A Theoretical Study on the Reactions of Hg with Halogens:  Atmospheric Implications

Khalizov, Alexei F.; Viswanathan, Balakrishnan; Larrégaray, P.; Ariya, Parisa A.

doi:10.1021/jp0350722

Cited by 89 publications

(63 citation statements)

References 50 publications

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“…[36][37][38][39][40][41][42][43][44] For example, mechanisms associated with the Hg−C bond cleavage by halogenic acids have been investigated by Barone and co-workers. 15 Ni et al 36 investigated possible mechanisms for degrading chloromethylmercury (CH 3 −Hg−Cl) and dimethylmercury (CH 3 −Hg−CH 3 ) involving thiol and ammonium residues.…”

Section: Introductionmentioning

confidence: 99%

“…15 Ni et al 36 investigated possible mechanisms for degrading chloromethylmercury (CH 3 −Hg−Cl) and dimethylmercury (CH 3 −Hg−CH 3 ) involving thiol and ammonium residues. Khalizov et al 37 studied the reactions of Hg with halogens and discussed their atmospheric implications. Shepler et al 38 have analyzed the effects of aqueous solvation on the thermochemistry of reactions between Hg and small halogen molecules.…”

Section: Introductionmentioning

confidence: 99%

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Stability of Dimethylmercury and Related Mercury-containing Compounds with Respect to Selected Chemical Species Found in Aqueous Environment

Bytautas¹

2013

Croat. Chem. Acta

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Abstract. Dimethylmercury (CH 3 −Hg−CH 3 ) and other Hg-containing compounds can be found in atmospheric and aqueous environments. These substances are highly toxic and pose a serious environmental and health hazard. Therefore, the understanding of chemical processes that affect the stability of these substances is of great interest. The mercury-containing compounds can be detected in atmosphere, as well as soil and aqueous environments where, in addition to water molecules, numerous ionic species are abundant. In this study we explore the stability of several small, Hg-containing compounds with respect to water molecules, hydronium (H 3 O + ) ions as well as other small molecules/ions using density functional theory and wave function quantum chemistry methods. It is found that the stability of such molecules, most notably of dimethylmercury, can be strongly affected by the presence of the hydronium H 3 O + ions. Although the present theoretical study represents gas phase results, it implies that pH level of a solution should be a major factor in determining the degree of abundance for dimethylmercury in aqueous environment. In particular, it is found that CH 3 −Hg−CH 3 reacts readily with the H 3 O + ion producing CH 3 −Hg−OH 2 + and methane indicating that low-pH levels favor the decomposition of dimethylmercury. On the other hand, our study suggests that high-pH levels in aqueous environment would favor stronglybound complexes of [CH 3 −Hg−CH 3 OH]  species. Overall, the theoretical evidence presented in this study offers an explanation for the available experimental data concerning the stability of dimethylmercury and other mercury-containing compounds having the general structure

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stability of Dimethylmercury and Related Mercury-containing Compounds with Respect to Selected Chemical Species Found in Aqueous Environment

Bytautas¹

2013

Croat. Chem. Acta

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“…This same group also reported a theoretical estimate of 2.04ϫ 10 −12 cm 3 molecule −1 s −1 for the rate constant at 298 K and 1 atm using variational transition state theory ͑VTST͒ in which pressure effects were included using a simple capture model that assumed strong collisional deactivation. 21 Another theoretical estimate from Goodsite et al 22 1.1ϫ 10 −12 cm 3 molecule −1 s −1 , was determined from Rice-Ramsperger-Kassel-Marcus ͑RRKM͒ theory using a master equation formalism that included N 2 as a stabilizing third body. Most recently a direct measurement of the Hg + Br recombination rate using a pulsed laser photolysispulsed laser induced fluorescence technique by Donohoue et al 23 determined a rate constant of just 3.6 ϫ 10 −13 cm 3 molecule −1 s −1 at 298 K and 760 Torr.…”

Section: Introductionmentioning

confidence: 99%

Hg + Br → Hg Br recombination and collision-induced dissociation dynamics

Shepler

Balabanov

Peterson

2007

The Journal of Chemical Physics

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A global potential energy surface has been constructed for the system HgBr+Ar-->Hg+Br+Ar to determine temperature dependent rate constants for the collision-induced dissociation (CID) and recombination of Hg and Br atoms. The surface was decomposed using a many-body expansion. Accurate two-body potentials for HgBr, HgAr, and ArBr were calculated using coupled cluster theory with single and double excitations and a perturbative treatment of triple excitations [CCSD(T)], as well as the multireference averaged coupled pair functional method. Correlation consistent basis sets were used to extrapolate to the complete basis set limit and corrections were included to account for scalar and spin-orbit relativistic effects, core-valence correlation, and the Lamb shift. The three-body potential was computed with the CCSD(T) method and triple-zeta quality basis sets. Quasiclassical trajectories using the final analytical potential surface were directly carried out on the CID of HgBr by Ar for a large sampling of initial rotational, vibrational, and collision energies. The recombination rate of Hg and Br atoms is a likely first step in mercury depletion events that have been observed in the Arctic troposphere during polar sunrise. The effective second order rate constant for this process was determined in this work from the calculated CID rate as a function of temperature using the principle of detailed balance, which resulted in k(T) = 1.2 x 10(-12) cm(3) molecule(-1) s(-1) at 260 K and 1 bar pressure.

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“…The rate expressions for two additional reactions were plotted in Figure 4, i.e., HgCl + M T Hg + Cl + M 38 and Cl 2 + M T 2Cl + M. 39,40 Within each of these unimolecular reactions, M is the collision partner or gas bath, which does not participate chemically in the reactions, but is taken into account within the pressure-dependent kinetic predictions using RRKM theory. The depletion of HgCl as temperature decreases is faster than the three HgCl formation reactions, while (14) comparable to the formation reactions involving HOCl and Cl 2 at high temperatures. The dissociation reaction of Cl 2 to chlorine radicals is comparable to the formation reactions involving HOCl and Cl 2 at high temperatures, but is slower at low temperatures, which ensures the presence of chlorine radicals at high temperatures.…”

Section: Data Comparisonmentioning

confidence: 75%

A Kinetic Investigation of High-Temperature Mercury Oxidation by Chlorine

Wilcox

2009

J. Phys. Chem. A

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First-stage mercury oxidation reactions typical of coal combustion flue gases were investigated. The present study is a determination of the kinetic and thermodynamic parameters of the bimolecular reactions, Hg + Cl 2 T HgCl + Cl, Hg + HCl T HgCl + H, and Hg + HOCl T HgCl + OH, at the B3LYP/RCEP60 VDZ level of theory over a temperature range of 298.15 to 2000 K at atmospheric pressure. Conventional transition state theory was used to predict the forward and reverse rate constants for each reaction and ab initio based equilibrium constant expressions were calculated as a function of temperature. Reasonable agreement was achieved between the calculated equilibrium constants and the available experimental values.

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A Theoretical Study on the Reactions of Hg with Halogens: Atmospheric Implications

Cited by 89 publications

References 50 publications

Stability of Dimethylmercury and Related Mercury-containing Compounds with Respect to Selected Chemical Species Found in Aqueous Environment

Stability of Dimethylmercury and Related Mercury-containing Compounds with Respect to Selected Chemical Species Found in Aqueous Environment

Hg + Br → Hg Br recombination and collision-induced dissociation dynamics

A Kinetic Investigation of High-Temperature Mercury Oxidation by Chlorine

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