Further studies of oxidation processes on filter surfaces: Evidence for oxidation products and the influence of time in service

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    Abstract

    The sensory pollutants emitted by loaded ventilation filters are assumed to include products formed via oxidation of organics associated with captured particles. In this study, experiments were performed that used either particle production or ozone removal as probes to further improve our understanding of such processes. The measured ratio of downstream to upstream submicron particle concentrations increased when ozone was added to air passing through samples from loaded particle filters. Such an observation is consistent with low volatility oxidation products desorbing from the filter and subsequently partitioning between the gas phase and the surface of particles that have passed through the filter, including particles that were previously too small (<20 nm) to be detected by the instrument used in these studies. A related set of experiments conducted with unused filters and filters that had been in service from 2 to 16 weeks found that ozone removal efficiencies changed in a manner that indicated at least two different removal mechanisms-reactions with compounds present on the filter media following manufacturing and reactions with compounds associated with captured particles. The contribution from the former varies with the type and manufacturer of the filter, while that of the latter varies with the duration of service and nature of the captured particles. In complimentary experiments, a filter sample protected from ozone during its 9 weeks of service had higher ozone removal efficiencies than an identical filter not protected from ozone during the same 9 weeks of service filtering the same air. This result indicates that a filter's exposure history subsequently influences the quantity of oxidation products generated when ozone-containing air flows through it. (c) 2007 Elsevier Ltd. All rights reserved.
    Original languageEnglish
    JournalAtmospheric Environment
    Volume41
    Issue number25
    Pages (from-to)5202-5212
    ISSN1352-2310
    DOIs
    Publication statusPublished - 2007
    Event10th International Conference on Indoor Air Quality and Climate - Beijing, China
    Duration: 4 Sept 20059 Sept 2005
    Conference number: 10

    Conference

    Conference10th International Conference on Indoor Air Quality and Climate
    Number10
    Country/TerritoryChina
    CityBeijing
    Period04/09/200509/09/2005

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