Reaction Of Mercury Research Articles

In situ hydrothermal synthesis of 2D mercury(I)–organic framework from 3-aminopyrazine-2-carboxylic acid and mercury(II) acetate

A new mercury(I)–organic framework based on Hg22 + dumbbell, [Hg2(apca)2]n, 1, [apca = 3-aminopyrazine-2-carboxylate] has been synthesized from an in situ reduction reaction of mercury(II) acetate and 3-aminopyrazine-2-carboxylic acid under hydrothermal condition. 1 has been characterized by elemental analysis, infrared spectra, and single-crystal X-ray diffraction and has shown a 2D-layer structure constructed from Hg22 + dumbbell and bridging 3-aminopyrazine-2-carboxylate, which features a (63) topological network. The 2D compound is further assembled by hydrogen bonds and CH⋯N interactions into 3D supramolecular networks. Fluorescence property and thermogravimetric analysis of 1 were also investigated.

Mn and Fe Modified Fly Ash As a Superior Catalyst for Elemental Mercury Capture under Air Conditions

The objective of this study was to investigate the effects of fly ash (FA) and Mn and Fe modified FA on elemental mercury capture under air at 120 °C. X-ray fluorescence spectrometry (XRF), Brunauer–Emmett–Teller (BET) surface area, scanning electron micrographs (SEMs), X-ray diffraction (XRD), thermogravimetric (TG) analysis, and X-ray photoelectron spectroscopy (XPS) were employed to characterize the samples. The results showed that the cooperation of Mn and Fe loaded on FA improved the performance of elemental mercury capture in a laboratory packed-bed reactor. In the presence of O2, Mn(2)–Fe(3)–FA (FA modified with an Mn/Fe molar ratio of 2/3) possessed the best reactivity and its Hg0 removal efficiency stayed around 98% within 8 h. The heterogeneous mercury reaction could be speculated as: Hg0 was physically adsorbed on the cation vacancies and then was oxidized to HgO by Mn4+ and Fe3+ cations. The reduced forms of Mn3+ and Fe2+ reoxidized under air, and HgO was finally adsorbed on the surface of the...

Biosequestration, Transformation, and Volatilization of Mercury by Lysinibacillus fusiformis Isolated from Industrial Effluent

In the present study, an efficient mercury-tolerant bacterial strain (RS-5) was isolated from heavy-metalcontaminated industrial effluent. Under shake flask conditions, 97% of the supplemented mercuric chloride was sequestered by the biomass of RS-5 grown in a tryptone soy broth. The sequestered mercuric ions were transformed inside the bacterial cells, as an XRD analysis of the biomass confirmed the formation of mercurous chloride, which is only feasible following the reaction of the elemental mercury and the residual mercuric chloride present within the cells. Besides the sequestration and intracellular transformation, a significant fraction of the mercury (63%) was also volatilized. The 16S rRNA gene sequence of RS-5 revealed its phylogenetic relationship with the family Bacillaceae, and a 98% homology with Lysinibacillus fusiformis, a Gram-positive bacterium with swollen sporangia. This is the first observation of the sequestration and volatilization of mercuric ions by Lysinibacillus sp.

Traceability study of hay with a mass spectrometer based on ion-molecule reactions of krypton, xenon and mercury using multivariate data analysis

The application of mountain hay for wellness purposes has led to a substantial valorisation. To assure the quality associated with the high standards of production, which are often related to a characteristic distribution of plants and a variety of essential oils, a mass spectrometer, based on ion-molecule-reactions (IMR) of mercury, krypton and xenon, was employed to analyse characteristic VOCs of hay such as coumarin or typical monoterpenes and then used to develop an approach for the traceability of single hay samples based on concepts of multivariate statistics. The application of the primary gases to aqueous solutions of the pure compounds shows their suitability to deal with this problem, reveals important factors for the creation of a measurement set-up of such gas mixtures and indicates different mechanisms for the fragmentation, as shown for coumarin. The limit of determination (3*sR/SEN) for aqueous solutions of p-cymene is 0.13 mg L−1 using PLS1 and the presented combined mercury and xenon set-up, which confirms that this strategy is appropriate for an integration of compounds, which are present in low concentrations only, into a qualitative model. The results of the principal component analyses (PCA) of 136 hay samples were verified for the suitability to characterize single types of hay using three measurements of nine mountain hay samples, three normal hay samples and three aftermath samples for evaluation and applying SIMCA for classification at a significance level of 5%. The traceability of mountain hay samples is good (93% correctly classified) and can be used to protect these valuable samples.

Syntheses and coordination studies of 2-(diphenylphosphinomethyl)pyridine and its oxide towards mercury(II)

Several coordination complexes of mercury(II) have been synthesized by the reaction of mercury(II) salts with 2-(diphenylphosphinomethyl)pyridine (L1) and its corresponding oxide (L2). The synthesized complexes were fully characterized by elemental analysis and multinuclear NMR spectroscopy techniques. The crystal structures were determined by single-crystal X-ray crystallography. Different geometries were observed around the metal center, including distorted trigonal–pyramidal (1,3), distorted tetrahedral (2) and distorted octahedral (4,5), with the degree of distortion depending on the steric effects and the chelating capability of 2-(diphenylphosphinomethyl)pyridine and its oxide.

Synthesis, Spectral and Thermal Characterization of Bis(pyridine-3- carboxy-2-thiolato-S)mercury(II). Crystal Structure of Dibromobis(3- metoxycarbonylpyridine-2-thiolato-S)mercury(II)

2-mercaptonicotinic acid (H_2mna = 2-HS(C_5H_3N)COOH) gave a thiolato compound of the formula Hg(Hmna)_2 by a reaction with various mercury(II) salts, HgX_2 (X = Cl^−, Br^−, I^−, SCN^−) in an ethanol or methanol solution irrespectively of the molar ratio of the reactants (1:1 or 1:2). The same compound was obtained from the reaction of mercury(II) acetate in an aqueous-ethanol solution. Hg(Hmna)_2 was characterized by vibrational spectroscopy and thermal analysis. 1^H and 13^C NMR measurements provided additional information on the thiol-thione tautomerism in H2mna and Hg(Hmna)_2 and also on the binding mode to mercury in the DMSO-d6 solution. HgBr_2(CH_3-Hmna)_2 was obtained from the reaction of H2mna with HgBr_2 in methanol after filtering off the main product Hg(Hmna)_2 (CH_3-Hmna = 2- HS(C_5H_3N)COOCH_3). The crystal structures of H2mna and HgBr_2(CH_3-Hmna)_2 were determined by the X-ray structure analysis. 2-mercaptonicotinic acid exists in the crystalline state in the thione tautomeric form. Two bromine atoms and two S-bound CH_3-Hmna ligands form a tetrahedral coordination sphere around the mercury atom in HgBr_2(CH_3-Hmna)_2.

Mercury(II) Complexes Containing the [Hg(L)2]2–, [Hg(L)(HL)]−, and [Hg(HL)2] Units [H2L = 3-(2-Chlorophenyl)-2-sulfanylpropenoic Acid]. Structural and Spectroscopic Effects of the Different Degrees of Ligand Protonation

The reaction of mercury(II) acetate with 3-(2-chlorophenyl)-2- sulfanylpropenoic acid (H2Clpspa) in ethanol in the presence (or absence) of diisopropylamine or triethylamine yielded the compounds [HQ] 2[Hg(Clpspa)2] (1), [HP][Hg(Clpspa)(HClpspa)] (2) (where HQ = diisopropylammonium and HP = triethylammonium cations), and [Hg(HClpspa)2] (3). All of the new compounds were characterized by elemental analysis, IR, and NMR (1H, 13C, 199Hg) spectroscopy. The crystal structures of 1, 2, and 3•4H2O were determined by X-ray diffractometry. Diisopropylammonium cations and [Hg(Clpspa)2]2- anions were detected in the first compound, triethylammonium cations and [Hg(Clpspa)(HClpspa)] anions were found in the second compound, and molecular [Hg(HClpspa)2] units were found in the third. The different degrees of ligand protonation modify the structural parameters of the Hg-kernel as well as the supramolecular association in the compounds. Furthermore, the spectroscopic characteristics of the compounds in the solid (IR) and in solution (NMR) are sensitive to this ligand protonation. © 2011 American Chemical Society.

A review of the sources of uncertainties in atmospheric mercury modeling II. Mercury surface and heterogeneous chemistry – A missing link

Despite direct and indirect evidence suggesting that heterogeneous surfaces potentially play a key role in mercury chemistry, there is little known about mercury reactions and equilibrium processes that take place at atmospherically relevant surfaces. The lack of knowledge of mercury surface chemistry is a major gap for adequate modeling of mercury cycling. In part I of this review, we assessed the sources of uncertainty associated with existing kinetic parameters. In this part, we present evidence that supports surface–mercury interactions in the ecosystem elucidating the importance of heterogeneous and interfacial chemistry from a fundamental viewpoint. Consequently, we draw attention to the chemical processes that are missing and/or are inadequately incorporated in the atmospheric mercury models and highlight some of the recent advances in this field. We reveal that adsorption equilibrium of mercury species, most of which are not well characterized, to natural surfaces such as atmospheric particles and air/water interface are not known. Gas–liquid partitioning of mercury and its compounds are not adequately implemented. Equilibrium constants for aqueous phase complex formation with dissolved organic matters and formation of possible solid mercury clusters and nanoparticles are not considered in the global models. Potential heterogeneous mercury reduction reactions that can be important in mercury cycling require further evaluation which includes characterizing the influence of surfaces on mercury chemistry. The implementation of chemical processes for which information is available but not currently included in the models bears the potential of greatly reducing the uncertainties that are currently present in the models.

A review of uncertainties in atmospheric modeling of mercury chemistry I. Uncertainties in existing kinetic parameters – Fundamental limitations and the importance of heterogeneous chemistry

Mercury and its related compounds are widely recognized as global pollutants. The accurate atmospheric modeling of its transport and fate has been the subject of much research throughout the last decade. Atmospheric gas, aqueous and heterogeneous chemistry are expected to occur for Hg-containing species and accurate implementation of their chemical parameters is essential for realistic modeling of mercury cycling. Although significant progress has been made, the current state of knowledge of mercury chemistry exhibits numerous uncertainties. The objective of this two-part review is to explore the sources of uncertainty from the viewpoint of mercury chemistry. In this first part, we assess the discrepancy that exists in the currently available mercury kinetic parameters for the gas and aqueous phases. Theoretical and experimental approaches of rate constant determination exhibit various levels of limitation and accuracy. We present an overview of the available techniques and the assumptions and shortcomings associated with these methods in order to assist the atmospheric modellers. We review specific mercury oxidation and reduction reactions that have been investigated and are commonly implemented in mercury models with respect to the uncertainties associated with them. We reveal that for most of these mercury reactions our current state of knowledge reflects a lack of proper understanding of their mechanisms. Atmospheric heterogeneity is a topic of great importance and we elaborate upon it in part II of this review.

Structural, theoretical and multinuclear NMR study of mercury(II) complexes with a new ambidentate phosphorus ylide

The reaction of the new ambidentate ylide, Ph 3PCHCOCH 2COOC 2H 5 (EAPPY), with HgX 2 (X = Cl, Br and I) in equimolar ratios using methanol as the solvent leads to binuclear complexes of the type [EAPPY·HgX 2] 2 (X = Cl ( 1), Br ( 2) and I ( 3)). Single crystal X-ray analysis reveals the presence of a centrosymmetric dimeric structure containing the ylide and HgX 2 (X = Br or I) . The IR and NMR data of the product [(EAPPY)·HgCl 2] 2 ( 1), formed by the reaction of mercury(II) chloride with the same ylide, are similar to those of 2 and 3. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products. Theoretical studies indicate that the nature of the R group in ylides of the type Ph 3PCHCOR has a weak effect on the Hg–C(ylide) bond length in binuclear Hg 2L 2I 4 complexes.

Synthesis and structure of new Schiff base derivatives obtained from 2-(formylphenyl)mercury bromide

Reactions of (2-formylphenyl)mercury(II) bromide 10 with primary amines give mono-, bis- and tris- Schiff base derivatives ( 11– 18). Structures of the synthesized compounds show the presence of five-membered intramolecular Hg⋯N interaction. Luminescence studies of the compounds have been performed. Attempts to use the synthesized compounds for binding neutral donor molecules or fluoride ions were unsuccessful.

Mechanistic Study on the Ozone‐Mercury Reaction and the Effect of Water and Water Dimer Molecules

AbstractThe thermodynamics and mechanism of the reaction of elemental mercury with ozone has been studied computationally. The effect of water and water dimer molecules on the reaction has also been investigated. For dry reaction, we obtained two pathways and geometry optimization, atoms in molecules analysis and vibrational frequencies of all component of reaction have been used for confirming of reaction mechanism. Thermodynamic variable of reaction has been calculated. For the reaction in the presence of the water, our studies focus on ozone‐mercury complex reaction with water and water dimer and obtained the mechanism of reactions. Comparison of wet and dry reaction shows the energy profile of reaction decreases with water molecule correspond to experimental prediction. Calculated thermodynamic variable of all reaction shows the Gibbs free energy of reaction decreases with the number of water molecule.

A Theoretical Study of Abiotic Methylation Reactions of Gaseous Elemental Mercury by Halogen-Containing Molecules

Methylation reactions of gaseous elementary mercury by halogen containing molecules such as halogenomethane species CH(3)X (with X = Cl, Br, and I) and the dimethylchlorinium ion CH(3)ClCH(3)(+) were investigated at the density functional level. With CH(3)X, the reaction is predicted to be almost athermic and kinetically demanding for a thermal reaction. The reaction can proceed photochemically in the visible range; therefore sunlight may increase the reaction rate. These results compare well with the experimental data. Consecutive methylation of the CH(3)HgX products (with X = Cl, Br, and I) and subsequent formation of CH(3)HgCH(3) were also studied. These reactions are predicted to be kinetically inaccessible and thermodynamically unfavorable. With CH(3)ClCH(3)(+), the reaction is predicted to be athermic but kinetically easy. This is due to the suitability of the methyl transfer reagent. Geometrical and electronic data were systematically analyzed in order to rationalize the results.

Heterogeneous Mercury Reaction Chemistry on Activated Carbon

ABSTRACT 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 surface-bound 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. IMPLICATIONS The design of Hg capture sorbents from air has application to Hg removal from dentist offices because of the elevated elemental mercury vapor concentrations in these environments from amalgam use or replacement. This work serves as the foundation for potential optimization of AC's properties to make this capture technology more effective and potentially less costly

Ab initio-based Mercury Oxidation Kinetics via Bromine at Postcombustion Flue Gas Conditions

Because direct mercury measurements are difficult throughout the postcombustion flue gas environment, it is practical to use mercury reaction kinetics to theoretically determine mercury speciation based upon coal composition, plant equipment, and operating conditions. Elemental mercury cannot be captured in wet scrubbers; however, its oxidized forms can. Mercury−bromine oxidation kinetics have been studied with electronic structure calculations using a broad range of ab initio methods. Reaction enthalpies, equilibrium bond distances, vibrational frequencies, and rate constants have all been predicted using density functional theory as well as coupled cluster methods. Upon the basis of comparisons to available experimental and high-level theoretical data in the literature, quantum-based methods for the following Hg−Br reactions have been validated: Hg + Br ↔ HgBr, Hg + Br2 ↔ HgBr + Br, and HgBr + Br ↔ HgBr2. The use of these methods for predicting forward and reverse rate constants for the following Hg−Br reactions has been carried out for the first time: Hg + HBr ↔ HgBr + H, HgBr + Br2 ↔ HgBr2 + Br, and HgBr + HBr ↔ HgBr2 + H. Understanding the speciation of mercury in the flue gases of coal combustion is paramount to the development of efficient control technologies.

Thermal and electrochemical study of solid-state reaction of mercury with Pt–20% Rh alloy

Thermogravimetry (TG), energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM), mapping surface and X-ray diffraction (XRD) have been used to study the reaction of mercury with platinum–rhodium (Pt–Rh) alloy. The results suggest that, when heated, the electrodeposited Hg film reacts with Pt–Rh to form intermetallic compounds each having a different stability, indicated by separate third mass-loss steps. In the first step, between room temperature and 170 °C, only the bulk Hg is removed. From this temperature to about 224 °C, the mass loss can be attributed to decomposition of the intermetallic PtHg4. The third step, from 224 to 305 °C, can be ascribed to thermal decomposition of solid solution composed of intermetallic species RhHg2 and PtHg2. Intermetallic compound such as PtHg4, PtHg2, and RhHg2 was characterized by XRD. These intermetallic compounds were the main products formed on the surface of the samples after partial removal of the bulk mercury via thermal desorption.

Understanding the effects of sulfur on mercury capture from coal-fired utility flue gases

Coal combustion continues to be a major source of energy throughout the world and is the leading contributor to anthropogenic mercury emissions. Effective control of these emissions requires a good understanding of how other flue gas constituents such as sulfur dioxide (SO2) and sulfur trioxide (SO3) may interfere in the removal process. Most of the current literature suggests that SO2 hinders elemental mercury (Hg0) oxidation by scavenging oxidizing species such as chlorine (Cl2) and reduces the overall efficiency of mercury capture, while there is evidence to suggest that SO2 with oxygen (O2) enhances Hg0 oxidation by promoting Cl2 formation below 100 °C. However, studies in which SO2 was shown to have a positive correlation with Hg0 oxidation in full-scale utilities indicate that these interactions may be heavily dependent on operating conditions, particularly chlorine content of the coal and temperature. While bench-scale studies explicitly targeting SO3 are scarce, the general consensus among full-scale coal-fired utilities is that its presence in flue gas has a strong negative correlation with mercury capture efficiency. The exact reason behind this observed correlation is not completely clear, however. While SO3 is an inevitable product of SO2 oxidation by O2, a reaction that hinders Hg0 oxidation, it readily reacts with water vapor, forms sulfuric acid (H2SO4) at the surface of carbon, and physically blocks active sites of carbon. On the other hand, H2SO4 on carbon surfaces may increase mercury capacity either through the creation of oxidation sites on the carbon surface or through a direct reaction of mercury with the acid. However, neither of these beneficial impacts is expected to be of practical significance for an activated carbon injection system in a real coal-fired utility flue gas.

The Effect of Reducing Conditions and Temperature on Mercury Release from Coal

Coals contain small quantities of mercury that have the potential to be emitted to the atmosphere during thermal processing. While significant research effort has improved knowledge of mercury emissions from direct combustion of coal in power stations to produce electricity, much less effort has been devoted to mercury behavior from coal under reducing conditions, typical for smelting and metal processing. This article discusses laboratory investigations of mercury release from coal during heating under reducing conditions. Two coals, one of Australian and one of United States origin, were subjected to thermal treatment to temperatures ranging between 100 and 800°C. The level of mercury was monitored using cold-vapor atomic fluorescence spectrometry. The largest fraction of mercury was released at temperatures of up to 500°C, however some strongly bonded mercury was retained in coal samples even at temperatures of 600°C. Reducing atmospheric conditions revealed a likely delay to higher temperatures in the release of mercury from coal. Speciation of mercury in coal was further determined with a six-stage sequential selective extraction method. Mercury reaction mechanisms occurring during the heating of coal under both reducing and oxidizing conditions relevant to direct ironmaking processes are discussed.

Mechanistic Study of Ozone‐Water Reaction and Their Reaction Products with Gas Phase Elemental Mercury: A Computational Study

AbstractThe interaction of oxygen of water and central oxygen of ozone produces stable H2O‐O3 complex with no barrier. With decomposition of this complex through H‐abstraction by O3 and O‐abstraction by H2O, four possible product channels have been found. The reaction of mercury and the products of water‐ozone reaction have been studied. All geometrical and AIM parameters of intermediate, transition states, and the products of reactions are calculated and thermodynamic parameters are obtained. The negative value of free energy show that channels Hg+H2OO, Hg+H2O2 and Hg+H2O4 in hydrogen tetroxide form (HTO) may be the main reaction channels.

Sn9HgSn9]6–: An Intermetalloid Zintl Ion with Two Sn9 Connected by Heteroatom

AbstractThe title compound [K([2,2,2]crypt)]12[Sn9]2[Sn9HgSn9] has been obtained by reaction of elemental mercury with the binary phase K4Sn9 in ethylenediamine after addition of [2,2,2]crypt and layering with toluene. The X‐ray single crystal analysis shows that the compound consists of two isolated Sn9 clusters and two Sn9 clusters connected by a mercury atom.