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Factors Affecting Mercury Emissions From Coal Fired Combustors
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Book Synopsis Factors Affecting Mercury Emissions from Coal Fired Combustors by : Shawn Andrew Kellie
Download or read book Factors Affecting Mercury Emissions from Coal Fired Combustors written by Shawn Andrew Kellie and published by . This book was released on 2005 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation investigated some of the factors affecting mercury emissions from coal fired power plants. The research was conducted in three studies. The first study involved the use of a lab scale 0.10 MWth fluidized bed combustor (FBC) to investigate the effects of the Ca/S mole ratio, co-firing municipal solid waste (MSW), combustion conditions and coal chlorine concentration on mercury emissions. The second and third study presented an unprecedented opportunity to study several coals at the same commercially operated 100 MWth boiler. The second study focused on comparing two methods of measuring mercury in flue gas, the Ontario Hydro Method (OHM) and semi-continuous emissions monitoring (SCEM). The third study focused on the mechanism of mercury transformation in flue gas. The data from all the studies lead to the development of a mechanism for the transformation of mercury. In the first study, several factors were found to affect mercury emissions. The chlorine content of the coal and secondary/primary air ratio were found to be important factors.
Book Synopsis CONTROL OF MERCURY EMISSIONS FROM COAL COMBUSTORS... EPA/600/A-96/053... U.S. ENVIRONMENTAL PROTECTION AGENCY. by : United States. Environmental Protection Agency
Download or read book CONTROL OF MERCURY EMISSIONS FROM COAL COMBUSTORS... EPA/600/A-96/053... U.S. ENVIRONMENTAL PROTECTION AGENCY. written by United States. Environmental Protection Agency and published by . This book was released on 1998* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Coal Fired Flue Gas Mercury Emission Controls by : Jiang Wu
Download or read book Coal Fired Flue Gas Mercury Emission Controls written by Jiang Wu and published by Springer. This book was released on 2015-03-17 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury (Hg) is one of the most toxic heavy metals, harmful to both the environment and human health. Hg is released into the atmosphere from natural and anthropogenic sources and its emission control has caused much concern. This book introduces readers to Hg pollution from natural and anthropogenic sources and systematically describes coal-fired flue gas mercury emission control in industry, especially from coal-fired power stations. Mercury emission control theory and experimental research are demonstrated, including how elemental mercury is oxidized into oxidized mercury and the effect of flue gas contents on the mercury speciation transformation process. Mercury emission control methods, such as existing APCDs (air pollution control devices) at power stations, sorbent injection, additives in coal combustion and photo-catalytic methods are introduced in detail. Lab-scale, pilot-scale and full-scale experimental studies of sorbent injection conducted by the authors are presented systematically, helping researchers and engineers to understand how this approach reduces the mercury emissions in flue gas and to apply the methods in mercury emission control at coal-fired power stations. Readers will arrive at a comprehensive understanding of various mercury emission control methods that are suitable for industrial applications. The book is intended for scientists, researchers, engineers and graduate students in the fields of energy science and technology, environmental science and technology and chemical engineering.
Book Synopsis Control of mercury emissions from coalfired electric utility boilers interim report including errata dated 32102 by :
Download or read book Control of mercury emissions from coalfired electric utility boilers interim report including errata dated 32102 written by and published by DIANE Publishing. This book was released on with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Regulating Mercury Emissions from Power Plants: Will It Protect Our Health by :
Download or read book Regulating Mercury Emissions from Power Plants: Will It Protect Our Health written by and published by Am Cncl on Science, Health. This book was released on 2005 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mercury Control by : Evan J. Granite
Download or read book Mercury Control written by Evan J. Granite and published by John Wiley & Sons. This book was released on 2015-01-20 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: This essential handbook and ready reference offers a detailed overview of the existing and currently researched technologies available for the control of mercury in coal-derived gas streams and that are viable for meeting the strict standards set by environmental protection agencies. Written by an internationally acclaimed author team from government agencies, academia and industry, it details US, EU, Asia-Pacific and other international perspectives, regulations and guidelines.
Book Synopsis MERCURY EMISSIONS FROM COAL FIRED POWER PLANTS LOCAL IMPACTS ON HUMAN HEALTH RISK. by : J. ADAMS
Download or read book MERCURY EMISSIONS FROM COAL FIRED POWER PLANTS LOCAL IMPACTS ON HUMAN HEALTH RISK. written by J. ADAMS and published by . This book was released on 2005 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough quantitative understanding of the processes of mercury emissions, deposition, and translocation through the food chain is currently not available. Complex atmospheric chemistry and dispersion models are required to predict concentration and deposition contributions, and aquatic process models are required to predict effects on fish. However, there are uncertainties in all of these predictions. Therefore, the most reliable method of understanding impacts of coal-fired power plants on Hg deposition is from empirical data. A review of the literature on mercury deposition around sources including coal-fired power plants found studies covering local mercury concentrations in soil, vegetation, and animals (fish and cows). There is strong evidence of enhanced local deposition within 3 km of the chlor-alkali plants, with elevated soil concentrations and estimated deposition rates of 10 times background. For coal-fired power plants, the data show that atmospheric deposition of Hg may be slightly enhanced. On the scale of a few km, modeling suggests that wet deposition may be increased by a factor of two or three over background. The measured data suggest lower increases of 15% or less. The effects of coal-fired plants seem to be less than 10% of total deposition on a national scale, based on emissions and global modeling. The following summarizes our findings from published reports on the impacts of local deposition. In terms of excesses over background the following increments have been observed within a few km of the plant: (1) local soil concentration Hg increments of 30%-60%, (2) sediment increments of 18-30%, (3) wet deposition increments of 11-12%, and (4) fish Hg increments of about 5-6%, based on an empirical finding that fish concentrations are proportional to the square root of deposition. Important uncertainties include possible reductions of RGM to Hg{sub 0} in power plant plumes and the role of water chemistry in the relationship between Hg deposition and fish content. Soil and vegetation sampling programs were performed around two mid-size coal fired power plants. The objectives were to determine if local mercury hot-spots exist, to determine if they could be attributed to deposition of coal-fired power plant emissions, and to determine if they correlated with model predictions. These programs found the following: (1) At both sites, there was no correlation between modeled mercury deposition and either soil concentrations or vegetation concentrations. At the Kincaid plant, there was excess soil Hg along heavily traveled roads. The spatial pattern of soil mercury concentrations did not match the pattern of vegetation Hg concentrations at either plant. (2) At both sites, the subsurface (5-10 cm) samples the Hg concentration correlated strongly with the surface samples (0-5 cm). Average subsurface sample concentrations were slightly less than the surface samples; however, the difference was not statistically significant. (3) An unequivocal definition of background Hg was not possible at either site. Using various assumed background soil mercury concentrations, the percentage of mercury deposited within 10 km of the plant ranged between 1.4 and 8.5% of the RGM emissions. Based on computer modeling, Hg deposition was primarily RGM with much lower deposition from elemental mercury. Estimates of the percentage of total Hg deposition ranged between 0.3 and 1.7%. These small percentages of deposition are consistent with the empirical findings of only minor perturbations in environmental levels, as opposed to ''hot spots'', near the plants. The major objective of this study was to determine if there was evidence for ''hot-spots'' of mercury deposition around coal-fired power plants. Although the term has been used extensively, it has never been defined. From a public health perspective, such a ''hot spot'' must be large enough to insure that it did not occur by chance, and it must affect water bodies large enough to support a population of subsistence fishers. The results of this study support the hypothesis that neither of these conditions has been met.
Book Synopsis Mercury Emission and its Control in Chinese Coal-Fired Power Plants by : Jinsong Zhou
Download or read book Mercury Emission and its Control in Chinese Coal-Fired Power Plants written by Jinsong Zhou and published by Springer. This book was released on 2015-01-13 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mercury Emission and its Control in Chinese Coal-Fired Power Plants" focuses on investigating mercury emissions samplings and measurement in Chinese coal-fired power plants, mercury emission estimations and future trends, mercury speciation transformation during coal combustion, mercury control and mercury stability in byproducts. The book not only introduces mercury emissions from actual coal-fired power plants, but also presents studies on the mechanism of mercury emission and its control. This is a valuable reference for engineering thermal physicists, thermal engineers, and chemical engineers. Jinsong Zhou, Zhongyang Luo, and Mengxiang Fang are Professors in the College of Mechanical and Energy Engineering, Zhejiang University, China. Yanqun Zhu is Associate Professor in the College of Mechanical and Energy Engineering, Zhejiang University, China.
Book Synopsis LOCAL IMPACTS OF MERCURY EMISSIONS FROM COAL FIRED POWER PLANTS. by : J. ADAMS
Download or read book LOCAL IMPACTS OF MERCURY EMISSIONS FROM COAL FIRED POWER PLANTS. written by J. ADAMS and published by . This book was released on 2004 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough quantitative understanding of the processes of mercury emissions, deposition, and translocation through the food chain is currently not available. Complex atmospheric chemistry and dispersion models are required to predict concentration and deposition contributions, and aquatic process models are required to predict effects on fish. There are uncertainties in all of these predictions. Therefore, the most reliable method of understanding impacts of coal-fired power plants on Hg deposition is from empirical data. A review of the literature on mercury deposition around sources including coal-fired power plants found studies covering local mercury concentrations in soil, vegetation, and animals (fish and cows (Lopez et al. 2003)). There is strong evidence of enhanced local deposition within 3 km of the chlor-alkali plants, with elevated soil concentrations and estimated deposition rates of 10 times background. For coal-fired power plants, the data show that atmospheric deposition of Hg may be slightly enhanced. On the scale of a few km, modeling suggests that wet deposition may be increased by a factor of two or three over background. The measured data suggest lower increases of 15% or less. The effects of coal-fired plants seem to be less than 10% of total deposition on a national scale, based on emissions and global modeling. The following summarizes our findings from published reports on the impacts of local deposition. In terms of excesses over background the following increments have been observed within a few km of the plant: (1) local soil concentration Hg increments of 30%-60%, (2) sediment increments of 18-30%, (3) wet deposition increments of 11-12%, and (4) fish Hg increments of about 5-6%, based on an empirical finding that fish concentrations are proportional to the square root of deposition. Important uncertainties include possible reductions of RGM to Hg(0) in power plant plumes and the role of water chemistry in the relationship between Hg deposition and fish content. Soil and vegetation sampling programs were performed around two mid-size coal fired power plants. The objectives were to determine if local mercury hot spots exist, to determine if they could be attributed to deposition of coal-fired power plant emissions, and to determine if they correlated with model predictions. These programs found the following: (1) At both sites, there was no correlation between modeled mercury deposition and either soil concentrations or vegetation concentrations. At the Kincaid plant, there was excess soil Hg along heavily traveled roads. The spatial pattern of soil mercury concentrations did not match the pattern of vegetation Hg concentrations at either plant. (2) At both sites, the subsurface (5-10 cm) samples the Hg concentration correlated strongly with the surface samples (0-5 cm). Average subsurface sample concentrations were slightly less than the surface samples, however, the difference was not statistically significant. (3) An unequivocal definition of background Hg was not possible at either site. Using various assumed background soil mercury concentrations, the percentage of mercury deposited within 10 km of the plant ranged between 1.4 and 8.5% of the RGM emissions. Based on computer modeling, Hg deposition was primarily RGM with much lower deposition from elemental mercury. Estimates of the percentage of total Hg deposition ranged between 0.3 and 1.7%. These small percentages of deposition are consistent with the empirical findings of only minor perturbations in environmental levels, as opposed to ''hot spots'', near the plants. The major objective of this study was to determine if there was evidence for ''hot spots'' of mercury deposition around coal-fired power plants. Although the term has been used extensively, it has never been defined. From a public health perspective, such a ''hot spot'' must be large enough to insure that it did not occur by chance, and it must affect water bodies large enough to support a population of subsistence fishers. The results of this study support the hypothesis that neither of these conditions have been met.
Download or read book Mercury Emissions to the Air written by and published by . This book was released on 2004 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: On December 15, 2003, the Environmental Protection Agency (EPA) proposed standards for emissions of mercury from coal-fired electric power plants, under the authority of Sections 111 and 112 of the Clean Air Act. (The proposal appeared in the Federal Register January 30, 2004.) In their first phase, the standards could require a 29% reduction in emissions by 2008 or 2010, depending on the regulatory option chosen. A nearly 70% reduction would take effect in 2018, although EPA indicates that flexibility built into the proposed standards could delay the full 70% reduction to as late as 2030. EPA's analysis of the proposed rule indicates that its benefits would outweigh the compliance costs by a factor of at least 16 to 1, leading many critics of the proposal to ask why the regulations should not be more stringent, or implemented more quickly. The Agency's official position is that technology will not be available to achieve reductions greater than 30% until after 2010. EPA's own Office of Research and Development (ORD) appears to disagree, however. A recent ORD white paper found that reductions of 72% - 98%, depending on coal type, are already being achieved at some plants using current technology. Other issues likely to be raised in the public comment period, which extends until June 29, include the impacts on eastern coal production and the effect of the proposals on mercury "hot spots." In addition to EPA's regulatory effort, in the current Congress nine bills have been introduced to regulate these emissions. An Administration bill, the "Clear Skies Act," has many points in common with the EPA regulatory proposal. The other bills before Congress are generally more stringent than the Administration's approach. These regulatory and legislative proposals reflect increasing concern over the potential health effects of mercury emissions. Mercury is a potent neurotoxin that can affect human health at very low concentrations. EPA considers children born to women with umbilical cord blood-mercury concentrations above 5.8 parts per billion to be at increased risk for adverse health effects, such as delayed development, neurological defects, and mental retardation. Recent EPA studies conclude that at least 7.8% (and possibly as many as 15.7%) of American women of child-bearing age have blood mercury levels above this threshold. U.S. air emissions of mercury come from eight principal sources. Of these, the largest source, and the last major source for which emission standards have been proposed, is coal-fired electric power plants. Coal-fired power plants account for between one-third and one-half of total U.S. mercury emissions. This report provides background on mercury and reviews regulatory and legislative proposals to reduce emissions of mercury to the air. CRS Report RL32203 and CRS Report RL31908 discuss legal issues raised by EPA's proposed rules and mercury in products and waste, respectively. This report will be updated as warranted.
Book Synopsis Fate of Trace Mercury in the Combustion of Coal by : R. C. Diehl
Download or read book Fate of Trace Mercury in the Combustion of Coal written by R. C. Diehl and published by . This book was released on 1972 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Evaluation of Precombustion Control of Mercury Emissions from Coal Combustion by Mild Pyrolysis in a Rijke Pulse Combustor by : Andrew T. Wolf
Download or read book Evaluation of Precombustion Control of Mercury Emissions from Coal Combustion by Mild Pyrolysis in a Rijke Pulse Combustor written by Andrew T. Wolf and published by . This book was released on 1997 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Assessment of Mercury Emissions and Health Risks from a Coal-fired Power Plant by :
Download or read book An Assessment of Mercury Emissions and Health Risks from a Coal-fired Power Plant written by and published by . This book was released on 1994 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: Title 3 of the 1990 Clean Air Act Amendments (CAAA) mandated that the US Environmental Protection Agency (EPA) evaluate the need to regulate mercury emissions from electric utilities. In support of this forthcoming regulatory analysis the U.S. DOE, sponsored a risk assessment project at Brookhaven (BNL) to evaluate methylmercury (MeHg) hazards independently. In the US MeHg is the predominant way of exposure to mercury originated in the atmosphere. In the BNL study, health risks to adults resulting from Hg emissions from a hypothetical 1,000 MW coal-fired power plant were estimated using probabilistic risk assessment techniques. This study showed that the effects of emissions of a single power plant may double the background exposures to MeHg resulting from consuming fish obtained from a localized area near the power plant. Even at these more elevated exposure levels, the attributable incidence in mild neurological symptoms was estimated to be quite small, especially when compared with the estimated background incidence in the population. The current paper summarizes the basic conclusions of this assessment and highlights issues dealing with emissions control and environmental transport.
Author :United States. Congress. House. Committee on Science. Subcommittee on Environment, Technology, and Standards Publisher : ISBN 13 : Total Pages :112 pages Book Rating :4.0/5 (12 download)
Book Synopsis Mercury emissions by : United States. Congress. House. Committee on Science. Subcommittee on Environment, Technology, and Standards
Download or read book Mercury emissions written by United States. Congress. House. Committee on Science. Subcommittee on Environment, Technology, and Standards and published by . This book was released on 2004 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mercury Emissions from Electric Power Plants by : James E. McCarthy (Specialist in environmental policy)
Download or read book Mercury Emissions from Electric Power Plants written by James E. McCarthy (Specialist in environmental policy) and published by . This book was released on 2005 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: EPA studies conclude that at least 7.8% of American women have blood mercury levels sufficient to increase the risk of adverse health effects (especially lower IQs) in children they might bear. Thus, there was great interest in the agencys March 15, 2005, announcement that it was finalizing new regulations to control mercury (Hg) emissions from coal-fired electric power plants -- power plants account for 42% of total U.S. mercury emissions, according to EPA. In announcing the regulations, however, EPA stated that most mercury in the atmosphere comes from non-U.S. global sources. Thus, even if regulations could reduce power plant mercury emissions to zero, the agency concluded, there would be little change in the mercury health effects it has identified. Instead of more stringent requirements, EPA promulgated "cap-and-trade" standards that rely heavily on cobenefits from sulfur dioxide and nitrogen oxide controls installed under a separate agency rule, the Clean Air Interstate Rule (CAIR). This approach minimizes costs for electric utilities: by 2015, less than 1% of coal-fired power plants will have installed equipment specifically designed to control mercury, according to EPA. By 2020, only 4% of plants will have such equipment. Ten states have filed suit to overturn the agency s action, arguing that EPA is required by the Clean Air Act to impose more stringent Maximum Achievable Control Technology standards at each individual plant. Beginning in 2010, the cap-and-trade standards limit total power plant mercury emissions to 38 tons annually (a 21% reduction vs. 1999 levels). A second phase caps annual emissions at 15 tons, starting in 2018. According to the agency, trading and banking of emission allowances will result in lower than required emissions in the early years, but will delay achievement of the 15-ton cap to at least 2025. Thus, the net effect of the rule appears to be to postpone until the 2020s direct regulation of mercury (except as a co-benefit achieved from regulating other pollutants). EPA has sent contradictory signals regarding the importance of controlling mercury emissions. Its January 2004 analysis of the proposed rule estimated that the indirect benefits of more stringent regulations ($15 billion annually) would outweigh compliance costs by a factor of at least 16 to 1. Direct benefits (although unquantifiable) were said to be "large enough to justify substantial investment in Hg control." The analysis of the final rule, by contrast, concludes that quantifiable direct and indirect benefits of mercury control are just $43 million per year, with annual costs as high as $896 million. EPA s calculations did not include consideration of an academic study that it had funded, a factor contributing to the calculation of smaller benefits. This decision was one of several irregularities in the regulatory process alleged by the agency's Inspector General, GAO, and critics of the rule. In addition to EPAs regulatory effort, five bills that would regulate these emissions have been introduced so far in the 109th Congress, with more expected. S. 131, the Clear Skies Act, has many points in common with the EPA regulatory approach. This report will be updated.
Book Synopsis POTENTIAL HEALTH RISK REDUCTION ARISING FROM REDUCED MERCURY EMISSIONS FROM COAL FIRED POWER PLANTS. by :
Download or read book POTENTIAL HEALTH RISK REDUCTION ARISING FROM REDUCED MERCURY EMISSIONS FROM COAL FIRED POWER PLANTS. written by and published by . This book was released on 2001 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Environmental Protection Agency (EPA) has announced plans to regulate mercury (Hg) emissions from coal-fired power plants. EPA has not prepared a quantitative assessment of the reduction in risk that could be achieved through reduction in coal plant emissions of Hg. To address this issue, Brookhaven National Laboratory (BNL) with support from the U.S. Department of Energy Office of Fossil Energy (DOE FE) prepared a quantitative assessment of the reduction in human health risk that could be achieved through reduction in coal plant emissions of Hg. The primary pathway for Hg exposure is through consumption of fish. The most susceptible population to Hg exposure is the fetus. Therefore the risk assessment focused on consumption of fish by women of child-bearing age. Dose response factors were generated from studies on loss of cognitive abilities (language skills, motor skills, etc.) by young children whose mothers consumed large amounts of fish with high Hg levels. Population risks were estimated for the general population in three regions of the country, (the Midwest, Northeast, and Southeast) that were identified by EPA as being heavily impacted by coal emissions. Three scenarios for reducing Hg emissions from coal plants were considered: (1) A base case using current conditions; (2) A 50% reduction; and, (3) A 90% reduction. These reductions in emissions were assumed to translate linearly into a reduction in fish Hg levels of 8.6% and 15.5%, respectively. Population risk estimates were also calculated for two subsistence fisher populations. These groups of people consume substantially more fish than the general public and, depending on location, the fish may contain higher Hg levels than average. Risk estimates for these groups were calculated for the three Hg levels used for the general population analyses. Analysis shows that the general population risks for exposure of the fetus to Hg are small. Estimated risks under current conditions (i.e., no specific Hg controls) ranged from 5.7 x 10−6 in the Midwest to 2 x 10−5 in the Southeast. Reducing emissions from coal plants by 90% reduced the estimated range in risk to 5 x 10−6 in the Midwest and 1.5 x 10−5 in Southeast, respectively. The population risk for the subsistence fisher using the Southeast regional fish Hg levels was 3.8 x 10−3, a factor of 200 greater than the general population risk. For the subsistence fishers and the Savannah River Hg levels, the population risk was 4.3 x 10−5, a factor of 2 greater than for the general population. The estimated risk reductions from a 90% reduction in coal plant Hg emissions ranged from 25%-68%, which is greater than the assumed reduction in Hg levels in fish, (15.5%). To place this risk in perspective, there are approximately 4 x 106 births/year in the U.S (National Vital Statistics Report, 2000). Assuming that the Southeast risk level (the highest of the regions) is appropriate for the entire U.S., an estimate of 80 newborn children per year have a 5% chance of realizing any of the 16 adverse effects used to generate the DRF. If Hg emissions from power plants are reduced 90%, the number of children at risk is reduced to 60.
Book Synopsis Fundamental Understanding of Mercury Removal from Coal Combustion by : Erdem Sasmaz
Download or read book Fundamental Understanding of Mercury Removal from Coal Combustion written by Erdem Sasmaz and published by Stanford University. This book was released on 2011 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coal-fired power plants are a major anthropogenic source of worldwide mercury (Hg) emissions. Since mercury is considered to be one of the most toxic metals found in the environment, Hg emissions from coal-fired power plants is of major environmental concern. Mercury in coal is vaporized into its gaseous elemental form throughout the coal combustion process. Elemental Hg can be oxidized in subsequent reactions with other gaseous components (homogeneous) and solid materials (heterogeneous) in coal-fired flue gases. While oxidized Hg in coal-fired flue gases is readily controlled by its adsorption onto fly ash and/or its dissolution into existing solution-based sulfur dioxide (SO2) scrubbers, elemental Hg is not controlled. The extent of elemental Hg formed during coal combustion is difficult to predict since it is dependent on the type of coal burned, combustion conditions, and existing control technologies installed. Therefore, it is important to understand heterogeneous Hg reaction mechanisms to predict the speciation of Hg emissions from coal-fired power plants to design and effectively determine the best applicable control technologies. In this work, theoretical and experimental investigations have been performed to investigate the adsorption and in some cases the oxidation, of Hg on solid surfaces, e.g., calcium oxide (CaO), noble metals and activated carbon (AC). The objective of this research is to identify potential materials that can be used as multi-pollutant sorbents in power plants by carrying out both high-level density functional theory (DFT) electronic structure calculations and experiments to understand heterogeneous chemical pathways of Hg. This research uses a fundamental science-based approach to understand the environmental problems caused by coal-fired energy production and provides solutions to the power generation industry for emissions reductions. Understanding the mechanism associated with Hg and SO2 adsorption on CaO will help to optimize the conditions or material to limit Hg emissions from the flue gas desulfurization process. Plane-wave DFT calculations were used to investigate the binding mechanism of Hg species and SO2 on the CaO(100) surface. The binding strengths on the high-symmetry CaO adsorption sites have been investigated for elemental Hg, SO2, mercury chlorides (HgCl and HgCl2) and mercuric oxide (HgO). It has been discovered that HgCl, HgCl2, and SO2 chemisorb on the CaO(100) surface at 0.125 ML coverage. Binding energies of elemental Hg are minimal indicating a physisorption mechanism. Noble metals such as palladium (Pd), gold (Au), silver (Ag), and copper (Cu) have been proposed to capture elemental Hg. Plane-wave DFT calculations have been carried out to investigate the mercury interactions with Pd binary alloys and overlays in addition to pure Pd, Au, Ag, and Cu surfaces. It has been determined that Pd has the highest mercury binding energy in comparison to other noble metals. In addition, Pd is found to be the primary surface atom responsible for increasing the adsorption of Hg with the surface in both Pd binary alloys and overlays. Deposition of Pd overlays on Au and Ag has been found to enhance the reactivity of the surface by shifting the d-states of surface atoms up in energy. The possible binding mechanisms of elemental Hg onto virgin, brominated and sulfonated AC fiber and brominated powder AC sorbents have been investigated through packed-bed experiments in a stream of air and simulated flue gas conditions, including SO2, hydrogen chloride (HCl), nitrogen oxide (NO) nitrogen dioxide (NO2). A combination of spectroscopy and plane-wave DFT calculations was used to characterize the sorption process. X-ray photoelectron spectroscopy (XPS) and x-ray absorption fine structure (XAFS) spectroscopy were used to analyze the surface and bulk chemical compositions of brominated AC sorbents reacted with Hg0. Through XPS surface characterization studies it was found that Hg adsorption is primarily associated with halogens on the surface. Elemental Hg is oxidized on AC surfaces and the oxidation state of adsorbed Hg is found to be Hg2+. Though plane-wave DFT and density of states (DOS) calculations indicate that Hg is more stable when it is bound to the edge carbon atom interacting with a single bromine bound atop of Hg, a model that includes an interaction between the Hg and an additional Br atom matches best with experimental data obtained from extended x-ray absorption fine structure (EXAFS) spectroscopy. The flue gas species such as HCl and bromine (Br2) enhance the Hg adsorption, while SO2 is found to decrease the Hg adsorption significantly by poisoning the active sites on the AC surface. The AC sorbents represent the most market-ready technology for Hg capture and therefore have been investigated by both theory and experiment in this work. Future work will include similar characterization and bench-scale experiments to test the metal-based materials for the sorbent and oxidation performance.
