Atmospheric aerosol particles also known as atmospheric particulate matter or particulate matter (PM) are microscopic particles (solid or liquid) suspended in air, which is one of six air pollutants in US air quality standard. PM is classified as coarse particles with diameters between 2.5 to 10 mm, fine particles with a diameter less than 2.5 mm (PM2.5), and ultrafine particles with the diameter less than 0.1 mm (PM0.1). Epidemiological studies have already showed the adverse health effects (such as asthma, lung cancer and respiratory and cardiovascular disease) resulted from exposure to the fine and ultrafine particles. Monitoring the PM concentration (i.e., either mass or surface area concentration of PM) is critical for the protection of public health and environment and for the regulatory control. Various PM sensors are now available in market. A majority of these PM sensors are optical sensors, whose readouts are highly depended on the physical property and composition of PM. Several PM monitors based on the measurement principle of electrical charging are also available. However, the empirical calibration of the readout of these electrical PM monitors via the use of standard dust particles makes it difficult to obtain the true mass concentration of PM when PM size distribution is different from that of standard dust. The overall objective of this dissertation is to advance our scientific knowledge on the performance of cost-effective PM monitors for measuring either mass or surface area concentration of fine and ultrafine PM. This thesis includes two parts: (1) is on the evaluation of existing PM sensor for PM mass concentration measurement; (2) is on the development of new PM monitor for PM surface area concentration measurement. For the first part of this dissertation, four low-cost optical sensors, one Personal Dust Monitor (PDM) and DustrakTM were experimentally evaluated. Particles in the size distribution having different mean size, standard deviation value and material were used as test aerosol particles. The readouts of these low-cost and portable sensors are compared to that of a standard TEOM (Tapered Element Oscillation Microbalance). For the second part of this dissertation, a new electrical PM monitor, consisting of a corona-based aerosol charger, a precipitator and high sensitive current meter, has been proposed for measuring surface area concentration of fine and ultrafine PM. Particles are electrically charged upon entering an electrical PM monitor. Instead of using Faraday cage and current meter to measure the charges carried by particles in existed electrical PM sensors, the new PM monitor measures the current carried by particles deposited directly on the wall of the precipitator. A thorough evaluation has been carried out to evaluate the fundamental performance of this new PM monitor. In addition, small cyclones (i.e., quadru-inlet and tapered-body cyclones) were also evaluated as the size-selective inlet of these PM sensors/monitors to minimize the potential interface from the presence of PM with large sizes in the air. The small quadru-inlet cyclone is to resolve the issue of directional sampling; and the tapered-body cyclones is to reduce the cyclone pressure drop while having small cyclone cutoff particle size. Each cyclone has been evaluated via the measurement of particle penetration curve and pressure drop. Semi-empirical models have been obtained for the prediction of cyclone performance.

The bioavailability of metabolizable organic matter within marine sediments is one of the more important driving mechanisms controlling benthic pelagic communities. Interactions between organic material and mineral surfaces within the sediment, such as adsorption, can cause organic matter to be unavailable for degradation by organisms; therefore for this study we have used the relationship of organic carbon-to-sediment surface area as an indicator of available organic carbon in northern Gulf of Mexico sediments. We have determined that these sediment interactions demonstrate a significant association with benthic fauna abundances; however they are not the most dominant environmental variables. It may be the combination of biogeochemical parameters, such as organic carbon content, sediment surface area, grain size, water depth and other geophysical variables, that is the ultimate control on the bioavailability of metabolizable organic matter in the northern Gulf of Mexico.

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The bioavailability of metabolizable organic matter within marine sediments is one of the more important driving mechanisms controlling benthic pelagic communities. Interactions between organic material and mineral surfaces within the sediment, such as adsorption, can cause organic matter to be unavailable for degradation by organisms; therefore for this study we have used the relationship of organic carbon-to-sediment surface area as an indicator of available organic carbon in northern Gulf of Mexico sediments. We have determined that these sediment interactions demonstrate a significant association with benthic fauna abundances; however they are not the most dominant environmental variables. It may be the combination of biogeochemical parameters, such as organic carbon content, sediment surface area, grain size, water depth and other geophysical variables, that is the ultimate control on the bioavailability of metabolizable organic matter in the northern Gulf of Mexico.

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Bacterial pathogens on the surfaces of raw produce may be difficult to remove for identification and enumeration. The first part of this project examined whether ultrasonic treatment (40 kHz) of a rinse solution would enhance recovery of Salmonella spp. from various produce surfaces. Strawberries, apples, and cantaloupe were surface inoculated with a five-strain cocktail of nalidixic acid resistant Salmonella spp. Samples were subjected to one of six different treatments using different combinations of agitation methods (manual shaking or ultrasound), diluent temperatures (25°C and 40°C), and agitation times (60 and 120 seconds). After treatment, diluent was spiral plated onto tryptic soy agar supplemented with 50 ppm of nalidixic acid and plates were incubated at 37°C for 48 hours. Results from this study indicate that ultrasonic treatment of a rinse solution did not enhance or diminish recovery of Salmonella spp. from produce surfaces, as compared to manual agitation. The effects of diluent temperature and exposure time appeared to have a significant effect on recovery, depending on the type of produce. The second part of this project used a computer imaging system to determine the surface area of various types of produce. The imaging system acquired and stored multiple images of the produce samples. From these images, surface fitting and approximation of a 3-D wire frame model were used to calculate surface area. From these measurements, it was determined that there were statistical relationships between surface area and weight. Surface area measurements were used to develop equations to predict surface area from weight measurements. / Master of Science

This thesis investigates the feasibility of producing activated carbon from polysaccharides. Activated carbons are high surface area solids with rich surface functionality and as a result, find use in a variety of industrial separation processes. The market for activated carbon is already established and growing but there is a huge push to find sustainable alternatives for the raw material used for its production, which is primarily coal. While there exists a significant amount of research on agricultural residues as potential replacements, there is minimal information on using polysaccharides as precursors for the production of activated carbon. Using the patented PGX process, two separate approaches were employed for the synthesis of activated carbon. The first method relied on the porous network of PGX materials to be maintained during pyrolysis while the second approach used a chemical agent to create porosity during the pyrolysis. Gas sorption analysis revealed that the PGX structure was not maintained during the pyrolysis stage hence losing all its pore network and extended surface area. Additionally, no significant variation between the PGX and non PGX variants of the chemically activated polymers was observed. However, it was revealed that the interaction between zinc chloride and pectin produced exceptionally high specific surface area (exceeding 2000 m2 g-1) activated carbon. The produced carbon had a high degree of microporosity (up to 100%) with some flexibility present in tuning the porosity. Elemental analysis revealed the carbon to have high surface functionality and preliminary adsorption test for removal of heavy metal ions from water (Pb2+ and Cd2+) showed promising results with the in-house carbon performing better than a representative commercial carbon. This study relies on statistical methods including multiple design of experiment studies and advanced characterization techniques to analyze the manufacturing process and the properties of carbon in an attempt to find the best conditions for producing activated carbon from polysaccharides. / Thesis / Master of Applied Science (MASc)

The behavior during dissolution of edge and basal surfaces of the mica phlogopite were examined using in situ atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) in an attempt to characterize the reactive surface area during dissolution. Mica minerals are the ideal material for this study because they offer a high degree of structural anisotropy. Therefore surfaces with different structures are easily identified. Dissolution is shown to proceed preferentially by removal of material from {hk0} edges. Dissolution rates were calculated by measuring the volume of material removed from etch pits, and normalizing to either the "reactive" surface area of {hk0} edges exposed at pit walls, or to a total "BET-equivalent" surface area. Rates normalized to total surface area are in the range of dissolution rates reported in the literature. Edge surface normalized rates are about 100 times faster. Long-term in situ AFM observations of phlogopite dissolution reveal that exposed (001) surfaces also display a distinct reactivity, though it operates on a different time scale. The top layer is shown to expand between 39 and 63 hours in contact with pH 2 HCl solution. Subsequent LEED analysis shows that the (001) surface becomes amorphous upon reacting with pH 2 HCl. Compositional characterization of the phlogopite after reaction shows that for pitted phlogopite surfaces, dissolution is characterized by leaching of octahedral cations and polymerization of the silica-enriched residual layer. No chemical changes or polymerization are observed for freshly cleaved unpitted phlogopite after reaction with pH 2 HCl for 24 hours. This suggests a gallery access mechanism is facilitated by edge attack, and is only significant on exposed (001) surfaces after a certain amount of dissolution by edge attack. / Master of Science

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