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Volume 10, No. 6, December 2010, Pages 616-624 PDF(367 KB)  
doi: 10.4209/aaqr.2010.04.0033   

Performance Test of an Inertial Fibrous Filter for Ultrafine Particle Collection and the Possible Sulfate Loss when Using an Aluminum Substrate with Ultrasonic Extraction of Ionic Compounds

Kyung Hwan Kim1, Kazuhiko Sekiguchi1,2, Shinji Kudo1, Kazuhiko Sakamoto1,2, Mitsuhiko Hata3, Masami Furuuchi3, Yoshio Otani3, Naoko Tajima4

1 Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570, Japan
2 Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570, Japan
3 Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
4 Japanese Kanomax Inc., 2-1 Shimizu Suita, Osaka 565-0805, Japan

 

Abstract

 

A sampler using inertial fibrous filters (INF) has been recently developed for ultrafine particle collection by impaction and filtration. This new sampler has a low pressure drop (20–30 kPa) and can separate particles smaller than 0.1 µm with a high sampling flow rate (40 L/min). In this study, sampling performance of the INF sampler was evaluated in comparison with a reference sampler in the field as well as in the laboratory and the possible sulfate ion loss when using aluminum substrates for ion extraction in ultrasonic bath was discovered and investigated. When sampling ultrafine particles (Dp ≤ 0.1 µm) such as carbonaceous and ionic species both in the field and in the laboratory, the performance of the INF sampler was similar to that of a reference sampler despite differences of sampling mechanism, cut-point diameter, and substrate proving that the INF sampler can be an alternative for ultrafine particle collection. Underestimation of sulfate concentration appeared to be unavoidable in ultrasonic extractions from aluminum substrates regardless of whether the extraction time was 30 or 90 min. The average sulfate loss during aluminum filter extraction was 45% (± 12%; min: 12%; max: 94%). Therefore, ultrasonic extraction from aluminum filters should be avoided to obtain unbiased measurements of sulfate concentration in ambient air or other ion extraction methods should be considered to minimize sulfate loss (dissolution of aluminum ions) from aluminum filters with sufficient extraction efficiency of ionic species.
    The results of this study indicate that the performance of the INF sampler is almost similar to that of the nano-MOUDI sampler for ultrafine particle collection, while advantageous in terms of convenience, and analysis. Furthermore, the INF sampler can collect amounts of ultrafine particles that are sufficient for chemical analysis in a relatively short time, and the particles can be uniformly collected with a quartz fiber filter.

 

 

Keywords: Inertial classification; Ultrafine particles (PM0.1); nano-MOUDI; Sulfate loss; Aluminum substrate.

 

 

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