| Description |
Particulate emission from fuel combustion is a serious concern. This EPA sponsored project aims at using microscopy to collect single particle data on ash generated from different coal combustion conditions. The special interest on coal combustion is because it produces particulate matter in all size ranges, consisting of mixture of elements, relevant to toxicology and biological response studies. Developing methods of sample collection from sources and resuspension of archived and bulk samples was a major part of this thesis. A direct deposit sampling method was developed to collect fly ash samples from a pilot scale furnace. Samples from conventional and 10w-NOx coal combustion conditions were analyzed using Computer Controlled Scanning Electron Microscopy. The differences in particle size, composition and morphology between conventional and 10w-NOx combustion were analyzed and compared with a similar earlier study. The differences found were comparable to the uncertainty in the measurements. Microscopy analysis of archived bulk powder and filter deposit samples requires transferring the particles to a substrate suitable for imaging. Resuspension by dispersion in ethanol caused artifacts such as formation of clusters that could affect the interpretation of results. A liquid nitrogen resuspension method based on a technique used by group of Japanese researchers was tested to resuspend the bulk fly ash particles. This experiment was a qualitative success and would be continued for quantified comparison with direct deposit sample collection method. |
