Mechanisms for ozone-initiated removal of biomass burning products from the atmosphere

2018 ◽  
Vol 15 (2) ◽  
pp. 83 ◽  
Author(s):  
Jianfei Sun ◽  
Qiong Mei ◽  
Bo Wei ◽  
Long Huan ◽  
Ju Xie ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Rate Constants ◽  
Computational Method ◽  
Atmospheric Conditions ◽  
Reaction Products ◽  
Positive Dependence ◽  
Elementary Reactions ◽  
Criegee Intermediates ◽  
Ozone Addition ◽  
Kinetics Of

Environmental contextAn important product of biomass burning is catechol: its presence in the atmosphere can have adverse effects on health, and can lead to the formation of secondary organic aerosols. We report a theoretical study on the mechanisms and kinetics of removal of catechol from the atmosphere by reaction with ozone. These data will provide insight into the ozonolysis of other lignin compounds produced by biomass burning. AbstractWe examined the ozone-initiated oxidation of catechol, an intermediate of lignin pyrolysis in the atmosphere, by using the theoretical computational method at the M06-2X/aug-cc-pVDZ//M06-2X/6-31+G(d,p) level. Six ozone-addition channels of the initial reactions and the further reactions of the Criegee intermediates are proposed. The complete degradation processes of the Criegee intermediates in the presence of NO and H2O were elucidated. The predicted reaction products for the ozonolysis of catechol, such as malealdehyde (P10), oxalic acid (P11) and CO2, were detected experimentally in the gas-phase. Moreover, the microcanonical rate constants of the crucial elementary reactions were determined by the Rice–Ramsperger–Kassel–Marcus theory. The total rate constant for the ozonolysis of catechol under atmospheric conditions is 1.37 × 10−18 cm3 molecule−1 s−1, which compares favourably to the experimentally determined values. The bimolecular rate constants showed positive dependence on temperature and negative dependence on pressure. The atmospheric lifetime of catechol with respect to ozone was estimated to be 12.07 days. We also found that the ozonolysis of catechol is more likely to occur in aqueous solution. The present work has provided a comprehensive investigation of the ozonolysis of catechol. The methods we used can serve as a model for analysing the ozonolysis of other lignin compounds.

Kinetic Study of the Oxidation of Alcohols with Quaternary Ammonium Permanganates

1993 ◽  
Vol 58 (8) ◽  
pp. 1777-1781 ◽  
Author(s):  
Robert Šumichrast ◽  
Vladislav Holba
Keyword(s):  
Kinetic Study ◽  
Catalytic Reaction ◽  
Rate Constants ◽  
Quaternary Ammonium ◽  
Iterative Procedure ◽  
Activation Parameters ◽  
Reaction Products ◽  
Thermodynamic Activation Parameters ◽  
Oxidation Of Alcohols ◽  
Kinetics Of

Kinetics of the oxidation of 2-propanol, 1-butanol, and 1-pentanol with tetraalkylammonium permanganates have been investigated as function of temperature. The studied reactions are partly autocatalytic, colloidal manganese dioxide as one of the reaction products has been identified as the autocatalyst.A computerized iterative procedure has been used in order to obtained the rate constants of both non-catalytic and catalytic reaction steps together with the thermodynamic activation parameters.

Kinetics of oxidation of cis-bis(ethylenediamine)isothiocyanatonitrocobalt(III) ion with peroxodisulphate

1979 ◽  
Vol 44 (12) ◽  
pp. 3588-3594 ◽  
Author(s):  
Vladislav Holba ◽  
Olga Volárová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Oxidation Kinetics ◽  
Reaction Rate ◽  
Salt Effect ◽  
Activation Parameters ◽  
Reaction Products ◽  
Kinetics Of Oxidation ◽  
Thermodynamic Activation Parameters ◽  
Kinetics Of

The oxidation kinetics of cis-bis(ethylenediamine)isothiocyanonitrocobalt(III) ion with peroxodisulphate was investigated in the medium of 0.01 M-HClO4 in dependence on the ionic strength and temperature and the reaction products were identified. Extrapolated values of thermodynamic activation parameters were determined from the temperature dependence of the rate constants extrapolated to zero ionic strength. The distance of the closest approach was estimated for the reacting ions by evaluating the primary salt effect. To elucidate the mechanism, the influence of the cyclic polyether 18-crown-6 on the reaction rate was followed.

scholarly journals Kinetics of a Criegee intermediate that would survive high humidity and may oxidize atmospheric SO2

2015 ◽  
Vol 112 (35) ◽  
pp. 10857-10862 ◽  
Author(s):  
Hao-Li Huang ◽  
Wen Chao ◽  
Jim Jr-Min Lin
Keyword(s):  
Water Vapor ◽  
Atmospheric Chemistry ◽  
High Water ◽  
Water Dimer ◽  
Atmospheric Conditions ◽  
Oxidation Reactions ◽  
Criegee Intermediates ◽  
Reaction With Water ◽  
The Impact ◽  
Kinetics Of

Criegee intermediates are thought to play a role in atmospheric chemistry, in particular, the oxidation of SO2, which produces SO3 and subsequently H2SO4, an important constituent of aerosols and acid rain. However, the impact of such oxidation reactions is affected by the reactions of Criegee intermediates with water vapor, because of high water concentrations in the troposphere. In this work, the kinetics of the reactions of dimethyl substituted Criegee intermediate (CH3)2COO with water vapor and with SO2 were directly measured via UV absorption of (CH3)2COO under near-atmospheric conditions. The results indicate that (i) the water reaction with (CH3)2COO is not fast enough (kH2O < 1.5 × 10−16 cm3s−1) to consume atmospheric (CH3)2COO significantly and (ii) (CH3)2COO reacts with SO2 at a near–gas-kinetic-limit rate (kSO2 = 1.3 × 10−10 cm3s−1). These observations imply a significant fraction of atmospheric (CH3)2COO may survive under humid conditions and react with SO2, very different from the case of the simplest Criegee intermediate CH2OO, in which the reaction with water dimer predominates in the CH2OO decay under typical tropospheric conditions. In addition, a significant pressure dependence was observed for the reaction of (CH3)2COO with SO2, suggesting the use of low pressure rate may underestimate the impact of this reaction. This work demonstrates that the reactivity of a Criegee intermediate toward water vapor strongly depends on its structure, which will influence the main decay pathways and steady-state concentrations for various Criegee intermediates in the atmosphere.

Chemical Reactions of Antioxidants Used in Vulcanized Rubber

1957 ◽  
Vol 30 (2) ◽  
pp. 681-688
Author(s):  
P. Schneider
Keyword(s):  
Natural Rubber ◽  
Chemical Reactions ◽  
Aromatic Amines ◽  
Unsaturated Compound ◽  
Partition Chromatography ◽  
Atmospheric Conditions ◽  
Reaction Products ◽  
Kinetics Of Oxidation ◽  
Vulcanized Rubber ◽  
Kinetics Of

Abstract The work of Farmer and other authors has shown that the oxidation of unsaturated polymers proceeds via primary formed hydroperoxides. The addition of antioxidants, including chiefly compounds of the class of the phenols and secondary aromatic amines, makes it possible to delay to a great extent the chemical changes taking place in unsaturated compounds. The mechanism of the action of phenols in the oxidation has been explained by Bolland. It is difficult to separate from the polymer the reaction products which are formed from the antioxidant by the dehydrogenating action of the polymeric hydroperoxide radical. In view of the fact, however, that the kinetics of oxidation in the presence of added peroxide corresponds to the autoxidation of the unsaturated compound, the reaction between phenols or secondary aromatic amines and organic or inorganic oxidation agents has been studied in detail by several workers. Depending on type, position, and number of the substituents, different reaction products are formed from phenols. Diphenylamine reacts with manganese dioxide to form a mixture of N,N′-diphenylbenzidine and the corresponding quinonedianil. N,N,N′-tri-2-naphthyl-1,2-naphthylenediamine is formed from di-2-naphthylamine with potassium permanganate, whereas under similar conditions phenyl-2-naphthylamine forms N,N′-diphenyl-N-2-naphthyl-1,2-naphthylenediamine. Starting from the deduction that the chemical reaction products of the antioxidants accumulate on the surface of the vulcanized rubber due to decreasing solubility, pure gum stocks of cured natural rubber containing diphenylamine, N-phenyl-1- and 2-naphthylamine have been exposed to atmospheric conditions for 8 months. The dark colored reaction products could be removed mechanically from the surface of the cured goods after wetting with methanol. After evaporation, the residue was taken up in ethylidene chloride and the resulting solution evaporated to dryness. Amorphous mixtures of brown colored compounds were isolated from the vulcanizate containing diphenylamine and N-phenyl-2-naphthylamine, the reaction products of the N-phenyl-2-napthylamine being obtained as a dark colored tar. In addition to other compounds, the presence of the N,N′-diphenyl-N-2-naphthyl-1,2-naphthylenediamine was proved by paper partition chromatography of the resulting azodyestuff obtained from the mixture of the reaction products from phenyl-2-naphthylamine by coupling with diazotized 1-aminonaphthalene trisulfonic acid. The presence of this compound had also been shown by the ultraviolet spectra. In the same manner, small quantities of the N,N′-diphenylbenzidine could be recognized from the corresponding azodyestuff formed from the reaction product of diphenylamine. Due to extensive oxidation, the presence of reaction products could not be proved in any appreciable quantity from the reaction mixture of the phenyl-1-naphthylamine.

scholarly journals OXIDATIVE-REDUCING PROCESSES WITH PARTICIPATION OF MANGANESE IONS INITIATED BY AN ELECTRIC DISCHARGE IN AQUEOUS SOLUTION

2018 ◽  
Vol 61 (9-10) ◽  
pp. 23-29 ◽  
Author(s):  
Dmitriy A. Shutov ◽  
Aleksandra V. Sungurova ◽  
Kristina V. Smirnova ◽  
Anna S. Manukyan ◽  
Vladimir V. Rybkin
Keyword(s):  
Aqueous Solution ◽  
Electric Discharge ◽  
Rate Constants ◽  
Experimental Studies ◽  
Effective Rate ◽  
Solid Particles ◽  
Manganese Ions ◽  
Reaction Products ◽  
X Ray ◽  
Kinetics Of

The results of experimental studies of the kinetics of oxidation-reduction of Mn7+ ions (MnO4-) in aqueous solutions initiated by the action of a discharge of a direct current of atmospheric pressure in air are analyzed in the article. A solution of potassium permanganate served as a discharge cathode. The range of initial solution concentrations for Mn7+ ions was (0.44-2.5) mmol/l, and discharge currents (20-60) mA. It was found that the discharge action leads to the reduction of Mn7+ ions and discoloration of the solution. At the same time, dark solid particles with a size of 0.1 μm to 20 μm are formed. X-ray diffraction analysis showed that the particles are amorphous, and energy dispersive X-ray analysis showed that the powder is manganese oxide (IV). The kinetics of reduction-oxidation of Mn7+ ions is measured. It is shown that the obtained data on the kinetics of the reduction of Mn7+ ions in the best way (the determination coefficient R2≈0.99) can be described by the scheme X↔Y↔Z, where X is the starting material, and Y and Z are the reaction products. The processing of kinetic curves on the basis of this scheme found the effective rate constants of the corresponding stages. It was found that the effective rate constants depend on the initial concentration of the solution. At a discharge current of 20 mA, an increase in the concentration from 0.44 to 2.5 mol/l led to a decrease in the rate constant for the reduction of Mn7+ ions from (2.48 ± 0.5) ·10-2 to (7.2 ± 1.5) ·10-3 s-1, respectively. Possible mechanisms of processes are discussed. It is assumed that the main particles involved in the oxidation reactions of the reduction of manganese ions are H2O2, HO2, OH and solvated electrons that are formed in the solution under the action of a discharge. For citation: Shutov D.A., Sungurova A.V., Smirnova K.V., Manukyan A.S., Rybkin V.V. Oxidative-reducing processes with participation of manganese ions initiated by electric discharge in aqueous solution. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 23-29

The Kinetics of Inhibition of the Action of Thrombin by the Fibrinopeptides Formed during the Clotting of Fibrinogen

1966 ◽  
Vol 16 (01/02) ◽  
pp. 277-295 ◽  
Author(s):  
A Silver ◽  
M Murray
Keyword(s):  
Amino Acids ◽  
Competitive Inhibition ◽  
Amorphous Material ◽  
Peptide Bond ◽  
Initial Reaction ◽  
Reaction Products ◽  
Coagulation Mechanism ◽  
Kinetics Of ◽  
Kinetics Of Inhibition ◽  
Burk Plot

SummaryVarious investigators have separated the coagulation products formed when fibrinogen is clotted with thrombin and identified fibrinopeptides A and B. Two other peaks are observed in the chromatogram of the products of coagulation, but these have mostly been dismissed by other workers. They have been identified by us as amino acids, smaller peptides and amorphous material (37). We have re-chromatographed these peaks and identified several amino acids. In a closed system of fibrinogen and thrombin, the only reaction products should be fibrin and peptide A and peptide B. This reasoning has come about because thrombin has been reported to be specific for the glycyl-arginyl peptide bond. It is suggested that thrombin also breaks other peptide linkages and the Peptide A and Peptide B are attacked by thrombin to yield proteolytic products. Thrombin is therefore probably not specific for the glycyl-arginyl bond but will react on other linkages as well.If the aforementioned is correct then the fibrinopeptides A and B would cause an inhibition with the coagulation mechanism itself. We have shown that an inhibition does occur. We suggest that there is an autoinhibition to the clotting mechanism that might be a control mechanism in the human body.The experiment was designed for coagulation to occur under controlled conditions of temperature and time. Purified reactants were used. We assembled an apparatus to record visually the speed of the initial reaction, the rate of the reaction, and the density of the final clot formed after a specific time.The figures we derived made available to us data whereby we could calculate and plot the information to show the mechanism and suggest that such an inhibition does exist and also further suggest that it might be competitive.In order to prove true competitive inhibition it is necessary to fulfill the criteria of the Lineweaver-Burk plot. This has been done. We have also satisfied other criteria of Dixon (29) and Bergman (31) that suggest true competitive inhibition.

Submerged upflow biotower operation and computer simulation

1994 ◽  
Vol 30 (11) ◽  
pp. 143-146
Author(s):  
Ronald D. Neufeld ◽  
Christopher A. Badali ◽  
Dennis Powers ◽  
Christopher Carson
Keyword(s):  
Computer Simulation ◽  
Benzoic Acid ◽  
Computer Model ◽  
Rate Constants ◽  
Batch Mode ◽  
Operational Conditions ◽  
First Order ◽  
Low Concentrations ◽  
Biological Transformation ◽  
Kinetics Of

A two step operation is proposed for the biodegradation of low concentrations (&lt; 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.

Kinetics of the catalytic hydrodesulphurization reaction system; hydrogenolysis of thiophene

1980 ◽  
Vol 45 (10) ◽  
pp. 2728-2741 ◽  
Author(s):  
Pavel Fott ◽  
Petr Schneider
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Flow Reactor ◽  
Kinetic Equations ◽  
Reaction System ◽  
Reaction Products ◽  
Molybdenum Catalyst ◽  
Cobalt Molybdenum Catalyst ◽  
Kinetics Of ◽  
Reaction Schemes

Kinetics have been studied of the reaction system taking place during the reaction of thiophene on the cobalt-molybdenum catalyst in a gradientless circulation flow reactor at 360 °C and atmospheric pressure. Butane has been found present in a small amount in the reaction products even at very low conversion. In view of this, consecutive and parallel-consecutive (triangular) reaction schemes have been proposed. In the former scheme the appearance of butane is accounted for by rate of desorption of butene being comparable with the rate of its hydrogenation. According to the latter scheme part of the butane originates from thiophene via a different route than through hydrogenation of butene. Analysis of the kinetic data has revealed that the reaction of thiophene should be considered to take place on other active sites than that of butene. Kinetic equations derived on this assumption for the consecutive and the triangular reaction schemes correlate experimental data with acceptable accuracy.

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