Reactivity of Ozone with Solid Potassium Iodide Investigated by Atomic Force Microscopy

Brown, Matthew A.; Ashby, Paul D.; Ogletree, D. Frank; Salmerón, Miquel; Hemminger, John C.

doi:10.1021/jp801620w

Cited by 16 publications

(32 citation statements)

References 18 publications

(38 reference statements)

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“…(1): It is noted that the oxidation of KI to form KIO 3 (as shown in Eq. (2) is unlikely to occur during the sampling period because its progression requires a relatively dry environment (Brown et al, 2008).…”

Section: Collection Efficiencymentioning

confidence: 99%

Technical Note: Concerns on the Use of Ozone Scrubbers for Gaseous Carbonyl Measurement by DNPH-Coated Silica Gel Cartridge

Ip²,

et al. 2013

Aerosol Air Qual. Res.

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ABSTRACT2,4-Dinitrophenylhydrazine (DNPH) is a typical derivatizing agent coated on sorbent cartridges for detection of carbonyl compounds at ambient levels. However, airborne oxidant of ozone (O 3 ) can react with DNPH to form side products that can interfere with the accurate detection of carbonyls. It is the most critical interferer degrading carbonyl-DNP-hydrazone formed on the cartridge during sampling, resulting in underestimation of carbonyl concentrations; this strong oxidant can be removed by installing a denuder or scrubber coated or filled with potassium iodide (KI) upstream. The purpose of this study is to demonstrate and discuss the usage of novel KI-filled ozone traps in affecting carbonyl collection efficiency of DNPH-coated silica gel cartridges in field and laboratory settings. Results of the study showed that measured carbonyls concentrations were 4.9-13.5% lower in samples collected without any ozone traps compared to those collected with a commercially available ozone scrubber or KI denuder. Although ozone can be reduced efficiently by KI, both environmental relative humidity (RH) and byproducts formed from the oxidation of KI with ozone, namely iodine (I 2 ) and hydroxyl ion (OH -), can inhibit derivatization kinetics and contribute to degradation of the carbonyl-DNP-hydrazones formed during sampling. Placement of an acid-permeated polyethylene filter between the ozone scrubbers and the DNPH-coated cartridge notably improved carbonyl collection efficiency by neutralizing the byproduct OH -. End-users of the DNPH method should consider these findings and evaluate the performance of ozone scrubbers accordingly during sampling events.

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Section: Collection Efficiencymentioning

confidence: 99%

Technical Note: Concerns on the Use of Ozone Scrubbers for Gaseous Carbonyl Measurement by DNPH-Coated Silica Gel Cartridge

Ip²,

et al. 2013

Aerosol Air Qual. Res.

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“…Further oxidation leads to passivation by KIO 3 , with oxide crystallites 4-6 nm in height and 10-30 nm in width. 24 Figure 3 shows AFM images after a passivated KIO 3 oxide layer is exposed to 65% relative humidity for 1 h. The water vapor content of the cell was removed by flowing dry nitrogen prior to imaging. After exposure to 65% relative humidity for 1 h, the surface loses its roughness and large stepless terraces are regenerated.…”

Section: X-ray Photoemission Spectroscopy (Xps)mentioning

confidence: 99%

Interfacial Dushman-like Chemistry in Hydrated KIO₃ Layers Grown on KI

et al. 2010

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Ozone is known to readily oxidize the heavier alkali halides in the form of sea salt aerosols, and this chemistry is thought to be a probable candidate for the formation of reactive gas-phase halogens in the troposphere. Water that becomes adsorbed at the interface following the oxidation process is believed to play a vital role in the mechanisms that release these gas-phase halogens. We have carried out studies that utilize X-ray photoemission spectroscopy and atomic force microscopy to follow the surface chemistry and topography of KIO 3 films as they are exposed to water vapor at room temperature. The KIO 3 films were grown under dry conditions by the heterogeneous reaction of ozone with a model low defect density KI(100) single crystal. As the water vapor pressure is increased above the surface dissolution point, the KIO 3 layer becomes solvated and ionic mobility at the surface increases. This mobility results in a ripening process that creates large crystallites of KIO 3 . The inhomogeneous KIO 3 layer continues to evolve at relative humidities near the bulk deliquescence point of the KI(100) substrate. Under these conditions, surface-adsorbed water molecules dissociate at defect sites generated during the initial heterogeneous reaction process and provide the necessary protons to initiate a Dushman-like surface reaction, where IO 3 and Ireact to release gas-phase iodide compounds. Vacancies created in lattice sites during the release of gas-phase iodide species are replaced by OHgroups to form a stable adlayer of KOH (which is likely partially hydrated). As a result of the KOH × H 2 O adlayer, which does not react further with O 3 , only a portion of the particle's iodide content is available for reaction.

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“…Some ions accumulate at a specific depth layer of water–hydrophobes (e.g., air, oil, and biomembranes) interfaces, while other ions prefer to remain in bulk water and react homogeneously. − Long-chain carboxylate ions, due to the amphiphilic property, − play key roles in the nucleation, growth, and photochemical aging process of atmospheric aerosol. − For example, bubble-bursting from surface of the ocean is responsible for enriching marine aerosols with long-chain carboxylate ions, ,,, thereby influencing the chemistry of marine boundary layers. ,− Long-chain carboxylate ions act as a film covering atmospheric particles, directly confirmed by field measurement studies. − Recent studies have suggested long-chain carboxylate ions could induce cloud droplet formation, thereby affecting global climate change. ,− Benzoate ion, C 6 H 5 -COO – , has been recently found to be one of the most abundant organic species observed in PM 2.5 of polluted areas, where the concentration on PM 2.5 exceeds 1 μg/m 3 …”

Section: Introductionmentioning

confidence: 99%

Carboxylate Ion Availability at the Air–Water Interface

et al. 2016

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Amphiphilic organic compounds at the air−water interface play key roles in the nucleation, growth, and aging process of atmospheric aerosol. Surface-active species are expected to react preferentially with atmospheric oxidants, such as the OH radical, at the air−water interface via specific mechanisms. Establishing the relative availability of the different amphiphilic species to gas-phase oxidants at the air−water interface under atmospherically relevant conditions is, however, challenging. Here we report the interfacial availability of atmospherically relevant carboxylate ions R n -COO − (n = 1−7) and n-, cyclo-, aromatic-R 6 -COO − at the air−water interface via a novel application of mass spectrometry of aqueous microjets. The breakup mechanism of microjets lets us determine the relative interfacial affinities of carboxylate ions in equimolar solutions of the corresponding carboxylic acids in the 1 μM to 1 mM range under ambient conditions. We find that the interfacial affinity of R n -COO − increases exponentially with both chain-length and solvent-accessible surface area (SASA) except in the case of R 1 -COO − . The relative interfacial affinities for n-heptanoate (n-R 6 -COO − ) > cyclohexanecarboxylate (c-R 6 -COO − ) > benzoate (Ar-R 6 -COO − ) are also determined. We attribute the smallest availability of Ar-R 6 -COO − at the air−water interface among the three carboxylate ions to a strong π−H bonding between the aromatic ring and water molecule. Molecular mechanisms on the availability of carboxylate ions at the air−water interface and the atmospheric implications are discussed.

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Reactivity of Ozone with Solid Potassium Iodide Investigated by Atomic Force Microscopy

Cited by 16 publications

References 18 publications

Technical Note: Concerns on the Use of Ozone Scrubbers for Gaseous Carbonyl Measurement by DNPH-Coated Silica Gel Cartridge

Technical Note: Concerns on the Use of Ozone Scrubbers for Gaseous Carbonyl Measurement by DNPH-Coated Silica Gel Cartridge

Interfacial Dushman-like Chemistry in Hydrated KIO₃ Layers Grown on KI

Carboxylate Ion Availability at the Air–Water Interface

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Reactivity of Ozone with Solid Potassium Iodide Investigated by Atomic Force Microscopy

Cited by 16 publications

References 18 publications

Technical Note: Concerns on the Use of Ozone Scrubbers for Gaseous Carbonyl Measurement by DNPH-Coated Silica Gel Cartridge

Technical Note: Concerns on the Use of Ozone Scrubbers for Gaseous Carbonyl Measurement by DNPH-Coated Silica Gel Cartridge

Interfacial Dushman-like Chemistry in Hydrated KIO3 Layers Grown on KI

Carboxylate Ion Availability at the Air–Water Interface

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Product

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Interfacial Dushman-like Chemistry in Hydrated KIO₃ Layers Grown on KI