Liquid Hydrogen Sulfide Research Articles

Simulation of Liquid and Supercritical Hydrogen Sulfide and of Alkali Ions in the Pure and Aqueous Liquid

A polarizable model for hydrogen sulfide (H2S) is optimized based on the experimental properties of the monomer and of the bulk liquid. The model is characterized by rigid SH bonds but flexible HSH angle and the polarizability is based on the Drude oscillator model. Bonded parameters and atomic charges are based on the experimental properties of the gaseous monomer. Atomic Lennard-Jones (LJ) parameters are adjusted based on the density of H2S around the critical point (in the temperature range 363-393 K and pressure range 8.023-10.013 MPa). The model gives binding energies for H2S dimers, trimers, and tetramers in good agreement with ab initio MP2(full)/6-311++G(d,p) results. It shows a liquid structure in very good agreement with neutron diffraction data. The model also gives density, self-diffusion coefficient, heat of vaporization, and dielectric constant of liquid hydrogen sulfide at the normal boiling point in good agreement with experimental data. In addition, the model is transferable to high temperature and pressure conditions, as evidenced from simulations up to 542.2 K and 40 MPa. The model is used in combination with the SWM4-NDP water model, with LJ parameters between the S and O atoms adjusted to reproduce the experimental hydration free energy of H2S. Simulations suggest that, in its first solvation shell, a single H2O molecule is solvated by 10 H2S molecules while a single H2S molecule is solvated by 20.5 H2O molecules. Pair-specific LJ parameters between alkali ions (Li(+), Na(+), K(+), Rb(+), Cs(+)) and the S atom are adjusted to reproduce ab initio binding energies of the ion-H2S pairs at the CCSD(T) level. Simulations based on these parameters show that alkali ions have higher coordination numbers and lower solvation free energies in liquid H2S than in liquid water or liquid ammonia. The model is also used to investigate the preferential solvation of the ions in aqueous solutions with a 10% H2S mole fraction. Results show that the ions are preferentially solvated by water in their first solvation shell but have no significant selectivity to either ligands in their second shells.

Solubility of CO2 and H2S in the ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate

The solubility of two single gases carbon dioxide and hydrogen sulfide in the ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([C2mim][eFAP]) was experimentally determined at temperatures from (303 to 353)K and pressures up to about 2.0MPa. Results show that hydrogen sulfide is more soluble in that particular ionic liquid than carbon dioxide. At fixed temperature and pressure, the amount of dissolved H2S is more than twice the amount of CO2. The new experimental data were used to determine the Henry’s law constants, which again were used to derive some thermodynamic functions of the gas/solvent systems, such as, for example, the change of the partial molar Gibbs free energy of the gases upon solution in the ionic liquid. Two models were used to correlate the new experimental data: (1) a model comprised of the extended Henry’s law and Pitzer's virial expansion for the excess Gibbs free energy, and (2) a generic Redlich–Kwong (RK) cubic equation of state recently proposed for gas-ionic liquid systems. Both models are equally suited to correlate the experimental results. The (CO2+H2S) selectivity of [C2mim][eFAP] was calculated from the RK EoS at various temperatures, pressures and CO2/H2S feed ratios and compared with the recently reported results for the selectivity of other ionic liquids.

Study of the solubility of CO2, H2S and their mixture in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate: Experimental and modelling

New experimental results are presented for the solubility of carbon dioxide, hydrogen sulfide in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) at temperatures range from (303.15 to 353.15)K and pressures up to about 2MPa. The solubility of the mixture of CO2/H2S in [C8mim][PF6] under various feed compositions were also measured at temperatures of (303.15, 323.15 and 343.15)K and the pressure up to 1MPa. The solubility of carbon dioxide and hydrogen sulfide increased with increasing pressure and decreased with increasing temperature and the solubility of H2S is about three times that of CO2 in the particular ionic liquid studied. The measured data were correlated using extended Henry’s law included Pitzer’s virial expansion for the excess Gibbs energy, and the generic Redlich–Kwong cubic equation of state proposed for gas/ionic liquid systems. The correlations from the two models show quite good consistency with the experimental data for CO2/IL and H2S/IL binary mixtures within experimental uncertainties. For CO2/H2S/IL ternary mixtures, the RK model shows better correlation with the experimental values. We also studied the effect of cation alkyl chain length on the CO2 and H2S solubility by comparison of the experimental data of this study with those of previous reports. As the cation alkyl chain length became longer, the solubility of CO2 and H2S increased in the ionic liquid. Additionally, the influence of the anion on the solubility is studied by comparing the solubility of CO2 and H2S in [C8mim][PF6] with those in [C8mim][Tf2N]. As a result, CO2 and H2S have higher solubility in the IL with [Tf2N]− as the anion.

A Drude Polarizable Model for Liquid Hydrogen Sulfide

A polarizable force field for liquid hydrogen sulfide (H2S) has been developed based on the Drude oscillator model. This force field has been designed to be analogous to the SWM4-NDP water model; the model is rigid with point charges assigned to the H and S atoms and a lone pair on the bisector of ∠HSH in the molecular plane. Positions of the lone pair and the charges have been defined such that the model has a static dipole moment of 0.98 D, equal to the experimental value. Polarizability is incorporated by a charged (Drude) particle attached to the S atom through a harmonic potential. Intermolecular nonbonded forces are included by use of a Lennard-Jones potential between S atoms. The model was parametrized to reproduce the density, enthalpy of vaporization, and dielectric constant of pure H2S at 212 K and 1 atm. The calculated density, enthalpy of vaporization, shear viscosity coefficient, and self-diffusion coefficient are in good agreement with experiment over the temperature range 212-298 K along the liquid-vapor coexistence curve of liquid H2S. The radial distribution function calculated from this model is in good agreement with experimental diffraction data and ab initio molecular dynamics simulations.

Liquid hydrogen sulphide (H<sub>2</sub>S) fluid inclusions in unheated tanzanites (zoisite) from Merelani,Tanzania: Part 2. Influence on gem integrity during and after heat treatment

Liquid hydrogen sulphide (H<sub>2</sub>S) fluid inclusions in unheated tanzanites (zoisite) from Merelani,Tanzania: Part 2. Influence on gem integrity during and after heat treatment

Hypothermia and neuroprotection by sulfide after cardiac arrest and cardiopulmonary resuscitation

Background Poor neurological outcome remains a major problem in patients suffering cardiac arrest. Recent data have demonstrated potent neuroprotective effects of the administration of sulfide donor compounds after ischaemia/reperfusion injury following cardiac arrest and resuscitation. Therefore, we sought to evaluate the impact of sodium sulfide (Na 2S), a liquid hydrogen sulfide donor on core body temperature and neurological outcome after cardiac arrest in rats. Methods Fifty male Wistar rats were randomized into two groups (sulfide vs. placebo, n = 25 per group). Cardiac arrest was induced by transoesophageal ventricular fibrillation during general anaesthesia. After 6 min of global cerebral ischaemia, animals were resuscitated by external chest compressions combined with defibrillation. An investigator blinded bolus of either Na 2S (0.5 mg/kg body weight) or placebo 1 min before the beginning of CPR, followed by a continuous infusion of Na 2S (1 mg/kg body weight/h) or placebo for 6 h, was administered intravenously. 1 day, 3 days, and 7 days after restoration of spontaneous circulation, neurological outcome was evaluated by a tape removal test. After 7 days of reperfusion, coronal brain sections were analyzed by TUNEL- and Nissl-staining. A caspase activity assay was used to determine antiapoptotic properties of Na 2S. Results Temperature course was similar in both groups (mean minimal temperature in the sulfide group 31.3 ± 1.2 °C vs. 30.8 ± 1.9 °C in the placebo group; p = 0.29). Despite significant neuroprotection demonstrated by the tape removal test after 3 days of reperfusion in the sulfide treated group, there was no significant difference in neuronal survival at day 7. Likewise results from TUNEL-staining revealed no differences in the amount of apoptotic cell death between the groups after 7 days of reperfusion. Conclusion In our rat model of cardiac arrest, sulfide therapy was associated with only a short term beneficial effect on neurological outcome.

HYDROGEN SULFIDE DOES NOT INCREASE RESUSCITABILITY IN A PORCINE MODEL OF PROLONGED CARDIAC ARREST

Treatment options to improve resuscitability and neurological prognosis after cardiac arrest (CA) are limited. Hydrogen sulfide has demonstrated remarkable improvements in outcomes in small animal models of severe hypoxia or hemorrhage. We investigated the influence of sodium sulfide (Na2S), a liquid hydrogen sulfide donor, on resuscitability, postresuscitation hemodynamics, and neurological performance in a porcine model of prolonged CA and cardiopulmonary resuscitation. Twenty-four male pigs were instrumented with arterial and pulmonary artery catheters before 10 min of CA was induced. During resuscitation, animals were randomized to receive either high-dose (1 mg/kg; n = 8) or low-dose (0.3 mg/kg; n = 8) Na2S (IK-1001; Ikaria, Clinton, NJ) or control (saline placebo; n = 8) i.v. injection and consecutive infusion. Cardiopulmonary resuscitation was performed for 6 min before defibrillation was attempted. Hemodynamic variables were taken at baseline and 10, 30, 60, 120, and 240 min after successful resuscitation. Neurological outcome was evaluated on 4 postoperative days before brains and hearts were harvested for histopathologic analysis. No differences in hemodynamic parameters were observed at baseline. Initial resuscitability was not improved by Na2S. Animals exposed to high- and low-dose Na2S showed significantly reduced cardiac output, heart rate, and pulmonary arterial pressure compared with control animals during the early postresuscitation period. Strikingly, two of the high-dose Na2S animals died during the postresuscitation period, whereas all other animals survived. High-dose Na2S significantly decreased microglial activation in striatal areas, although this did not translate into improved neurological outcome. Although animals receiving Na2S developed higher troponin T serum levels, these differences remained insignificant. In this investigation, Na2S did not improve resuscitability but significantly compromised postresuscitation hemodynamics.

Solubility and Diffusion of H2S and CO2 in the Ionic Liquid 1-(2-Hydroxyethyl)-3-methylimidazolium Tetrafluoroborate

The solubilities and diffusion coefficients of hydrogen sulfide and carbon dioxide gases in the ionic liquid (IL) 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([hemim][BF4]), at temperatures ranging from (303.15 to 353.15) K and pressures up to 1.1 MPa, were determined. The solubility data were correlated using the Krichevsky−Kasarnovsky equation, and Henry’s law constants at different temperatures were obtained. From the solubility data, the partial molar thermodynamic functions of solution such as Gibbs energy, enthalpy, and entropy were calculated. The diffusion coefficients were obtained for H2S and CO2 using a semi-infinite volume approach, and a correlation equation with temperature is presented for each gas. A comparison showed that the solubility of H2S was about three times its magnitude, and its diffusion coefficient is of the same order of magnitude as that of CO2 in the IL studied in this work.

Survival of mussels in extremely acidic waters on a submarine volcano

Increasing atmospheric carbon dioxide levels are causing ocean acidification, compromising the ability of some marine organisms to build and maintain support structures. An analysis of mussels from a submarine volcano setting with natural low-pH conditions shows low shell thicknesses and growth rates, but survival over up to four decades. Increasing atmospheric carbon dioxide levels are causing ocean acidification1,2, compromising the ability of some marine organisms to build and maintain support structures3 as the equilibrium state of inorganic carbon moves away from calcium carbonate4. Few marine organisms tolerate conditions where ocean pH falls significantly below today’s value of about 8.1 and aragonite and calcite saturation values below 1 (refs 5, 6). Here we report dense clusters of the vent mussel Bathymodiolus brevior in natural conditions of pH values between 5.36 and 7.29 on northwest Eifuku volcano, Mariana arc, where liquid carbon dioxide and hydrogen sulphide emerge in a hydrothermal setting. We find that both shell thickness and daily growth increments in shells from northwest Eifuku are only about half those recorded from mussels living in water with pH>7.8. Low pH may therefore also be implicated in metabolic impairment7. We identify four-decade-old mussels, but suggest that the mussels can survive for so long only if their protective shell covering remains intact: crabs that could expose the underlying calcium carbonate to dissolution are absent from this setting. The mussels’ ability to precipitate shells in such low-pH conditions is remarkable. Nevertheless, the vulnerability of molluscs to predators is likely to increase in a future ocean with low pH.

Solubility of Hydrogen Sulfide in [bmim][PF6

New experimental data are presented for the solubility of hydrogen sulfide in the ionic liquid 1-N-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) at five temperatures in the range (298–403) K at pressures up to 9.6 MPa. The ionic liquid [bmim][PF6] is a good solvent for hydrogen sulfide. At 9 MPa the mole fraction H2S in the liquid is about 0.7. The solubility is a strong function of temperature; at 2 MPa the solubility (mole fraction H2S) decreases from about 0.84 at 298 K to about 0.2 at 403 K. The Krichevsky–Kasarnovsky equation was used to correlate the experimental data, and Henry’s constants were obtained. The solution thermodynamic properties at standard temperature and pressure were calculated.

Anhydrous proton conductivity in hydrogen alkali thiogermanates

Ionic conductivities have been investigated for mixed hydrogen alkali thiogermanates possessing the adamantane-like Ge 4S 10 4− structural complex anion. Anhydrous compounds of the form H x M 4− x Ge 4S 10 (M=K and Rb) and H x Cs 4− x Ge 4S 10· yH 2S for 0≤ x≤4 and 0≤ y≤1 were synthesized using a novel preparation method involving reacting the respective alkali thiogermanate glass or adamantane-like crystalline phase with liquid hydrogen sulfide. The reaction products were characterized by mass, thermogravimetric analysis, and Raman and infrared spectroscopies. Conductivity values in the range of 10 −10 to 10 −5 S/cm were determined from a.c. impedance measurements of the protonated phases below a typical thermal decomposition temperature of ∼175 °C. The decrease in ionic conductivity above the decomposition temperature is consistent with the loss of mobile protons as hydrogen sulfide. Higher proton mobility in the mixed hydrogen alkali thiogermanates vs. the anhydrous thiogermanic acid H 4Ge 4S 10 may be partially attributed to lower decomposition temperatures and increased hydrogen bonding.

Crystal Structure of Thiogermanic Acid H4Ge4S10.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Crystal structure of thiogermanic acid H(4)Ge(4)S(10).

X-ray diffraction analysis reveals the thiogermanic acid H(4)Ge(4)S(10) possesses discrete adamantane-like Ge(4)S(10)(4)(-) complex anions. Each thioanion is composed of four corner shared GeS(2.5)(-) tetrahedral units. Crystals were grown from anhydrous liquid hydrogen sulfide reactions with glassy germanium sulfide at room temperature. The crystal structure was solved and refined from single crystal diffractometer data (Mo Kalpha radiation) obtained at 173 K. H(4)Ge(4)S(10) is triclinic, centrosymmetric space group Ponemacr;, with a = 8.621(4) A, b = 9.899(4) A, c = 10.009(4) A, alpha = 85.963(7) degrees, beta = 64.714(7) degrees, gamma = 89.501(8) degrees, and Z = 2. Average bridging and terminal d(Ge-S) distances are 2.229 and 2.206 A, respectively. Vibrational mode assignments are reported from Raman scattering and IR absorption spectra of polycrystalline samples. The nu(s)(Ge-S-Ge) and nu(s)(Ge-S(-)) stretching modes are observed at 354 and 405 cm(-)(1), respectively.

Synthesis and Characterization of the Thiogermanic Acids H4Ge4S10 and H2Ge4S9.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and Characterization of the Thiogermanic Acids H4Ge4S10 and H2Ge4S9

The synthesis and structure of the thiogermanic acids H 4 Ge 4 S 1 0 and H 2 Ge 4 S 9 are reported. A novel preparation method consisting of reacting germanium oxide with liquid hydrogen sulfide containing a trace amount of water is used to form Ge 4 S 1 0 4- ions. Evaporating the hydrogen sulfide solution at room temperature leaves an unstable H 4 Ge 4 S 1 0 .xH 2 O product. The stoichiometry and structure of the thermally stable anhydrous phase are dependent on reaction time. An H 4 Ge 4 S 1 0 product with an adamantane-like cage structure is obtained at shorter reaction times. Longer reaction times produce an H 2 Ge 4 S 9 product with a more complex cage unit, a higher symmetry unit cell, and increased thermal stability. Raman, infrared, powder X-ray diffraction, and thermogravimetric data are reported for both structures.

Single particle dynamics in fluid and solid hydrogen sulphide: An inelastic neutron scattering study

Inelastic neutron scattering experiments were performed at intermediate and high momentum transfer, up to 88.2 Å−1, to study the temperature dependence of single hydrogen mean kinetic energy in polycrystalline and liquid hydrogen sulphide (H2S), in the temperature range 16–206 K. Values of the hydrogen mean kinetic energy were extracted, within the impulse approximation, by fitting to the high momentum transfer data a model response function, obtained from a momentum distribution which is the orientational average of a multivariate Gaussian function. The extracted kinetic energies are compared with a harmonic model for the vibrational and roto-translational dynamics. The model makes use of the hydrogen-projected density of states worked out from intermediate momentum transfer data, as well as of optical frequencies determined from Raman and infrared (IR) spectroscopy. A fairly good agreement is obtained in the whole temperature range, while noticeably lower values for the kinetic energy are found if a single atom momentum distribution of isotropic Gaussian shape is assumed in the model response function.

Orientational correlations in liquid hydrogen sulphide

Neutron diffraction data on liquid H2S, D2S and an equimolar mixture of the two are presented for two thermodynamic states along the liquid—vapour coexistence curve. Comparison of the site-site radial distribution functions obtained with those of a model fluid where orientational correlations are absent and with those of water demonstrates that, although hydrogen sulphide does not form hydrogen bonds, nevertheless weak orientational correlations between first neighbouring molecules are detectable in both thermodynamic states. An analysis of the molecular configurations compatible with the experimental data, as calculated by applying the empirical potential structural refinement, is presented also.

Orientational correlations in liquid hydrogen sulphide

Orientational correlations in liquid hydrogen sulphide

Chemically deposited zinc oxide thin film gas sensor

Zinc oxide (ZnO) thin films were prepared by a low cost chemical deposition technique using sodium zincate bath. Structural characterizations by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM) indicate the formation of ZnO films, containing 0.05–0.50 μm size crystallites, with preferred c-axis orientation. The electrical conductance of the ZnO films became stable and reproducible in the 300–450 K temperature range after repeated thermal cyclings in air. Palladium sensitised ZnO films were exposed to toxic and combustible gases e.g., hydrogen (H2), liquid petroleum gas (LPG), methane (CH4) and hydrogen sulphide (H2S) at a minimum operating temperature of 150 °C; which was well below the normal operating temperature range of 200–400 °C, typically reported in literature for ceramic gas sensors. The response of the ZnO thin film sensors at 150 °C, was found to be significant, even for parts per million level concentrations of CH4 (50 ppm) and H2S (15 ppm).

Application of a new Gibbs ensemble Monte Carlo method to site-site interaction model fluids

A new Gibbs ensemble Monte Carlo simulation method has been tested for rigid site–site interaction model fluids. In this method the total system is considered at constant enthalpy, pressure and number of particles. Vapour-liquid equilibrium data were determined for a potential model of liquid carbon disulphide and a potential model of liquid hydrogen sulphide. Conventional Gibbs ensemble Monte Carlo simulations were also carried out for comparison. The two methods yielded essentially the same results, but the new scheme showed some advantages.