Donald V. Martello

Microscopic study of spheres and microspheres in fly ash

Abstract Spherical particulates in fly ash from two bituminous coals, two subbituminous coals and one lignite have been studied by interference contrast polarized light microscopy (ICT-PLM) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). Most of the glassy spheres were between 8 and 50 μm in diameter. Second phase material was seen on many of the solid sphere surfaces. Microspheres attached to the surfaces of larger spheres were found to have different compositions from that of the host sphere. Microparticulate capture by the larger spheres is a phenomenon that needs more study before the capture mechanism and its efficiency can be understood.

Apportionment of Ambient Primary and Secondary Fine Particulate Matter at the Pittsburgh National Energy Laboratory Particulate Matter Characterization Site Using Positive Matrix Factorization and a Potential Source Contributions Function Analysis

Abstract Fine particulate matter (PM2.5) concentrations associated with 202 24-hr samples collected at the National Energy Technology Laboratory (NETL) particulate matter (PM) characterization site in south Pittsburgh from October 1999 through September 2001 were used to apportion PM2.5 into primary and secondary contributions using Positive Matrix Factorization (PMF2). Input included the concentrations of PM2.5 mass determined with a Federal Reference Method (FRM) sampler, semi-volatile PM2.5 organic material, elemental carbon (EC), and trace element components of PM2.5. A total of 11 factors were identified. The results of potential source contributions function (PSCF) analysis using PMF2 factors and HYSPLIT-calculated back-trajectories were used to identify those factors associated with specific meteorological transport conditions. The 11 factors were identified as being associated with emissions from various specific regions and facilities including crustal material, gasoline combustion, diesel combustion, and three nearby sources high in trace metals. Three sources associated with transport from coal-fired power plants to the southeast, a combination of point sources to the northwest, and a steel mill and associated sources to the west were identified. In addition, two secondary-material-dominated sources were identified, one was associated with secondary products of local emissions and one was dominated by secondary ammonium sulfate transported to the NETL site from the west and southwest. Of these 11 factors, the four largest contributors to PM2.5 were the secondary transported material (dominated by ammonium sulfate) (47%), local secondary material (19%), diesel combustion emissions (10%), and gasoline combustion emissions (8%). The other seven factors accounted for the remaining 16% of the PM2.5 mass.

The regional nature of PM2.5 episodes in the upper Ohio River Valley

Abstract From October 1999 through September 2000, particulate matter (PM) with aerodynamic diameter ≥2.5 μm (PM2.5) mass and composition were measured at the National Energy Technology Laboratory Pittsburgh site, with a particle concentrator Brigham Young University-organic sampling system and a tapered element oscillating microbalance (TEOM) monitor. PM2.5 measurements had also been obtained with TEOM monitors located in the Pittsburgh, PA, area, and at sites in Ohio, including Steub-enville, Columbus, and Athens. The PM data from all these sites were analyzed on high PM days; PM2.5 TEOM particulate mass at all sites was generally associated with transitions from locally high barometric pressure to lower pressure. Elevated concentrations occurred with transport of PM from outside the local region in advance of frontal passages as the local pressure decreased. During high-pressure periods, concentrations at the study sites were generally low throughout the study region. Further details related to this transport were obtained from surface weather maps and estimated back-trajectories using the hybrid single-particle Lagrangian integrated trajectory model associated with these time periods. These analyses indicated that transport of pollutants to the Pittsburgh site was generally from the west to the southwest. These results suggest that the Ohio River Valley and possible regions beyond act as a significant source of PM and its precursors in the Pittsburgh area and at the other regional sites included in this study.

Enhanced magnetic response of fluids using self-assembled petal-like iron oxide particles

Using self-assembled iron oxide (SAIO) particles with petal-like morphology, aqueous fluids containing magnetic particles were prepared and the effect of hierarchical particle surface on the viscoelasticity under magnetic was investigated. The fluids consisting of self-assembled iron oxide particles exhibit highly tunable viscoelasticity which is controlled by applying external magnetic field. A difference between SAIO particles and spherical particles is explained by the fact that surface features of the self-assembled particles increased the network strength between particles in the fluids.

Apportionment of ambient primary and secondary PM2.5 during a 2001 summer intensive study at the netl pittsburgh site using PMF2 and EPA UNMIX

Apportionment of primary and secondary pollutants during a July 2001 intensive study at the National Energy Technology Laboratory is reported. PM2.5 was apportioned into primary and secondary contributions using PMF2, and results were compared with apportionment based on UNMIX 2.3. Input to PMF2 included PM2.5 mass data from four per 24 hour PC-BOSS filters and TEOM, NOx, NO2, O3, non-volatile, semi-volatile, and volatile organic material, elemental carbon, sulfate, and PIXE determined trace metals. Nine factors were identified in the PMF analysis. Six factors were associated with primary particles from crustal, mobile (gasoline and diesel), and three local sources high in trace metals. Three factors were associated with secondary sources. Two were associated with local emissions dominated by organic material, one was dominated by transported ammonium sulfate. UNMIX was able to identify the two major mobile sources, major local secondary source and transported secondary source. The three major sources of PM2.5 were identified as secondary transported material (dominated by ammonium sulfate) from west and southwest (46%), secondary material formed during mid-day photochemical processes (21%), and primary emissions from diesel (10%) and gasoline (8%) mobile sources. The other five sources accounted for the remaining 15% of the PM2.5. These findings are consistent with the majority of secondary ammonium sulfate in the Pittsburgh area resulting from distant transport, and so decoupled from local activity involving organic pollutants in the metropolitan area. In contrast, the major local secondary sources were dominated by organic material.

The petrography and mineralogy of two Indian coals

Abstract Two coals, Kathara bituminous middlings from north-eastern India (Damodar Valley) and Neyveli lignite from south-eastern India (Tamil Nadu), were petrographically characterized. The Kathara sample is a high-ash coal produced in the beneficiation of a bituminous coking coal. It is relatively high in inertinite and mineral matter, with an unusually large amount of iron oxides in the form of hematite, magnetite and hydrated iron oxides. The Neyveli sample is relatively low in ash and sulfur, and consists mostly of the huminite group of macerals, with a considerable amount of liptinite also present. Low-temperature ashes and bottom ash samples of both coals were analysed by X-ray diffraction to help in interpreting the petrographic data. These coals were also tested for combustion characteristics.

Apportionment of ambient primary and secondary fine particulate matter during a 2001 summer intensive study at the CMU Supersite and NETL Pittsburgh site.

Gaseous and particulate pollutant concentrations associated with five samples per day collected during a July 2001 summer intensive study at the Pittsburgh Carnegie Mellon University (CMU) Supersite were used to apportion fine particulate matter (PM2.5) into primary and secondary contributions using PMF2. Input to the PMF2 analysis included the concentrations of PM2.5 nonvolatile and semivolatile organic material, elemental carbon (EC), ammonium sulfate, trace element components, gas-phase organic material, and NO(x), NO2, and O3 concentrations. A total of 10 factors were identified. These factors are associated with emissions from various sources and facilities including crustal material, gasoline combustion, diesel combustion, and three nearby sources high in trace metals. In addition, four secondary sources were identified, three of which were associated with secondary products of local emissions and were dominated by organic material and one of which was dominated by secondary ammonium sulfate transported to the CMU site from the west and southwest. The three largest contributors to PM2.5 were secondary transported material (dominated by ammonium sulfate) from the west and southwest (49%), secondary material formed during midday photochemical processes (24%), and gasoline combustion emissions (11%). The other seven sources accounted for the remaining 16% of the PM2.5. Results obtained at the CMU site were comparable to results previously reported at the National Energy Technology Laboratory (NETL), located approximately 18 km south of downtown Pittsburgh. The major contributor at both sites was material transported from the west and southwest. Some difference in nearby sources could be attributed to meteorology as evaluated by HYSPLIT model back-trajectory calculations. These findings are consistent with the majority of the secondary ammonium sulfate in the Pittsburgh area being the result of contributions from distant transport, and thus decoupled from local activity involving organic pollutants in the metropolitan area. In contrast, the major local secondary sources were dominated by organic material.

Photocatalytic production of methanol and hydrogen from methane and water

Abstract Investigation of direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of our current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. Research in our laboratory is directed toward adapting the chemistry developed for photolysis of water to that of methane conversion. The reaction sequence of interest uses visible light, a doped tungsten oxide photocatalyst and an electron transfer molecule to produce a hydroxyl radical. Hydroxyl radical can then react with a methane molecule to produce a methyl radical. In the preferred reaction pathway, the methyl radical then reacts with an additional water molecule to produce methanol and hydrogen.

Apportionment of ambient primary and secondary pollutants during a 2001 summer study in pittsburgh using U.S. environmental protection agency UNMIX

Abstract Apportionment of primary and secondary pollutants during the summer 2001 Pittsburgh Air Quality Study (PAQS) is reported. Several sites were included in PAQS, with the main site (the supersite) adjacent to the Carnegie Mellon University campus in Schenley Park. One of the additional sampling sites was located at the National Energy Technology Laboratory, located ∼18 km southeast of downtown Pittsburgh. Fine particulate matter (PM2.5) mass, gas-phase volatile organic material (VOM), particulate semivolatile and nonvolatile organic material (NVOM), and ammonium sulfate were apportioned at the two sites into their primary and secondary contributions using the U.S. Environmental Protection Agency UNMIX 2.3 multivariate receptor modeling and analysis software. A portion of each of these species was identified as originating from gasoline and diesel primary mobile sources. Some of the organic material was formed from local secondary transformation processes, whereas the great majority of the secondary sulfate was associated with regional transformation contributions. The results indicated that the diurnal patterns of secondary gas-phase VOM and particulate semivolatile and NVOM were not correlated with secondary ammonium sulfate contributions but were associated with separate formation pathways. These findings are consistent with the bulk of the secondary ammonium sulfate in the Pittsburgh area being the result of contributions from distant transport and, thus, decoupled from local activity involving organic pollutants in the metropolitan area.

Characterization of Ash Deposit Structure from Planar Sections: Results and Challenges

Three-dimensional structural parameters were measured for fouling ash deposits from two Powder River Basin subbituminous coals using direct microscopical methods on planar sections through the deposits. These parameters included solid and pore volume fractions; specific surface area; particle contiguity; and mean solid, particle, and pore chord lengths. Spatial trends in the results for the two deposits indicated that the solid volume fraction remained relatively constant from the tube side to the flame side, but the solid phase coarsened in this direction. An increase in the contiguity between ash particles indicated that the coarsening mechanism was sintering, both via increased particle agglomeration and encapsulation of particles by a glassy phase. The bulk averages of the results were identical for both deposits, with a solid volume fraction of 0.23, a specific surface area of 0.6 x 106 m−1, a contiguity of 0.23, a mean solid chord length of 16 pm, a mean particle chord length of 12 µm, and a mean pore chord length of 53 µm. In addition, a two-dimensional structural parameter, the density-density correlation function, was measured for one of the deposits. This result indicated that the cross-sectional profiles of the solid regions with diameters less than 20 µm were isotropically oriented, and that the larger solid region profiles were preferentially oriented in the direction of the incoming particle trajectories.