New aspect of the mechanism of photocatalytic oxidation of organic compounds by polyoxometalates in aqueous solutions. The selective photooxidation of propan-2-ol to propanone: The role of OH radicals

1999 ◽  
Vol 1 (3) ◽  
pp. 437-440 ◽  
Author(s):  
Athanasios Mylonas ◽  
Anastasia Hiskia ◽  
Evaggelia Androulaki ◽  
Dimitra Dimotikali ◽  
Elias Papaconstantinou
Keyword(s):  
Aqueous Solutions ◽  
Organic Compounds ◽  
Photocatalytic Oxidation ◽  
Oh Radicals ◽  
Oxidation Of Organic Compounds

scholarly journals Role of Criegee intermediates in the formation of sulfuric acid at a Mediterranean (Cape Corsica) site under influence of biogenic emissions

2021 ◽  
Vol 21 (17) ◽  
pp. 13333-13351
Author(s):  
Alexandre Kukui ◽  
Michel Chartier ◽  
Jinhe Wang ◽  
Hui Chen ◽  
Sébastien Dusanter ◽  
...  
Keyword(s):  
Steady State ◽  
Sulfuric Acid ◽  
Organic Compounds ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Additional Source ◽  
So2 Oxidation ◽  
Criegee Intermediates ◽  
Volatile Organic

Abstract. Reaction of stabilized Criegee intermediates (SCIs) with SO2 was proposed as an additional pathway of gaseous sulfuric acid (H2SO4) formation in the atmosphere, supplementary to the conventional mechanism of H2SO4 production by oxidation of SO2 in reaction with OH radicals. However, because of a large uncertainty in mechanism and rate coefficients for the atmospheric formation and loss reactions of different SCIs, the importance of this additional source is not well established. In this work, we present an estimation of the role of SCIs in H2SO4 formation at a western Mediterranean (Cape Corsica) remote site, where comprehensive field observations including gas-phase H2SO4, OH radicals, SO2, volatile organic compounds (VOCs) and aerosol size distribution measurements were performed in July–August 2013 as a part of the project ChArMEx (Chemistry-Aerosols Mediterranean Experiment). The measurement site was under strong influence of local emissions of biogenic volatile organic compounds, including monoterpenes and isoprene generating SCIs in reactions with ozone, and, hence, presenting an additional source of H2SO4 via SO2 oxidation by the SCIs. Assuming the validity of a steady state between H2SO4 production and its loss by condensation on existing aerosol particles with a unity accommodation coefficient, about 90 % of the H2SO4 formation during the day could be explained by the reaction of SO2 with OH. During the night the oxidation of SO2 by OH radicals was found to contribute only about 10 % to the H2SO4 formation. The accuracy of the derived values for the contribution of OH + SO2 reaction to the H2SO4 formation is limited mostly by a large, at present factor of 2, uncertainty in the OH + SO2 reaction rate coefficient. The contribution of the SO2 oxidation by SCIs to the H2SO4 formation was evaluated using available measurements of unsaturated VOCs and steady-state SCI concentrations estimated by adopting rate coefficients for SCI reactions based on structure–activity relationships (SARs). The estimated concentration of the sum of SCIs was in the range of (1–3) × 103 molec. cm−3. During the day the reaction of SCIs with SO2 was found to account for about 10 % and during the night for about 40 % of the H2SO4 production, closing the H2SO4 budget during the day but leaving unexplained about 50 % of the H2SO4 formation during the night. Despite large uncertainties in used kinetic parameters, these results indicate that the SO2 oxidation by SCIs may represent an important H2SO4 source in VOC-rich environments, especially during nighttime.

Some applications of polarography for investigation of equlibria in aqueous solutions of organic compounds

2009 ◽  
Vol 74 (11-12) ◽  
pp. 1777-1789 ◽  
Author(s):  
Petr Zuman
Keyword(s):  
Aqueous Solutions ◽  
Organic Compounds ◽  
Carbonyl Compounds ◽  
Limiting Current ◽  
Nitroso Compounds ◽  
Primary Amines ◽  
Acid Base ◽  
Fast Reactions ◽  
Half Wave

There are two possibilities how to follow equilibria of organic compounds established in aqueous solutions using polarography: for very fast reactions, information can be obtained from shifts of half-wave potentials. For slowly established equilibria, the changes in the limiting current are followed. In both cases variation of the half-wave potentials or limiting currents with concentration of a reactant, present in excess, is followed. The types of reactions, which had been followed in this way, are as follows: hydration–dehydration equilibria, additions of hydroxide ion to carbonyl and nitroso compounds, the role of slowly established acid–base equilibria involving C-acids; further also reactions involving the addition of ammonia, primary amines, hydroxylamine, and hydrazine to carbonyl compounds.

Photocatalytical oxidation of de-icing agents in aqueous solutions and aqueous extract of jet fuel

2001 ◽  
Vol 44 (5) ◽  
pp. 1-6 ◽  
Author(s):  
Krichevskaya M. ◽  
Malygina T. ◽  
Preis S. ◽  
Kallas J.
Keyword(s):  
Titanium Dioxide ◽  
Aqueous Solutions ◽  
Aqueous Extract ◽  
Jet Fuel ◽  
Military Bases ◽  
Oh Radicals ◽  
Oh Radical ◽  
Heavy Pollution ◽  
Shallow Ponds

Improper handling of jet fuel at abandoned military bases has resulted in heavy pollution of the soil and groundwater. Experimental research of photocatalytical oxidation (PCO) of jet fuel aqueous extract and aqueous solutions of de-icing agents was undertaken. The influence of different parameters - pH, concentration of substances to be oxidised, presence of inorganic admixtures, effect of OH• radical generators - on the PCO of solutions of de-icing agents and jet fuel aqueous extract was determined. The role of OH• radicals was found to be less important in determining the PCO rate. The PCO of organic pollutants was also investigated using a catalyst immobilised onto the surface of buoyant hollow glass micro-spheres. Attached titanium dioxide (TiO2) showed lower photocatalytical activity than when suspended in slurry, although it allows waters to be treated in simple shallow ponds without intensive stirring. The biodegradability of aqueous solutions of de-icing agents and jet fuel aqueous extract increased as PCO proceeded.

Ti(iv) nanoclusters as a promoter on semiconductor photocatalysts for the oxidation of organic compounds

2016 ◽  
Vol 4 (5) ◽  
pp. 1784-1791 ◽  
Author(s):  
Ryota Inde ◽  
Min Liu ◽  
Daiki Atarashi ◽  
Etsuo Sakai ◽  
Masahiro Miyauchi
Keyword(s):  
Organic Compounds ◽  
Photocatalytic Oxidation ◽  
Oxidation Of Organic Compounds

Ti(IV) clusters act to accelerate the photocatalytic oxidation of organic compounds.

Photocatalytic oxidation of organic compounds on Mars

Nature ◽  
1978 ◽  
Vol 274 (5674) ◽  
pp. 875-876 ◽  
Author(s):  
SANDY F. S. CHUN ◽  
KEVIN D. PANG ◽  
JAMES A. CUTTS ◽  
JOSEPH M. AJELLO
Keyword(s):  
Organic Compounds ◽  
Photocatalytic Oxidation ◽  
Oxidation Of Organic Compounds

scholarly journals Study of the factors that determine the transfer of water and organic compounds into the gas phase from aqueous solutions in a discharge with a liquid cathode

2021 ◽  
Vol 2100 (1) ◽  
pp. 012025
Author(s):  
A V Chistolinov ◽  
M A Khromov ◽  
R V Yakushin ◽  
M Kh Gadzhiev ◽  
A S Tyuftyaev
Keyword(s):  
Aqueous Solution ◽  
Free Surface ◽  
Aqueous Solutions ◽  
Gas Phase ◽  
Organic Compounds ◽  
Direct Current ◽  
Current Discharge ◽  
Liquid Cathode ◽  
Direct Current Discharge

Abstract A study was performed to investigate the transfer of organic compounds and water from an aqueous solution to the gas phase under the action of a direct current discharge, in which an aqueous solution that contains organic compounds plays the role of a cathode. The effect of the area of the free surface of a liquid in various reactors, as well as the effect of the stirring mode of a solution near the surface of a liquid on the rate of transfer of water and organic compounds under the action of a discharge of this type, have been investigated. It is shown that a change in the area of the free surface of a liquid has no significant effect on the rate of transfer of water and organic compounds from solution to the gas phase under the action of a direct current discharge with a liquid cathode. It is shown that the stirring mode and the temperature of the solution, on the contrary, have a very significant effect on the rate of nonequilibrium transfer of both water and organic compounds from solution to the gas phase under the action of a discharge with a liquid cathode.

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