Heterogeneous Uptake And Reactions Of Atmospheric Gaseous Elemental Mercury And Its Application To Remediation Technologies

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Heterogeneous Uptake and Reactions of Atmospheric Gaseous Elemental Mercury and Its Application to Remediation Technologies

Author : Uday Kurien
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)

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Book Synopsis Heterogeneous Uptake and Reactions of Atmospheric Gaseous Elemental Mercury and Its Application to Remediation Technologies by : Uday Kurien

Download or read book Heterogeneous Uptake and Reactions of Atmospheric Gaseous Elemental Mercury and Its Application to Remediation Technologies written by Uday Kurien and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mercury (Hg) is a persistent global toxicant that is recognized as a priority contaminant by the United Nations Environment Program (UNEP). To combat the hazards associated with the environmental inputs of Hg, the Minamata treaty was signed by 128 countries in 2013. The treaty calls for a reduction in the anthropogenic release of Hg and for research to better understand Hg’s behaviour in the environment and atmosphere. This thesis addresses some of these challenges, by (1) identifying and characterizing potentially important gas phase and surface reactions of Hg (Theme 1) and (2) developing a proof-of-concept energy neutral technology to remove and recycle Hg from consumer electronics (Theme 2). The specific issues addressed within Theme 1 are: (1) Gaseous elemental mercury’s (Hg0(g)) uptake on the reactive components (iron(oxyhydr)oxide particles) of mineral dust and (2) particle surface mediated Hg0(g)-O3 reactions. Theme 2 addresses the development of an energy neutral technology for the recycling of Hg from Compact Fluorescent Lights (CFLs).In the first part of Theme 1, the uptake of Hg0(g) on iron (oxyhydr)oxides nanoparticles was investigated. Loss of gas phase Hg0(g) was observed when the iron (oxyhydr)oxides were irradiated with ultra violet and visible radiation (300 nm ≤ [lambda] ≤ 700 nm). Irradiation caused the rates of the uptake reactions to increase by up to 900-fold relative to dark reactions. Humidity was found to inhibit the uptake reaction. Possible mechanisms of the radiation enhanced uptake reactions and its inhibition by humidity are discussed. Adsorption isotherms for the visible radiation assisted uptake of Hg0(g) on [alpha]-Fe2O3 were evaluated and found to fit the Langmuir-Hinshelwood model. In the second part of Theme 1, the effect of [alpha]-Fe2O3 particles on the oxidation of Hg0(g) by O3 was investigated. Depending on the mass loading of the particles, the rates of the surface mediated oxidation reaction were found to be ~ 80 -2000-fold larger than those of the pure gas phase reaction, re-investigated in this study using particle free air. This evidence supports the longstanding belief that Hg0(g)-O3 oxidation kinetics are highly surface sensitive. The rates of the surface mediated reactions were found to be independent of O3 concentrations (1 – 40 ppm) and 0 % ≤ RH ≤ 75 %. At RH = 100 % the Hg0(g) loss profiles shifted from an exponential decay, typical of pseudo first order reactions, to a linear decay. The reaction rates were, however, still elevated relative to homogeneous reactions. Possible mechanisms of the surface mediated reaction and the effect of humidity are discussed.In Theme 2, we exploit the uptake of Hg0(g) on iron oxide surfaces to develop a laboratory scale energy neutral technology for the remediation of Hg0(g) from Compact Fluorescent Lights (CFLs). The application of this technology is intended to replace the presently employed high energy thermal desorption remediation techniques. Hg0(g) from CFLs was successfully trapped onto iron oxide nanoparticles (Fe3O4 and [alpha]-Fe2O3) of high crustal abundance, using batch and flow-through systems. Recovery (~ 40 % - 90 %) of Hg from the iron oxide nanoparticles and regeneration of the iron oxide nanoparticle surfaces were achieved via electrolysis in an aqueous solution of NaCl. The post-electrolysis iron oxide nanoparticles were reused to trap Hg0(g) in further remediation experiments. Even after 4 adsorption-electrolysis cycles, the iron oxides’ capacity to adsorb Hg0(g) did not diminish"--

Homogeneous and Heterogeneous Oxidation of Gaseous Elemental Mercury

Author : Graydon Snider
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (841 download)

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Book Synopsis Homogeneous and Heterogeneous Oxidation of Gaseous Elemental Mercury by : Graydon Snider

Download or read book Homogeneous and Heterogeneous Oxidation of Gaseous Elemental Mercury written by Graydon Snider and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury is an atmospheric global pollutant with complex cycling behavior. Two-thirds of the mercury present in our atmosphere is anthropogenic in origin. Chemical oxidation of gaseous elemental mercury governs the deposition rate of mercury over most lakes, land, and oceans. A major uncertainty comes from the effect of atmospheric surfaces such as aerosols. Much research is devoted to mercury capture technologies to be used in coal fire power plants, which are the major source of anthropogenic emissions.This thesis is a report on oxidation kinetics and mechanistic studies relevant to mercury-scavenging reactions. It provides an overview of the mechanisms of mercury oxidation by ozone, nitrogen dioxide, and titanium dioxide (exposed to ultra-violet light). The role of surfaces was quantified, as appropriate for each system. Crossover effects between gaseous co-pollutants (e.g. CO, SO2) and surfaces (SiO2, TiO2) are discussed. Rate constants were measured for each...

Development of a Coated-wall Flow Tube Reactor System to Investigate the Uptake Kinetics of Gaseous Elemental Mercury on Atmospherically-relevant Surfaces

Download Development of a Coated-wall Flow Tube Reactor System to Investigate the Uptake Kinetics of Gaseous Elemental Mercury on Atmospherically-relevant Surfaces PDF Online Free

Author : Heon Ho Lee
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)

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Book Synopsis Development of a Coated-wall Flow Tube Reactor System to Investigate the Uptake Kinetics of Gaseous Elemental Mercury on Atmospherically-relevant Surfaces by : Heon Ho Lee

Download or read book Development of a Coated-wall Flow Tube Reactor System to Investigate the Uptake Kinetics of Gaseous Elemental Mercury on Atmospherically-relevant Surfaces written by Heon Ho Lee and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mercury (Hg) is a persistent, bioaccumulative and toxic pollutant that is cycled and dispersed globally throughout the environment. Its predominant form in the atmosphere is gaseous elemental Hg (Hg0(g)), and it is understood that the processes controlling the physicochemical conversion of Hg0(g) to gaseous oxidized Hg (GOM) and particulate-bound Hg (PBM) have significant implications to its fate and distribution throughout the environment.The atmospheric chemistry of Hg occurs through gas, aqueous and heterogeneous/interfacial reactions. Recent studies have shown that semiconductor oxides, which are present in the atmosphere as constituents of mineral dust, have the capacity to mediate the heterogeneous uptake and photocatalytic oxidation of Hg0(g). To date, however, just a few studies have systematically investigated the kinetics of these reactions at atmospherically relevant conditions or have considered their implications to the tropospheric cycling of Hg. To address these knowledge gaps, the objectives of this thesis were two parts: (1) first, to develop an experimental technique using the coated-wall flow tube reactor with cold vapor atomic fluorescence spectroscopy detection (CWFT-CVAFS), and (2) to use the CWFT-CVAFS system to measure the kinetic parameters (i.e., the uptake coefficients) of the uptake of Hg0(g) on a survey of semiconductor oxide surfaces (i.e., TiO2, Fe2O3 and Al2O3) and to determine the effects of radiation and relative humidity (RH) on the uptake kinetics. Consistent with previous reports from the literature, Hg0(g) uptake on the semiconductor oxides tested were highly dependent on light. Under visible and UV-A irradiation, Hg0(g) uptake on TiO2 was significantly limited by the mass transfer (i.e., gas phase diffusion) of Hg0(g) to the reactor walls, with uptake coefficients on the order of 10-4 and >10-3, respectively. With increasing relative humidity, the uptake coefficient of Hg0(g) on TiO2 decayed exponentially, with the uptake coefficient at 60% RH around 3 orders of magnitude smaller than under dry conditions. The uptake on Fe2O3 and Al2O3 were substantially slower than TiO2, which can be explained by the improved charge separation efficiency on TiO2 compared to Fe2O3, and the lack of band gap photoexcitation on Al2O3. Hg0(g) re-emission was induced on TiO2 and Al2O3 by the presence of water vapor under dark conditions (i.e., attributed to the displacement of physisorbed Hg0(ads)) and under UV irradiation (i.e., attributed to the photocatalytic reduction of chemisorbed HgO(ads)).The atmospheric implications were discussed under some simple approximations to investigate the conditions under which the heterogeneous uptake of Hg0(g) on mineral dust might be significant in the atmosphere. Based on the uptake coefficients measured in this report, it was found that under conditions with low %RH and high dust loading masses (>1000 μg m-3), the uptake of Hg0(g) on mineral dust could compete with gas phase processes"--

Environmental Chemistry and Toxicology of Mercury

Author : Guangliang Liu
Publisher : John Wiley & Sons
ISBN 13 : 1118146638
Total Pages : 435 pages
Book Rating : 4.1/5 (181 download)

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Book Synopsis Environmental Chemistry and Toxicology of Mercury by : Guangliang Liu

Download or read book Environmental Chemistry and Toxicology of Mercury written by Guangliang Liu and published by John Wiley & Sons. This book was released on 2011-11-07 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the fundamentals, recent developments, and future research needs for critical mercury transformation and transport processes, as well as the experimental methods that have been employed in recent studies. The coverage discusses the environmental behavior and toxicological effects of mercury on organisms, including humans, and provides case studies at the end of each chapter. Bringing together information normally spread across several books, this text is unique in covering the entire mercury cycle and providing a baseline for what is known and what uncertainties remain in respect to mercury cycling.

Mercury Contaminated Sites

Author : Ralf Ebinghaus
Publisher : Springer Science & Business Media
ISBN 13 : 3662037548
Total Pages : 538 pages
Book Rating : 4.6/5 (62 download)

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Book Synopsis Mercury Contaminated Sites by : Ralf Ebinghaus

Download or read book Mercury Contaminated Sites written by Ralf Ebinghaus and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: An up-to-date overview of the characterization, risk assessment and remediation of mercury-contaminated sites. The book summarizes, for the first time, works from Europe, Russia and the American continent, and review chapters are supplemented by detailed, international case studies.

Molecular Insights Into the Redox of Atmospheric Mercury Through Laser Spectroscopy

Author : Rongrong Wu Cohen
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (136 download)

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Book Synopsis Molecular Insights Into the Redox of Atmospheric Mercury Through Laser Spectroscopy by : Rongrong Wu Cohen

Download or read book Molecular Insights Into the Redox of Atmospheric Mercury Through Laser Spectroscopy written by Rongrong Wu Cohen and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The widespread pollution of mercury motivates research into its atmospheric chemistry and transport. Gaseous elemental mercury (Hg(0)) dominates mercury emission to the atmosphere, but the rate of its oxidation to mercury compound (Hg(II)) plays a significant role in controlling where and when mercury deposits to ecosystems. Atomic bromine is regarded as the main oxidant for Hg(0) oxidation, known to initiate the oxidation via a two-step process in the atmosphere – formation of BrHg (R1) and subsequent reactions of BrHg with abundant free radicals Y, i.e., NO2, HOO, etc. (R2), where the reaction of BrHg +Y could also lead to the reduction of Hg(I) to Hg(0) (R3). A different oxidation pathway of BrHg + O3 (R4) is currently regarded as the dominant Hg(II) oxidation pathway in the atmosphere. Hg + Br + M → BrHg + M (R1) BrHg + Y + M → BrHgY + M (R2) BrHg + Y → BrY +Hg (R3) BrHg + O3 → BrHgO + O2 (R4) While the rate constants of R1 have been experimentally measured a decade ago, this research focuses on the experimental kinetic studies on the reaction of R2-R4 to better assist the efforts to predict how emission reductions impact the spatial distribution of mercury entry into ecosystems. The kinetic studies of BrHg redox chemistry are conducted by utilizing laser photolysis-laser induced fluorescence-cavity ringdown spectroscopy (LP-LIF-CRDS) systems, where BrHg radicals are generated via laser photolysis and monitored in the reaction via LIF and CRDS measurements. We report mainly on our experimental kinetic studies of the redox reactions of BrHg with relatively abundant trace gases such as NO2, NO, O3, O2, and VOCs, especially on the temperature and pressure dependence of the reaction rate constants using our LP-LIF system. We present the development and the characterization of a novel LP-CRDS system, which is a powerful tool to study reactions during which fluorescence quenching interferes with LIF measurement, and to study the spectroscopy of Hg(I) and Hg(II) compounds.

Kinetic Studies of the Oxidation Pathways of Gaseous Elemental Mercury

Author : Deanna L. Donohoue
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (668 download)

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Book Synopsis Kinetic Studies of the Oxidation Pathways of Gaseous Elemental Mercury by : Deanna L. Donohoue

Download or read book Kinetic Studies of the Oxidation Pathways of Gaseous Elemental Mercury written by Deanna L. Donohoue and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is the first direct measurement of a kinetic rate coefficient for these reactions, and the first work which employed one photon LIF to monitor the HgCl and HgBr products. The second aspect of this work was the development of new laser based techniques to detect atmospheric mercury and its oxidation products for both laboratory and field application. In this work a LIF technique was develop to detect HgCl and HgBr. In addition, a two photon LIF technique initially developed by Bauer et al., 2002 was verified and expanded. The two photon LIF technique was used to directly monitor Hg(0) atoms in-situ, to monitor Hg(0) evolving form a gold tube, and to monitor the Hg(0) evolving from the thermal decomposition of reactive gaseous mercury collected on a KCl coated or uncoated denuder. This work represents a significant advance in the development of a viable method the detect mercury and the mercury oxidation products in the laboratory and in the field and is the first study to observe clear differences in the characteristic desorption profiles of HgO and HgX2. This work has broad implications, it enhanced our current knowledge concerning the biogeochemical cycling of mercury, broadened our understanding of the mercury chemistry in high halogen environment, and provided new techniques which can be applied in future field and laboratory studies.

Fundamental Understanding of Mercury Removal from Coal Combustion

Author : Erdem Sasmaz
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (746 download)

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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 . This book was released on 2011 with total page 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.

Elucidating the Effect of Photons and Aerosols on the Physical and Chemical Transformations of Atmospheric Mercury

Author : Sean Alan Tacey
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (134 download)

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Book Synopsis Elucidating the Effect of Photons and Aerosols on the Physical and Chemical Transformations of Atmospheric Mercury by : Sean Alan Tacey

Download or read book Elucidating the Effect of Photons and Aerosols on the Physical and Chemical Transformations of Atmospheric Mercury written by Sean Alan Tacey and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The release of mercury to the atmosphere presents notable concerns due to its toxicity, as it can have significant adverse health effects on humans and wildlife. When it is released to the atmosphere, mercury exists in three primary chemical forms: elemental gaseous (Hg(0)), oxidized gaseous (Hg(II)), and particulate-bound (Hg(p)) mercury. Each chemical form exhibits unique atmospheric transport properties and deposition mechanisms, as Hg(0) remains in the atmosphere for months to years and undergoes global transport, while Hg(II) and Hg(p) deposit relatively quickly and undergo local transport. Therefore, it is critical to develop fundamental insights into the transformations between these three chemical forms, as they will have significant implications for the fate of mercury. Accordingly, this work seeks to address atomic-level mechanistic understandings for the physical and chemical transformations of atmospheric mercury that are lacking in the literature. First, the reduction mechanism for Hg(II) species to Hg(0), shown experimentally to require photons and aerosols, is elucidated on sodium-chloride, iron-oxide, and a range of metal-salt surfaces. Second, we develop a framework for deriving DFT-calculated partitioning coefficients to describe the gas-to-particle phase partitioning of atmospheric mercury. Last, we extend these computational methodologies for studying mercury chemistry to develop descriptors to target novel metal-salt materials for use in mercury-capture technologies. Through this work, we hope to provide information critical to the development of improved atmospheric transport models with increased predictive power, as well as target the implementation of enhanced mercury-capture technologies to mitigate the anthropogenic release of mercury to the atmosphere and prevent its adverse health effects on humanity and wildlife.

Removal of Elemental Mercury from a Gas Stream Facilitated by a Non-Thermal Plasma Device

Author : Charles Mones
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (316 download)

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Book Synopsis Removal of Elemental Mercury from a Gas Stream Facilitated by a Non-Thermal Plasma Device by : Charles Mones

Download or read book Removal of Elemental Mercury from a Gas Stream Facilitated by a Non-Thermal Plasma Device written by Charles Mones and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury generated from anthropogenic sources presents a difficult environmental problem. In comparison to other toxic metals, mercury has a low vaporization temperature. Mercury and mercury compounds are highly toxic, and organic forms such as methyl mercury can be bio-accumulated. Exposure pathways include inhalation and transport to surface waters. Mercury poisoning can result in both acute and chronic effects. Most commonly, chronic exposure to mercury vapor affects the central nervous system and brain, resulting in neurological damage. The CRE technology employs a series of non-thermal, plasma-jet devices to provide a method for elemental mercury removal from a gas phase by targeting relevant chemical reactions. The technology couples the known chemistry of converting elemental mercury to ionic compounds by mercury-chlorine-oxygen reactions with the generation of highly reactive species in a non-thermal, atmospheric, plasma device. The generation of highly reactive metastable species in a non-thermal plasma device is well known. The introduction of plasma using a jet-injection device provides a means to contact highly reactive species with elemental mercury in a manner to overcome the kinetic and mass-transfer limitations encountered by previous researchers. To demonstrate this technology, WRI has constructed a plasma test facility that includes plasma reactors capable of using up to four plasma jets, flow control instrumentation, an integrated control panel to operate the facility, a mercury generation system that employs a temperature controlled oven and permeation tube, combustible and mercury gas analyzers, and a ductless fume hood designed to capture fugitive mercury emissions. Continental Research and Engineering (CR & E) and Western Research Institute (WRI) successfully demonstrated that non-thermal plasma containing oxygen and chlorine-oxygen reagents could completely convert elemental mercury to an ionic form. These results demonstrate potential the application of this technology for removing elemental mercury from flue gas streams generated by utility boilers. On an absolute basis, the quantity of reagent required to accomplish the oxidation was small. For example, complete oxidation of mercury was accomplished using a 1% volume fraction of oxygen in a nitrogen stream. Overall, the tests with mercury validated the most useful aspect of the CR & E technology: Providing a method for elemental mercury removal from a gas phase by employing a specific plasma reagent to either increase reaction kinetics or promote reactions that would not have occurred under normal circumstances.

Mercury Reaction Chemistry in Combustion Flue Gases from Experiments and Theory

Author : Bihter Padak
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (743 download)

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Book Synopsis Mercury Reaction Chemistry in Combustion Flue Gases from Experiments and Theory by : Bihter Padak

Download or read book Mercury Reaction Chemistry in Combustion Flue Gases from Experiments and Theory written by Bihter Padak and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Emissions from coal combustion processes constitute a significant amount of the elemental mercury released into the atmosphere today. Coal-fired power plants in the United States, with the capacity of just over 300GW, are the greatest anthropogenic source of mercury emissions. Mercury exists in coal combustion flue gas in a variety of forms depending on the coal type and combustion conditions; i.e., elemental, oxidized and particulate. Particulate mercury in the flue gas can be removed using air pollution control devices such as electrostatic precipitators and fabric filters. Oxidized mercury is easily captured by wet flue gas desulfurization scrubbers, while gaseous elemental mercury passes through the scrubbers readily. Activated carbon, when injected into the gas stream of coal-fired boilers, is effective in capturing both elemental and oxidized mercury through adsorption processes. However, the mechanism by which mercury adsorbs on activated carbon is not exactly known and its understanding is crucial to the design and fabrication of effective capture technologies for mercury. The objective of the current study is to apply theoretical-based cluster modeling to examine the possible binding mechanism of mercury on activated carbon. The effects of activated carbon's different surface functional groups and halogens on elemental mercury adsorption have been examined. Also, a thermodynamic approach is followed to examine the binding mechanism of mercury and its oxidized species such as HgCl and HgCl2 on a simulated carbon surface with and without Cl. Energies of different possible surface complexes and possible products are compared and dominant pathways are determined relatively. Since different methods are employed to capture varying forms of mercury, understanding mercury speciation during combustion and how the transformations occur between different forms is essential to developing an effective control mechanism for removing mercury from flue gas. In this study, homogeneous oxidation of mercury via chlorine is examined experimentally in a simulated flue gas environment. Mercury and chlorine are introduced into a laminar premixed methane-air flame. Cooled flue gas is sampled and sent to a custom-built electron ionization quadrupole mass spectrometer specially designed for mercury measurement on the order of parts per billion (ppb) in flue gas. The use of a mass spectrometer allows for distinguishing between the different forms of oxidized mercury (Hg+, Hg+2). By directly measuring mercury species accurately, one can determine the actual extent of mercury oxidation in the flue gas, which will aid in further developing mercury control technologies.

Mercury as a Global Pollutant

Author : Donald B. Porcella
Publisher : Springer
ISBN 13 : 9789401040693
Total Pages : 0 pages
Book Rating : 4.0/5 (46 download)

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Book Synopsis Mercury as a Global Pollutant by : Donald B. Porcella

Download or read book Mercury as a Global Pollutant written by Donald B. Porcella and published by Springer. This book was released on 2014-08-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: ACKNOWLEDGEMENTS xiv PART I MERCURY AND HUMAN HEALTH B. WHEATLEY and S. PARADIS I Exposure of Canadian Aboriginal Peoples to Methylmercury 3-11 M. GIRARD and C. DUMONT I Exposure of James Bay Cree to Methylmercury during Pregnancy for the Years 1983-91 13-19 M. RICHARDSON, M. MITCHELL, S. COAD and R. RAPHAEL I Exposure to Mercury in Canada: A Multimedia Analysis 21-30 M. RICHARDSON, M. EGYED and D. J. CURRIE I Human Exposure to Mercury may Decrease as Acidic Deposition Increases 31-39 L. E. FLEMING, S. WATKINS, R. KADERMAN, B. LEVIN, D. R. AVYAR, M. BIZZIO, D. STEPHENS and J. A. BEAN I Mercury Exposure in Humans through Food Consumption from the Everglades of Florida 41-48 J. M. GEARHART, H. J. CLEWELL III, K. S. CRUMP, A. M. SHIPP and A. SILVERS I Pharmacokinetic Dose Estimates of Mercury in Children and Dose-Response Curves of Performance Tests in a Large Epidemiological Study 49-58 I. SKARE I Mass Balance and Systemic Uptake of Mercury Released from Dental Amalgam Fillings 59-67 J. DELLINGER, N. KMIECIK, S. GERSTENBERGER and H. NGU I Mercury Contamina tion of Fish in the Ojibwa Diet: I. Walleye Fillets and Skin-On versus Skin-Off Sampling 69-76 J. DELLINGER, L. MALEK and M. BEATTIE I Mercury Contamination of Fish in the Ojibwa Diet: II. Sensory Evoked Responses in Rats Fed Walleye 77-83 H. AKAGI, O. MALM, F. J. P. BRANCHES, Y. KINJO, Y. KASHIMA, J. R. D. GUIMARAES, R. B. OLIVEIRA, K. HARAGUCHI, W. C. PFEIFFER, Y.

Monitored Natural Attenuation of Inorganic Contaminants in Ground Water

Author :
Publisher :
ISBN 13 :
Total Pages : 124 pages
Book Rating : 4.3/5 (121 download)

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Book Synopsis Monitored Natural Attenuation of Inorganic Contaminants in Ground Water by :

Download or read book Monitored Natural Attenuation of Inorganic Contaminants in Ground Water written by and published by . This book was released on 2007 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: V.3 ... consists of individual chapters that describe 1) the conceptual background for radionuclides, including tritium, radon, strontium, technetium, uranium, iodine, radium, thorium, cesium, plutonium-americium and 2) data requirements to be met during site characterization.

Soil pollution: a hidden reality

Author : Food and Agriculture Organization of the United Nations
Publisher : Food & Agriculture Org.
ISBN 13 : 9251305056
Total Pages : 156 pages
Book Rating : 4.2/5 (513 download)

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Book Synopsis Soil pollution: a hidden reality by : Food and Agriculture Organization of the United Nations

Download or read book Soil pollution: a hidden reality written by Food and Agriculture Organization of the United Nations and published by Food & Agriculture Org.. This book was released on 2018-04-30 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document presents key messages and the state-of-the-art of soil pollution, its implications on food safety and human health. It aims to set the basis for further discussion during the forthcoming Global Symposium on Soil Pollution (GSOP18), to be held at FAO HQ from May 2nd to 4th 2018. The publication has been reviewed by the Intergovernmental Technical Panel on Soil (ITPS) and contributing authors. It addresses scientific evidences on soil pollution and highlights the need to assess the extent of soil pollution globally in order to achieve food safety and sustainable development. This is linked to FAO’s strategic objectives, especially SO1, SO2, SO4 and SO5 because of the crucial role of soils to ensure effective nutrient cycling to produce nutritious and safe food, reduce atmospheric CO2 and N2O concentrations and thus mitigate climate change, develop sustainable soil management practices that enhance agricultural resilience to extreme climate events by reducing soil degradation processes. This document will be a reference material for those interested in learning more about sources and effects of soil pollution.

Toxicological Effects of Methylmercury

Author : National Research Council
Publisher : National Academies Press
ISBN 13 : 0309171717
Total Pages : 364 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Toxicological Effects of Methylmercury by : National Research Council

Download or read book Toxicological Effects of Methylmercury written by National Research Council and published by National Academies Press. This book was released on 2000-09-27 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury is widespread in our environment. Methylmercury, one organic form of mercury, can accumulate up the aquatic food chain and lead to high concentrations in predatory fish. When consumed by humans, contaminated fish represent a public health risk. Combustion processes, especially coal-fired power plants, are major sources of mercury contamination in the environment. The U.S. Environmental Protection Agency (EPA) is considering regulating mercury emissions from those plants. Toxicological Effects of Methylmercury reviews the health effects of methylmercury and discusses the estimation of mercury exposure from measured biomarkers, how differences between individuals affect mercury toxicity, and appropriate statistical methods for analysis of the data and thoroughly compares the epidemiological studies available on methylmercury. Included are discussions of current mercury levels on public health and a delineation of the scientific aspects and policy decisions involved in the regulation of mercury. This report is a valuable resource for individuals interested in the public health effects and regulation of mercury. The report also provides an excellent example of the implications of decisions in the risk assessment process for a larger audience.

Mercury in the Environment

Author :
Publisher :
ISBN 13 :
Total Pages : 4 pages
Book Rating : 4.:/5 (318 download)

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Book Synopsis Mercury in the Environment by :

Download or read book Mercury in the Environment written by and published by . This book was released on 2000 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Natural Water Remediation

Author : James G. Speight
Publisher : Butterworth-Heinemann
ISBN 13 : 0128038829
Total Pages : 392 pages
Book Rating : 4.1/5 (28 download)

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Book Synopsis Natural Water Remediation by : James G. Speight

Download or read book Natural Water Remediation written by James G. Speight and published by Butterworth-Heinemann. This book was released on 2019-08-29 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural Water Remediation: Chemistry and Technology considers topics such as metal ion solubility controls, pH, carbonate equilibria, adsorption reactions, redox reactions and the kinetics of oxygenation reactions that occur in natural water environments. The book begins with the fundamentals of acid-base and redox chemistry to provide a better understanding of the natural system. Other sections cover the relationships among environmental factors and natural water (including biochemical factors, hydrologic cycles and sources of solutes in the atmosphere). Chemical thermodynamic models, as applied to natural water, are then discussed in detail. Final sections cover self-contained applications concerning composition, quality measurement and analyses for river, lake, reservoir and groundwater sampling. Covers the fundamentals of acid-base and redox chemistry for environmental engineers Focuses on the practical uses of water, soil mineral and bedrock chemistry and how they impact surface and groundwater Includes applications concerning composition, quality measurement and analyses for river, lake, reservoir and groundwater sampling