Reaction Of Mercury Research Articles

Heterogeneous Processes in Detoxification of Metal Ions

The conditions for the synthesis of sparingly soluble salts of lead, cadmium, mercury(II), copper(II) and iron(II, III) with anions of some organic acids HmL were given. Based on their solubility data (ionic strength I = 0.1), the solubility constants KS were calculated; based on the [Mn+]/MPCM ratio, conclusions were drawn about the applicability of low-toxic organic ligands as precipitators (antidotes) of toxic metal ions. It was shown that deactivation is also possible during the redox reaction of mercury(II), copper(II) with ascorbic acid. According to adsorption data on activated carbon, a number of ions were established to reduce sorption (deactivation ability): Pb2+ (96.6%), Fe3+ (95.4%), Hg2+ (80.6%), Cd2+ (42.4%). Adsorption data complemented the results of reagent methods for studying the detoxification of metal ions.

Detection of Mercury in Skin Lightening Cosmetics Marketed in Katsina Metropolis, Katsina State, Nigeria

Deliberate use of metals as active cosmetic ingredients has been banned in many countries due to their persistent nature, toxicity and transdermal exposure over a certain period of time. Fifteen (15) samples were purposively sampled to cover the most frequently used brands as the samples for the study. The samples cover five (5) of each of the skin lightening creams, lotions and soaps from different cosmetics shops in Katsina central market and other outlets within the metropolis of Katsina. Qualitative inorganic analysis was conducted for the detection of the presence of mercury in the samples. Also quantitative analysis of the mercury was carried out using Atomic Absorption Spectrometry (AAS). The results for the qualitative inorganic analysis showed that all the samples were mercury (II) positive with 0.5N KI reagent through the formation of reddish orange precipitate, and no positive reaction of mercury was detected using 2.0N NaOH reagent. Quantitative analysis of the mercury revealed the presence of mercury in all the analyzed samples. The concentration of mercury ranged from 27.7 ± 0.0006 to 61.5 ±0. 0007 ppm. From the results obtained, it is thus evident that the analyzed samples were mercury (II) positive and above the recommended WHO permissible limit. Therefore, there may be a serious health hazard to the users of such products in Katsina metropolis. It is recommended that periodic analysis of such skin lightening products should be conducted by the regulatory bodies to ascertain their safety to the users.

Synthesis, crystal structures, and NMR (1H, 13C) spectroscopy of PdII/HgII complexes with N, S-donor thiosemicarbazone/heterocyclic-2-thione ligands

The reaction of 2-benzoylpyridine thiosemicarbazone, {(C6H5)(py-N1)C2=N2-N3H-C1(=S)-N4H2, bzpytscH}, with palladium(II) chloride in acetonitrile yielded a heteroleptic complex, [Pd(N1,N2,S-bzpytsc)Cl] (1), in which the thio-ligand coordinated through pyridyl nitrogen (N1), azomethine nitrogen (N2) and sulfur as terdentate anion (N,N,S-bzpytsc–). In another reaction, pyrimidine-2-thione (pymtH) with mercury(II) chloride in CH3CN-DMF mixture formed a homoleptic compound, [Hg(N,S-pymt)2] (2), similar to the literature report of formation of a homoleptic compound, [Hg(κ1S-pyt)2], from HgCl2 and pytH in CH3CN-DMF. A reaction of mercury(II) bromide with pyridine-2-thione (pytH) in CH3CN-DMF mixture did not remove the bromides and rather yielded a heteroleptic complex of composition, [HgBr2(κ1S-pytH)2] (3). NMR (1H, 13C NMR) spectroscopy and infrared spectroscopy of 1–4 as well as crystal structures of 1, 3, and 4 are reported.

MERCURSOLVOADDUCTS FROM 1-METHYL-2-(2-NITROPHENYL) CYCLOPROPANE AND THEIR TRANSFORMATIONS IN FLUOROSULFONIC ACID

The conjugated addition reaction of mercury (II) acetate in formic acid from the corresponding 1-methyl-2-(2-nitrophenyl)cyclopropanes was used to obtain 1-formyloxy-1-(2-nitrophenyl)-2-methyl-3-chloromercurpropanes and their transformations into fluorosulfonic acid. The interaction of these adducts with FSO3H at a kinetically controlled stage gives predominantly fluorosulfonates of chloromercuric substituted N-oxo-benz[2,1]isoxazolinium ions. As these ions are kept in FSO3H at 20 °C, their protodemercuration occurs, accompanied by the formation of fluorosulfonates of nonmetallated cyclic ions. The complete conversion of fluorosulfonates of metalated ions into non-metallated ions occurs within 84 h from the moment of dissolution of the mercuric solvent adducts in fluorosulfonic acid. In the process of studying the possibilities of synthetic use of 3-chloromercuric-substituted ortho-nitrosoacylbenzenes, it was found that these compounds can easily transform into a previously unknown class of compounds - 3-vinylbenz[c]isoxazoles, which turned out to be very promising synthons. For example, they were used in the synthesis of such hard-to-reach heterocyclic compounds as 1,4-benzodiazepin-2-one dimers, in which benzodiazepinone rings are linked through C5 atoms, and the linker is a cyclobutane ring. Taking into account the fact that the transformation of mercursol water adducts into the corresponding 3-chloromercuric substituted ortho-nitrosoacylbenzenes must proceed through cyclic ions of the benzo[2,1]isoxazolinium type, certain efforts were made to obtain evidence for their formation from 1-methyl-2-mercursol water adducts of (2-nitrophenyl)cyclopropane and 1-methyl-2-(4-bromo-2-nitrophenyl)-cyclopropane in fluorosulfonic acid. Therefore, obtaining new data on the possibilities of the formation of metalated cyclic ions from mercursolvo adducts and on their stability in solutions of strong acids, on the possibilities of isomeric transformations of these ions, as well as their transformation into non-metalated analogs due to protodemercuration, is important both from a practical and theoretical point of view. For citation: Bandaev S.G., Gulov T.Y., Murodov D.S., Kabirov D.N. Mercursolvoadducts from 1-methyl-2-(2-nitrophenyl) cyclopropane and their transformations in fluorosulfonic acid. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 6. P. 13-22. DOI: 10.6060/ivkkt.20236606.6761.

Oxidation Enhancement of Gaseous Elemental Mercury Using Waste Steel Slag under Various Experimental Conditions

In this study, the oxidation characteristics of elemental mercury were assessed based on the input gas environment, temperature, and particle size distribution of the steel slag. Experiments were performed at room temperature, 100 °C and 200 °C, under air and simulated gas environments. The oxidation reaction of elemental mercury was conducted using steel slag samples of 1 mm, 2.36 mm, and 4.75 mm at various conditions. From the basic characteristic analysis of the steel slag, it was found that the steel slag exhibits a similar composition to that of fly ash, and it can be utilized as an oxidizing agent. Results show that regardless of the temperature and the particle size distribution of steel slag, the oxidation reaction of elemental mercury rarely occurred in the air environment. However, in the case of the HCl gas environment, it was observed that the smaller the steel slag particle size, the stronger the oxidation reaction. It is believed that the oxidation efficiency of the steel slag increased as the contact area between the gas and particles increased. The oxidation reactivity was nearly two times higher in the temperature range of 100 °C to 200 °C than it was at room temperature. It is advised that further research be undertaken in order to determine the precise temperature range at which the oxidation reaction occurs.

SO2 resistance of CeO2- and Co3O4-supported activated carbon during removal of mercury from flue gas: A comparative study

How to enhance the SO2 tolerance of transition metal oxide-supported activated carbon is one of the hottest issues in the field of mercury capture from flue gas. Addition of a foreign metal ion to prepare bimetallic adsorbent is a common method of improving the SO2 tolerance of adsorbent. However, this approach suffers from high cost and a complex preparation process. In this study, CeO2- and Co3O4-supported activated carbon (m%CeO2/AC and m%Co3O4/AC), with various loading values of active center, were prepared by an incipient wetness impregnation method, and their SO2 tolerances were compared. The mercury removal performance and SO2 tolerance of both CeO2/AC and Co3O4/AC could be remarkably improved through increasing the loading amount of the active center. Co3O4/AC exhibited high affinity with SO2, and the chemisorbed oxygen in Co3O4 would be largely consumed, when SO2 was present in the flue gas, resulting in a significant decrease of mercury removal efficiency. The mercury removal efficiencies of 20%CeO2/AC, 40%CeO2/AC and 60%CeO2/AC were 86.1%, 93.7% and 93.7%, respectively, during removal of mercury from flue gas at 150 °C in the presence of SO2. 20%CeO2/AC was the optimal adsorbent for mercury capture from flue gas, owing to its excellent mercury removal efficiency, strong SO2 tolerance and relatively lower cost. The mercury species formed over spent 20%CeO2/AC were HgO and HgSO4. The HgO was generated through the reaction of mercury and chemisorbed oxygen, while the formation of HgSO4 was due to the reaction between mercury, SO2 and chemisorbed oxygen. The regeneration investigation indicated that the activity of spent 20%CeO2/AC could be almost fully recovered through a temperature-programmed decomposition and desorption process. The present study showed that the SO2 tolerance of CeO2/AC could be easily improved through regulation of the loading amount of the active center.

Crownphyrins: Metal-Mediated Transformations of the Porphyrin-Crown Ether Hybrids.

Crownphyrins are hybrid macrocycles combining structural features of porphyrin and crown ethers. The molecular architecture renders them an intriguing class of hosts capable of binding neutral, and ionic guests. The presence of dynamic covalent imine linkages connecting the dipyrrin segment with the ether chain enables unusual coordination behavior of crownphyrins, as demonstrated by the formation of two classes of strikingly different complexes. The remarkable metal-mediated expansion to the helical [2+2] macrocyclic complex is reversible. The reaction of the figure-eight mercury(II) assembly with [2.2.2]cryptand results in ring contraction providing the metal-free crownphyrin macrocycle.

Evidence against Rapid Mercury Oxidation in Photochemical Smog

Mercury pollution is primarily emitted to the atmosphere, and atmospheric transport and chemical processes determine its fate in the environment, but scientific understanding of atmospheric mercury chemistry is clouded in uncertainty. Mercury oxidation by atomic bromine in the Arctic and the upper atmosphere is well established, but less is understood about oxidation pathways in conditions of anthropogenic photochemical smog. Many have observed rapid increases in oxidized mercury under polluted conditions, but it has not been clearly demonstrated that these increases are the result of local mercury oxidation. We measured elemental and oxidized mercury in an area that experienced abundant photochemical activity (ozone >100 ppb) during winter inversion (i.e., cold air pools) conditions that restricted entrainment of air from the oxidized mercury-rich upper atmosphere. Under these conditions, oxidized mercury concentrations decreased day-upon-day, even as ozone and other pollutants increased dramatically. A box model that incorporated rapid kinetics for reactions of elemental mercury with ozone and OH radical overestimated observed oxidized mercury, while incorporation of slower, more widely accepted reaction rates did not. Our results show that rapid gas-phase mercury oxidation by ozone and OH in photochemical smog is unlikely.

Chemical Oxidation and Reduction Pathways of Mercury Relevant to Natural Waters: A Review

Mercury (Hg) pollution in the environment is a global issue and the toxicity of mercury depends on its speciation. Chemical redox reactions of mercury in an aquatic environment greatly impact on Hg evasion to the atmosphere and the methylation of mercury in natural waters. Identifying the abiotic redox pathways of mercury relevant to natural waters is important for predicting the transport and fate of Hg in the environment. The objective of this review is to summarize the current state of knowledge on specific redox reactions of mercury relevant to natural waters at a molecular level. The rate constants and factors affecting them, as well as the mechanistic information of these redox pathways, are discussed in detail. Increasing experimental evidence also implied that the structure of natural organic matter (NOM) play an important role in dark Hg(II) reduction, dark Hg(0) oxidation and Hg(II) photoreduction in the aquatic environment. Significant photooxidation pathways of Hg(0) identified are Hg(0) photooxidation by hydroxyl radical (OH•) and by carbonate radical (CO3−•). Future research needs on improving the understanding of Hg redox cycling in natural waters are also proposed.

Numerical Study on the Homogeneous Reactions of Mercury in a 600 MW Coal-Fired Utility Boiler

The homogeneous oxidation of elemental mercury (Hg0) can promote Hg pollution control in coal-fired power plants, while the mechanisms and quantitative contributions of homogeneous reactions in Hg0 oxidation, especially the reactions between Hg and chlorine (Cl), are still unclear. Here, a numerical study on the homogeneous reactions of Hg was conducted within a 600 MW tangentially fired boiler for the first time. A novel Hg sub-model was established by coupling the thermodynamics, reaction kinetics and fluid dynamics. The results showed that the higher Cl content in coal was beneficial to the oxidation of Hg0. The homogeneous reactions of Hg mainly occurred in the vertical flue pass at low temperature. Hg0 was still the dominant Hg-containing species at the boiler exit, and the concentration of mercury chloride (HgCl2) was the highest among the oxidized mercury. When low-Cl coal was fired, the addition of a small amount of chlorine species into the boiler at the burnout area increased the ratio of HgCl2 by over 16 times without causing serious chlorine corrosion problems.

Mercury (II) benzisothiazolinate (bit) complexes with diamine or phosphine co-ligands, and subsequent conversion to 2-mercaptobenzamide complexes. Crystal structures of [Hg(bit)2(L2)], L2 = bipyridine or phenanthroline

Reaction of mercury(II) acetate [Hg(Ac)2] or mercury(II) chloride [HgCl2] with two moles equivalent of Na[bit] (bit = benzisothiozolinate) afforded [Hg(bit)2] as white solid in 96 and 70% yield respectively. Treatment of [Hg(bit)2] with the bidentate ligands; 2,2-bipyridine (bipy), 1, 10-phenanthroline (phen) or ethylene diamine (en) in absolute ethanol afforded the complexes; [Hg(bit)2(bipy)], [Hg(bit)2(phen)] or [Hg(bit)2(en)] as white solids in 82–88% yields. The crystal structures of [Hg(bit)2(bipy)] and [Hg(bit)2(phen)] were determined, each showing a distorted tetrahedral geometry around mercury with the two benzisothiazolinate (bit) ligands being coordinated via nitrogen atom and lying almost perpendicular to each other. Reactions of [Hg(bit)2] with two moles equivalent of Ph3P in absolute EtOH at room temperature or one mole equivalent of 1,3-is(diphenylphosphino)propane (dppp) in boiling CHCl3, afford [Hg(bit)2(Ph3P)2] and a (2:1) mixture of [Hg(bit)2(κ2-dppp)] and [Hg(bit)2(μ2-dppp)]n. Treatment of [Hg(bit)2] with bis(diphenylphosphino)methane (dppm), afford [Hg(mbm)2] (Hmbm = 2-mercaptobenzamide), while treatment with bis(diphenylphosphino)butane afford [Hg(mbm)2(dppb)]. A sulfur-nitrogen bond breaking within the heterocyclic ring of the bit ligand took place followed by protonation of the nitrogen atom to afford the final product.

Ion exchange resin derived magnetic activated carbon as recyclable and regenerable adsorbent for removal of mercury from flue gases

Regenerable ion exchange resin derived magnetic activated carbon (Fe/AC) was prepared to remove mercury from flue gases at 120–180 °C under a high space velocity of 240000 h−1, in this study. The Fe/AC showed higher mercury removal efficiency than those of either magnetic activated carbon without activation or commercial coconut-activated carbon. The optimum temperature for removal of mercury from flue gases was determined to be 120 °C and the existence of SO2 in flue gases promoted the mercury removal efficiency of Fe/AC. Mercury compounds of HgS (metacinnabar), HgO, HgS (cinnabar) and HgSO4 were found over spent adsorbents. The HgO was generated through the reaction of mercury with lattice oxygen and chemisorbed oxygen, while the formation of HgS was due to the reaction between mercury, FeS and sulfur over the adsorbent. The lattice oxygen could oxidize SO2 to SO3, which further reacted with mercury to form HgSO4. The Fe/AC presented excellent regeneration and reuse ability, the mercury removal efficiency of which showed a great increase even after 5 runs of regeneration. The crystalline structure of Fe/AC changed remarkably after regeneration and the FeS over Fe/AC was converted to Fe3O4. The above excellent properties suggest that Fe/AC might be a promising adsorbent to remove mercury from flue gases.

Halide bridged organophosphorus complexes of HgX2 (X: I, Br and Cl): Synthesis, structure and theoretical studies

Three organophosphorus mercury (II) coordination compounds [Hg2(µ-X)2X2(PPh3)2] {X: I (1), Br (2), and Cl (3)} have been synthesized by the reaction of mercury (II) halides with triphenylphosphine. The prepared complexes were characterized by spectroscopic techniques as well as by elemental analysis. The crystal structure of [Hg2(µ-I)2I2(PPh3)2] (1) was obtained by single-crystal X-ray diffraction study. Crystal data for [Hg2(µ-I)2I2(PPh3)2], C36H30Hg2I4P2: Monoclinic, space group P21/c (no. 14), a = 19.2115(13) Å, b = 11.1291(8) Å, c = 19.0599(14) Å, β = 90.461(2)°, V = 4075.0(5) Å3, Z = 4, T = 293.15 K, μ (MoKα) = 10.657 mm-1, Dcalc = 2.336 g/cm3, 46095 reflections measured (4.23° ≤ 2Θ ≤ 49.994°), 7182 unique (Rint = 0.0563, Rsigma = 0.0365) which were used in all calculations. The final R1 was 0.0322 (I > 2σ(I)) and wR2 was 0.0780 (all data). The single crystal analysis of [Hg2(µ-I)2I2(PPh3)2] complex revealed that it has dimeric structure with bridged halides. [Hg2(µ-I)2I2(PPh3)2] complex has also a supramolecular arrangement through I···H-C interactions. The crystal packing and supramolecular features of these coordination compounds have also been studied using geometrical analysis, Hirshfeld surface analysis and DFT studies. Hirshfeld surface analysis indicated that H···H (49.3%), C···H (10.6%), and I···H (12.8%) interactions are the primary contributors to the intermolecular stabilization in the crystal. The equilibrium geometries of the studied complexes are investigated theoretically at the B3LYP/LANL2DZ level of theory. The calculated energy gap between HOMO-LUMO orbitals for complexes 1, 2, and 3 are in the trend of complex 3 > 2 > 1.

Development of a technology for immobilizing mercury in solid mercury-containing wastes

According to United Nations Environment Programme technical guidelines there are two main chemical approaches to the immobilization mercury in chemical conversion to mercury sulfide and amalgamation. This article is devoted to the development of a general approach to the wastewater-less method of mercury conversion to mercury sulfide in solid waste carried out under normal conditions. The solid-phase reaction of mercury from sulfur carried out in ball or vibration mills, is proposed to use. The article presents an original technological scheme. It was found that, for energy efficiency, the duration of the interaction of mercury-containing waste with sulfur for 1.5–2 ​h is appropriate. The remaining mercury to safe concentrations in the approach developed by the authors is to be immobilized by the addition of oxidizing agents. An original method is devoted to removing reaction masses from apparatuses, which using a homogenizing medium based on bentonite. In the paper determined the optimal concentration of GNB-30 brand bentonite in the suspension (2.5% of the weight). The optimal amount of homogenizing medium is 80% or more. Additionally, It was found that from 30 to 60% of mercury oxide can be converted to mercury sulfide with an excess of sulfur (mercury: sulfur ​= ​1: 3) and a grinding time of 1.5–2 ​h. • Development of a technological scheme for the stabilization of mercury in waste. • Dependence of the Hg 0 immobilization % at reaction with S 8 on various parameters. • Selection of the amount of bentonite and water as a homogenizing medium. • Immobilization results of HgO in reaction with S 8 .

The Reaction of (1,3,4-Oxadiazole-Thiolato) Mercury(II) with Triphenyl Phosphine

The reaction of 5-phenyl-1,3,4-oxadiazole-2-thiol with mercury(II) acetate in ethanol led to the isolation of the complex [Hg(L)2] (1). Further reaction of 1 with a twofold molar excess of triphenylphosphine led to the isolation of [Hg(L)2(PPh3)2] (2). The complex 2 was characterized by infrared, ultraviolet–visible and nuclear magnetic resonance spectroscopy techniques, as well as by X-ray diffraction analysis.

Study on the Chemical Reaction and Deposition Calculation of Mercury in the Atmosphere

The source-attribution of atmospheric mercury is one of the important issues for public health today. This paper discussed the assessment of chemical reaction and deposition of mercury in the atmosphere. The air quality model from the chemical reaction and atmospheric diffusion aspects simulated the mercury in the ecosystem. The deposition processes of mercury were divided into the near field and far field in the atmosphere. Two air quality models, ISTST and CAMx used for the simulation of mercury transport were introduced in this study. Details on the atmospheric diffusion and the gas-phase and aqueous-phase mercury chemistry mechanisms implemented in the model were presents in this paper. The uncertainty of simulation models such as the elemental mercury, aerosol mercury, oxidized mercury, dry deposition, and wet deposition was discussed. The results of this study will aid in the implementation of mercury transport model in the regional model.

One-pot synthesis, crystallographic characterization, evaluation as in vitro antibacterial and cytotoxic agents of two mercury(II) complexes containing pyridine dicarboxylic acid derivatives

Two new mercury(II) complexes (C1) and (C2) were prepared through one-pot reactions of pyridine dicarboxylic acid derivatives, aminopyridine derivatives, and mercury(II) chloride metal salt. The structures of both complexes were exactly determined by X-ray crystallography. Also, studies were done by elemental and thermal analysis, FT-IR, UV-Vis, and 1HNMR spectroscopy on them. In this research, the antibacterial effect of all compounds was evaluated against three Gram-positive bacteria namely Staphylococcus aureus, Streptococcus pyogenes and Staphylococcus epidermidis, and also three Gram-negative bacteria namely Escherichia coli, Pseudomonas aeruginosa, and Proteus vulgaris. The established antibacterial tests were including the broth microdilution method and the agar well diffusion method. S. aureus was considered as the most susceptible bacterium following treatment of the C1 (MIC=16 µg/mL, IZD=21 mm) and C2 (MIC=32 µg/mL, IZD=18 mm). Also, cytotoxicity of the compounds was studied in vitro using oxaliplatin as a standard by MTT assay against three cancer cell lines including human breast cancer (MCF7), human colon adenocarcinoma (HT29) and human lymphocyte (HL60). The strongest anti-proliferative effect of the C1 and C2 was exhibited toward MCF7 cells with IC50 values equal to 100 and 1μM, respectively.

Enhanced elemental mercury removal via chlorine-based hierarchically porous biochar with CaCO3 as template

Mercury emission from coal-fired flue gas has threatened the natural environment. It is an urgent demand for developing more effective and cheap sorbents to substitute the high-cost commercial activated carbon for removing elemental mercury. In this work, an innovative route is proposed to prepare hierarchical porous biochar via one-step co-pyrolysis of waste rice straw and polyvinyl chloride with CaCO3 as a template. The optimum material (RPC-313) delivers over 90% capture performance for Hg0 at 120 °C under 225000 h−1 of GHSV. Characterization results show that the high efficiency of this sorbent is attributed to the synergistic effect of high chlorine-containing active sites (2.02%) and the developed hierarchically pores (large specific surface area of 554.9 m2/g and pore volume of 0.6397 m3/g). It also indicates that during the preparation process, the H–Cl generated from PVC react with CC groups on the surface of bio-chars to form the C–Cl groups. The employed CaCO3 as a template creates a hierarchical structure for the sorbent. Moreover, the mercury reaction mechanism is identified as a chemisorption process which can be divided into two parts: adsorption and oxidation. An excellent mesoporous ratio (70%) accelerates mercury diffusion inside the CaCO3-activated adsorbent. And the C–Cl groups are directly beneficial for the adsorption of Hg0 according to DFT calculation. Furthermore, the C–Cl bonds and active oxygen species on the micropores surface of adsorbent act as reaction sites for oxidizing the adsorbed Hg0 into HgCl2 and HgO, respectively. The HgCl is considered as an intermediate in the reaction pathway.

Synthesis and Molecular Structure Study of New Organotellurium and Organomercury Compounds Based on 4-Bromonaphthalen-1-amine

The new organic derivatives of mercury and tellurium have been prepared by a reaction of 4-bromonaphthalen-1-amine with Hg(CH3COO)2 and further with TeBr4. Reaction of (1-amino-4-bromonaphthalen-2-yl)mercury(II) chloride with benzaldehyde then TeBr4 has produced the new aryaltellurium(IV) tribromide containing the azomethine moiety. Reaction of 4-bromo-2-(tribromo-λ4-tellanyl)naphthalen-1-amine with 4-hydroxyphenyl mercury(II) chloride gives asymmetrical diaryaltellurium(IV) dibromide. Reduction of aryaltellurium tribromide and diaryaltellurium dibromide by hydrazine hydrate leads to the corresponding diaryalditelluride and diaryaltullride. Structures of the synthesized compounds have been elucidated from FT-IR, 1H, and 13C NMR spectra. The molecular structures and energies for the compounds were also calculated according to the DFT concept.

Developing a statistical model to explain the observed decline of atmospheric mercury

Mercury is a ubiquitous environmental toxicant and a cause for global concern due to its persistence and bioaccumulation in the environment. Evaluating the effectiveness of mercury emission control has become a significant issue after the entry into force of the Minamata Convention on Mercury in 2017. Atmospheric mercury concentration is an important indicator for anthropogenic emission control. Although Eulerian models are generally applied to evaluate emission reduction and policy effectiveness, the uncertainty of mercury reaction mechanisms and the insufficient grid accuracy of simulations limit the applications of this method at particular sites. In this study, we applied a statistical approach (the Generalized Additive Model, GAM) to explain the decline of atmospheric mercury concentration in Beijing, China, which followed a trend (Sen's slope) of −0.37 ng m−3 yr−1 (−8.0% yr−1). The statistical model represented 56.5% of the variance in mercury concentration and the adjusted R2 reached 0.547. Reduction of anthropogenic mercury emission, variation in meteorological condition, and change in global background level explained 51.5%, 47.1%, and 1.4% of the decrease of air mercury concentration, respectively. We validated the results using Hg emission inventories, seasonal Hg/CO value, and meteorological data. Considering the limitations of Eulerian models and the simplicity of statistical models, we suggest the application of GAM as an assessment method for long-term variation of atmospheric mercury.