Reaction Rate
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ACS Omega ◽  
2021 ◽  
Author(s):  
Yukihiko Matsumura ◽  
Yuito Suganuma ◽  
Takayuki Ichikawa ◽  
Wookyung Kim ◽  
Yutaka Nakashimada ◽  
...  

2021 ◽  
Author(s):  
Mike J. Newland ◽  
Yangang Ren ◽  
Max R. McGillen ◽  
Lisa Michelat ◽  
Véronique Daële ◽  
...  

Abstract. Furans are emitted to the atmosphere during biomass burning from the pyrolysis of cellulose. They are one of the major contributing VOC classes to OH and NO3 reactivity in biomass burning plumes. The major removal process of furans from the atmosphere at night is reaction with the nitrate radical, NO3. Here we report a series of relative rate experiments in the 7300 L indoor simulation chamber at CNRS-ICARE, Orléans, using a number of different reference compounds to determine NO3 reaction rate coefficients for four furans, two furanones, and pyrrole. In the case of the two furanones, this is the first time that NO3 rate coefficients have been reported. The recommended values (cm3 molecule−1 s−1) are: furan (1.50 ± 0.23) × 10−12, 2-methylfuran (2.37 ± 0.55) × 10−11, 2,5-dimethylfuran (1.10 ± 0.33) × 10−10, furan-2-aldehyde (9.28 ± 2.3) × 10−14, 5-methyl-2(3H)-furanone (3.00 ± 0.45) × 10−12, 2(5H)-furanone < 1.410−16, and pyrrole (7.35 ± 2.06) × 10−11. The furan-2-aldehyde + NO3 reaction rate is found to be an order of magnitude lower than previously reported. We also recommend a faster rate for the α-terpinene+NO3 reaction ((2.70 ± 0.81) × 10−10 cm3 s−1). These experiments show that for furan, alkyl substituted furans, 5-methyl-2(3H)-furanone, and pyrrole, reaction with NO3 will be the dominant removal process at night, and may also contribute during the day. For 2(5H)-furanone, reaction with NO3 is not an important atmospheric sink.


2021 ◽  
pp. 122312
Author(s):  
S.B. Dubovichenko ◽  
A.V. Dzhazairov-Kakhramanov ◽  
N.A. Burkova

2021 ◽  
Author(s):  
Pınar N. TANATTI

Abstract The purpose of this study is to investigate the treatability of electrocoagulated biodiesel wastewater (ECBD) by potassium permanganate (KMnO4) and potassium permanganate/ozone (KMnO4/O3) processes. The ECBD removal efficiencies of both combined method and KMnO4 methods were compared and the KMnO4/O3 process gave better results than the KMnO4 process. For the ECBD removal efficiencies, the experimental parameters including pH, potassium permanganate dose, ozone dose and reaction time parameters were optimized by changing the one parameter at a time. As a result of 6 h of KMnO4 oxidation, 91.74% of COD and 95.93% of MeOH removal was achieved under the optimum conditions (pH 2, 5 g/L KMnO4 dose). However, under optimum conditions (pH 13, 2 g/L KMnO4 dose, 3000 mg/L O3 dose, 6 h reaction time), the COD and MeOH removal efficiencies have been obtained for KMnO4/O3 as 97.79% and 98.30%, respectively. The second order kinetic model has been found to be the most suitable model for both processes and the regression coefficients (R2) has been found as 0.999 and 0.999 for KMnO4 and KMnO4/O3, respectively. The reaction rate constants (k) have been also calculated as 6x10-5 L/mg.min and 1.63x10-4 L/mg.min for COD and MeOH in KMnO4 oxidation, respectively. Furthermore, the reaction rate constants (k) have been also calculated as 6x10-5 L/mg.min and 1.6x10-4 L/mg.min for COD and MeOH in KMnO4/O3 oxidation, respectively.


2021 ◽  
Vol 9 ◽  
Author(s):  
Fuli Yan ◽  
Yongmin Shi ◽  
Yu Tian

Acid fracturing is an effective method to develop ultra-low permeability reservoirs. However, the fast reaction rate reduces the effect of the acid fracturing and increases the near-well collapse risk. Therefore, it is necessary to retard the acid–rock reaction rate. In this work, we synthesized an acid-resistant Gemini zwitterionic viscoelastic surfactant (named VES-c), which has good performances such as temperature resistance, salt resistance, and shear resistance. Besides, a low concentration of VES-c increases the viscosity of the acid solution. The CO2 drainage method was used to measure the reaction rate between the dibasic acid and dolomite/broken core. We find that the dibasic acid containing 0.3% VES-c retards the dolomite reaction rate of 3.22 times compared with only dibasic acid. Furthermore, the dibasic acid containing 0.3% VES-c exhibits uniform distribution and is not easy to adhere to the solid surface. The VES-c also is favorable to reduce the formation of amorphous calcium carbonate. Retarding the rate of acid–rock reaction and enhancing the acidification are mainly attributed to VES-c's salt-tolerance, anti-adsorption, and the property of increasing the viscosity of the solution. Hopefully, this kind of surfactant retarding reaction rate is applied to other acid–rock reactions.


Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5096
Author(s):  
Victor Xing ◽  
Corentin Lapeyre ◽  
Thomas Jaravel ◽  
Thierry Poinsot

Deep learning has recently emerged as a successful approach to produce accurate subgrid-scale (SGS) models for Large Eddy Simulations (LES) in combustion. However, the ability of these models to generalize to configurations far from their training distribution is still mainly unexplored, thus impeding their application to practical configurations. In this work, a convolutional neural network (CNN) model for the progress-variable SGS variance field is trained on a canonical premixed turbulent flame and evaluated a priori on a significantly more complex slot burner jet flame. Despite the extensive differences between the two configurations, the CNN generalizes well and outperforms existing algebraic models. Conditions for this successful generalization are discussed, including the effect of the filter size and flame–turbulence interaction parameters. The CNN is then integrated into an analytical reaction rate closure relying on a single-step chemical source term formulation and a presumed beta PDF (probability density function) approach. The proposed closure is able to accurately recover filtered reaction rate values on both training and generalization flames.


2021 ◽  
Vol 4 (3) ◽  
Author(s):  
Deepak Singh Rathore ◽  
Vimlesh Kumar Meena ◽  
Chandra Pal Singh Chandel ◽  
Krishna Swarup Gupta

Hydrogen sulfide is an important acid rain precursor and this led us to investigate the kinetics of its oxidation in aqueous phase by atmospheric oxygen. The kinetics was followed by measuring the depletion of oxygen in a reactor. The reaction was studied under pseudo order conditions with [H2S] in excess. The kinetics followed the rate law: -d[O2]/dt = k[S][O2]t (A) Where [S] represents the total concentration of hydrogen sulfide, [O2]t is the concentration of oxygen at time t and k is the second order rate constant. The equilibria (B - C) govern the dissolution of H2S; the sulfide ion in water forms different species: H2S K1 HS- + H+ (B) HS- K2 S2- + H+ (C) Where K1 and K2 are first and second dissociation constants of H2S. Although, H2S is present as undissociated H2S, HS- and S2- ions, nature of [H+ ] dependence of reaction rate required only HS- to be reactive and dominant. The rate law (A) on including [H+ ] dependence became Equation (D). -d[O2]/dt = k1K1[H+ ][S][O2]t / ([H+ ] 2 + K1[H+ ] + K1K2) (D) Our results indicate anthropogenic VOCs such as acetanilide, benzene, ethanol, aniline, toluene, benzamide, o-xylene, m-xylene, p-xylene and anisole to have no significant effect on the reaction rate and any observed small effect is within the uncertainty of the rate measurements.


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