Carbon-Centered Free Radicals in Particulate Matter Emissions from Wood and Coal Combustion.
Electron paramagnetic resonance (EPR) spectroscopy was used to measure the free radicals in the particulate matter (PM) emissions from wood and coal combustion. The intensity of radicals in PM dropped linearly within two months of sample storage and stabilized after that. This factor of storage time was adjusted when comparing radical intensities among different PM samples. An inverse relationship between coal rank and free radical intensities in PM emissions was observed, which was in contrast with the pattern of radical intensities in the source coals. The strong correlation between intensities of free radical and elemental carbon in PM emissions suggests that the radical species may be carbon-centered. The increased g-factors, 2.0029-2.0039, over that of purely carbon-centered radicals may indicate the presence of vicinal oxygen heteroatom. The redox and biology activities of these carbon-centered radicals are worthy of evaluation.
Tian
Linwei
L
School of Public Health, Chinese University of Hong Kong, Shatin-NT, Hong Kong, China, School of Public Health, Energy and Resources Group, and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, and The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Koshland
Catherine P
CP
Yano
Junko
J
Yachandra
Vittal K
VK
Yu
Ignatius T S
IT
Lee
S C
SC
Lucas
Donald
D