Mercury binding on activated carbon

Padak, Bihter; Brunetti, Michael; Lewis, Amanda L.; Wilcox, Jennifer

doi:10.1002/ep.10165

Cited by 106 publications

(86 citation statements)

References 35 publications

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“…29 -32 Previous studies have considered models of C edges comprised of armchair and zigzag sites. [33][34][35][36] The major conclusion from these previous investigations is that the zigzag sites with carbene atoms are the most reactive with the C atom having two unpaired electrons. 37,38 The goal of this work is to identify trends in the adsorption and oxidation of Hg 0 on functionalized edge sites under relevant conditions of the surrounding flue gas.…”

Section: Resultsmentioning

confidence: 99%

Heterogeneous Mercury Reaction Chemistry on Activated Carbon

Wilcox

Sasmaz

Kirchofer

et al. 2011

Journal of the Air & Waste Management Association

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Experimental and theory-based investigations have been carried out on the oxidation and adsorption mechanism of mercury (Hg) on brominated activated carbon (AC). Air containing parts per billion concentrations of Hg was passed over a packed-bed reactor with varying sorbent materials at 140 and 30°C. Through X-ray photoelectron spectroscopy surface characterization studies it was found that Hg adsorption is primarily associated with bromine (Br) on the surface, but that it may be possible for surfacebound oxygen (O) to play a role in determining the stability of adsorbed Hg. In addition to surface characterization experiments, the interaction of Hg with brominated AC was studied using plane-wave density functional theory. Various configurations of hydrogen, O, Br, and Hg on the zigzag edge sites of graphene were investigated, and although Hg-Br complexes were found to be stable on the surface, the most stable configurations found were those with Hg adjacent to O. The Hg-carbon (C) bond length ranged from 2.26 to 2.34 Å and is approximately 0.1 Å shorter when O is a nearest-neighbor atom rather than a next-nearest neighbor, resulting in increased stability of the given configuration and overall tighter Hg-C binding. Through a density of states analysis, Hg was found to gain electron density in the six p-states after adsorption and was found to donate electron density from the five s-states, thereby leading to an oxidized surface-bound Hg complex.

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Section: Resultsmentioning

confidence: 99%

Heterogeneous Mercury Reaction Chemistry on Activated Carbon

Wilcox

Sasmaz

Kirchofer

et al. 2011

Journal of the Air & Waste Management Association

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“…These deconvolution results suggest that carbonyl content could increase with elevating CuCl 2 impregnation content. It is important to note that lactone and carbonyl functionality groups have been suggested to promote Hg adsorption through chemisorption based on the bonding energies calculated by density functional theory (Padak et al, 2006). Furthermore, Skodras et al (2007) reported that oxygen functional groups can facilitate the electron-transfer process and Hg 0 oxidation on the carbon surface and act as potential adsorption centers of Hg 0 .…”

Section: Properties Of Adsorbents Prior To and After Cucl 2 Impregnationmentioning

confidence: 99%

Influences of Copper(II) Chloride Impregnation on Activated Carbon for Low-Concentration Elemental Mercury Adsorption from Simulated Coal Combustion Flue Gas

Tsai

Chiu

Chuang

et al. 2017

Aerosol Air Qual. Res.

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In this study, the Hg 0 adsorption equilibrium and kinetics of a coconut-shell-based activated carbon impregnated with CuCl 2 were examined with respect to their resulting physical and chemical properties. Integrating the results from N 2 adsorption isotherm at 77 K, scanning electron microscopy, elemental analysis, X-ray photoelectron spectroscopy, and Hg 0 adsorption experiments under N 2 and simulated coal-combustion flue gases conditions, it was found that HCl pretreatment could enhance Hg 0 adsorption of crude activated carbon; the Hg 0 adsorption capacities of crude and HCl-pretreated activated carbon under N 2 condition were 95.8 and 225.4 µg g -1 , respectively. Additionally, CuCl 2 impregnation further increased the adsorption capacity of crude. The Hg 0 adsorption capacity of crude activated carbon with 8% CuCl 2 impregnation was 631.1 µg g -1 . However, the equilibrium Hg 0 adsorption capacity decreased when Cu loading exceeded 8 wt%, suggesting that adequate forms of surface Cu, O and Cl interacting with flue gas components and Hg 0 , as well as the presence of pores with specific size ranges allowing rapid transport of the Hg molecules into the interior of the activated carbon and as energy sinker govern the overall chemisorption process. Pseudo-second-order kinetic model could best describe the adsorption behaviors of tested samples under both test conditions, indicating that Hg 0 adsorbed on the activated carbon surface could be explained by bimolecular reaction mechanisms.

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“…However, neither TPD analyses nor XPS analyses of carbon black samples treated by N 2 + HCl (without Hg) revealed the existence of Cl on carbon surface (Table 11). It is possible that the binding energy between Cl and carbon surface (20) is so low that Cl are removed under the ultra high vacuum conditions used in TPD and XPS analysis. However, previous studies (21,2,22,16) have detected Cl on carbonaceous surfaces upon exposure to flue gas containing Hg.…”

Section: Figure 25 Effects Of H 2 O On Hg Uptake By Sh Fly Ash In Flmentioning

confidence: 99%

“…N 2 adsorption on graphite carbon (54,55,56) and carbon gasification (50,51,53) were understood very well. Many other heterogeneous reaction systems, such as titanium oxide photocatalysts stabilized on an active carbon surface (60), SO 2 oxidation catalyzed by carbon (59), mercury binding on activated carbon (20), oxidation of graphite by gas phase nitric acid (58), and methane oxidation mechanism on Pt (61) were also studied. However, a theoretical study of the mercury oxidation reactions on carbon has not yet been reported.…”

Section: Introductionmentioning

confidence: 99%

Mercury Speciation in Coal-Fired Power Plant Flue Gas-Experimental Studies and Model Development

Vidić¹,

Flora²,

Borguet³

2008

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The overall goal of the project was to obtain a fundamental understanding of the catalytic reactions that are promoted by solid surfaces present in coal combustion systems and develop a mathematical model that described key phenomena responsible for the fate of mercury in coalcombustion systems. This objective was achieved by carefully combining laboratory studies under realistic process conditions using simulated flue gas with mathematical modeling efforts. Laboratory-scale studies were performed to understand the fundamental aspects of chemical reactions between flue gas constituents and solid surfaces present in the fly ash and their impact on mercury speciation. Process models were developed to account for heterogeneous reactions because of the presence of fly ash as well as the deliberate addition of particles to promote Hg oxidation and adsorption. Quantum modeling was used to obtain estimates of the kinetics of heterogeneous reactions. Based on the initial findings of this study, additional work was performed to ascertain the potential of using inexpensive inorganic sorbents to control mercury emissions from coal-fired power plants without adverse impact on the salability fly ash, which is one of the major drawbacks of current control technologies based on activated carbon. EXECUTIVE SUMMARYThe overall goal of the project was to obtain a fundamental understanding of the catalytic reactions that are promoted by solid surfaces present in coal combustion systems and develop a mathematical model that described key phenomena responsible for the fate of mercury in coalcombustion systems. This objective was achieved by carefully combining laboratory studies under realistic process conditions using simulated flue gas with mathematical modeling efforts. Laboratory-scale studies were performed to understand the fundamental aspects of chemical reactions between flue gas constituents and solid surfaces present in the fly ash and their impact on mercury speciation. Process models were developed to account for heterogeneous reactions because of the presence of fly ash as well as the deliberate addition of particles to promote Hg oxidation and adsorption. Quantum modeling was used to obtain estimates of the kinetics of heterogeneous reactions. Based on the initial findings of this study, additional work was performed to ascertain the potential of using inexpensive inorganic sorbents to control mercury emissions from coal-fired power plants without adverse impact on the salability fly ash, which is one of the major drawbacks of current control technologies based on activated carbon.The impact of fly ash on mercury speciation was evaluated for six different fly ash samples in simulated flue gas using a fixed bed reactor. Similar experiments were conducted with specific inorganic constituents to elucidate the key fly ash surface characteristics that affect mercury speciation in flue gas. No homogeneous mercury oxidation was observed at 140 °C. Mercury uptake tests with different fly ash samples revealed that loss o...

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Mercury binding on activated carbon

Cited by 106 publications

References 35 publications

Heterogeneous Mercury Reaction Chemistry on Activated Carbon

Heterogeneous Mercury Reaction Chemistry on Activated Carbon

Influences of Copper(II) Chloride Impregnation on Activated Carbon for Low-Concentration Elemental Mercury Adsorption from Simulated Coal Combustion Flue Gas

Mercury Speciation in Coal-Fired Power Plant Flue Gas-Experimental Studies and Model Development

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