Cationic Mercury Research Articles

Syntheses and characterization of neutral and cationic cyclic (alkyl)(amino)carbene mercury [cAAC-Hg(II)] complexes

Reactions of cyclic (alkyl)(amino)carbenes, cAACMe and cAACcy with equimolar quantity of HgX2 salts afforded their corresponding halide bridged dimeric complexes, [cAACMeHgCl(μ-Cl)]2 (1), [cAACcy∙HgCl(μ-Cl)]2 (2), [cAACMe∙HgI(μ-I)]2 (3) and [cAACcy∙HgI(μ-I)]2 (4) (Me = methyl and cy = cyclohexyl). It has been possible to perform stepwise substitution of Br− in [cAACcy∙HgBr(μ-Br)]2 with NO3− leading to the isolation and characterization of the mononitrate species, cAACcy∙HgBr(NO3) (5) and the dinitrate compound [cAACcy∙Hg(NO3)(μ-NO3)]2 (6). The cationic mercury species, [(cAACMe)2Hg(NO3)]+[NO3]‒ (7) has also been synthesized by the reaction of adduct, [cAACMe∙HgBr(μ-Br)]2 with 2 eq. of AgNO3. On reaction of [cAACcy∙HgCl(μ-Cl)]2 (2) with AgClO4, only one chlorine could be substituted by perchlorate resulting in the formation of chlorine bridged dimeric complex, [cAACcy∙Hg(ClO4)(μ-Cl)]2 (8). On performing the reaction between cAACcy and HgCl2 in 2:3 relative stoichiometry, a dicationic mercury species [(cAACyc)2Hg]2+[Hg2Cl6]2‒ (9) was isolated in moderate yield.

MERCURY REDUCTASE ACTIVITY OF AN INDIGENOUS MERCURY RESISTANT BACTERIAL ISOLATE (Bacillus sp. S1) FROM KALIMAS-SURABAYA AS A POTENTIAL REDUCING AGENT FOR MERCURIAL ION (HG2+)

<p>Mercury reductase activity and Hg2+ lowering capacity of a Mercury Resistant Bacteria (MRB) (Bacillus sp. S1) which was isolated from Kalimas River of Surabaya, Indonesia were studied. The activity was determined by Mercury Reductase Assay System (MRAS) in a solution mixture contained 50 mM PBS (pH ± 7.0), 0.5 mM EDTA, 200 µM MgSO4, 0.1% (v/v) ß-merchaptoethanol, 200 µM NADH2 and 25 mg/L HgCl2 and one volume of crude extract incubated at room temperature for various interval period of time. Mercury reductase activity was measured spectrophotometrically at 340 nm. One unit of reductase activity was defined as one molar of oxidized NADH2 produced per total cell per minute. Results of study showed that, the isolate could resist the concentration of HgCl2 up to 11 mg/L. At 30 minute incubation period at room temperature, the highest mercury reductase activity and the Hg2+ lowering capacity was found to be 0.006 unit/109cell and <br />1.48 mg/L/109cell/minute, respectively with the reduction efficiency of Hg2+ to Hg0 of 0.18% per minute. Therefore, it can be concluded that the Bacillus sp. S1 isolate could be assumed to be exellent mercury bioremediation agent since it was found to be highly mercury resistant and very efficient to reduce cationic mercury (Hg2+) to elemental mercury (Hg0). </p><p><strong>Keywords</strong>: Kalimas-Surabaya, Bacillus sp. S1, Mercury resistant, Mercury reductase</p>

Selective removal of Hg(II) from aqueous solution by functionalized magnetic-macromolecular hybrid material

A new hybrid material was prepared using chitosan, glycidyl methacrylate and magnetite microparticles. The concentration of amine groups on the sorbent was increased by grafting diethylenetriamine. These materials were tested for the sorption of Hg(II) metal ions. These materials showed high affinity and selectivity for Hg(II) uptake from aqueous solutions: maximum sorption capacity reached 2.6mmolg−1 at pH 4.0. The influence of pH was tested on the selective separation of Hg(II) from a mixture of Hg(II), Co(II), Cu(II), Fe(II), Ni(II), Zn(II) and Mg(II). The effect of counter anions was also studied at different pH values. Sorption may occur by chelation of cationic mercury species on amino groups or by ion exchange of chloroanionic mercury species on protonated amino groups. Uptake kinetics and sorption isotherms were modeled using the pseudo-second order rate equation and the Langmuir equation, respectively. The distribution coefficient was obtained at different temperatures and the thermodynamic parameters have been calculated: the sorption is endothermic, spontaneous and contributes to increase the entropy of the system. Potassium iodide was used for Hg(II) desorption from loaded sorbents: desorption yields 99%, and the sorbent could be efficiently recycled for a minimum of three sorption/desorption cycles.

Donnan membrane equilibrium studies of mercury salts with Nafion-117 membrane

ABSTRACT The Donnan membrane equilibrium experiments using two compartment cell have been carried out to understand the effect of speciation on the transport behavior of mercury ion through Nafion-117 ion-exchange membrane. The mercury ions have been observed to rapidly permeate to Cl− side from Hg(NO3)2 solution, showing the extraordinary preference of mercury ions for Cl− ion in aqueous solution. On the other hand, from HgCl2 solution, slow permeation of mercury ions through the membrane has been observed. Also the transport of mercury ion from HgCl2 solution has been found to be higher than expected based on Donnan membrane equilibrium principle considering the ionic concentration of HgCl2 calculated using speciation diagram. This has been attributed to the leakage of neutral HgCl2 molecules through the membrane. The leakage of neutral HgCl2 species through Nafion-117 membrane has been confirmed in different cationic forms of the membrane. An attempt has been made to determine the concentration of cationic mercury species in aqueous HgCl2 solution using conditions of Donnan membrane equilibrium. The total cationic mercury species has been found to be higher than that predicted by speciation calculations.

Interactions of a Cationic Mercury(II) Thiolate Complex [Hg(Tab)2](PF6)2 with N-Donor Ligands

Reactions of [Hg(Tab)(2)](PF(6))(2) (1) with phen, 2,2'-bipy, py, N-Meim, N-(i)Prim, en, eten, tmen, dap, and dpt gave rise to a family of cationic mercury(II) thiolate complexes, [Hg(Tab)(2)(L)](PF(6))(2).S (2, L = phen, S = 2MeOH; 3, L = 2,2'-bipy, S = DMF), [Hg(Tab)(2)(L)(2)](PF(6))(2) (4, L = py; 5, L = N-Meim), [Hg(Tab)(2)(N-(i)Prim)](PF(6))(2) (6), [Hg(Tab)(2)(L)](PF(6))(2).0.5MeCN (7, L = en; 8, L = eten), and [Hg(Tab)(2)(L)](PF(6))(2) (9, L = tmen; 10, L = dap; 11, L = dpt). These complexes were characterized by elemental analysis, IR spectra, UV-vis spectra, (1)H NMR, and single-crystal X-ray crystallography. The Hg atom in [Hg(Tab)(2)](2+) dications of 2-5 is further coordinated either by two N atoms from one phen or 2,2'-bipy ligand or by two N atoms from two py or N-Meim ligands, affording a distorted seesaw-shaped coordination geometry. In 6, the Hg atom of the [Hg(Tab)(2)](2+) dication is coordinated by one N atom of the N-(i)Prim ligand, forming a T-shaped coordination geometry, and these [Hg(Tab)(2)(N-(i)Prim)](2+) dications are further coordinated to another S atom of Tab from the adjacent unit, giving a chain structure. The Hg atoms in [Hg(Tab)(2)](2+) dications of 7-11 are chelated by two N atoms from one diamine molecule such as en in 7, eten in 8, tmen in 9, or dap in 10 or by two N atoms from the triamine molecule dpt in 11, forming a distorted seesaw-shaped coordination geometry. In all of these structures, the original trans configuration of the [Hg(Tab)(2)](2+) dication of 1 is changed via rotation and/or switching of the two Tab species along the S-Hg-S line together with the rotation of the phenyl groups of the Tab ligands. The results may provide interesting insight into mimicking of the interactions of the Hg(Cys)(2) linear species in Hg-MerR and Hg-MT with various N-donor ligands encountered in nature and its potential changes in the structural chemistry (bond length, angles, configurations, etc.).

Dowex anion exchanger-loaded-baker’s yeast as bi-functionalized biosorbents for selective extraction of anionic and cationic mercury(II) species

Dowex anion exchanger-immobilized-baker’s yeast [ Dae-yeast] were synthesized and potentially applied as environmental friendly biosorbents to evaluate the up-take process of anionic and cationic mercury(II) species as well as other metal ions. Optimization of mass ratio of Dowex anion exchanger versus yeast (1:1–1:10) in presence of various interacting buffer solutions (pH 4.0–9.0) was performed and evaluated. Surface modification of [ Dae-yeast] was characterized by scanning electron microscopy (SEM) and infrared spectroscopy. The maximum metal biosorption capacity values of [ Dae-yeast] towards mercury(II) were found in the range of 0.800–0.960, 0.840–0.950 and 0.730–0.900 mmol g −1 in presence of buffer solutions pH 2.0, 4.0 and 7.0, respectively. Three possible and different mechanisms are proposed to account for the biosorption of mercury and mercuric species under these three buffering conditions based on ion exchange, ion pair and chelation interaction processes. Factors affecting biosorption of mercury from aqueous medium including the pH effect of aqueous solutions (1.0–7.0), shaking time (1–30 min) and interfering ions were searched. The potential applications of modified biosorbents for selective biosorption and extraction of mercury from different real matrices including dental filling waste materials, industrial waste water samples and mercury lamp waste materials were also explored. The results denote to excellent percentage extraction values, from nitric acid as the dissolution solvent with a pH 2.0, as determined in the range of 90.77–97.91 ± 3.00–5.00%, 90.00–93.40 ± 4.00–5.00% and 92.31–100.00 ± 3.00–4.00% for the three tested samples, respectively.

Application of new sol–gel electrochemical sensors to the determination of trace mercury

The aim of this work was the synthesis and characterization of new modified sol–gel carbon composite electrodes and their application to the determination of trace mercury species with positive charge. Two types of modified electrodes were synthesized, sol–gel and sol–gel-PVSA carbon composite electrodes. In the last ones, poly(vinylsulfonic acid) (PVSA) was used as a functional polymer entrapped within the sol–gel material due to its cationic exchange properties. In a first stage, parameters affecting both, the sol–gel process and the electrode preparation were optimized. In a second stage, usefulness of developed electrodes applied to the determination of cationic mercury species was evaluated, optimizing the activation, preconcentration, measurement and regeneration steps. Developed electrodes showed very favourable electroanalytical properties for their use as amperometric sensors, such as small size, low cost, simple fabrication and handling, renewability and reusability. By means of an easy and low-cost methodology, satisfactory experimental results were obtained in Hg 2+ determination. In this sense, developed analytical methodology showed adequate response times, linear concentration range up to three orders of magnitude (from 5.0 × 10 −8 to 5.0 × 10 −5 M) and detection limits of 1.5 × 10 −8 M (3.0 μg L −1). These results suggest that the incorporation of different receptor molecules at the sol–gel carbon composite material in combination with a selected electrochemical reaction could improve the detection limit achieved and obtain electrochemical sensors adapted to the determination of different species of mercury and other heavy metals.

Photoabsorption spectra of cationic mercury clusters

The experimental photoabsorption spectra of singly charged cationic mercury clusters ($\mathrm{Hg}_{N}{}^{+}$) show a sharp change in behavior at cluster size $N=6$. Both relativistic density functional theory (DFT) and wave function based methods reveal that this corresponds to a structural change from linear to three-dimensional isomers. The simulated electronic excitation spectra obtained from time-dependent relativistic DFT agree well with the experimental results. Our quantum theoretical treatment confirms the change from single electron-hole excitations in small linear clusters to plasmonlike collective transitions for the larger three-dimensional clusters.

Speciation of mercury at ng/ml concentration levels by capillary electrophoresis with amperometric detection

A technique based on capillary electrophoresis and amperometric detection (CE-AD) has been developed for the speciation of mercury. This technique has the unique capability to detect only cationic mercury species that are electrochemically active. Capillary electrophoresis with electrokinetic injection allows efficient separation of inorganic mercury and organomercury cations in 8 min. Selective detection of these electrochemically active species is attained by controlling the reduction potential applied on the micro-electrode. For Hg 2+, an optimal potential of −0.2 V can be used to prevent interference by less electroactive toxic metals and other substances found in complex environmental samples. The amperometric signal is linearly proportional to the Hg 2+ concentration over three orders of magnitude, with a detection limit of 0.2 ng/ml. The mass detection limit corresponds to 8 fg of Hg 2+ in an injection volume of 40 nl. For CH 3Hg +, the detection limit is 3 ng/ml when a potential of −0.5 V is used. These detection sensitivities are attractive for environmental monitoring of contaminated sediments in ecosystems. Steam distillation is evaluated for the extraction of CH 3Hg + from the sediment matrix. It yields an unknown mercury species which is unsuitable for CE-AD determination under the specified conditions.

Determination of Total Mercury in Soils, Waste Water and Sewage Effluents

The cationic mercury(II)-1,10-phenanthroline binary chelate reacts with the acidic dye Thymol Blue (TB), in the pH range 5.2–7.0, to form an ion-pair extractable into chloroform. The effect of primary ligand and counter ion concentrations, pH, extraction solvent, extractability, standing time and co-existing ions has been thoroughly investigated. The molar absorptivity of the ion-pair, in chloroform, is 1.27×105 l.mol−1.cm−1 at 420 nm. The calibration graph is rectilinear for 0.09–1.72 μg ml−1 of mercury. The sensitivity index of the method is 0.0002 μg Hg.cm2– and the detection limit is 0.018 μg ml−1 of mercury. The stoichiometry of the extracted ion-pair is 1:2:1 (Hg-Phen-TB). The developed method has been successfully used to determine total mercury in soils, waste water and sewage effluents.

An electrospray mass spectrometric study of some mercury phosphine complexes

Electrospray mass spectra have been obtained for a number of cationic mercury phosphine systems and mixtures thereof in methanol solution. Complexes of the type Hg(PR 3) 2X 2 (PR 3=monodentate phosphine; XClO 4, CF 3COO) all give peaks in their electrospray mass spectra corresponding to the principal ion [Hg(PR 3) 2X] +, although with the perchlorates the base peak is due to [Hg(PR 3) 2(CH 3COO)] +, the acetate being present in the mobile phase used in the spectrometer. Many of these systems are known to be labile on the NMR timescale at room temperature, but they all give good electrospray mass spectra at room temperature and for the rapidly exchanging mixtures all of the individual cationic species are observed. Addition of free phosphine leads to the formation of the tris(phosphine) complexes in solution and the principal ions [Hg(PR 3) 2X] + are observed in the electrospray mass spectra. Collisionally activated decomposition (CAD) mass spectra, both within the ion source and in MS/MS experiments, show that the tris(phosphine) complexes very readily lose one phosphine, thus demonstrating the mechanism of phosphine exchange in these systems.

Mercuric reductase activity in the adaptation to cationic mercury, phenyl mercuric acetate and multiple antibiotics of a Gram-negative population isolated from an aerobic fixed-bed reactor

Eighty-eight strains, isolated from an aerobic fixed-bed reactor and identified to the genus level, were examined for resistance to 21 antibiotics, cationic mercury and phenylmercuric acetate. All except three were able to grow on Mueller-Hinton agar plates containing 8 micrograms/ml mercuric chloride, but only 42 exhibited a mercuric reductase and an organomercurial lyase activity. Furthermore, 82 of them were multiply-antibiotic resistant, whereas no positive correlation between this property and cationic mercury volatilization capacity was found. It was concluded that this bacterial community-adapted response to these selective agents, which has been most often shown to be mediated by R plasmids, was the result of two independent phenomena. Moreover, the high percentage of multiple antibiotic and mercury resistance found in this population suggested that simultaneous selections occurred on filters of bacteria which exhibited mucoid colonies and tolerance to these two categories of stress agents.

ChemInform Abstract: PHOSPHORUS‐31 AND MERCURY‐199 NMR MEASUREMENTS OF CATIONIC MERCURY PHOSPHITE COMPLEXES

Chemischer InformationsdienstVolume 14, Issue 52 Physical Organic Chemistry ChemInform Abstract: PHOSPHORUS-31 AND MERCURY-199 NMR MEASUREMENTS OF CATIONIC MERCURY PHOSPHITE COMPLEXES P. PERINGER, P. PERINGERSearch for more papers by this authorD. OBENDORF, D. OBENDORFSearch for more papers by this author P. PERINGER, P. PERINGERSearch for more papers by this authorD. OBENDORF, D. OBENDORFSearch for more papers by this author First published: December 27, 1983 https://doi.org/10.1002/chin.198352046Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue52December 27, 1983 RelatedInformation

Phosphorous-31 and mercury-199 NMR measurements of cationic mercury phosphite complexes

Spectre RMN de 31 P et 199 Hg des complexes [HgX 2 {P(OR) 3 } n ] avec X=Cl, I R=Et n=1,2 et du complexe cationique [Hg(P(OR) 3 ) n ] 2+ avec n=1 a 4

Thiopyrazolone derivatives as analytical reagents. XVI. Extraction-spectrophotometric determination of trace of mercury by ternary complex formed from mercury(II) and thiopyrine in the presence of eosine.

When an aqueous solution containing mercury (II), thiopyrine and eosine was shaken with 1, 2-dichloroethane at pH 10, an ion pair formed from cationic mercury (II)-thiopyrine complex and anionic eosine was extracted into the organic phase. Based on this reaction, a sensitive extraction-spectrophotometric determination method for trace of mercury was established by the absorbance measurement at 540 nm. This method is applicable to the determination of mercury less than 2.5 μg/ml. Various common cations and anions except for silver (I) and iodide did not interfere the determination practically. Molar ratio of mercury (II) to thiopyrine and eosine was found to be 1 : 2 : 1 by the continuous variation method.

On the Hg(II)-induced demethylation of methylcobalamin

Using conventional and stopped-flow kinetic techniques, the Hg(II)-induced dealkylation of methylcobalamin was studied in the three solvents (a) chloride, unbuffered, (b) acetate, buffered, and (c) water, unbuffered, in an attempt to gather information as far as the participation of the 5,6-dimethyl-benzimidazolyl (DMBz) moiety of the coenzyme in the reaction is concerned and also to gain insights into the chemical nature of the Hg(II) entity attacking CH 3B 12. In solvents (a) and (b), the transfer of the methyl group from the central cobalt atom to Hg(II) was found to occur without cleavage of the DMBz-cobalt coordinate bond thereby dispelling the notion, maintained by some, that (in acetate) displacement of DMBz from methylcobalamin occurs as a prerequisite to methyl transfer. The rate constants, pertaining to the group transfer in the two solvents, were evaluated. Demethylation proceeds rapidly in acetate but slowly in chloride. In water, appropriate concentrations of cationic mercury, Hg *(II)  Hg 2+ + Hg(OH) +, will displace DMBz from the central cobalt atom. Group transfer, therefore, involves here methylcobalamin which is primarily in the so-called “base-off” form. Its rate of dealkylation was determined. Also determined were the rates of the interconversion reaction CH 3B 12 + Hg *(II) ⇌ CH 3B 12Hg, where CH 3B 12 denotes methylcobalamin with DMBz coordinated to cobalt and where CH 3B 12Hg is the configuration in which DMBz is removed from coordination as a result of complexing with Hg *(II). The experimental findings pertaining to acetate as a solvent are discussed in relation to what is known from the literature and agreements as well as discrepancies are noted.