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Performance of ultraviolet photocatalytic oxidation for indoor air cleaning applications.
Indoor Air. 2007 Aug; 17(4):305-16.IA

Abstract

Ultraviolet photocatalytic oxidation (UVPCO) systems for removal of volatile organic compounds (VOCs) from air are being considered for use in office buildings. Here, we report an experimental evaluation of a UVPCO device with tungsten oxide modified titanium dioxide (TiO2) as the photocatalyst. The device was challenged with complex VOC mixtures. One mixture contained 27 VOCs characteristic of office buildings and another comprised 10 VOCs emitted by cleaning products, in both cases at realistic concentrations (low ppb range). VOC conversion efficiencies varied widely, usually exceeded 20%, and were as high as approximately 80% at about 0.03 s residence time. Conversion efficiency generally diminished with increased airflow rate, and followed the order: alcohols and glycol ethers > aldehydes, ketones, and terpene hydrocarbons > aromatic and alkane hydrocarbons > halogenated aliphatic hydrocarbons. Conversion efficiencies correlated with the Henry's law constant more closely than with other physicochemical parameters. An empirical model based on the Henry's law constant and the gas-phase reaction rate with hydroxyl radical provided reasonable estimates of pseudo-first order photocatalytic reaction rates. Formaldehyde, acetaldehyde, acetone, formic acid and acetic acid were produced by the device due to incomplete mineralization of common VOCs. Formaldehyde outlet/inlet concentration ratios were in the range 1.9-7.2.

PRACTICAL IMPLICATIONS

Implementation of air cleaning technologies for both VOCs and particles in office buildings may improve indoor air quality, or enable indoor air quality levels to be maintained with reduced outdoor air supply and concomitant energy savings. One promising air cleaning technology is ultraviolet photocatalytic oxidation (UVPCO) air cleaning. For the prototype device evaluated here with realistic mixtures of VOCs, conversion efficiencies typically exceeded the minimum required to counteract predicted VOC concentration increases from a 50% reduction in ventilation. However, the device resulted in the net generation of formaldehyde and acetaldehyde from the partial oxidation of ubiquitous VOCs. Further development of the technology is needed to eliminate these hazardous air pollutants before such a UVPCO device can be deployed in buildings.

Authors+Show Affiliations

Indoor Environment Department, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. athodgson@lbl.govNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

17661927

Citation

Hodgson, A T., et al. "Performance of Ultraviolet Photocatalytic Oxidation for Indoor Air Cleaning Applications." Indoor Air, vol. 17, no. 4, 2007, pp. 305-16.
Hodgson AT, Destaillats H, Sullivan DP, et al. Performance of ultraviolet photocatalytic oxidation for indoor air cleaning applications. Indoor Air. 2007;17(4):305-16.
Hodgson, A. T., Destaillats, H., Sullivan, D. P., & Fisk, W. J. (2007). Performance of ultraviolet photocatalytic oxidation for indoor air cleaning applications. Indoor Air, 17(4), 305-16.
Hodgson AT, et al. Performance of Ultraviolet Photocatalytic Oxidation for Indoor Air Cleaning Applications. Indoor Air. 2007;17(4):305-16. PubMed PMID: 17661927.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Performance of ultraviolet photocatalytic oxidation for indoor air cleaning applications. AU - Hodgson,A T, AU - Destaillats,H, AU - Sullivan,D P, AU - Fisk,W J, PY - 2007/7/31/pubmed PY - 2007/12/6/medline PY - 2007/7/31/entrez SP - 305 EP - 16 JF - Indoor air JO - Indoor Air VL - 17 IS - 4 N2 - UNLABELLED: Ultraviolet photocatalytic oxidation (UVPCO) systems for removal of volatile organic compounds (VOCs) from air are being considered for use in office buildings. Here, we report an experimental evaluation of a UVPCO device with tungsten oxide modified titanium dioxide (TiO2) as the photocatalyst. The device was challenged with complex VOC mixtures. One mixture contained 27 VOCs characteristic of office buildings and another comprised 10 VOCs emitted by cleaning products, in both cases at realistic concentrations (low ppb range). VOC conversion efficiencies varied widely, usually exceeded 20%, and were as high as approximately 80% at about 0.03 s residence time. Conversion efficiency generally diminished with increased airflow rate, and followed the order: alcohols and glycol ethers > aldehydes, ketones, and terpene hydrocarbons > aromatic and alkane hydrocarbons > halogenated aliphatic hydrocarbons. Conversion efficiencies correlated with the Henry's law constant more closely than with other physicochemical parameters. An empirical model based on the Henry's law constant and the gas-phase reaction rate with hydroxyl radical provided reasonable estimates of pseudo-first order photocatalytic reaction rates. Formaldehyde, acetaldehyde, acetone, formic acid and acetic acid were produced by the device due to incomplete mineralization of common VOCs. Formaldehyde outlet/inlet concentration ratios were in the range 1.9-7.2. PRACTICAL IMPLICATIONS: Implementation of air cleaning technologies for both VOCs and particles in office buildings may improve indoor air quality, or enable indoor air quality levels to be maintained with reduced outdoor air supply and concomitant energy savings. One promising air cleaning technology is ultraviolet photocatalytic oxidation (UVPCO) air cleaning. For the prototype device evaluated here with realistic mixtures of VOCs, conversion efficiencies typically exceeded the minimum required to counteract predicted VOC concentration increases from a 50% reduction in ventilation. However, the device resulted in the net generation of formaldehyde and acetaldehyde from the partial oxidation of ubiquitous VOCs. Further development of the technology is needed to eliminate these hazardous air pollutants before such a UVPCO device can be deployed in buildings. SN - 0905-6947 UR - https://www.unboundmedicine.com/medline/citation/17661927/Performance_of_ultraviolet_photocatalytic_oxidation_for_indoor_air_cleaning_applications_ L2 - https://doi.org/10.1111/j.1600-0668.2007.00479.x DB - PRIME DP - Unbound Medicine ER -