Preparation, Solubility, Infrared Spectra and Radiolysis of Tetramethylammonium Hydrogenselenate Monohydrate and Lithium Tetramethylammonium Selenate Tetrahydrate

2006 ◽  
Vol 71 (3) ◽  
pp. 411-422 ◽  
Author(s):  
David Havlíček ◽  
Libor Turek ◽  
Jiří Plocek ◽  
Zdeněk Mička
Keyword(s):  
Chemical Analysis ◽  
Rate Constant ◽  
Infrared Spectra ◽  
Molecular Spectroscopy ◽  
Anhydrous Salt ◽  
First Order ◽  
First Order Kinetics ◽  
New Compounds

Solubility in the (Me4N)2SeO4-H2SeO4-H2O and (Me4N)2SeO4-Li2SeO4-H2O systems were studied. The new compounds, tetramethylammonium hydrogenselenate monohydrate ((Me4N)HSeO4·H2O) and lithium tetramethylammonium selenate tetrahydrate (Li(Me4N)SeO4·4H2O), have been found in these systems. Both substances were characterised by chemical analysis and IR molecular spectroscopy. Both of the title substances decompose under the influence of X-radiation and, thus, their structures cannot be determined. The radiolysis of both substances was studied in greater detail. Tetramethylammonium hydrogenselenate monohydrate is dehydrated by X-radiation to form the anhydrous salt. The reaction is controlled by first-order kinetics with a rate constant of 1.30(3) × 10-3 s-1.

Effects of oxidant concentration and temperature on decolorization of azo dye: comparisons of UV/Fenton and UV/Fenton-like systems

2012 ◽  
Vol 65 (11) ◽  
pp. 1970-1974 ◽  
Author(s):  
C. Y. Kuo ◽  
C. Y. Pai ◽  
C. H. Wu ◽  
M. Y. Jian
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Azo Dye ◽  
Activation Energies ◽  
First Order ◽  
First Order Kinetics ◽  
Oxidant Concentration ◽  
Decolorization Efficiency ◽  
Pseudo First Order ◽  
Reactive Red 2

This study applies photo-Fenton and photo-Fenton-like systems to decolorize C.I. Reactive Red 2 (RR2). The oxidants were H2O2 and Na2S2O8; Fe2+, Fe3+, and Co2+ were used to activate these two oxidants. The effects of oxidant concentration (0.3–2 mmol/L) and temperature (25–55 °C) on decolorization efficiency of the photo-Fenton and photo-Fenton-like systems were determined. The decolorization rate constants (k) of RR2 in the tested systems are consistent with pseudo-first-order kinetics. The rate constant increased as oxidant concentration and temperature increased. Activation energies of RR2 decolorization in the UV/H2O2/Fe2+, UV/H2O2/Fe3+, UV/Na2S2O8/Fe2+ and UV/Na2S2O8/Fe3+ systems were 32.20, 39.54, 35.54, and 51.75 kJ/mol, respectively.

Analysis of the Rate Constant for Hydration Kinetics of the Cement and Ash Fly in the Solidified Residues System Based on the Measurement of Ca(OH)2

2013 ◽  
Vol 380-384 ◽  
pp. 4395-4399
Author(s):  
Qin Li ◽  
Xiao Jun Zhou ◽  
Ke Wei Sun
Keyword(s):  
Chemical Analysis ◽  
Rate Constant ◽  
Matrix Material ◽  
Order Reaction ◽  
First Order Reaction ◽  
Cement Matrix ◽  
Analysis Method ◽  
Hydration Kinetics ◽  
First Order ◽  
Kinetics Of

Based on the hydration kinetics of the cement matrix material, the paper presents a chemical analysis method by means of analyzing the contents of Ca(OH)2 in cement matrix material. The kinetics constant for the cement, ash fly in the residues system solidified by recycled cement, ash fly was determined at different temperature. The hydration kinetics characteristic of the residues system after being hydrated 7 days is first order reaction.

Kinetics of the Ce3+/BrO2-Reaction in Sulfuric Acid Medium

1985 ◽  
Vol 40 (4) ◽  
pp. 368-372 ◽  
Author(s):  
H. D. Försterling ◽  
H. J. Lamberz ◽  
H. Schreiber
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Acid Medium ◽  
Rate Constant ◽  
Constant Concentration ◽  
First Order ◽  
Sulfuric Acid Medium ◽  
First Order Kinetics ◽  
Belousov Zhabotinsky Reaction ◽  
Kinetics Of

The reaction of Ce3+ with BrO2 in sulfuric acid solution (which is the starting step in the inorganic reaction subset of the Belousov-Zhabotinsky-reaction) is followed spectroscopically in a reaction mixture containing BrO2 at constant concentration. From first order kinetics (Br02 in excess) the rate constant for this reaction is evaluated.

Thermal decomposition of citraconic anhydride

1971 ◽  
Vol 24 (4) ◽  
pp. 771 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constant ◽  
Arrhenius Equation ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
First Order ◽  
First Order Kinetics ◽  
Citraconic Anhydride

Citraconic anhydride decomposes in the gas phase over the range 440- 490� to give carbon dioxide, carbon monoxide, and propyne which undergoes some polymerization to trimethylbenzenes. The decomposition obeys first-order kinetics, and the Arrhenius equation ������������������� k1 = 1015.64 exp(-64233�500/RT) (s-1) describes the variation of rate constant with temperature. The rate constant is unaffected by the addition of isobutene or by increase in the surface/volume ratio of the reaction vessel. The reaction appears to be unimolecular and if a diradical intermediate is involved it may not be fully formed in the transition state.

scholarly journals Acetazolamide-insensitive carbonic anhydrase activities in liver and tonic skeletal muscle of adult male rats with streptozotocin-induced diabetes mellitus

1990 ◽  
Vol 272 (2) ◽  
pp. 553-556 ◽  
Author(s):  
J B Moynihan ◽  
S Ennis
Keyword(s):  
Diabetes Mellitus ◽  
Skeletal Muscle ◽  
Carbonic Anhydrase ◽  
Rate Constant ◽  
Adult Male ◽  
Turnover Rate ◽  
Male Rats ◽  
First Order ◽  
First Order Kinetics ◽  
Streptozotocin Induced Diabetes

One of the four discrete isoenzymes of carbonic anhydrase hitherto characterized, CA III, has the lowest turnover rate and the greatest resistance to inhibition by sulphonamides. Streptozotocin-induced diabetes mellitus resulted in a reduction in acetazolamide-resistant activity of carbonic anhydrase in the liver, but not in tonic skeletal muscle, of adult male rats. The hepatic activity declined with apparent first-order kinetics [calculated rate constant (k) 0.089 day-1] to a minimum of approx. 6% of control values; the reduction in activity was moderated by administration of insulin.

scholarly journals Belousov-Zhabotínsky oscillatory reaction. Kinetics of malonic acid decomposition

2000 ◽  
Vol 65 (10) ◽  
pp. 709-713 ◽  
Author(s):  
Slavica Blagojevic ◽  
Natasa Pejic ◽  
Slobodan Anic ◽  
Ljiljana Kolar-Anic
Keyword(s):  
Sulfuric Acid ◽  
Reaction Kinetics ◽  
Rate Constant ◽  
Malonic Acid ◽  
Oscillatory Reaction ◽  
Acid Decomposition ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of the Belousov-Zhabotinsky (BZ) oscillatory reaction was analyzed. With this aim, the tune evolution of a reactionmixture composedof malonic acid, bromate, sulfuric acid and cerium(III) was studied at 298 K. Pseudo-first order kinetics with respect to malonic acid as the species undergoing decomposition with a corresponding rate constant, k = 7.5x10-3 min-1, was found.

scholarly journals Diastase number changes during thermaland  microwave processing of honey

2012 ◽  
Vol 30 (No. 1) ◽  
pp. 21-26 ◽  
Author(s):  
S. Kowalski ◽  
M. Lukasiewicz ◽  
S. Bednarz ◽  
M. Panuś
Keyword(s):  
Thermal Treatment ◽  
Rate Constant ◽  
Microwave Processing ◽  
Enzyme Inactivation ◽  
Local Market ◽  
Short Term ◽  
First Order ◽  
First Order Kinetics ◽  
Constant Rate

The presented paper covers the preliminary studies on microwave inactivation of honey enzymes described as diastase number (DN). All the investigations were done on commercially available honey from Polish local market. Microwave processes were compared to the conventional ones. In the case of conventional conditions, the constant rate of diastase enzyme inactivation was estimated using the first order kinetics. In the case of microwave heated samples, it was impossible to establish the rate constant; however, the investigation proved the suitability of such kind of processing for short-term thermal treatment of honey.  

scholarly journals KINETIKA FOTODEGRADASI KLOROFIL, TOKOFEROL, DAN KAROTENOID DALAM MINYAK SAWIT MERAH (Photodegradation Kinetics of Chlorophyll, Tocopherol, and Carotenoid in Red Palm Oil)

2016 ◽  
Vol 36 (02) ◽  
pp. 117 ◽  
Author(s):  
Dewi Fortuna Ayu ◽  
Nuri Andarwulan ◽  
Purwiyatno Hariyadi ◽  
Eko Hari Purnomo
Keyword(s):  
Light Intensity ◽  
Rate Constant ◽  
Palm Oil ◽  
Prolonged Storage ◽  
K Value ◽  
Red Palm Oil ◽  
First Order ◽  
First Order Kinetics ◽  
Light Intensities ◽  
Kinetics Of

The objective of this research was to assess the photodegradation kinetics of chlorophyll, tocopherol, and carotenoid in red palm oil (RPO) during storage under flourescent light intensities of 5000, 10000, and 15000 lux. Photodegradation was followed by measuring the changes of chlorophyll, tocopherol, and carotene contents in RPO filled in transparent bottles stored in incubator box (31.60±0.69 oC) with controlled light intensity. As reference, pure RPO was filled in dark and transparent bottles then was stored at roomy temperature (31.46±1.04 °C) and lighting (476.25-484.89lux). The result showed that photodegradation of chlorophyll followed first order kinetics with two distinct photodegradation periods. First, rapid photodegradation period during the first 6 hours of storage with k values of 3.81x10-2, 4.45x10-2, 5.64x10-2 day-1, followed by a slower photodegradation period at prolonged storage more than 6 hours, with k values of 1.41x10-2, 3.01x10-2, 4.59x10-2 day-1 under light intensities of 5000, 10000, and 15000 lux, respectively. Photodegradation of tocopherol and carotene also followed first order kinetics. Photodegradation of tocopherol had the highest rate constant (k value of 9.10x10-2, 12.02x10-2, 17.33x10-2 day-1), meanwhile carotene had the lowest rate constant (k value of 0.80x10-2, 1.40x10-2, 1.98x10-2 day-1) under light intensities of 5000, 10000, and 15000 lux, respectively. The light intensity coefficient (zi) as dependence indicator of k on the changes of light intensity were measured. The zi values ofchlorophyll, tocopherol, and carotene were 20000, 33333, and 25000 lux, respectively; indicated that the degradation rate of chlorophyll was the most sensitive to the changes of light intensity. Keywords: Red palm oil, photo-oxidation, chlorophyll, tocopherol, carotene ABSTRAKPenelitian ini bertujuan untuk mengkaji laju fotodegradasi klorofil, tokoferol, dan karoten dalam minyak sawit merah (MSM) selama penyimpanan dalam kondisi terpapar cahaya fluoresen pada intensitas 5000, 10000, dan 15000 lux. Fotodegradasi dikaji dengan mengukur perubahan kadar klorofil, tokoferol, dan karoten MSM pada botol transparan yang disimpan dalam kotak inkubator (31,60±0,69 oC) dengan intensitas cahaya dipertahankan konstan. Sebagai pembanding, MSM murni dalam botol gelap dan transparan disimpan pada suhu (31,46±1,04 °C) dan pencahayaan normal laboratorium (476,25-484,89 lux). Hasil penelitian menunjukkan bahwa klorofil mengalami fotodegradasi mengikuti model reaksi ordo pertama dalam dua periode; yaitu periode fotodegradasi cepat selama penyimpanan 6 jam pertama dengan nilai konstanta laju (k) 3,81x10-2, 4,45x10-2, 5,64x10-2 hari-1, diikuti periode fotodegradasi lambat pada penyimpanan yang lebih lama dengan nilai k 1,41x10-2, 3,01x10-2, 4,59x10-2 hari-1 masing-masing pada intensitas cahaya 5000, 10000, dan 15000 lux. Fotodegradasi tokoferol dan karoten juga mengikuti model reaksi ordo pertama. Fotodegradasi tokoferol berlangsung dengan laju paling tinggi (nilai k 9,10x10-2, 12,02x10-2, 17,33x10-2 hari-1), sedangkan fotodegradasi karoten berlangsung dengan laju paling rendah (nilai k 0,80x10-2, 1,40x10-2, 1, 98x10-2 hari-1) masing-masing pada perlakuan intensitas cahaya 5000, 10000, dan 15000 lux. Konstanta intensitas cahaya (zi) sebagai indikator ketergantungan nilai k terhadap perubahan intensitas cahaya untuk klorofil, tokoferol, karoten berturut-turut adalah 20000, 33333, dan 25000 lux. Hal ini mengindikasikan bahwa laju degradasi klorofil paling sensitif terhadap perubahan intensitas cahaya. Kata kunci: Minyak sawit merah, foto-oksidasi, klorofil, tokoferol, karoten

Degradation of Pendimethalin in Soil

Weed Science ◽  
1984 ◽  
Vol 32 (3) ◽  
pp. 408-412 ◽  
Author(s):  
Robert L. Zimdahl ◽  
Pietro Catizone ◽  
Ann C. Butcher
Keyword(s):  
Soil Moisture ◽  
Chemical Analysis ◽  
Soil Temperature ◽  
Soil Type ◽  
Half Life ◽  
Field Capacity ◽  
Quadratic Model ◽  
Laboratory Studies ◽  
First Order ◽  
First Order Kinetics

Pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] degradation in three soils did not follow first-order kinetics but could be described by a quadratic model. Degradation increased as soil temperature increased in the order 10, 20, 35, and 30C. The rate was the same as 75 and 100% field capacity but slower at 50%. At the same temperature and soil moisture the influence of soil type was small. Based on chemical analysis of soil from field and laboratory studies, the half-life was approximately 47 days. Based on biological analyses of soil, the half-life was 78 to 111 days.

Measurement of the Rate of Clot Retraction

1974 ◽  
Vol 31 (03) ◽  
pp. 452-456 ◽  
Author(s):  
Michio Itoh ◽  
Yoshihisa Nishimura ◽  
Osamu Takenaka ◽  
Yuji Inada
Keyword(s):  
Rate Constant ◽  
Clot Retraction ◽  
First Order ◽  
First Order Kinetics ◽  
Two Parameters ◽  
The Way

SummaryThe volume of serum exuded from clot was measured with time in the presence of platelets. The change of the volume of clot followed the first order kinetics with respect to time and the rate constant (k) was introduced to assay for clot retraction. The value of k and maximal serum volume exuded from clot, Vf, are dependent on the number of platelets, but the way k depends on the number of platelets is different from that Vf does on it. This suggests that these two parameters reflect the different phases of clot retraction.

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