Woo, Sang-Hee Jang, Hyungjoon Na, Min Young Chang, Hye Jung Lee, Seokhwan 2024-01-19T12:01:25Z 2024-01-19T12:01:25Z 2022-05-27 2022-06 1352-2310 https://pubs.kist.re.kr/handle/201004/115155 The physicochemical characteristics of micro-and nano-sized brake particles emitted from non-asbestos organic (NAO) and low-metallic (LM) brake pads were investigated under normal and harsh braking conditions using a brake dynamometer. Under normal braking conditions, 28% and 12% of the total wear mass of brake pad and disc was emitted as PM10 and PM2.5, respectively. Overall, the LM pad emitted 4 times higher brake wear PM than the NAO pad. There was no difference in the morphology of brake wear particles (BWPs) according to pad type from the two pad types. BWPs emitted from the NAO pad were mainly composed of Fe oxide and potassium hexatitanate particles, whereas BWPs from the LM pad were almost entirely of Fe oxide particles. Even when the critical pad temperature was not reached, nanoparticles 80-200 nm in size were emitted from both pad types, and the emission concentration of the LM pad was 3-4 times higher than that of the NAO pad. When the pad temperature exceeded the critical temperature by repeated harsh braking, high particle number (PN) concentrations of volatile nanoparticles were measured. Brake nanoparticles 10-50 nm in size formed out of 10 nm sized particles through volatilization and nucleation. Notably, the PN concentration of volatile NAO pad nanoparticles was 3-4 times higher than that of LM pad nanoparticles due to a higher organic fraction in NAO pads. Volatile nanoparticles smaller than 50 nm could be efficiently removed using volatile particle removers such as an evaporation tube and a catalytic stripper, and the evaporation tube had a higher removal efficiency of volatile nanoparticle than the catalytic stripper. Scanning transmission electron microscopy and energy dispersive spectroscopy analysis showed that nanoparticles of size around 50 nm were round and adhered to larger particles. English Elsevier BV Characterization of brake particles emitted from non-asbestos organic and low-metallic brake pads under normal and harsh braking conditions Article 10.1016/j.atmosenv.2022.119089 1 Atmospheric Environment, v.278 Atmospheric Environment 278 N scie scopus 000792898100002 Environmental Sciences Meteorology & Atmospheric Sciences Environmental Sciences & Ecology Meteorology & Atmospheric Sciences Article PARTICULATE MATTER ON-ROAD WEAR EMISSIONS ULTRAFINE COARSE CYCLE FINE Brake pad type Brake wear particles Brake nanoparticles Non-exhaust particulate matter SEM-EDS TEM-EDS