Size-resolved aerosol emissions from lignocellulosic biomass and biomass constituent pyrolysis under variable dilution temperatures

Abstract

Biomass burning events produce significant amounts of particulate matter which influence global radiative forcing, decrease air quality and visibility, and have negative health impacts. The quantity, size distribution, and volatility of biomass burning aerosol emissions are influenced by the combustion mode and ensuing dilution process of the emissions mixing into ambient air. This work examined the emissions from lignocellulosic biomass and its major constituents under laboratory pyrolysis conditions to understand biomass composition and dilution temperature influences on aerosol formation. The major constituents of lignocellulosic biomass, hemicellulose (xylan), cellulose and lignin, were pyrolyzed and the resultant aerosol emissions were characterized in terms of size-resolved number and mass emission factors under variable dilution temperatures. The aerosol emissions formed from biomass constituents were then compared to those of pine and corn stover, and a summative model for predicting characteristics of biomass burning emissions from the behavior of individual constituents was assessed. Results showed a significant influence of dilution temperature on particle size, number, and distribution, with the nucleation mode of particle formation dominating. The summative model performed well in predicting particle number formation from lignocellulosic biomass, but highlighted the effect of uncertainty on predicting particle mass formation.