ChemInform Abstract: Aqueous-Phase Oxidation: Rate Enhancement Studies.

ChemInform ◽  
1987 ◽  
Vol 18 (30) ◽  
Author(s):  
R. S. WILLMS ◽  
D. D. REIBLE ◽  
D. M. WETZEL ◽  
D. P. HARRISON
Keyword(s):  
Aqueous Phase ◽  
Oxidation Rate ◽  
Rate Enhancement ◽  
Phase Oxidation

Aqueous-phase oxidation: rate enhancement studies

1987 ◽  
Vol 26 (3) ◽  
pp. 606-612 ◽  
Author(s):  
Richard S. Willms ◽  
Danny D. Reible ◽  
David M. Wetzel ◽  
Douglas P. Harrison
Keyword(s):  
Aqueous Phase ◽  
Oxidation Rate ◽  
Rate Enhancement ◽  
Phase Oxidation

scholarly journals Influence of NO2 and metal ions on oxidation of aqueous-phase S(IV) in atmospheric concentrations

2008 ◽  
Vol 80 (2) ◽  
pp. 279-290 ◽  
Author(s):  
Cláudia R. Martins ◽  
Janete J.F. Alves ◽  
Wanessa B.D. Carvalho ◽  
Cristiane S.C. Cardoso ◽  
Jailson B. de Andrade
Keyword(s):  
Metal Ions ◽  
Aqueous Phase ◽  
Oxidation Rate ◽  
Reaction Rate ◽  
Experimental Conditions ◽  
Phase Oxidation ◽  
Clean Air ◽  
Sulfate Formation ◽  
Presence And Absence ◽  
Atmospheric Concentrations

An investigation was made of the influence of atmospheric concentrations (15 or 130 ppbv) of NO2 on the aqueous-phase oxidation rate of S(IV) in the presence and absence of Fe(III), Mn(II) and Cr(VI) metal ions under controlled experimental conditions (pH, T, concentration of reactants, etc.). The reaction rate in the presence of the NO2 flow was slower than the reaction rate using only clean air with an initial S(IV) concentration of 10-4 mol/L. NO2 appears to react with S(IV), producing a kind of inhibitor that slows down the reaction. Conversely, tenfold lower concentrations of S(IV) ([S(IV)]º = 10-5 mol/L) caused a faster reaction in the presence of NO2 than the reaction using purified air. Under these conditions, therefore, the equilibrium shifts to sulfate formation. With the addition of Fe(III), Mn(II) or Cr(VI) in the presence of a NO2 flow, the reaction occurred faster under all the conditions in which S(IV) oxidation was investigated.

scholarly journals Structure–activity relationship for the estimation of OH-oxidation rate constants of carbonyl compounds in the aqueous phase

2013 ◽  
Vol 13 (23) ◽  
pp. 11625-11641 ◽  
Author(s):  
J.-F. Doussin ◽  
A. Monod
Keyword(s):  
Aqueous Phase ◽  
Rate Constants ◽  
Oxidation Rate ◽  
Carbonyl Compounds ◽  
Estimation Method ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Oh Radicals ◽  
Structure Activity ◽  
Polyfunctional Compounds

Abstract. In the atmosphere, one important class of reactions occurs in the aqueous phase in which organic compounds are known to undergo oxidation towards a number of radicals, among which OH radicals are the most reactive oxidants. In 2008, Monod and Doussin have proposed a new structure–activity relationship (SAR) to calculate OH-oxidation rate constants in the aqueous phase. This estimation method is based on the group-additivity principle and was until now limited to alkanes, alcohols, acids, bases and related polyfunctional compounds. In this work, the initial SAR is extended to carbonyl compounds, including aldehydes, ketones, dicarbonyls, hydroxy carbonyls, acidic carbonyls, their conjugated bases, and the hydrated form of all these compounds. To do so, only five descriptors have been added and none of the previously attributed descriptors were modified. This extension leads now to a SAR which is based on a database of 102 distinct compounds for which 252 experimental kinetic rate constants have been gathered and reviewed. The efficiency of this updated SAR is such that 58% of the rate constants could be calculated within ±20% of the experimental data and 76% within ±40% (respectively 41 and 72% for the carbonyl compounds alone).

scholarly journals The formation of nitro-aromatic compounds under high NO<sub><i>x</i></sub> and anthropogenic VOC conditions in urban Beijing, China

2019 ◽  
Vol 19 (11) ◽  
pp. 7649-7665 ◽  
Author(s):  
Yujue Wang ◽  
Min Hu ◽  
Yuchen Wang ◽  
Jing Zheng ◽  
Dongjie Shang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Aromatic Compounds ◽  
Total Concentration ◽  
Fine Particulate Matter ◽  
Oxidation Products ◽  
Urban Atmosphere ◽  
Formation Pathway ◽  
Relative Contribution ◽  
Phase Oxidation ◽  
Nitro Aromatic

Abstract. Nitro-aromatic compounds (NACs), as important contributors to the light absorption by brown carbon, have been widely observed in various ambient atmospheres; however, their formation in the urban atmosphere was little studied. In this work, we report an intensive field study of NACs in summer 2016 at an urban Beijing site, characterized by both high-NOx and anthropogenic VOC dominated conditions. We investigated the factors that influence NAC formation (e.g., NO2, VOC precursors, RH and photolysis) through quantification of eight NACs, along with major components in fine particulate matter, selected volatile organic compounds, and gases. The average total concentration of the quantified NACs was 6.63 ng m−3, higher than those reported in other summertime studies (0.14–6.44 ng m−3). 4-Nitrophenol (4NP, 32.4 %) and 4-nitrocatechol (4NC, 28.5 %) were the top two most abundant NACs, followed by methyl-nitrocatechol (MNC), methyl-nitrophenol (MNP), and dimethyl-nitrophenol (DMNP). The oxidation of toluene and benzene in the presence of NOx was found to be a more dominant source of NACs than primary biomass burning emissions. The NO2 concentration level was found to be an important factor influencing the secondary formation of NACs. A transition from low- to high-NOx regimes coincided with a shift from organic- to inorganic-dominated oxidation products. The transition thresholds were NO2 ∼ 20 ppb for daytime and NO2∼25 ppb for nighttime conditions. Under low-NOx conditions, NACs increased with NO2, while the NO3- concentrations and (NO3-)/NACs ratios were lower, implying organic-dominated products. Under high-NOx conditions, NAC concentrations did not further increase with NO2, while the NO3- concentrations and (NO3-)/NACs ratios showed increasing trends, signaling a shift from organic- to inorganic-dominated products. Nighttime enhancements were observed for 3M4NC and 4M5NC, while daytime enhancements were noted for 4NP, 2M4NP, and DMNP, indicating different formation pathways for these two groups of NACs. Our analysis suggested that the aqueous-phase oxidation was likely the major formation pathway of 4M5NC and 3M5NC, while photo-oxidation of toluene and benzene in the presence of NO2 could be more important for the formation of nitrophenol and its derivatives. Using the (3M4NC+4M5NC) ∕ 4NP ratios as an indicator of the relative contribution of aqueous-phase and gas-phase oxidation pathways to NAC formation, we observed that the relative contribution of aqueous-phase pathways increased at elevated ambient RH and remained constant at RH > 30 %. We also found that the concentrations of VOC precursors (e.g., toluene and benzene) and aerosol surface area acted as important factors in promoting NAC formation, and photolysis as an important loss pathway for nitrophenols.

Aqueous phase oxidation of sulfites by ozone in the presence of iron and manganese

1982 ◽  
Vol 16 (5) ◽  
pp. 1039-1041 ◽  
Author(s):  
Halstead Harrison ◽  
Timothy V. Larson ◽  
Carol Smith Monkman
Keyword(s):  
Aqueous Phase ◽  
Phase Oxidation ◽  
Iron And Manganese

Modelling and Construction of a Deep Well Aqueous Phase Oxidation Process

1993 ◽  
Vol 27 (5-6) ◽  
pp. 457-468 ◽  
Author(s):  
Pieter H. A. M. J. de Bekker ◽  
Jan J. van den Berg
Keyword(s):  
Aqueous Phase ◽  
High Performance ◽  
Plug Flow ◽  
Process Conditions ◽  
Gaseous Oxygen ◽  
Deep Well ◽  
Reactor Length ◽  
Phase Oxidation ◽  
Environmentally Sound ◽  
Heavy Construction

Aqueous phase oxidation is the process in which organic material is oxidized in the liquid phase with gaseous oxygen under elevated temperature and pressure. The VerTech-process uses a vertical subsurface oxidation vessel consisting of two concentric tubes with a length of approximately 1 200 metres. The advantages of which are: an ideal plug flow regime for a high performance, an efficient heat exchange along the reactor length and a less heavy construction compared to surface techniques. The production of residues is minimal and environmentally sound: off-gas consists mostly of carbon dioxide, solid residue is non teachable and the liquid effluent can be purified easily to a high extent. For the design of the oxidation vessel the use of mathematical models is essential: reaction kinetics, hydrodynamics and heat transfer have been brought in models in such a way that up- and downscaling is possible. On the other hand process conditions may be controlled by the model, once it has been approved. The original model has been tested at the demonstration plant at Longmont, Colorado, USA in 1985. A further development will be tested at the first commercial scale plant at Apeldoorn, the Netherlands. This plant will come into full service as of January 1993.

Oxidation rate enhancement of SiGe epitaxial films oxidized in dry ambient

2003 ◽  
Vol 83 (18) ◽  
pp. 3713-3715 ◽  
Author(s):  
M. Spadafora ◽  
G. Privitera ◽  
A. Terrasi ◽  
S. Scalese ◽  
C. Bongiorno ◽  
...  
Keyword(s):  
Oxidation Rate ◽  
Epitaxial Films ◽  
Rate Enhancement
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