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1

Impact of the water composition on the degradation kinetics of natural organic matter in photocatalytic membrane reactors

Rajca M

Environment Protection Engineering

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2015

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Vol. 41, nr 1

29--39

EN

Decomposition kinetics of natural organic substances during the photocatalytic process with a semi-conductor TiO2 has been investigated. In the study, a laboratory reactor Heraeus and in a photocatalytic membrane reactor were used. Simulated solutions of deionized water, surface water and fulvic acids, differing in composition, were tested in the experiment. In order to determine reaction rate constants, the Langmuir–Hinshelwood kinetic model based on the first order reaction was applied. It was found that photocatalytic process enabled effective degradation of natural organic substances although its run was affected by inorganic ions, mainly those producing water hardness, present in water.

2

Comparative study of the kinetic approach on the alcoholic fermentation procedure conducted in laboratory and scale-up systems by inverse gas chromatography

Lainioti G. Ch., Kapolos J., Koliadima A., Karaiskakis G.

Acta Chromatographica

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2014

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Vol. 26, no. 2

371--389

EN

The major objective of the present work was to compare the kinetic study of alcoholic fermentations conducted in the presence of wheat supported biocatalysts in laboratory scale and in a scale-up system of 80 L and to compare these results with those reported in literature. The kinetic study of fermentation processes was accomplished with the technique of reversed flow gas chromatography (RFGC), which is a version of inverse gas chromatography. The wine yeast species used was Saccharomyces cerevisiae AXAZ-1, and fermentations were conducted between 20 and 2°C. At low temperatures, maximal ethanol productivity and fermentation rate were reduced. The rate constants, determined through a mathematical model obtained from RFGC, were higher in the laboratory scale comparing to the scale-up system at the temperatures of 20 and 15°C. However, with the reduction of temperature, both systems presented almost similar values proving the great fermentative ability of immobilized cells even at extremely low temperatures. Activation energies of the alcoholic fermentations in the two systems presented their higher values at the second phase (stationary) compared to those observed at the other two phases (growth and decline).

3

Addition of bisulfite ions to methyl vinyl ketone and methacrolein relevant to atmospheric processes

Szmigielski R., Rudziński K. J.

Ecological Chemistry and Engineering. A

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2013

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Vol. 20, nr 9

935--949

PL

Metakroleina oraz keton metylowo-winylowy są bardzo reaktywnymi zawiązkami karbonylowymi, które odgrywają istotną rolę w procesach atmosferycznych, w tym – w tworzeniu pyłów zwieszonych w powietrzu. Obydwa związki są produktami utleniania izoprenu – węglowodoru emitowanego do atmosfery w ogromnych ilościach. W pracy przedyskutowano mechanizmy chemiczne zaniku metakroleiny oraz ketonu metylowo-winylowego w wyniku addycji anionu wodorosiarczanowego w rozcieńczonych roztworach wodnych, odzwierciedlające procesy zachodzące w kroplach wód atmosferycznych w rejonach o znaczącym stężeniu ditlenku siarki. W pracy pokazano, że reakcje addycji anionu wodorosiarczynowego do badanych związków karbonylowych prowadzą do tworzenia pierwotnych i wtórnych hydroksysulfonianów, które mogą uczestniczyć w tworzeniu aerozoli atmosferycznych. Wyznaczono stałe szybkości wszystkich reakcji w mechanizmie addycji. Pierwotna addycja anionów wodorosiarczynowych do metakroleiny okazała się znacznie szybsza niż do ketonu metylowo-winylowego (stałe szybkości kMAC1f = 8 i kMVK1f = 0.18 mol–1 dm3 s–1 w temperaturach pokojowych). Stała szybkości addycji do cząsteczki metakroleiny była dziesięciokrotnie większa od stałej opublikowanej w literaturze. Analiza kinetyczna i badania produktów reakcji za pomocą spektrometrii mas wykazały, że w przypadku każdego z badanych związków karbonylowych dominującym produktem reakcji był C4 alfa-hydroksysulfonian (addukt pierwotny), natomiast C4 hydroksydwusulfonian (addukt wtórny, diaddukt) powstawał w ilościach śladowych. Pierwotna addycja anionów wodorosiarczynowych do metakroleiny i ketonu metylowo-winylowego może mieć znaczenie w konwersji reaktywnych związków karbonylowych w atmosferze i powinna być uwzględniana w badaniach dotyczących rejonów o znaczącej obecności ditlenku siarki, gwarantującej wysokie stężenia anionów wodorosiarczynowych w wodach atmosferycznych.

EN

Methacrolein and methyl vinyl ketone are highly reactive carbonyls that play a pivotal role in the formation of secondary organic aerosols in the Earth’s atmosphere. Both carbonyls are the major products of isoprene oxidation. We show that among the atmospheric sinks of methacrolein and methyl vinyl ketone, the aqueous-phase addition of bisulfite anions to their molecules can be relevant under polluted conditions with the increased presence of sulfur dioxide. We demonstrate that aqueous-phase reactions of methyl vinyl ketone and methacrolein with bisulfite anions lead to the formation of primary and secondary organic hydroxysulfonates which currently are not included in the atmospheric chemistry modelling, but can be relevant in mechanisms explaining the formation and growth of the secondary organic aerosols from atmospheric carbonyls. The rate constants for all aqueous-phase reactions involved were determined. The primary addition of bisulfite anions to methacrolein was found significantly faster than that to methyl vinyl ketone, with rate constants kMAC1f = 8 and kMVK1f = 0.18 mol–1 dm3 s–1 at room temperatures, respectively. The rate constant for the bisulfite addition to methacrolein was ten times faster than reported in the literature. The kinetic and mass spectrometric analyses revealed that in both cases, the dominating product was the C4 alpha-hydroxysulfonate (a primary adduct), while the C4 alpha-hydroxy disulfonate (a secondary adduct or diadduct) was produced only in trace quantities. The primary addition of bisufite anions to methacrolein and methyl vinyl ketone should be considered in atmospheric studies relevant to areas with enhanced presence of sulfur dioxide providing sufficiently high concentrations of bisulfite ions in atmospheric waters.

4

Reaction kinetics and thiourea removal by ozone oxidation

Xie Q., Dong X., Huang W., Xu H., Du H.

Environment Protection Engineering

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2012

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Vol. 38, nr 4

87--98

EN

Thiourea is a toxicant which will bring some adverse effects to the public health. In the study, thiourea was degraded via ozonation process. The results show that the ozonation is an effective method to remove thiourea from wastewaters. When the ozone flow rate was 600 cm3*min-1, pH was 7.3, the temperature was 20 °C, 93.97% of thiourea (200 cm3 solution of 3 g dm-3) could be degraded after 9 min of reaction. The reaction order of ozonation of thiourea n was 0.11, and the reaction rate constant k = 0.4898 g0.89 (dm3)-0.89*min -1.

5

Photocatalytic degradation of an organic dye in some aqueous buffer solutions using nano titanium dioxide: A kinetic study

Montazerozohori M., Nasr-Esfahani M., Joohari S.

Environment Protection Engineering

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2012

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Vol. 38, nr 3

45--55

EN

Photocatalytic degradation of an organic dye, emerald green, on nano titanium dioxide (anatase 99.5%) at basic buffer pH of 7, 8 and 9 has been investigated. The effects of various operating parameters such as initial concentration of dye, catalyst dosage, bufferic pH and irradiation time on photocatalytic degradation have been studied in a photoreactor cell containing high pressure mercury lamp to obtain the optimum conditions. COD removal was found to be 65-71% confirming considerable mineralization. The photodegradation of the dye obeyed a pseudo-first order kinetics according to the Langmuir-Hinshelwood model at all used buffer pH. The observed rate constants (Kobs) of photocatalytic degradation were 3.3 ×10-2 min-1, 7.09 × 10-2 min-1 and 1.32 × 10-1 min-1 at buffer pH of 7-9 respectively. Furthermore, the Langmuir-Hinshelwood rate constants, kr and adsorption constants, KA are reported for current process at various buffer pH.

6

Rate constants of electron-beam PAHs decomposition

Gerasimov G.

Nukleonika

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2007

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Vol. 52, nr 3

105-108

EN

The generalized kinetic model of the electron-beam induced processes in industrial flue gases elaborated earlier is used for the estimation of rate constants of hydroxyl-radicals interaction with high-ringed aromatic compounds. These data are received by means of the fit of the calculated PAHs concentrations to the measured ones as applied to benzo(a)anthracene, benzo(e)pyrene, benzo(a)pyrene, perylene, and dibenzo(a,h)anthracene. It is shown that the concentrations of PAHs decrease by more than an order of magnitude at the absorbed dose D = 20 kGy for compounds with rate constant of their interaction with OH-radical more than 1013 cm3źmol 1źs 1.

7

tert-Butylimino-tris(dimethylamino)phosphorane as a Proton Acceptor in the System of Reaction of 1-Nitro-1-(4-nitrophenyl)alkanes in THF

Wisłocka I., Nowak I., Jarczewski A.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 12

2017-2029

EN

Unexpectedly the reaction of deprotonation of carbon acids with phosphazene bases occurred very slowly. The kinetic study of the proton transfer reactions between C-acids of the series of nitroalkanes with increasing bulk of R = H, Me, Et, i-Pr substituents as 4-nitrophenylnitromethane (1), 1-nitro-1-(4-nitrophenyl)ethane (2), 1-nitro-1-(4-nitrophenyl) propane (3), 2-methyl-1-nitro-1-(4-nitrophenyl)propane (4) and the tert-butylimino-tris(dimethylamino)phosphorane (5) named P1-t-Bu phosphazene is elaborated. The reactions have been studied in THF under pseudo-first-order conditions. The product of the proton transfer reactionwith P1-t-Bu in THF appeared to be associated into ion pairs. The equilibrium constants range from >100000 to 11.8 decreasing along with growing bulk of alkyl substituent in the reacting C-acid. The second order rate constants (k2H) are rapidly declining: 9360, 2.31, 0.66, 0.09 dm3 mol–1 s–1for 1, 2, 3, and4 respectively, and could not be accounted for the small values of the enthalpies of activation HH = 6.1, 18.0, 20.7 and 11.1 kJ mol–1. The reactions show negative and relatively large values of the entropies of activation SH = –149.7, –176.5, –178.7, –227.8 J mol–1 deg–1. The primary deuterium kinetic isotope effects are large showing tendency of reverse relation towards steric hindrance of the reacting C-acids, kH/kD = 15.8, 13.6, 13.2 for 1,2, and 3, respectively. The results have been discussed in terms of the influence of steric effects brought by the bulk of alkyl substituents in the C-acid and the base on formation of the transition state. Also the influence of traces of residual water present in the reaction system has been taken into consideration.

8

Cognitive Aspects of the Cap-Pair Effect

Sykut K., Dalmata G., Marczewska B., Saba J.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 9

1583-1596

EN

The paper discusses the cap-pair rule discovered by the authors. The cap-pair rule is associated with acceleration of electrode processes by organic substances. The mechanism and the kinetics of electrode processes in aqueous solutions and aqueous-organic solvents are discussed. Anew concept of the "piloting ion" to study mixed adsorption layers based on the cap-pair rule is presented.

9

Dynamics of Molecular Hydrogen Exchange in Hydrogen-Bonded Systems

Bureiko S., Denisov G. S.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 9

1177-1190

EN

The kinetics of hydrogen exchange in molecular systems with H-bonds studied by kinetic IR spectroscopy and low-temperatureNMRspectroscopy methods is critically reviewed. The experimental rate constants and activation energies obtained so far for molecules capable of forming H-bonds as both proton donors and proton acceptors are collected and analyzed from the point of view of the influence of H-bond formation ability of the molecules- partners. The evidence available testifies to a molecular mechanism of the H-exchange reactions in inert solvents and in the gas phase via the formation of cyclic, mostly bimolecular, intermediates. The different mechanisms of the molecular H-exchange process in inert media are discussed and the possible paths of experimental elucidation of reaction mechanism are offered.