Thomas M. Holsen

PAH source fingerprints for coke ovens, diesel and, gasoline engines, highway tunnels, and wood combustion emissions

Abstract To evaluate the chemical composition (source fingerprint) of the major sources of polyaromatic hydrocarbons (PAHs) in the Chicago metropolitan area, a study of major PAH sources was conducted during 1990–1992. In this study, a modified high-volume sampling method (PS-1 sampler) was employed to collect airborne PAHs in both the particulate and gas phases. Hewlett Packard 5890 gas chromatographs equipped with the flame ionization and mass spectrometer detectors (GC/FID and GC/MS) were used to analyze the samples. The sources sampled were: coke ovens, highway vehicles, heavy-duty diesel engines, gasoline engines and wood combustion. Results of this study showed that two and three ring PAHs were responsible for 98, 76, 92, 73 and 80% of the total concentration of measured 20 PAHs for coke ovens, diesel engines, highway tunnels, gasoline engines and wood combustion samples, respectively. Six ring PAHs such as indeno(1,2,3- cd )pyrene and benzo( ghi )perylene were mostly below the detection limit of this study and only detected in the highway tunnel, diesel and gasoline engine samples. The source fingerprints were obtained by averaging the ratios of individual PAH concentrations to the total concentration of categorical pollutants including: (a) total measured mass of PAHs with retention times between naphthalene and coronene, (b) the mass of the 20 PAHs measured in this study, (c) total VOCs, and (d) total PM10. Since concentrations of the above categorical pollutants were different for individual samples and different sources, the chemical composition patterns obtained for each categorical pollutant were different. The source fingerprints have been developed for use in chemical mass balance receptor modeling calculations.

Polycyclic aromatic hydrocarbons (PAHs) in Chicago air

Ambient air samples were collected in Chicago, IL between June and October 1995 as part of a study to investigate the dry deposition and air–water exchange of polycyclic aromatic hydrocarbons (PAHs). A modified high-volume sampler (PS-1 sampler) was used to collect airborne PAHs in both the particulate and gas phases. The average total (gas+particulate) Σ14-PAH concentration was 428±240 ng m−3, similar to those previously observed in Chicago, IL and other urban areas. The particle/gas phase distribution varied widely. The gas phase percentage ranged from 1.1 to 99.4%, and generally decreased with increasing molecular weight. The amount of PAHs associated with the particulate phase increased with decreasing temperature, probably due to the temperature dependence of gas/particle partitioning. Concentrations of PAHs with molecular weights between 154 and 202 were correlated well with phenanthrene concentrations while compounds with molecular weights higher than 202 had little or no correlation with phenanthrene concentration, probably due to the different partitioning, transport and removal characteristics of low and high molecular weight compounds.

Dry Deposition Velocities as a Function of Particle Size in the Ambient Atmosphere

The atmospheric particle mass size distribution (0.1–100 μ m) and dry deposition flux were measured simultaneously with a wide range aerosol classifier (WRAC) and a smooth greased surface. Microscopic techniques were used to size the particles collected on the deposition surface and generate mass size distributions of deposited particles. All the depositional mass size distributions peaked (interval with the largest mass) between 30 and 100 μm in diameter. Deposition velocities were calculated by dividing the size segregated particle flux by the airborne particle concentration for each of the 10 WRAC stage intervals. Experimentally determined dry deposition velocities for atmospheric particles in the size range of 5–80 μm in diameter were greater than predictions made with the Sehmel-Hodgson deposition velocity model developed from wind tunnel experiments, particularly at higher wind speeds. A multistep method was used to calculate total and cumulative deposition fluxes with the Sehmel-Hodgson model. Calc...

A comparison of dry deposition modeled from size distribution data and measured with a smooth surface for total particle mass, lead and calcium in Chicago

For 11 sampling periods, atmospheric particle and elemental (Pb, Ca) mass size distributions (0.1–100 μm diameter) were measured with a Noll Rotary Impactor (NRI) and cascade impactor in Chicago, Illinois. The NRI and cascade impactor measurements were continuous; there was no displacement in the bimodal size distributions. Lead, a primarily anthropogenic element, tended to be associated with the fine-particle mode (< 2.5 μmdiameter); Ca, a primarily crustal element, was associated with the coarse particle mode (< 2.5 μmdiameter). Atmospheric dry deposition fluxes were simultaneously measured with a specially designed and constructed smooth surface pointed into the wind. A particle dry deposition velocity model was used in conjunction with the measured sized distributions to calculate dry deposition fluxes, which were then compared to the measured fluxes. The method, which combined a 12-step flux calculation with the particle dry deposition velocity model, agreed with the measured flux data to within a factor of two. The modeled cumulative fluxes show that fine particles are responsible for only a small fraction of the dry deposition flux. The per cent of the modeled flux due to particles less than 2.5 μm was 0.06, 0.5 and 0.06% for particle mass, Pb and Ca, respectively. The results indicate that atmospheric dry deposition is dominated by coarse particles due to their high deposition velocities.

Modeling the energy content of municipal solid waste using multiple regression analysis

In this research multiple regression analysis was used to develop predictive models of the energy content of municipal solid waste (MSW). The scope of work included collecting waste samples in Kaohsiung City, Taiwan, characterizing the waste, and performing a stepwise forward selection procedure for isolating variables. Two regression models were developed to correlate the energy content with variables derived from physical composition and ultimate analysis. The performance of these models for this particular waste was superior to that of equations developed by other researchers (e.g., Dulong, Steuer) for estimating energy content. Attempts at developing regression models from proximate analysis data were not successful.

Dry Deposition Fluxes and Atmospheric Size Distributions of Mass, Al, and Mg Measured in Southern Lake Michigan during AEOLOS

ABSTRACT In this study, which was a part of the Atmospheric Exchange Over Lakes and Oceans Study (AEOLOS) investigation, the dry deposition fluxes and atmospheric size distributions (ASDs) of mass and crustal metals (aluminum and magnesium) were measured over the southern basin of Lake Michigan (in Chicago, over Lake Michigan, and in South Haven, Michigan). Airborne crustal metals arise primarily from fugitive dust emissions and are associated with the coarse fraction of atmospheric aerosol. Consequently, they can serve as fingerprints for the atmospheric behavior of fugitive dust. The flux of these metals were substantially higher in Chicago than in either South Haven or over Lake Michigan. The measured average mass, aluminum, and magnesium fluxes were 138, 2.23, and 5.32 mg/m2-day in Chicago, 47.8, 0.24, and 0.28 mg/m2-day over Lake Michigan, and 37.4, 0.17, and 0.12 mg/m2-day in South Haven, respectively. The ASDs of crustal metals measured in Chicago had higher concentrations of coarse particles than ...

The use of a porous ceramic diaphragm for the removal of metallic impurities from chromium plating baths

The ‘porous pot’ has been used in the plating industry and can be classified as an electrolytic separation technique [1‐3]. Compared with other separation techniques, there are several advantages in using a porous ceramic diaphragm to separate metal impurities from plating solutions. Theoretically, metallic impurities from the plating solutions accumulate inside the ceramic pot and can either be precipitated as sludge or deposited onto the cathode. Concurrently, Cr(III) may be oxidized to Cr(VI) at the anode in the plating bath solution, thereby keeping its concentration low. An advantage of the porous pot is that it can be operated concurrently with the plating process, thereby allowing semi-continuous removal of metallic impurities and oxidation of Cr(III). This is desirable since the presence of high concentrations of Cr(III) in the plating bath causes surface roughness of the hard-chromium deposit and reduces current efficiency. Among previous investigators, Mandich [2, 3] claimed the ‘porous-pot method’ to be the most cost-efficient process to separate impurities from the plating solution, at least for relatively small operations. Cushnie and Anderson [1] considered its separation efficiency to be marginal. The porous ceramic material is a stable and relatively inexpensive diaphragm, compared to ion-exchange resins,electrodialysismembranes,andsemi-permeablepoly

Electrochemical chromic acid regeneration process with fuel-cell electrode assistance. Part I: Removal of contaminants

This paper presents the results of work carried out on a laboratory cell for regeneration of spent hard chrome plating solution. The electrolysis cell consists of a rectangular tank divided into two compartments with an ion exchange membrane (Nafion-117), and uses a lead anode and a gas diffusion electrode as the cathode. The laboratory scale cell was used as a simulated plating bath containing Cu2+, Fe2+, Ni2+, and Cr3+ as contaminants, for different experimental conditions at room temperature. The separation performance of the process was assessed by operating the cell under three constant current conditions. The cell was also tested under different initial concentrations and catholyte-to-anolyte volume ratios. The results indicate the possibility of decreased energy consumption and better removal rates over traditional methods.

Chromic acid regeneration process with fuel cell electrode assistance. Part II: Electrochemical characterization, material compatibility and energy consumption

Electrochemical characteristics, energy consumption and material compatibility aspects of a novel process for regeneration of spent hard chromium plating baths using a Nafion-117 separator and a fuel cell cathode are discussed. Electrochemical impedance spectroscopy (EIS) and stationary polarization curves were used to characterize the performance of a fuel cell cathode in the regeneration cell. The configuration of the MEA, current collector, and flow distributing backing plate may, during long-term operation, lead to excessive ohmic resistance, which necessitates a special design of the cathode assembly. X-ray diffraction indicated that Cu, Fe, Ni, and Cr were deposited on the electrode matrix, leading to deactivation of the Pt-catalyst. The deactivation causes a rising cell voltage during electrolysis. Nevertheless, the energy consumption of the regeneration cell is at least 1 V less than that of a comparable cell with hydrogen evolving cathode.