Pure Hg Research Articles

Mercury speciation in highly contaminated soils from chlor-alkali plants using chemical extractions.

A four-step novel sequential extraction procedure (SEP) was developed to assess Hg fractionation and mobility in three highly contaminated soils from chlor-alkali plants (CAPs). The SEP was validated using a certified reference material (CRM) and pure Hg compounds. Total, volatile, and methyl Hg concentrations were also determined using single extractions. Mercury was separated into four fractions defined as water-soluble (F1), exchangeable (F2) (0.5 M NH4Ac-EDTA and 1 M CaCl2 were tested), organic (F3) (successive extractions with 0.2 M NaOH and CH3COOH 4% [v/v]), and residual (F4) (HNO3 + H2SO4 + HClO4). The soil characterization revealed extremely contaminated (295 +/- 18 to 11 500 +/- 500 mg Hg kg(-1)) coarse-grained sandy soils having an alkaline pH (7.9-9.1), high chloride concentrations (5-35 mg kg(-1)), and very low organic carbon content (0.00-18.2 g kg(-1)). Methyl Hg concentrations were low (0.2-19.3 microg kg(-1)) in all soils. Sequential extractions indicated that the majority of the Hg was associated with the residual fraction (F4). In Soils 1 and 3, however, high percentages (88-98%) of the total Hg were present as volatile Hg. Therefore, in these two soils, a high proportion of volatile Hg was present in the residual fraction. The nonresidual fraction (F1 + F2 + F3) was most abundant in Soil 1 (14-42%), suggesting a higher availability of Hg in this soil. The developed and validated SEP was reproducible and efficient for highly contaminated samples. Recovery ranged between 93 and 98% for the CRM and 70 and 130% for the CAP-contaminated soils.

Electron concentration and phase stability in binary alloys in–pb and hg–sn under high pressure

High-pressure diffraction studies of binary alloys provide information on what factors control the formation of solid solutions and intermetallic phases, their composition ranges and crystal structure. We have investigated effects of pressure on binary alloys In–Pb with 10, 15 and 22 at.% Pb and Hg–Sn of equiatomic composition with diamond anvil cells using synchrotron radiation up to pressures of 30 GPa under pressure, In–Pb alloy with 10 at.% Pb undergoes a phase transition from one face-centred tetragonal (fct) phase to another fct phase through a two-phase co-existence region from 7 to 20 GPa, with a discontinuous jump in the axial ratio c/a from > 1 to < 1. The α-Hg phase with a rhombohedral distortion of a face-centered cubic structure, known to be stable only up to 3.7 GPa in pure Hg, is found here to be stabilised by the alloying of 5–10 at.% Sn up to pressures of at least 30 GPa. This rhombohedral phase, hR1-(Hg), reveals strong anisotropy on compression with an increase in c/a from 1.99 to 2.25 in the pressure range of its stability from 2.6 to 29.9 GPa. Tetragonal distortions in the In–Pb alloys, stabilisation of the hR1-(Hg) phase by alloying Hg with Sn and range of solubility of Sn in α-Hg are discussed within the concept of the Brillouin zone–Fermi sphere interactions.

Hg-Ir (Mercury-Iridium)

Experimental information about the Hg-Ir system is sparse but it is sufficient to sketch an assessed phase diagram. [Moffatt] presented the low-temperature part of the diagram at constrained pressure. In this evaluation we present the phase relationships at 0.101 MPa in Fig. 1. Since the melting point of Hg (−38.8290 °C) [ITS-1990] is not measurably shifted by the presence of Ir, it may be concluded that the solids are almost completely immiscible. Virtually pure (Ir) is in equilibrium with virtually pure liquid Hg up to the boiling point of Hg (356.623 °C) and gaseous Hg is in equilibrium with almost pure Ir up to the melting point of Ir (2447 °C) [Massalski2]. [Moffatt]’s version of the diagram is similar to that shown in Fig. 1, except that the liquid, instead of the gas, is present above the boiling point of Hg. Hg may maintain as liquid up to its critical point (1492 °C and 151 MPa) [1992Gum]. [1956Str] attempted to determine a solubility of Ir in liquid Hg at room temperature by chemical analysis of filtrate of the saturated amalgam; its content in Hg was below the analytical detection limit of 0.001 at.% Ir. [1973Jan] performed similar experiments at 500 °C at a sensitivity level of 10 at.% Ir, and also, no Ir was found in the filtrate as a result of spectrophotometric analysis. [1989Gum] predicted the solubility at 25 °C based on a regular solution model (1 × 10 at.% Ir) and the cellular model of Miedema et al. [1983Nie] (2 × 10 at.% Ir). While the predictions are disparate, both indicate values far below detectability. Experimental corroboration comes from [1964Rhy] who found no attack on Ir by liquid Hg after the equilibration for 168 h at 550 °C and from [1987Kou], who observed no detectable solubility of Ir in Hg during electroanalytical measurements at room temperature. No interaction between the metals was observed in x-ray diffraction (XRD) studies of [1973Jan1] and [1981Sut], in the corrosion investigations by [1964Rhy], thermogravimetry by [1995Fer, 2002Fer], scanning electron microscopy [1995Fer, 1998Nol, 2002Fer], atomic force microscopy [1998Nol], energy dispersive x-ray microanalysis [1995Fer, 2002Fer], x-ray photoelectronic spectroscopy of amalgamated Ir as well as Ir-Pt surfaces by [1999Fer], nor in electroanalytical experiments of Hg redox processes on Ir electrodes by [1981Sut], [1986Kou], [1987Kou], [1998Nol], [1999Fer], and [1999Fer]. The effect of incomplete removal (∼95% efficiency) of electrodeposited Hg from Ir surface observed by [2003Mil] seems to be rather related to an interaction of Hg with Ir oxide than to any Hg-Ir interaction with formation of an intermetallic compound or a concentrated solid solution of Hg in Ir. In an attempt to determine Hg solubility in solid Ir, [1973Jan2] equilibrated Ir powder with Hg in a quartz ampoule at 800 °C for 350 h. The lattice

The Hg—Rh (Mercury‐Rhodium) System

AbstractFor Abstract see ChemInform Abstract in Full Text.

Liquid metals as electrodes in polymer light emitting diodes

We demonstrate that liquid metals can be used as cathodes in light emitting diodes (pLEDs). The main difference between the use of liquid cathodes and evaporated cathodes is the sharpness of the metal–polymer interface. Liquid metal cathodes result in significantly sharper metal–organic interfaces than vapor deposited cathodes, due to the high surface energy of the metals. The sharper interface in pLEDs with liquid metal cathodes is observed by neutral impact collision ion scattering spectroscopy and low energy ion scattering spectroscopy measurements. The influence of interface sharpness on device performance was studied by comparing current–voltage-light characteristics of devices with OC1C10 paraphenylenevinylene (PPV) as electroluminescent polymer and indium tin oxide (ITO) as hole injection electrode, and different cathodes. Comparison of devices using a liquid Ga cathode and an evaporated Al cathode showed that light emission for the liquid Ga cathode is two orders of magnitude larger than for the evaporated Al cathode, and that the external light efficiency is increased by an order of magnitude. Since the work function of Ga and Al is nearly the same, the poor performance for evaporated Al LEDs is attributed to the formation of an interfacial layer where Al has diffused into, and reacted with, the PPV. This interfacial layer has poor electrical conduction compared to pure PPV, and contains quenching sites which reduce light emission. Low work function liquid metal cathodes were studied by using liquid Ca and Ba amalgams. The improved performance of liquid amalgam pLEDs is attributed to the different structure of the metal–polymer interface. The enormous increase in light and current through the amalgam devices compared to those using pure Hg demonstrate that less than 1 ML of a metal with a low work function at the polymer-cathode interface can have a dramatic effect on the performance of the devices. Devices with a liquid Ca amalgam cathode showed an increase of the current (by 50%) and brightness (80%) compared to devices with an evaporated Ca cathode, which is ascribed to reduced diffusion of Ca into the emissive PPV layer.

The Hg-Rh (Mercury-Rhodium) system

Rh interacts with Hg to form stable intermediate phases. By combining data from several investigations, [1967Jan] constructed a phase diagram for pressures sufficiently high to retain Hg in condensed form. This diagram, with slight modification by the present author, is depicted in Fig. 1. The diagram in Fig. 2 is based on the same data and shows equilibria that would be expected at a pressure of 0.1013 MPa (1 atm). The invariant temperatures of both the higher pressure version and the ambient pressure version of Hg-Rh phase relationships are listed in Tables 1 and 2, respectively. These temperatures were estimated from the vapor pressure equations reported in [1967Jan] (for the equations, see Thermodynamics Section, Table 5); however, because of uncertainties in the logarithms of the vapor pressure data, the resultant invariant temperature values are unlikely to have precisions of better than 10%. Thus, the apparent inversions of the order between the decomposition temperatures of Hg5Rh and Hg4.63Rh in Fig. 1 and 2 may or may not be significant. Likewise, no difference between the melting points of pure Hg and Hg saturated with Rh is experimentally detectable; so whether the invariant equilibria between Hg and Hg5Rh is characterized by a peritectic or eutectic reaction is a meaningless discussion. An initial determination of Rh solubility in liquid Hg was made by [1956Str] by chemical analysis of the saturated filtrate. A value of 0.31 at.% Rh at room temperature was obtained. A later determination by [1973Jan1] reported a value of 1 × 10 at.% Rh at 500 °C. The determination again was made by analysis of the saturated filtrate, but the analysis was done spectroscopically after the Sn was added and then the Hg was evaporated. This latter analysis is believed to be more reliable than the former. [1971Ale] used residual resistivity measurements to estimate a value of <2 × 10 at.% Rh dissolved in solid Hg at −40 °C. In addition, estimates of the Rh solubility in liquid Hg are quite low, with [1964Koz] estimating a value of ∼10 at.% Rh at 25 °C from a semiempirical Schroeder-like formula and [1989Gum] estimating a value of 1.5 × 10 at.% Rh at 25 °C from the Miedema cellular model [1983Nie]. The lack of a meaningful shift in the melting temperature of Hg as well as its vapor pressure at 400 °C [1967Jan] upon Rh saturation also indicates a low Rh content of the Hg-rich solvus. From the presently available evidence, solvus compositions of the order of 10 at.% Rh or less as found by [1973Jan1] and [1971Ale] seem reasonable for either solid or liquid Hg. X-ray powder diffraction (XRD) studies have been performed on alloys in the Hg-Rh system [1967Ett, 1967Now, 1967Jan, 1976Gri, 1980Gri]. [1967Ett, 1967Now] reported

Determination of Coster–Kronig transition probabilities (L1 → L2, L1 → L3 and L2 → L3) for Hg and Bi in molecules

AbstractThe f12, f13 and f23 Coster–Kronig (CK) transitions (that is L1 → L2, L1 → L3 and L2 → L3 transitions) in Hg and Bi in molecules were studied at 59.5 keV excitation energy using an Si(Li) detector. A change in the CK transition probabilities was observed for different molecules. The change in the values for Hg compounds were greater than those for Bi compounds. Because we did not have pure Bi in the laboratory and also were not able to have specimen preparation conditions for pure Hg, we did not obtain experimental values for elemental Bi and Hg. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Synthesis and superconductivity study for (Hg,M)-1222 phase (M=W, Mo, V, Cr, Ti)

Hg-based (Hg,M)-1222 cuprates (Hg 0.75M 0.25)Sr 2(Gd 1.5Ce 0.5)Cu 2O z (M=W, Mo, V, Cr, Ti) have been synthesized using the precursor Sr 2(Gd 1.5Ce 0.5)Cu 2O z prepared by solid state reaction and citrate sol–gel process, respectively. X-ray powder diffraction indicates that the samples prepared by sol–gel process have better crystallization comparing with the solid state reaction. The citrate sol–gel process was improved by using diffluent Ce(NO 3) 3 to replace CeO 2 which is almost insoluble in nitric acid and pure (Hg,M)-1222 phase was obtained. Superconductivity was observed in the (Hg 0.75M 0.25)Sr 2(Gd 1.5Ce 0.5)Cu 2O z phase with M=W, Mo. Annealing under high oxygen pressure has apparently decreased the resistivity and improved T c for (Hg,M)-1222 (M=W, Mo) samples.

Mg(NH3)6Hg22, a Mercury Intercalation Compound

Very pure Mg dissolves in liquid NH3 with a blue color. Attempts to isolate solid Mg(NH3)x were not met with success. MgHg alloy reacts with liquid NH3 with formation of Mg(NH3)6Hg22, as established by a single-crystal structure determination. The octahedral Mg(NH3)6 units have Mg−N distances typical for Mg(NH3)62+. They are embedded in layers into cavities of the mercury metal matrix, resulting in a layered structure. Tc of this superconducting material is 3.6 K, which is lower than that of pure Hg (4.19 K).

Competition between Surface Layering and Surface Phase Formation in Dilute Liquid Hg−Au Alloys

We present temperature-dependent X-ray reflectivity measurements of liquid Hg alloyed with 0.06−0.20 atom % Au. At low Au concentrations, we find temperature-dependent surface-induced layering similar to that observed in pure Hg, except that the presence of Au reduces the layering amplitude. Upon approaching the solubility limit of Au in Hg, a new surface phase forms which is 1−2 atomic diameters thick and has a density of about half that of bulk Hg. We present a surface phase diagram, summarizing the evolution of this unexpected surface structure upon varying composition and temperature. Such surface modifications may account for the variations observed in catalytic and electrochemical reactions at liquid metal surfaces upon alloying.

Magnetization and relaxation in Hg-1223: bulk vs. surface irreversibility, anisotropy and the influence of Re-doping

Particle-size fractionization is used to separate bulk and surface hysteresis in pure and Re-doped Hg(15%)-1223. Re-doped samples have smaller surface barriers and higher bulk current densities than undoped Hg-1223. Neutron-irradiated samples exhibit practically no surface barrier effect. A `pinning roughness' model is suggested to unify the observations. The fractionization technique is extended to relaxation of magnetically aligned Hg-1223. In wide temperature regions, both surface and bulk currents do relax. However, near the irreversibility temperature, bulk currents decay to zero, whereas surface relaxation continues. Relaxation is a complex interplay of bulk/surface effects, which subsequent investigations in this field must regard. From magnetization measurements on magnetically oriented samples, anisotropy parameters are estimated to γ≈9±3 (Hg-1223) resp. γ≈4.5±2 (Hg(15% Re)-1223). This is a very drastic effect of Re-doping on the superconducting properties of Hg-1223.

Mercury in the HgMn Stars χ Lupi and HR 7775

Observations of mercury lines in the HgMn stars chi Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In chi Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure (204)Hg). Strong ionization anomalies are present, with UV Hg I lines being too weak and Hg III lines too strong for the abundance derived from lines of the majority ionization state, Hg rr. Observations of mercury in I;IR 7775 show less extreme isotope and ionization anomalies. We find that the ionization anomaly in the Hg I resonance lines can be plausibly explained as a non-LTE effect, but the same non-LTE calculations show that the Hg III ionization anomaly in chi Lupi cannot be explained in this way. Radiative force calculations show that the observed mercury abundance cannot be supported in the atmosphere by the radiative forces alone. We suggest that weak mixing brings mercury into the line-forming region from below the photosphere, while a wind of order 10(-14) M. yr(-1) supports a cloud of Hg III at very small optical depths. (Less)

Recovery of HgCl2 Using Polyaminated Highly Porous Chitosan Beads. Effect of Salt and Acid.

Adsorption of Hg(II) on polyaminated highly porous chitosan (PEI-CS) from washing solutions of refuse incinerator flue gases is technically feasible. Equilibrium isotherms for adsorption Hg(II) on PEI-CS were measured by a batch method. The experimental data correlate well with the Langmuir equation in the range of about 5 to 70 mol/m3 Hg(II) aqueous solution. When HCl exists in Hg(II) solution, the saturation capacity and equilibrium constant for adsorption of Hg(II) on PEI-CS decrease with increasing concentration of HCl, CHCl. When NaCl is in Hg(II) solution, the equilibrium constant is constant, but the saturation capacity decreases with an increase in the concentration of NaCl. Breakthrough curves for adsorption of 10 mol/m3 Hg(II) were measured using a PEI-CS packed column at Re′ = 5. The intraparticle effective diffusivities Deff of Hg(II) are determined from the experimental breakthrough curves. When HCl exists in Hg(II) solution, Deff increases with increasing C0, HCl when C0, HCl 180 mol/m3, it shows a constant value, which is about 8 times larger than that measured in pure Hg(II) aqueous solution. When NaCl is in Hg(II) solution, the shapes of the breakthrough curves are similar to those in pure Hg(II) solution. Deff is kept constant in the range of 0 ≤ C0, NaCl ≤ 1000 mol/m3.

In vitro cytotoxicity of amalgams made with binary Hg-In liquid alloys

Objective. Mercury vapor release from amalgams during setting significantly decreases when the amalgams are prepared with binary Hg-In liquid alloys. The objective of this study was to compare the cytotoxicity of amalgams made with experimental Hg-In alloys with that of amalgam without In and a commercial In-containing amalgam. Methods. Amalgam specimens were prepared by triturating a high-Cu alloy powder (Tytin, Kerr) with pure Hg or Hg-In liquid alloy containing 5, 20 or 50% In and also by triturating an In-containing high-copper alloy powder (Indiloy, Shofu) with pure Hg. After the specimens were aged for 2 wk, a cylindrical specimen of each amalgam was immersed consecutively in cell culture medium for 0–8, 8–48 and 48–72 h. The cytotoxicity of the extracts was determined by placing them in contact with Balb/c 3T3 mouse fibroblasts for 24 h, after which the succinic dehydrogenase (SDH) activity was measured and expressed as a percentage of the Teflon negative controls. The results were statistically compared using ANOVA and Tukey's test (α = 0.05). The concentration of elements released into the extracts was determined by atomic absorption spectrophotometry and evaluated by Kruskal-Wallis and non-parametric multiple comparisons. Results. For the 0–8 h and 8–48 h intervals, the 20% In amalgam was significantly (p < 0.05) less toxic than the other amalgams, and not different from the Teflon control. Results for the other amalgams were only slightly depressed compared to the Teflon control. For the 48–72 h interval, all amalgams were essentially no different from the control. Copper was the element dominantly released into the medium from all the amalgams tested. Significance. For amalgam tested after aging, alloying indium to mercury did not deleteriously affect the cytotoxicity of the resultant amalgam compared to the amalgam without indium.

Anomalous volume contraction of expanded mercury by the addition of impurity elements

The mass density of dilute amalgams containing 0.2 at.% Bi and Cd has been measured using a dilatometer up to 1600 °C and 2000 bar. The temperature and pressure variations of the density are nearly the same as those for pure Hg at densities above 10 g/cm 3. However, in the density range between 10 and 7 g/cm 3, which includes the metal-non-metal (M-NM) transition region, thermal expansion of fluid Hg is considerably suppressed by the addition of impurity elements, especially by the addition of Bi. The mechanism of the electron transfer from impurity to Hg atoms is discussed.

Fluid phase equilibrium of dilute mixtures of helium in near-critical mercury

The phase behaviour of dilute mixtures of the He in near-critical fluid Hg has been studied within the ranges 69 MPa to 332.5 MPa, 1433 K to 1882 K and amount-of-substance fractions x(He) within the values 0.0018 and 0.1020. A high pressure and high-temperature vessel was filled with known amounts of He and Hg (synthetic method) and heated; an isochoric record of pand Twas made while the temperature was gently decreased and the transition from homogeneous to two-phase systems was indicated by abrupt slope changes in the p-against- Tisochores. Two distinct fluid phases are shown to exist in (helium + mercury) at temperatures and pressures higher than those corresponding to the critical point of pure mercury (“fluid–fluid equilibrium of the first type”) and the system's critical line, beginning at the critical point of pure Hg, runs steeply to higher pressures and temperatures. Solubility values as high as 0.28 mol·dm −3were measured for He in near-critical fluid Hg, in contrast to the much lower values estimated for He dissolved in metallic liquid Hg at sub-critical temperatures. The isobaric solubility of He in Hg increases with temperature for super-critical pressures so that (helium + mercury) shows a positive enthalpy and entropy of dissolution under these conditions. At sufficiently high density, non-metallic near-critical Hg experiences a transition to a metallic state, resulting in a strong repulsive interaction between dissolved He and the surrounding conduction electrons, and hence the isothermal solubility of He decreases.

The Hg-Ru (mercury-ruthenium) system

The requisite eutectic depression or peritectic elevation of the melting of Hg is placed indistinguishably close to the melting point of pure Hg. Terminal solubilities are in both solid and liquid phases. Virtually pure Hg (G) is in equilibrium with pure Ru between the Hg boiling point and the Ru melting point. Both metals would be mutually miscible as gases at extremely high temperatures. Hg and Ru melt at -38.8290 and 2334 ~ respectively [Melt], and Hg boils at 356.623 ~ when pressure is 0.101325 MPa. [Moffatt] presented a low temperature version of the Hg-Ru phase diagram at constrained pressure; this diagram is similar to that shown in Fig. 1 except that Hg (G) instead of rig (L) is present above the Hg boiling point.

Synthesis and characterization of HgBa2Can−1 CunO2 n+2+ δ ( n = 1, 2, and 3)

We have successfully prepared the first three members of the mercury-based superconducting compounds Hg Ba 2 Ca n−1 Cu n O 2 n+2+ δ , namely Hg1201, Hg1212 and Hg1223 with high purity and very good quality. T he influence of the synthesis parameters is studied in detail. Using the sealed quartz tube method, very simple procedures are found to ensure a 100% reproducibility of nearly 100% pure Hg1201 and 85–90% Hg1212 and Hg1223. Oxygen annealing of the sample Hg1201 at 300°C for 18 h results in an enhancement of its critical temperature up to 97 K. The symmetry of the first and second members is tetragonal with lattice parameters a = 3.8831 (1) A ̊ , c = 9.5357 (2) A ̊ , and a = 3.8624 (1) A ̊ , c = 12.7045 (2) A ̊ , respectively. X-ray diffraction lines of Hg1223 can be indexed in a tetragonal cell with a = 3.8564 (1) A ̊ and c = 15.8564 (9) A ̊ as well as in an orthorhombic cell with lattice parameters a = 5.4537 (1) A ̊ , b = 5.4247 (1) A ̊ , and c = 15.8505 (7) A ̊ .

A perturbed angular-correlation study of the electric-field gradient at the In site in compounds of the Hg-In alloy system

The electric-field gradient (EFG) of dilute 111Cd nuclei in compounds of the Hg-In alloy system has been investigated by perturbed angular correlation (PAC) measurements of the electric quadrupole interaction (QI) of 111Cd on In sites. It has been found that, as in the pure metals Hg and In, the quadrupole frequency decreases with increasing temperature according to the relation nu q(T)= nu q(0)(1-BT32/). The strength constant B in the intermetallic phases, however, is up to 35% smaller than in the pure metals. The QI parameters are consistent with an orthorhombic gamma -Pu-type lattice for beta -Hg (Hg80In20), but are difficult to reconcile with the structures proposed for HgIn. An intermetallic compound HgIn2 has not been observed.

Simulation of the high-pressure mercury discharge lamp during the middle phase of start-up (medium mercury pressure)

This paper deals with the modelling of the medium pressure Hg and Hg-Ar positive column (Hg pressure range 5-350 Torr). The aim of this work is to simulate, in a first approximation, the middle phase of the Hg high-pressure lamp warm-up. In this approach, the main assumption is that time evolution of the discharge can be divided into a succession of stationary sub-phases characterized by the Hg partial pressure. Thus, we present here a self-consistent steady-state collisional-radiative model describing the middle sub-phase. This model includes volume recombination of Hg atomic and molecular ions, as well as several atom-atom inelastic scattering mechanisms. Calculations are carried out for both pure Hg and Hg-Ar discharges. Our results, which are in good agreement with experimental data from the literature, confirm that plasma thermalization occurs in the middle start-up phase (electron and gas temperatures become equal during this phase). Furthermore, this simulation shows the importance of different elementary processes, like atom-atom inelastic scattering, for the medium pressure plasma description. In fact, these mechanisms cannot be neglected until LTE conditions are reached.