potassium chlorate and concentrated fuming nitric acid. As-oxidized graphite was quantitatively and qualitatively analyzed with respect to the oxygen content and the species of oxygen-containing groups. Electrochemical measurements were performed in a two-electrode symmetric cell using KOH electrolyte. It was shown that prolonged oxidation causes an increase in the oxygen content while the interlayer distance remains constant. Specific capacitance increased with oxygen content in the electrode as a result of pseudo-capacitive effects, from 0.47 to 0.54 F/g for a scan rate of 20 mV/s and 0.67 to 1.15 F/g for a scan rate of 5 mV/s. Better cyclability was observed for the electrode with a higher oxygen amount.
15
Content available remote The kinetics of scale growth on Ti-25Al-12.5Nb alloy suring high temperature oxidation in 9%O2+0.2%HCl+0.08%SO2+N2 atmosphere
100%
Małecka J.
Advances in Materials Science
|
2015
|
tom Vol. 15, nr 2(44)
14--21
EN
The paper presents research results of isothermal oxidation of Ti-25Al-12.5Nb alloy. Oxidation was carried out in 9%O2+0,2%HCl+0,08%SO2+N2 atmosphere at the temperature of 700 and 750 ºC.
16
Content available remote Oxide coatings on titanium produced by oxidation in fluidized bed
100%
Jasiński J. , Mendzik K. , Tatar K. , Szota M.
Advances in Materials Science
|
2008
|
tom Vol. 8, nr 1(15)
48-53
EN
The main product of a process of titanium oxidation is titanium oxide, which covers the titanium surface. More-over oxidation in fluidized bed in temperature range of 600-700°C influences on outer layers of titanium specimen, where a diffusion layer of oxygen is observed. Microstructures of titanium with visible oxide coatings on its surface after thermo-chemical treatment are described. Microhardness measurements of titanium surface layers after oxidation process were made with a Knoop microhardness tester and showed significant differences accord-ing to oxidation parameters. Finally, the surfaces of titanium after oxidation in fluidized bed were scratched in aim to measure their adhesion to the substrate surface.
17
Content available Oxidative Degradation of 2-Chlorophenol by Persulfate
100%
Kuśmierek K. , Świątkowski A. , Dąbek L.
Journal of Ecological Engineering
|
2015
|
tom Vol. 16, nr 3
115--123
EN
The degradation of 2-chlorophenol (2-CP) by persulfate was investigated. The kinetics of persulfate oxidation of 2-chlorophenol in aqueous solutions at various pH, oxidant concentration, temperature, Fe2+ > and Cu2+ ions content was studied. Maximum of 2-CP degradation occurred at pH 8. The oxidation rate of 2-CP increased with increasing the persulfate molar excess. The degradation process was significantly influenced by temperature – the higher temperature results in a faster degradation of 2-CP. The activation of persulfate by ferrous and copper ions was also studied. Results showed that persulfate is activated more effectively by iron(II) than copper(II) ions. A comparison of different persulfate activation methods revealed that heat-activation was the most effective. Under optimal conditions, in the presence of ferrous ions at 50 °C, complete degradation of 2-chlorophenol was achieved after about 30 minutes.
18
Content available remote Oxidative Decarboxylation and Deamination of Essential Amino Acids by Nicotinium Dichromate – a Kinetic Study
100%
Vivekanandan K. , Lakshmi Narayanan R.
International Letters of Chemistry, Physics and Astronomy
|
2015
|
tom Vol. 45
66-72
EN
The oxidation of essential amino acids like valine, leucine, isoleucine, threonine, phenylalanine and histidine using nicotinium dichromate in aqueous medium in presence of perchloric acid at 313 K leads to the formation of corresponding aldehydes. The reaction is first order with respect to nicotinium dichromate, fractional order with respect to amino acids and second order with respect to perchloric acid. Increase in ionic strength by the addition of sodium perchlorate has no effect on the rate constant. There is no polymerization with acrylonitrile. The reaction has been studied at different temperatures and a mechanism confirming to the kinetic observations is suggested.
19
Content available Kinetics and mechanism of meso-tetraphenylporphyriniron(III) chloride (TPP) catalysed oxidation of indole by sodium perborate
100%
Kungumathilagam D. , Karunakaran K.
Polish Journal of Chemical Technology
|
2013
|
tom Vol. 15, nr 2
107–111
EN
Developing catalyst is very significant for biologically important reactions which yield products, used as drugs. Mechanistic study on meso-tetraphenylporphyriniron(III) chloride (TPP) catalysed oxidation of indole by sodium perborate in aqueous acetic acid medium have been carried out. The reaction follows a fractional order with respect to substrate and catalyst. The order with respect to oxidant was found to be one. Increase in the percentage of acetic acid and increase in the concentration of [H+] decreased the rate. The reaction fails to initiate polymerization, and a radical mechanism is ruled out. Activation and thermodynamic parameters have been computed. A suitable kinetic scheme based on these observations has been proposed. Significant catalytic activity is observed for the reaction system in the presence of TPP.
20
Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes : a Short Review
100%
Mąkosza M. , Staliński K.
Polish Journal of Chemistry
|
1999
|
tom vol. 73 nr 1
151-161
EN
Selected examples of oxidative nucleophilic aromatic substitution in nitroarenes are discussed with emphasis on the authors results. Generalization of this process is attempted.
first rewind previous Strona / 35 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.