HgII Ions Research Articles

2-Mercaptoimidazole Covalently Bonded to a Silica Gel Surface for the Selective Separation of Mercury(II) from an Aqueous Solution

Silica gel with a specific surface area of 365 m2·g−1 and an average pore diameter of 60 Å was chemically modified with 2-mercaptoimidazole. The degree of functionalization of the covalently attached molecule, (≡SiO)3(CH2)3—MI, where MI is the 2-mercaptoimidazole bound to the silica surface by a propyl group, was 0.58 mmol·g−1. In individual metal adsorption experiments from aqueous solutions by the batch procedure, the affinity order was HgII « CdII > CuII ∼ ZnII ∼ PbII > MnII at solution pHs between 4 and 7. Due to the high affinity by the sulfur atom, HgII is strongly bound to the functional groups. When solution containing a mixture of HgII, CdII, CuII, ZnII, PbII, and MnII ions was passed through a column packed with the adsorbent, HgII was the only one whose adsorption and elution was not affected by the presence of other ions.

Simultaneous determination of mercury and arsenic by anodic stripping voltammetry

AbstractAn electrochemical method for the simultaneous determinations of HgII concentration and total AsIII and AsV concentration has been developed. The method does not require the additional preliminary step of the chemical reduction of AsV to AsIII, or oxidation of AsIII to AsV before stripping analysis takes place. Also, the method for the simultaneous determination of HgII concentration and AsIII concentration is described. Measurements were performed in 0.1 M HCl using a gold‐plated graphite electrode as sensor. Detection limits for both methods are below 0.4 ppb. Relative standard deviation did not exceed 15%. The possible interference by other trace metals was investigated. Analyses of natural water and industrial solutions were made using proposed methods and AAS. The t‐test demonstrates that there was no significant difference between the results obtained with these methods. Proposed methods decrease the time of analysis because concentrations of the HgII and arsenic ions were measured simultaneously. Also, the removal of the additional step of chemical reduction of AsV to AsIII or oxidation of AsIII to AsV decreases analysis time, and also reduces the chance of contamination due to the use of additional reagents.

Mercury(II) Selenite Hemihydrate

The title compound, dimercury [bis(trioxoselenate(2-)]monohydrate, Hg2(SeO3)2.H2O, contains two inequivalent HgII ions with coordination numbers of five and seven. The coordination polyhedra of these ions are a tetragonal pyramid and a monocapped trigonal prism respectively. One of the two inequivalent selenite groups bridges three HgII ions and the other bridges four HgII ions, thus forming a structure extending in three dimensions.

Amminemercury(II) Selenite

The title compound {amminemercury(II) trioxoselenate(IV), [HgNH3SeO3} has a structure comprising of corrugated edge-sharing chains of HgNO5 octahedra and SeO3 pyramids. The chains are apparently held in position by hydrogen bonds. The octahedra are 2 + 4 distorted. The selenite group exhibits one significantly differing Se—O bond length involving an O atom coordinated to three HgII ions.

Sequence-selective interaction between mercury(II) ions and the DNA dodecamer [d(GCCGATATCGGC)]2 studied by 1H NMR spectroscopy.

The palindromic dodecamer [d(GCCGATATCGGC)]2 has been titrated by Hg(ClO4)2 in order to study sequence dependent HgII ion interactions. The titration pattern as monitored by 1D and 2D 1H NMR is consistent with a transition to a new conformer of the dodecamer induced by HgII ions. At intermediate stages of the titration, the proton signals from the new conformer coexist with those of the original one, indicating slow exchange between the two forms on the NMR timescale. The data clearly show that there is no major alteration in the secondary structure, e.g. B-->Z-form or duplex-->hairpin transition. The intra- and inter-residue sequential walk is completed except for a break between T6 and A7. At a concentration level r = [HgII]/[nucleobase] < 0.20 all four central imino signals are present. This definitely excludes thymine N3 as a possible mercuration site. In the imino region of the spectra HgII ions induce a large upfield shift of the thymine imino resonance T8-N3H, while the other thymine resonance T6-N3H is unperturbed. The guanine imino signal G4-N1H shows a large downfield ring current shift caused by major conformational changes in the duplex. The complete titration experiment indicates that mercury, initially, binds selectively to the A5'-T8 base pair. A tentative model is proposed where mercury is cross-linking the two strands via thymine T8-O4 and the deprotonated amino group of the complementary adenine base A5'.

Determination of mercury and silver at a modified carbon paste electrode containing glyoxal bis(2‐hydroxyanil)

AbstractModified carbon paste electrodes(CPEs) for the analysis of mercury and silver have been constructed by incorporating a Schiff base, glyoxal bis(2‐hydroxyanil) (GHA) into the graphite powder and mixing with Nujol oil. Simple immersing of the GHA‐modified CPE into the measuring solution led to the chemical deposition of the metal ions onto the electrode. The cyclic, differential pulse, and stripping voltammetry were used to characterize the modified electrodes, which selectively responded to the mercury(II) and silver(I) ions. The analyses of Hg and Ag were carried out separately with the CPE in the acetate buffer and neutral aqueous solution. The electrode surface was regenerated after each measurement, by cycling the potential from more positive than that for the stripping of the reduced Hg to the more negative than that for the reduction of AgI ion. After seven deposition/measurement/regeneration cycles, the peak current of the analyte decreased. The response reproduced around 5% relative standard deviation using the differential pulse stripping voltammetry. The detection limits for HgII and AgI ions were 1.0 × 10−9 M and 1.0 × 10−10 M, respectively, for 40 min of deposition. After pretreatment of silver(I) ion with KCl, we could not observe any interference by other metal ions in the determination of the HgII ion in aqueous solution. Our results obtained in the determination of mercury are verified using a certified standard urine reference material, SRM's 2670 (trace elements in urine).

Speciation of inorganic mercury ions using bacterial cells

The adsorption of soluble inorganic mercury ions from aqueous solutions on the external membrane of both lyophilized bacterial cells and living cells was studied as a function of solution pH, adsorption time, amount of adsorbent, concentration of mercury ions, and sample volume. Desorption studies were also performed using also both types of cells. Loaded membranes and the amount of the unadsorbed ions were measured by electrothermal atomic absorption spectrometry (ETAAS) and/or gamma spectrometry. The 203Hg radiotracer (t1/2= 46.6 d) was used to monitor recoveries in gamma spectrometry. The adsorption process was adapted to develop a method for the speciation of the HgII and HgI ions. Speciation is possible because mercury ions can be selectively retained by the bacterial external membrane depending on the solution pH.

Reaction of mercury(II)-thiosalicylate complex with picolinic acid and ultraviolet spectrophotometric determination of mercury(II)

The monothiosalicylate complex of mercury(II) reacts with picolinic acid (PIC) to form a ternary complex which has an absorption maximum at 295 nm in 50%V/V ethanol-water in the pH range 6.3–7.5. Beer's law is obeyed up to a 20.15 µg ml–1 concentration of HgII. The molar absorptivity of the ternary complex is 0.86 m2 mol–1 at 295 nm and the sensitivity for the HgII ion is 5.2 × 10–3µg cm–2 per 0.001 absorbance unit. The composition of the ternary complex is estimated to be Hg(TSA)(PIC). A number of ions which interfere with the determination could be masked by the addition of EDTA or fluoride ions as masking agents. Further information on the complex-forming equilibria and stability of the HgII ternary complex was obtained by potentiometric titrations at 20 ± 0.1 °C and 0.1 M(NaClO4) ionic strength.

Anodically generated mercury(II) ion as an indicator for metal–ligand formation equilibria

In the presence of solute species which complex with HgII ions, the polarographic anodic dissolution wave for mercury is displaced towards more negative potentials relative to the value shown in non-complexing media. Competition for a ligand between anodically generated HgII ions and other metal ions added to a solution may be used to calculate formation equilibrium data for mononuclear complexes of the latter species. These principles have been exemplified by investigation of the interaction between the cadmium ion and the analytical masking agents thiourea and thiosulphate ion.

ChemInform Abstract: REACTIONS OF METHYLMERCURY(II), MERCURY(II), AND ZINC(II) IONS WITH 2‐METHYL‐2‐(2‐PYRIDYL)THIAZOLIDINE, INCLUDING STOPPED‐FLOW RAPID‐SCANNING SPECTROPHOTOMETRIC STUDIES

AbstractDie sich zwischen der Titelverbindung (I) u:nd Methyl‐Hg‐chlorid‐ oder ‐acetat, Hg‐perchlorat, Zn‐perchlorat oder ‐acetat bildenden Gleichgewichte werden 1H‐ und 13C‐NMR‐ sowie UV‐spektroskopisch untersucht.

Reactions of methylmercury(II), mercury(II), and zinc(II) ions with 2-methyl-2-(2-pyridyl)thiazolidine, including stopped-flow rapid-scanning spectrophotometric studies

Equilibrium studies of the reactions of 2-methyl-2-(2-pyridyl)thiazolidine (A) with [HgMeX](X = Cl, MeCO2), HgII and ZnII ions have been investigated by 1H and 13C n.m.r. and by u.v. spectrophotometry, and kinetic studies of the reactions with HgII and ZnII ions by stopped-flow rapid-scanning u.v. spectrophotometry. The n.m.r. results show that opening of the thiazolidine ring occurs with the loss of a proton, to give thiolate-bound Schiff-base chelates. In the absence of buffer, the reaction with [HgMeCl] also gives a second species in which the thiazolidine ring is not opened, and addition of acetate buffer causes this minor species to deprotonate and convert to the ring-opened product. Kinetic studies using HgII reveal a single, very rapid reaction, close to the limits of stopped-flow detection, and approximately first order in [HgII]. Two distinct kinetic stages are apparent in the reaction with zinc(II) perchlorate in methanol solution, the first stage attributed to metal binding and the pH-dependent second stage to the opening of the thiazolidine ring. Using zinc(II) acetate the first stage is too rapid for stopped-flow detection, but the second stage is kinetically simpler because of the buffering effect of the acetate ions.

Encircling of mercury(II) by a macrocyclic ligand: X-ray crystal structure of 1,5,9,13-tetrathiacyclohexadecanemercury(II) perchlorate

The crystal structure of the most stable complex involving HgII co-ordinated to a macrocyclic tetrathia-ether (1,5,9,13-tetrathiacyclohexadecane) reveals that the HgII ion is situated almost in the centre of the four sulphur donor atoms, which themselves are twisted somewhat out of plane, with the inner co-ordination sphere being completed by two unequally bonded perchlorate ions situated along the z axis.

Kinetics of the reactions of saturated hydrocarbons with PdII, PtII?IV, HgII, CrVI, MnIII, MnIII-RuIII-IV, NO2 +, H2SO4, H2S2O8, and carbonium ions in sulfuric acid

Kinetics of the reactions of saturated hydrocarbons with PdII, PtII?IV, HgII, CrVI, MnIII, MnIII-RuIII-IV, NO2 +, H2SO4, H2S2O8, and carbonium ions in sulfuric acid

Struktur des Hexarhodano(II)‐di‐quecksilber(II)‐Benzol‐Komplexes

AbstractThe crystal structure of the pink complex of benzene with hexa‐thiocyanato‐cobalt(II)‐dimercury(II), [CoHg2(SCN)6, C6H6], has been determined by X‐ray analysis. Layers of the composition CoHg2(SCN)6 are separated by benzene molecules. The CoII ions are coordinated octahedrally by N, the HgII ions by four S atoms in a very distorted tetrahedral arrangement in which two of the S atoms form mercury bridges, magnified image. Each benzene molecule lies between two Hg atoms, the shortest HgC distances being about 3·6 Å. The stability of the complex is discussed in terms of polarization binding between benzene and HgII.