De-pollution efficacy of photocatalytic roofing granules
| Autor: | Jiachen Zhang, Rebecca L. Everman, Sharon Chen, Frank W. Klink, Marion L. Russell, Hugo Destaillats, Simon K. Shannon, Ronnen Levinson, Ughetta Lara K N, Sébastien Houzé de l’Aulnoit, George Ban-Weiss, Xiaochen Tang, Rachael A.T. Gould |
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| Rok vydání: | 2019 |
| Předmět: |
Pollution
Asphalt roofing shingle Aging Environmental Engineering Environmental Science and Management media_common.quotation_subject Weathering Geography Planning and Development Airflow 0211 other engineering and technologies Air pollution chemistry.chemical_element 02 engineering and technology NOx 010501 environmental sciences medicine.disease_cause Nitrate 01 natural sciences Aluminium Architecture medicine Building 021108 energy 0105 earth and related environmental sciences Civil and Structural Engineering media_common Building & Construction Precipitation (chemistry) Building and Construction Deposition (aerosol physics) chemistry Environmental chemistry Photocatalysis Environmental science Titanium dioxide |
| Popis: | Photocatalytic building surfaces can harness sunlight to reduce urban air pollution. The NOx abatement capacity of TiO2-coated granules used in roofing products was evaluated for commercial product development. A laboratory test chamber and ancillary setup were built following conditions prescribed by ISO Standard 22197-1. It was validated by exposing reference P25-coated aluminum plates to a 3 L min−1 air flow enriched in 1 ppm NO under UVA irradiation (360 nm, 11.5 W m−2). We characterized prototype granule-surfaced asphalt shingles and loose granules prepared with different TiO2 loadings and post-treatment formulations. Tests performed at surface temperatures of 25 and 60 °C showed that NOx abatement was more effective at the higher temperature. Preliminary tests explored the use of 1 ppm NO2 and of 1 ppm and 0.3 ppm NO/NO2 mixtures. Specimens were aged in a laboratory accelerated weathering apparatus, and by exposure to the outdoor environment over periods that included dry and rainy seasons. Laboratory aging led to higher NO removal and NO2 formation rates, and the same catalyst activation was observed after field exposure with frequent precipitation. However, exposure during the dry season reduced the performance. This inactivation was mitigated by cleaning the surface of field-exposed specimens. Doubling the TiO2 loading led to a 50–150% increase in NO removal and NOx deposition rates. Application of different post-treatment coatings decreased NO removal rates (21–35%) and NOx deposition rates (26–74%) with respect to untreated granules. The mass balance of nitrogenated species was assessed by extracting granules after UV exposure in a 1 ppm NO-enriched atmosphere. |
| Databáze: | OpenAIRE |
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