Thesis (Ph. D.)--University of Chicago, 1920. / "Private edition distributed by the University of Chicago libraries, Chicago, Illinois." "Reprinted from the Journal of the American chemical society, vol. XLII, no. 12. December, 1920." Also available on the Internet.

Currently, coal combustion plays an important role in meeting the energy needs of the United States. It is expected that the effective utilization of coal will be crucial for attaining energy independence for the nation in the next 25 to 30 years, if not longer. The United States burns about 20% of the world's annual coal production, second only to China. Strikingly, there are 200-300 more years of burn at our current rate of consumption, considering our massive coal reserves. Almost half of our electricity comes from coal power. Although coal is a fossil fuel that will become more and more depleted, it will be the principal fuel for utilities in the US for decades to come. Therefore, there is a need to design new strategies to clean coal. Mercury can be found in fly ash, bottom ash, and flue gas desulfurization (FGD) material. The Hg is transferred to these coal combustion products (CCPs) from its associated parent coal. These CCPs absorb a significant amount of the Hg released during the combustion process. With the EPA's recent emphasis on controlling the Hg emission by coal-burning electric utilities, the disposal and utilization of CCPs are under an environmental microscope. As EPA regulations become more stringent, Hg concentration in CCPs is expected to increase further; i.e., more Hg will be captured in the scrubber materials. The higher Hg concentrations will have serious consequences for the management of CCPs. Systematic measurements on Hg concentrations in the feed coal and the CCPs produced from two different power plants burning Illinois coal were carried out. Not only were there substantial variations in the total Hg concentration in the parent coal from week to week from a single mine, but there were also significant variations in the weekly Hg content of the CCPs. Surprisingly, there was no linear dependence between Hg content of coal and its CCPs. No correlation was observed between Hg content of fly ash and its loss-on-ignition (LOI) values. In order to control and further understand the fate of Hg in FGD scrubber material, the following was systematically examined: (a) whether there is a strong correlation between the parent coal and the Hg captured in FGD scrubber materials, (b) the thermal behavior of Hg in parent coal, FGD gypsum, and sulfite-rich FGD material, (c) whether there is a potential of Hg re-emission during gypsum-to-hemihydrate-to-gypsum transition, and (d) how Hg behaves in sulfite-rich scrubber material at higher temperatures and pressures. Ultimately, no direct correlation between the total Hg concentration of the parent coal and its associated FGD scrubber materials was found. Mercury desorbed from FGD gypsum at relatively low temperatures (90C < T < 250C), compared to the sulfite-rich scrubber materials which released Hg continuously at ambient pressures up to 600C. However, it was found that mildly-elevated pressures immobilized Hg, even at temperatures as high as 250C. Cleaning and dewatering coal has been a major challenge. Deeper pre-combustion cleaning of ashes and clays from coals can help utilize more of Illinois coal. Efforts have been underway for decades to reduce emissions from flue gas and toxic metal reduction. Now with carbon emissions under scrutiny, the effort to maximize coal's value is more important than ever before. In most coal preparation processes, significant amounts of fines and ultrafines are generated. Because these particles are difficult to dewater, they are often discarded in waste ponds. This translates into a major economic loss for the coal industry, not only because of the fuel value lost but also the substantial economic resources required to manage coal waste ponds in an environmentally-sound manner. A new approach developed using a high intensity sonication process in recovering, cleaning, and dewatering fine/ultrafine coal particles from the waste ponds, while concurrently reducing the Hg concentration in the fine and ultrafine particles was successful. Combining sonication with vegetable oil agglomeration significantly reduced the moisture, ash, and Hg content of the cleaned, recovered coal. Differential scanning calorimetry (DSC) measurements on the recovered coal were used to understand the interaction between the coal particles, water, and oil. The results suggested that vegetable oil was effective in displacing water from the coal-water interface, with the enthalpy of the water-vapor transition of oil-agglomerated coal particles decreasing on sonication of the particles. In fact, combining sonication treatment with oil agglomeration reduced the moisture content of run-of-mine (ROM) coal and waste coal, to 6 wt% and 12 wt% respectively, and increased their loss-on-ignition (LOI) content to 91 wt% and 76 wt%, respectively. Massive quantities of synthetic gypsum are produced when the flue gases from coal burning power plants are wet scrubbed with limestone. The sulfate-rich FGD scrubber material is largely construction-quality gypsum. Because of the large production of FGD gypsum every year, the economic and environmental impetus dictates that strategies be developed to effectively utilize FGD gypsum rather than just landfill it. Beneficial uses have been found in wallboard construction and agriculture. An important aspect of this research was to evaluate whether there was potential of Hg re-emission from scrubber materials during their utilization phase. Mercury emission occurs not only with elevated temperatures but with increased time. While external pressure retards these emissions, they are not the only concern associated with CCPs. The more global, urgent problems of greenhouse gases must be resolved. The dimension of the greenhouse gases problem is daunting; according to the Energy Information Agency, nearly 6 billion metric tons of CO2 were produced in the USA in 2007, with coal-burning power plants contributing about 2 billion metric tons. The success of large-size sequestration of CO2 in coal would hinge on a thorough understanding of coal-CO2 interactions and how these interactions control the mechanical behavior of coal. Moreover, these interactions could play a crucial role in evaluating any potential risks associated with sequestering CO2 in deep, unmineable coal seams. To evaluate the risk under non-equilibrium conditions, dynamic mechanical properties of pressurized Illinois coals were measured. The results suggest that Illinois bituminous coal in its unperturbed state, i.e., when not pressurized with CO2, showed large variations in its mechanical properties. The Young's modulus varied from 0.7 GPa to 3.4 GPa even though samples were extracted from a single chunk. No glass transition was observed for any Illinois bituminous coal under ambient conditions. Upon pressurizing the Illinois bituminous coals with CO2, the DMA results showed a transition at temperatures as low as ambient. This could be a potential risk for the structural integrity of a mine if any man-made or seismic activity were present.

Thesis (M.A.)--Boston University

No description available.

No description available.

Continuous current control, so familiar in the operation of high-vacuum tubes, has not been possible, except under special circumstances, for gas tubes. Even current interruption has been awkward, except for low currents, for the usual manner of interrupting the current is to decrease the anode potential to zero. The time to switch off the gas tube has been of the order of the deionization time for the gas employed. Now a method is developed for switching off mercury-pool arcs using a third electrode. There is no interference with the main power circuit and, in fact, the potential on the anode causing the electric field aids the dispersal of the charge carriers when the arc has been interrupted. The switching-off time is much decreased because this anode-to-cathode voltage sweeps all the charge carriers out of the tube. Switching off is effected by passing a reverse current of equal or greater magnitude than the arc cathode current through the tube for a time long enough to interrupt the cathode spot. A technical difficulty arises in that the third electrode introducing the reverse current has to have an already formed or an easily formed cathode spot since this third electrode is a cold cathode. Many methods for forming the cathode spot are discussed. The method finally used is probably not the best one but it has the virtue of being easily effected. There appears to be no limit as to the current that can be interrupted if the spot-forming mechanism is altered. Energy used in not an important factor. The amount varies with the time to switch off and does not influence the actual switching process. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The kinetics of the homogeneous reduction of mercuric salts by-molecular hydrogen in aqueous solution have been examined over a wide range of solution composition, temperature and hydrogen partial pressure. In perchlorate solutions, where Hg⁺⁺and Hg₂⁺⁺ are uncomplexed the kinetic results can be expressed by the equation: -d[H₂]J/dt = k₁[H₂][Hg⁺⁺] + k₂[H₂][Hg₂⁺⁺] where k₁ = 4.2 x 10¹⁰ exp [-18100/RT] 1.mole⁻¹ sec.⁻¹ and k₂ = 1.2 x 10¹¹ exp [-20400/RT] 1.mole⁻¹ sec.⁻¹ It was concluded that the rate-determining process of the reaction involves the bimolecular interaction of one H₂ molecule with either Hg⁺⁺ or Hg₂⁺⁺ , i.e., Hg⁺⁺ + H₂ [symobal omitted] Hg + 2H⁺ Hg₂⁺⁺ + H₂ [symbol omitted] 2Hg + 2H⁺ The Hg atoms thus formed undergo further rapid reactions to yield the observed products (Hg₂⁺⁺ or metallic mercury) the nature of which is determined by •' thermodynamic considerations. Mercuric complexes also reacted homogeneously with hydrogen but in most cases more slowly than the simple Hg⁺⁺ ions. The order of decreasing reactivity of the complexes, HgAc₂ > HgCl₂ > HgBr₂ > Hg(ethylenediamine)₂⁺⁺, is the same as the order of their increasing stability. This is attributed to the reduction of the electron affinity of Hg⁺⁺ through electron donation from the complexing ligand. The reactivity of mercuric complexes such as HgAc₂ and Hg(ethylenediamine)₂⁺⁺ is increased by anions such as 0H⁻, CO₃⁼, Ac⁻, etc., the influence of which increases in the same order as their basicity. This is attributed to stabilization, by the anions, of the H⁺ ions which are released in the rate-determining step of the reaction. Some conclusions are drawn concerning the mechanism of heterogeneous activation of hydrogen by solid catalysts. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

A spark gap with mercury jets as electrodes has been developed. Investigations show that the gap can be triggered reliably by photons from a trigger spark with a jitter in the formative time lags less than 0.2 µsec. To overcome uncertainties in the breakdown conditions produced by surface waves on the jet, it has been found necessary to trigger the spark no later than 0.5 sec. after starting the jets„ By suitably designing the geometry of the jets undesirable surface instabilities excited by electric fields have been eliminated. Since the spark gap is isolated electrically from the triggering source very little noise is produced in neighbouring measuring circuits when the main spark is fired. The continual regeneration of the electrode surfaces also eliminates the erratic features observed in normal spark gaps which are fitted with solid metal electrodes. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This study evaluates the toxicity, accumulation, chronic effects and mode of action of methylmercury on the reproduction of the teleost fish, Oryzias latipes. The median lethal concentration, 96h-LC50, for adult Oryzias was + 88+9.8 μg CH₃Hg⁺/1 as determined in a static system. Residue analysis by gas chromatography showed that fish exposed to 43 to 1000 μg CH₃Hg⁺/1 had tissue levels below 40 μg CH₃Hg⁺/g while fish exposed to more than 1000 μg CH₃Hg⁺/1 accumulated methylmercury steadily and reached levels as high as 408.1 μg CH₃Hg⁺/g. Death seems to occur when tissue level reaches 25 μg CH₃Hg⁺/g. Studies on long-term exposure to 0.0, 4,3, 10.7 and 21.5 μg of methylmercury in a flow-through system confirmed this observation. Four-hour exposure of 8.5 and 42.9 μg/1 of methylmercury on alternate days during the fish's normal oviposition period resulted in inhibition of oviposition. This observation occurred only oh days when fish were exposed to methylmercury but not on days when fish were returned to clean water. However, at a concentration of 85 μg CH₃Hg⁺/1, complete inhibition was observed even on days when fish were returned to clean water. High rates of accumulation with low rates of excretion of methylmercury were suggested explanations for these observations. Six-week exposure to 4.3, 10.7 and 21.5 μg/1 of methylmercury resulted in inhibition of spawning. This inhibition was directly related to the log of exposure concentrations. At the end of six weeks, both male and female gonads showed reduction in size; the females were more sensitive. However, hatchability of the spawned eggs was not affected by the exposure. Juvenile fish were very sensitive to methylmercury. After two weeks of exposure, one-week old juvenile exposed to 0.0, 4.3, 10.7 and 21.5 μg CH₃Hg⁺/1 had mortality rate of 2.2%, 54.3%, 64.9% and 99.4% respectively. Synthetic LH-RH, at concentrations of 100 and 1000 ng/g body weight, was effective in stimulating ovarian development in Oryzias. This shows that the LH-RH (synthesis based on structure of porcine LH-RH) has biological activity in Oryzias. When exposed to methylmercury, spawning activities were inhibited. LH injections were able to restore the spawning activities inhibited by the methylmercury treatment, but not LH-RH. However, histology of the pituitary gland showed stimulation of gonadotropic cells by LH-RH injection with no restoration of spawning activities. This suggests that methylmercury- may be blocking the release of gonadotropin. In vitro ovulation was affected by previous exposure to methylmercury. Addition of methylmercury directly to the incubation medium further reduced the percentage of in vitro ovulation in the previously treated fish. Using oocytes from untreated donor fish, the percent inhibition of in vitro ovulation by methylmercury was directly related to the log of doses used. A possible bioassay with in vitro ovulation was suggested. Among the various steroids used (progesterone, cortisone, estradiol and testosterone), cortisone was the only steroid effective in restoring in vitro ovulation blocked by the presence of methylmercury in the incubation medium. Ecological implications of these findings are discussed. / Science, Faculty of / Zoology, Department of / Graduate

This study is about the mercury sensitized photochemical reactions of cyclohexane.