Heterogeneous oxidation of indoor surfaces by gas-phase hydroxyl radicals

Indoor Air ◽  
2018 ◽  
Vol 28 (5) ◽  
pp. 655-664 ◽  
Author(s):  
R. Alwarda ◽  
S. Zhou ◽  
J. P. D. Abbatt
Keyword(s):  
Gas Phase ◽  
Hydroxyl Radicals ◽  
Heterogeneous Oxidation

scholarly journals Heterogeneous oxidation of saturated organic aerosols by hydroxyl radicals: Uptake kinetics and condensed-phase products

2007 ◽  
Vol 7 (3) ◽  
pp. 6803-6842 ◽  
Author(s):  
I. J. George ◽  
A. Vlasenko ◽  
J. G. Slowik ◽  
J. P. D. Abbatt
Keyword(s):  
Hydroxyl Radicals ◽  
Particle Density ◽  
Organic Aerosols ◽  
Oxidation Products ◽  
Photochemical Oxidation ◽  
Mass Spectrometry Analysis ◽  
Oh Radicals ◽  
Ionization Mass ◽  
Phase Reaction ◽  
Heterogeneous Oxidation

Abstract. The kinetics and reaction mechanism for the heterogeneous oxidation of saturated organic aerosols by gas-phase OH radicals were investigated under NOx-free conditions. The reaction of 150 nm diameter Bis(2-ethylhexyl) sebacate (BES) particles with OH was studied as a proxy for chemical aging of atmospheric aerosols containing saturated organic matter. An aerosol reactor flow tube combined with an Aerodyne time-of-flight aerosol mass spectrometer (ToF-AMS) and scanning mobility particle sizer (SMPS) was used to study this system. Hydroxyl radicals were produced by 254 nm photolysis of O3 in the presence of water vapour. The kinetics of the heterogeneous oxidation of the BES particles was studied by monitoring the loss of a mass fragment of BES with the ToF-AMS as a function of OH exposure. We measured an initial OH uptake coefficient of γ0 = 1.26 (±0.04), confirming that this reaction is highly efficient. The density of BES particles increased by up to 20% of the original BES particle density at the highest OH exposure studied, consistent with the particle becoming more oxidized. Electrospray ionization mass spectrometry analysis showed that the major particle-phase reaction products are multifunctional carbonyls and alcohols with higher molecular weights than the starting material. Volatilization of oxidation products accounted for a maximum of 17% decrease of the particle volume at the highest OH exposure studied. Tropospheric organic aerosols will become more oxidized from heterogeneous photochemical oxidation, which may affect not only their physical and chemical properties, but also their hygroscopicity and cloud nucleation activity.

Key Role of Equilibrium HONO Concentration over the Soil 

2021 ◽  
Author(s):  
Fengxia Bao ◽  
Hang Su ◽  
Uwe Kuhn ◽  
Yafang Cheng
Keyword(s):  
Gas Phase ◽  
Hydroxyl Radicals ◽  
Nitrous Acid ◽  
Measurement Method ◽  
Oxidative Capacity ◽  
Sources And Sinks ◽  
Dynamic Chamber ◽  
Open Question ◽  
Actinic Radiation

<p>Nitrous acid (HONO) is an important component of the nitrogen cycle. HONO can also be rapidly photolyzed by actinic radiation to form hydroxyl radicals (OH) and exerts a primary influence on the oxidative capacity of the atmosphere. The sources and sinks of HONO, however, are not fully understood. Soil nitrite, produced via nitrification or denitrification, is an important source for the atmospheric HONO production. [HONO]*, the equilibrium gas phase HONO concentration over the soil, has been suggested as key to understanding the environmental effects of soil fluxes of HONO (Su et al., 2011). But if and how [HONO]* may exist and vary remains an open question. In this project, a measurement method using a dynamic chamber has been developed to derive [HONO]* and the atmospheric soil fluxes of HONO can accordingly be quantified. We demonstrate the existence of [HONO]* and determine its variation in the course of soil drying processes. We show that when [HONO]* is higher than the atmospheric HONO concentration, HONO will be released from soil; otherwise, HONO will be deposited on soil. This work advances the understanding of soil HONO emissions, and the evaluation of its impact on the atmospheric oxidizing capacity and the nitrogen cycling.</p>

The gas phase reactions of hydroxyl radicals with a series of aliphatic ethers over the temperature range 240-440 K

1988 ◽  
Vol 20 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Timothy J. Wallington ◽  
Renzhang Liu ◽  
Philippe Dagaut ◽  
Michael J. Kurylo
Keyword(s):  
Gas Phase ◽  
Hydroxyl Radicals ◽  
Gas Phase Reactions ◽  
Temperature Range ◽  
Aliphatic Ethers

scholarly journals Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

2015 ◽  
Vol 15 (6) ◽  
pp. 3063-3075 ◽  
Author(s):  
A. T. Lambe ◽  
P. S. Chhabra ◽  
T. B. Onasch ◽  
W. H. Brune ◽  
J. F. Hunter ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Short Exposure ◽  
Heterogeneous Oxidation ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Environmental Chambers

Abstract. We performed a systematic intercomparison study of the chemistry and yields of secondary organic aerosol (SOA) generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0 × 108 to 2.2 × 1010 molec cm−3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 106 to 2 × 107 molec cm−3 over exposure times of several hours. The OH concentration in the chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. In most cases, for a specific SOA type the most-oxidized chamber SOA and the least-oxidized flow reactor SOA have similar mass spectra, oxygen-to-carbon and hydrogen-to-carbon ratios, and carbon oxidation states at integrated OH exposures between approximately 1 × 1011 and 2 × 1011 molec cm−3 s, or about 1–2 days of equivalent atmospheric oxidation. This observation suggests that in the range of available OH exposure overlap for the flow reactor and chambers, SOA elemental composition as measured by an aerosol mass spectrometer is similar whether the precursor is exposed to low OH concentrations over long exposure times or high OH concentrations over short exposure times. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed particles are routinely used.

Hybrid Gas/Liquid Electrical Discharge Reactors with Zeolites for Colored Wastewater Degradation

2005 ◽  
Vol 8 (2) ◽  
Author(s):  
Hrvoje Kušić ◽  
Natalija Koprivanac ◽  
Igor Peternel ◽  
Bruce R. Locke
Keyword(s):  
Hydrogen Peroxide ◽  
Liquid Phase ◽  
Gas Phase ◽  
Hydroxyl Radicals ◽  
Electrical Discharge ◽  
Organic Dye ◽  
Electrical Discharges ◽  
Colored Wastewater ◽  
Ozone Levels ◽  
Parallel Reactor

AbstractHybrid gas/liquid electrical discharge reactors have been used to degrade an organic dye in the presence and absence of zeolites. Simultaneous gas and liquid phase electrical discharges in the hybrid parallel and hybrid series reactors have been shown in previous work to lead to the formation of hydrogen peroxide and hydroxyl radicals in the liquid phase and ozone in the gas phase. These reactors differ in their electrode configuration, and in previous work it was shown that the ozone levels in the parallel reactor are seven times higher than in the series reactor (3000 ppm and 450 ppm, respectively), while both reactors produce the same levels of hydrogen peroxide (4.9 × 10

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