Ozone

Wojtowicz, J.

doi:10.1002/0471238961.1526151423151020.a01

Cited by 7 publications

(5 citation statements)

References 113 publications

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“…Because reaction conditions typically used to generate chlorohydrins from an alkene employ a large excess of HOCl in aqueous acid, very different from our potential reactions conditions of low HOCl concentration and nonprotic solvents, we studied HOCl reactions with TME under conditions similar to ours. Gaseous HOCl was generated by treating solid Ca(OCl) 2 with acid (H 2 SO 4 or HCl) and was vacuum transferred into solution. Alternatively, HOCl solutions were prepared by the reaction of HgO and Cl 2 in water-saturated solvents .…”

Section: Resultsmentioning

confidence: 99%

Photoreduction of Pt(IV) Halo-Hydroxo Complexes: Possible Hypohalous Acid Elimination

Wickramasinghe

Sharp

2014

Inorg. Chem.

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Concentrated hydrogen peroxide addition to trans-Pt(PEt3)2Cl(R) [1 (R = 9-phenanthryl), 2 (R = 4-trifluoromethylphenyl)] yields hydroxo-hydroperoxo complexes trans-Pt(PEt3)2(Cl)(OOH)(OH)(R) [5 (R = 9-phenanthryl), 4 (R = 4-trifluoromethylphenyl)], where the hydroperoxo ligand is trans to R. Complex 5 is unstable and reacts with solvent CH2Cl2 to give trans,cis-Pt(PEt3)2(Cl)2(OH)(9-phenanthryl) (3). Treatment of 4 with HCl yields analogous trans,cis-Pt(PEt3)2(Cl)2(OH)(4-trifluoromethylphenyl) (6) and HBr gives trans-Pt(PEt3)2(Br)(Cl)(OH)(4-trifluoromethylphenyl) (7), where the Br and 4-trifluoromethylphenyl ligands are trans. Photolysis of 3 or 6 at 313 or 380 nm causes reduction to trans-Pt(PEt3)2Cl(R) (1 or 2, respectively). Expected coproduct HOCl is not detected, but authentic solutions of HOCl are shown to decompose under the reaction conditions. Chlorobenzene and other unidentified products that oxidize PPh3 to OPPh3 are detected in photolyzed benzene solutions. Photolysis of 3 or 6 in the presence of 2,3-dimethyl-2-butene (TME) yields the chlorohydrin (2-chloro-2,3-dimethyl-3-butanol), 3-chloro-2,3-dimethyl-1-butene, and acetone, all expected products from HOCl trapping, but additional oxidation products are also observed. Photolysis of mixed chloro-bromo complex 7 with TME yields the bromohydrin (2-bromo-2,3-dimethyl-3-butanol) and 2, consistent with cis-elimination of HOBr. Computational results (TDDFT and DFT) and photochemistry of related complexes suggest a dissociative triplet excited state reaction pathway and that HOCl elimination may occur by an incipient hydroxo radical abstraction of an adjacent halogen atom, but a pathway involving hydroxo radical reaction with solvent or TME to generate a carbon-based radical followed by halogen abstraction from Pt cannot be eliminated.

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Section: Resultsmentioning

confidence: 99%

Photoreduction of Pt(IV) Halo-Hydroxo Complexes: Possible Hypohalous Acid Elimination

Wickramasinghe

Sharp

2014

Inorg. Chem.

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“…The use of ozone as an alternative oxidant for the catalytic oxidation of VOCs − and gaseous reduced sulfur compounds has been reported in the literature. Ozone is an allotropic form of oxygen with strong oxidizing power exceeded only by fluorine, the perxenate ion, atomic oxygen, OH radicals, and a few other such species …”

Section: Introductionmentioning

confidence: 99%

Acetone Oxidation Using Ozone on Manganese Oxide Catalysts

et al. 2005

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Supported manganese oxide catalysts were prepared by the impregnation of alumina foam blocks washcoated with alumina and silica. The manganese content based on the weight of the washcoats was 10 wt % calculated as MnO2. Fourier transform profiles of the Mn K-edge EXAFS spectra for these samples gave three distinctive peaks at 0.15, 0.25, and 0.32 nm and were close to the profiles of Mn3O4 and beta-MnO2. The number of surface active sites was determined through oxygen chemisorption measurements at a reduction temperature (Tred = 443 K) obtained from temperature-programmed reduction (TPR) experiments. Acetone catalytic oxidation was studied from room temperature to 573 K, and was found to be highly accelerated by the use of ozone on both catalysts with substantial reductions in the reaction temperature. The only carbon-containing product detected was CO2. The alumina-supported catalyst was found to be more active than the silica-supported catalyst in acetone and ozone conversion, with higher turnover frequencies (TOFs) for both reactions. The pressure drop through the foam was low and increased little (0.003 kPa/10 000 h(-1)) with space velocity. In situ steady-state Raman spectroscopy measurements during the acetone catalytic oxidation reaction showed the presence of an adsorbed acetone species with a C-H bond at 2930 cm(-1) and a peroxide species derived from ozone with an O-O bond at 890 cm(-1).

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“…National Institute of Occupational Safety and Health, 1994) the half-life of ozone to oxygen degradation can be very short under proper conditions, such as contact with water or a catalyst. (Wojtowicz, 2000) Ozone in the concentrations used here to kill PsA was catalytically converted back to oxygen in minutes. Ozone monitoring and destruction devices are necessary to ensure safety of personnel operating the device.…”

Section: Discussionmentioning

confidence: 99%

“…Ozone disinfectors are utilized in many applications, including water treatment. (Wojtowicz, 2000) Recently, continuous positive airway pressure (CPAP) mask disinfection systems utilizing gaseous ozone have been introduced to the market (without FDA approval), raising awareness of ozone disinfection but generating concern from the FDA due to reports of unexpected asthma attacks, headaches, and shortness of breath (U.S. Food and Drug Administration, 2020a).…”

Section: Introductionmentioning

confidence: 99%

Disinfection of N95 Respirators with Ozone

Manning

Stephens

Patel³

et al. 2020

Preprint

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The coronavirus disease 2019 crisis is creating a shortage of personal protective equipment (PPE), most critically, N95 respirators for healthcare personnel. Our group was interested in the feasibility of ozone disinfection of N95 respirators as an alternative for healthcare professionals and organizations that might not have access to other disinfection devices. We tested the effectiveness of ozone on killing Pseudomonas aeruginosa (PsA) on three different N95 respirators: 3M 1860, 3M 1870, and 3M 8000. We used an ozone chamber that consisted of: an airtight chamber, an ozone generator, an ozone destruct unit, and an ozone UV analyzer. The chamber was capable of concentrating ozone up to 500 parts per million (ppm) from ambient air, creating an airtight seal, and precisely measuring ozone levels within the chamber. Exposure to ozone at 400 ppm with 80% humidity for two hours effectively killed bacteria on N95 respirators, types 1860, 1870, and 8000. There were no significant changes in filtration efficiency of the 1860 and 1870 type respirators for up to ten cycles of ozone exposure at similar conditions. There was no change in fit observed in the 1870 type respirator after ozone exposure. There was no significant change in the strap integrity of the 1870 type respirator after ozone exposure. Tests for filtration efficiency were not performed on the 8000 type respirator. Tests for fit or strap integrity were not performed on the 8000 or 1860 type respirators. This study demonstrates that an ozone application achieves a high level of disinfection against PsA, a vegetative bacteria that the CDC identifies as more difficult to kill than medium sized viruses such as SARS-CoV-2 (Covid-19). Furthermore, conditions shown to kill these bacteria did not damage or degrade respirator filtration. This is the first report of successful disinfection of N95 PPE with ozone of which the authors are aware. It is also the first report, to the authors' knowledge, to identify necessary conditions for ozone to kill organisms on N95 masks without degrading the function of N95 filters.

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Ozone

Cited by 7 publications

References 113 publications

Photoreduction of Pt(IV) Halo-Hydroxo Complexes: Possible Hypohalous Acid Elimination

Photoreduction of Pt(IV) Halo-Hydroxo Complexes: Possible Hypohalous Acid Elimination

Acetone Oxidation Using Ozone on Manganese Oxide Catalysts

Disinfection of N95 Respirators with Ozone

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