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Title: Organic composition of ultrafine particles formed from automotive braking
Non-exhaust emissions (e.g., automotive brake and tire wear) are quickly replacing exhaust emissions as the dominant traffic particulate pollutant. A significant fraction of the emissions are complex mixtures of organic compounds whose composition is not well known. Due to their unique health implications, knowledge of the composition of ultrafine particles (<100 nm in diameter) is of particular interest. Here we report on the size-selected organic composition of ultrafine particles nucleated during high brake temperature conditions generated using a custom brake dynamometer system and two common brake pad types. Using high resolution mass spectrometry, we find that the organic composition of these particles is dominated by species containing oxygen (CHO) and nitrogen (CHN/CHON). Many of these compounds are unsaturated and are attributed to the thermal degradation of resin material used in the pad formulation. Other abundant compounds include various glycols and amines, several of which are unequivocally identified and discussed as potential marker compounds for brake wear emissions. A significant fraction of highly oxidized, low volatility species observed in ultrafine particles could not be conclusively attributed to the thermal degradation of the brake material, indicating the presence of chemical pathways unique to the frictional heating process. This emphasizes the importance of using a brake dynamometer to generate brake wear particles as opposed to other strategies.  more » « less
Award ID(s):
2327825
PAR ID:
10647596
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Royal Society of Chemistry
Date Published:
Journal Name:
Environmental Science: Processes & Impacts
ISSN:
2050-7887
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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