Polycyclic Aromatic Hydrocarbons in Coarse Fly Ash Particles Emitted from Fluidized-bed Combustion of Thai Rice Husk

Abstract

This work aimed to study the size distribution of polycyclic aromatic hydrocarbons (PAHs) in the fly ash emitted from a fluidized-bed combustor firing Thai rice husk. The particle size distribution and chemical composition of the fly ash are discussed. More than 80% of ash particles were found to have the volume mean diameter of 11 to 260 µm. SEM images of some fine and coarse particles are presented. The fine particles were found to show a tubular-shaped and polish-structured surface, while the coarse particles basically exhibited a hydroscopic-pores surface texture. Concentrations of eleven PAHs (napthalene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, indenol[1,2,3- cd]pyrene, benzo[g,h,i]perylene) were quantified for three groups of particle size, 0.5–125 µm, 125– 150 µm and 150–250 µm. The total PAH concentration was found to be quite substantial (271.6 µg/kg) in the 150–250 µm particles, while it was dramatically reduced with smaller particle size. The highest concentrations were observed for the most toxic compounds, benzo[a]pyrene, indenol[1,2,3-cd]pyrene and benzo[g,h,i]perylene Keywords: