H2S In Aqueous Solutions Research Articles

Modelling VLE data of CO2 and H2S in aqueous solutions of N-methyldiethanolamine based on non-random mixing rules

The vapor liquid equilibrium (VLE) data of carbon dioxide and hydrogen sulfide in N-methyldiethanolamine (MDEA) solutions has been investigated by Peng–Robinson and Soave–Redlish–Kwong equations of state (EOS). Random and non-random mixing rules have been used for calculating the parameters of the EOS. The predictions of the modelling are compared with the experimental data obtained from the literature for 2 and 4mole of MDEA per kg of water. It was shown that the data obtained by random mixing rules has 24.7 and 32.5% absolute relative deviation (ARD) for PR and SRK equations of state respectively in calculating the partial pressure of CO2. Also the results had more deviation from the experimental data when binary interaction parameters (kij) added to the random mixing rules. Finally the VLE data of CO2 and H2S is examined by non-random mixing rules and the results were in excellent agreement with the experimental data. The ARD in this case was 3.7 and 6.7% for PR and SRK equations of states respectively in calculating the partial pressure of H2S. The results of the modelling have been compared and discussed with other modelling results such as ePC-SAFC, eNRTL and UNIQUAC models.

Solubility of Hydrogen Sulfide in Aqueous Blends of 2-Amino-2-methyl-1-propanol and N-Methyldiethanoleamine: Experimental Measurement and Modeling

The solubility of H2S in aqueous solutions of 40 mass % MDEA + 5 mass % AMP, 30 mass % MDEA + 15 mass % AMP, and 22.5 mass % MDEA + 22.5 mass % AMP at (313.15, 333.15, and 353.15) K and pressure from the vapor pressure of the solutions up to 1.5 MPa using the isochoric saturation method were measured. The experimental data are presented as the partial pressure of H2S against acid gas loading (mole H2S/total moles of amine). The results showed that the H2S solubility decreases with an increase of temperature and increases with the rising of partial pressure of H2S, and also AMP concentration can improve absorption capacity of MDEA aqueous solution as [AMP]0/[MDEA]0 (ratio of AMP per MDEA concentration in fresh solutions) increases when total amine concentration is constant. The Deshmukh–Mather model and Peng–Robinson equation of state were used for liquid and vapor phase, respectively, to correlate the solubility data.

A Copper Porphyrin for Sensing H2S in Aqueous Solution via a “Coordinative‐Based” Approach

AbstractA “turn on” fluorescence‐based probe for sensing H2S in water via a coordinative‐based approach has been successfully devised. The probe can selectively detect H2S in aqueous solutions over other anions, biothiols, and common oxidants such as H2O2. 1H NMR spectroscopy and ESI‐MS experiments provide evidence that the turn‐on response in the presence of H2S is due to binding of the target anion to the copper center.

A coumarin-based colorimetric fluorescent probe for hydrogen sulfide

A coumarin-based fluorescent probe for selective detection of hydrogen sulfide (H2S) is presented. This ‘off–on’ probe exhibited high selectivity towards H2S in aqueous solution with a detection limit of 30 nM. Notably, because of its dual nucleophilicity, the probe could avoid the interference of thiols and other sulfur containing compounds. A novel coumarin-based, reaction-type fluorescent probe for detection of H2S in aqueous solution was synthesized through a two-step nucleophilic reaction.

H<sub>2</sub>S Adsorption Capability of Layered Double Hydroxide Containing Transition Metal

Many people worldwide assess themselves as having halitosis, often caused by bio-film and microbial putrefaction of the debris in the mouth, leading to the production of mal-odorous compounds, volatile sulfur compounds (VSC) such as hydrogen sulfide (H2S), methyl mercaptan and dimethyl sulfide. Some desulfurizing agents such as CaO and Na2CO3 in the industry are widely used, but there are few dental desulfurizing agents or adsorbents for removal of VSC. Ag ion exchanged zeolite material showed a high adsorptive property of H2S in aqueous solution (H2S water), however Ag sulfides were formed in aqueous solution. The VSC adsorption capabilities of layered double hydroxides, of which composition is A1-xAlx(OH)2Bx/n·mH2O, where A is Mg and/or Zn and B is CO32-, in aqueous medium was studied by FPD/GC. The concentration of H2S fell to 0% in 2 h when the Zn hydrotalcite was used, while that decreased to 20% in 18 h when the Mg hydrotalcite heated at 500 °C was used. The zinc ion was not detected in the H2S water after soaking for 18 hours.The Zn hydtotalcite is expected to be likely adsorbent for the fast removal of VSC from the mouth.

VSC Adsorption Capability of Layered Double Hydroxide Containing Transition Metal

Many people worldwide assess themselves as having halitosis, often caused by bio-film and microbial putrefaction of the debris in the mouth, leading to the production of mal-odorous compounds, volatile sulfur compounds (VSC) such as hydrogen sulfide (H2S), methyl mercaptan and dimethyl sulfide. Some desulfurizing agents such as CaO and Na2CO3 in the industry are widely used, but there are few dental desulfurizing agents or adsorbents for removal of VSC. Ag ion exchanged zeolite material showed a high adsorptive property of H2S in aqueous solution (H2S water), however Ag sulfides were formed in aqueous solution. The VSC adsorption capabilities of layered double hydroxides, of which composition is A1-xAlx(OH)2Bx/n·mH2O, where A is Mg and/or Zn and B is CO32-, in aqueous medium was studied by FPD/GC. The concentration of H2S fell to 0% in 2 h when the Zn hydrotalcite was used, while that decreased to 20% in 18 h when the Mg hydrotalcite heated at 500 °C was used. The zinc ion was not detected in the H2S water after soaking for 18 hours.The Zn hydtotalcite is expected to be likely adsorbent for the fast removal of VSC from the mouth.

A highly selective fluorescent chemodosimeter for imaging hydrogen sulfide in living cells

A 2-formylbenzoate-caged methylfluorescein chemodosimeter (1) was designed and synthesized to detect hydrogen sulfide (H2S) in aqueous solution and living cells. Chemodosimeter 1 could quantificationally detect H2S in a wide concentration range (2.5–1000 μM) by the fluorescence turn-on method. Chemodosimeter 1 showed excellent selectivity toward H2S owing to its inherent two electrophilic reaction sites and the dual nucleophilicity of H2S. Additionally, chemodosimeter 1 exhibited the color changes from colorless to yellow-green upon addition of H2S. Thus, 1 can serve as a “naked-eye” indicator for H2S. Further, the recognition mechanism of chemodosimeter 1 for H2S was confirmed using electrospray ionization mass spectrometry. Finally, the preliminary biological imaging experiments and low cytotoxicity investigations demonstrated that our proposed chemodosimeter provided a promising method for the determination of H2S in aqueous solution and living cells.

High-Sensitivity Naphthalene-Based Two-Photon Fluorescent Probe Suitable for Direct Bioimaging of H2S in Living Cells

H2S is the third endogenously generated gaseous signaling compound and has also been known to involve a variety of physiological processes. To better understand its physiological and pathological functions, efficient methods for monitoring of H2S in living systems are desired. Although quite a few one photon fluorescence probes have been reported for H2S, two-photon (TP) probes are more favorable for intracellular imaging. In this work, by employing a donor-π-acceptor-structured naphthalene derivative as the two-photon fluorophore and an azide group as the recognition unit, we reported a new two-photon bioimaging probe 6-(benzo[d]thiazol-2'-yl)-2-azidonaphthalene (NHS1) for H2S with improved sensitivity. The probe shows very low background fluorescence in the absence of H2S. In the presence of H2S, however, a significant enhancement for both one photon and TP excited fluorescence were observed, resulting in a high sensitivity to H2S in aqueous solutions with a detection limit of 20 nM observed, much lower than the previously reported TP probe. The probe also exhibits a wide linear response concentration range (0-5 μM) to H2S with high selectivity. All these features are favorable for direct monitoring of H2S in complex biological samples. It was then applied for direct TP imaging of H2S in living cells with satisfactory sensitivity, demonstrating its value of practical application in biological systems.

The VSC Adsorption on Hydrotalcite through Topochemical Reactions

Volatile sulfur compounds (VSCs) such as hydrogen sulfide (H2S), methyl mercaptan and dimethyl sulfide produced in mouth. Some oral (Gram-negative) bacteria produce VSCs, which induces permeability of mucous membrane, cause the oral malordor, dental caries, color change of the dental fillings. Thus, material which adsorbs VSCs should be useful to keep health in mouth. Previously, we reported the H2S adsorptive properties of zeolite and hydrotalcite materials having micro pores. The amount of H2S adsorbed on the zeolite or hydrotalcite at room temperature was found to be around 300-400 ppm, and and 3 % of H2S was desorbed when heated at 400 °C. The hydrotalcite, whose compositon is Mg1-xAlx(OH)2Ax/n·mH2O, where A is CO32-, and x is 0.25, was heat-treated at 500 °C, and put into aqueous solution containing H2S. In this study, the relation between heat-treatment tempearture and the sulfide adsorption on hydrotalcite in aqueous solution was investigated. The hydrotalcite materials were hydrothermally synthesized and identified by powder X-ray diffraction method. The change in concentrations of H2S in aqueous solution was measured using FPD gas chromatography (GC). The concentrations of H2S was decreased with time for the hydrotalcite heated at 500 °C or 600 °C, and fell to 20 % for 12 hours. But, the concentration was decreased by 40% for 12 hours for the hydrotalcite materials heated at higher temperatue. XRD and FT-IR analysis revealed that the sulfides were into or out of the hydrotalcite structure through topochemical reactions.

An NBD fluorophore-based colorimetric and fluorescent chemosensor for hydrogen sulfide and its application for bioimaging

Hydrogen sulfide (H2S) is an important gaseous mediator in cellular physiology and pathology. For understanding the biological action of H2S to both healthy and disease states, it is important to develop H2S-selective sensor. Herein we report a colorimetric and fluorescent probe, which employs an NBD moiety as fluorophore, and is equipped with azide group as H2S-active unit. The probe exhibits selective and sensitive response to H2S in aqueous solution. By employing 1 μM sensor, the detection limit was evaluated to be 680 nM with a signal-to-noise ratio of 3. Confocal microscopy imaging experiments demonstrate the probe has potential as a powerful tool for the imaging of hydrogen sulfide in living cells.

Solubility of H2S in Aqueous Diisopropanolamine + Piperazine Solutions: New Experimental Data and Modeling with the Electrolyte Cubic Square-Well Equation of State

The solubilities of H2S in aqueous solutions of diisopropanolamine (DIPA) and in aqueous mixtures of DIPA and piperazine (Pz) have been measured. The molality of DIPA was fixed at 2.96 m, and the concentration of Pz was (1.20 or 1.80) m. Experiments were carried out at (40, 60, and 80) °C over the pressure range (19 to 1554) kPa. For modeling of the DIPA + Pz + H2S + H2O system, the electrolyte cubic square well (eCSW) equation of state (EOS) (Haghtalab, A.; Mazloumi, S. H.Fluid Phase Equilib. 2009, 285, 96−104) was applied to predict the total and partial pressures of H2S over aqueous solutions of DIPA, Pz, and DIPA + Pz using only the interaction parameters, kij, of the H2S + H2O system. The reasonable agreement of the eCSW EOS and experimental results demonstrates the good accuracy of the eCSW EOS for thermodynamic modeling of the solubilities of acid gases in aqueous alkanolamine solutions.

Effect of soluble sulfide on the activity of luminescent bacteria.

Sulfide is an important water pollutant widely found in industrial waste water that has attracted much attention. S2−, as a weak acidic anion, is easy hydrolyzed to HS− and H2S in aqueous solution. In this study, biological tests were performed to establish the toxicity of sulfide solutions on luminescent bacteria. Considering the sulfide solution was contained three substances—S2−, HS− and H2S—the toxicity test was performed at different pH values to investigate which form of sulfide increased light emission and which reduced light emission. It was shown that the EC50 values were close at pH 7.4, 8.0 and 9.0 which were higher than pH 5 and 10. The light emission and sulfide concentrations displayed an inverse exponential dose-response relationship within a certain concentration range at pH 5, 6.5 and 10. The same phenomenon occurred for the high concentration of sulfide at pH 7.4, 8 and 9, in which the concentration of sulfide was HS− >> H2S > S2−. An opposite hormesis-effect appeared at the low concentrations of sulfide.

Reductive Coupling of Aldehydes by H2S in Aqueous Solutions, a CC Bond Forming Reaction of Prebiotic Interest

We report here a novel reductive coupling reaction of conjugated, non- or poorly enolizable aldehydes induced by H(2) S and operative in aqueous solutions under prebiotically relevant conditions. This reaction leads from retinal to β-carotene, and from benzylic aldehydes to the corresponding diarylethylenes. This novel reaction also opens a new potentially prebiotic pathway leading from glyoxylic acid to various compounds that are involved in the reductive tricarboxylic acid cycle. This C--C bond forming reaction of prebiotic interest might have been operative, notably, in the sulfide-rich environments of hydrothermal vents, which have been postulated as possible sites for the first steps of organic chemical evolution.

Equilibrium solubility of H2S in aqueous solutions of 1-amino-2-propanol as function of concentration, temperature, and pressure

Experimental values for the gas solubility of hydrogen sulphide (H2S) in aqueous solutions of 1-amino-2-propanol (MIPA) were measured at T=(313.15 and 393.15)K, over the pressure range of (51.4 to 1467.6)kPa. The concentrations of the aqueous MIPA solutions studied were (0.20, 0.30, 0.40, and 0.50) mass fraction. The results of gas solubility are reported as partial pressure of H2S, pH2S, against its liquid mole ratio, aH2S (mol H2S·mol−1 MIPA), and against its mole fraction in the solvent, xH2S. The experimental results show that the solubility of H2S increases as the concentration of MIPA in solution increases, at a given temperature throughout the pressure range considered; also the solubility values increase, under constant temperature, as the pressure increases in the studied concentration range of MIPA.The physicochemical model of Kent and Eisenberg was used to regress simultaneously all the experimental results of the solubility of H2S in the four studied aqueous solutions of MIPA. The model correlates satisfactorily the experimental results. The standard deviation of the regression for pressure is 68.0kPa using 69 experimental solubility points.The new experimental solubility results of H2S were compared with those reported in the literature for aqueous solutions of diethanolamine (DEA), diisopropanolamine (DIPA), N-methyldiethanolamine (MDEA), and 2-amino-2-methyl-1-propanol (AMP), under similar conditions of temperature and amine concentration. From this comparison, it is concluded that aqueous solutions of MIPA are a good solvent alternative to use in industrial gas purification processes at relatively high pressures, since the magnitude of the H2S solubility results in MIPA solutions was found to be higher than that in aqueous solutions of MDEA, DEA, and DIPA.

10.2478/s11814-009-0185-8

Modeling of solubility of acid gases in aqueous alkanolamine solutions is essential for design of an absorber for natural gas sweetening. In this work an apparatus similar to the device of Hayduk and Chen (1970), which was improved by Pahlavanzadeh and Motahhari (1997), for the measurement of gas solubility data by the synthetic method was used. The solubility of hydrogen sulfide in aqueous diisopropanolamine (DIPA) solution in mass concentration range of 30–40% for 101,325 Pa pressure and for temperature ranging from 313–343 K was reported. The obtained experimental solubility data of H2S in aqueous solutions of DIPA was used to predict the different interaction parameters of modified UNIQUAC-NRF model for calculating the activity coefficients. For nonideality of species in liquid phase, the UNIQUAC-NRF equation with ion-pair approach was applied. For long range interaction, the Pitzer-Debye-Huckel term was used.

Measurement and modeling of solubility of H2S in aqueous diisopropanolamine solution

Modeling of solubility of acid gases in aqueous alkanolamine solutions is essential for design of an ab- sorber for natural gas sweetening. In this work an apparatus similar to the device of Hayduk and Chen (1970), which was improved by Pahlavanzadeh and Motahhari (1997), for the measurement of gas solubility data by the synthetic method was used. The solubility of hydrogen sulfide in aqueous diisopropanolamine (DIPA) solution in mass con- centration range of 30-40% for 101,325 Pa pressure and for temperature ranging from 313-343 K was reported. The obtained experimental solubility data of H2S in aqueous solutions of DIPA was used to predict the different interaction parameters of modified UNIQUAC-NRF model for calculating the activity coefficients. For nonideality of species in liquid phase, the UNIQUAC-NRF equation with ion-pair approach was applied. For long range interaction, the Pitzer- Debye-Huckel term was used.

Die Kristallstruktur des Ethylendiammonium-hexasulfids (2. Mitteilung über Alkylammonium-Polysulfide [1])/The Crystal Structure of Ethylenediammonium Hexasulfide

Ethylenediammonium hexasulfide has been synthesized from ethylenediamine, sulfur, and gaseous H2S in aqueous solution. X-ray investigations on single crystals revealed its structure. The monoclinic unit cell contains eight formula units, the space group is Cc. The sulfur atoms form unbranched zig-zag chains S6 2- in all-trans-conformation.

Simultaneous absorption and/or desorption of hydrogen sulphide and ammonia.

Experiments on simultaneous absorption of H2S and NH3 in water, absorption of H2S in aqueous solutions of NH3 with simultaneous desorption of NH3, and simultaneous desorption of H2S and NH3 from aqueous solutions of NH3 and NH4HS were carried out using a continuous stirred-cell absorber. Absorption and desorption rates were analyzed on the basis of a theory of diffusion with instantaneous reversible chemical reaction. It was confirmed that the theory could be commonly applied to each case in the experiments, and gives a satisfactory interpretation of the effects of experimental conditions on the absorption as well as the desorption rate.

Synthetic Studies on Carbamoyl-O-methylisourea

Improved methods for the preparation of carbamoyl-O-methylisourea (CMI) and N-carbamoyl compounds of cyanamide derivertives using CMI were investigated.The reaction of cyanourea copper salt with methanol gave CMI copper complex, which was converted by treatment with H2S to CMI in good yield.1-Thioallophanic acid O-methyl ester was obtained by the reaction of CMI with H2S in aqueous solution at room temperature.CMI was hydrolyzed or decomposed in acidic or alkaline medium to biuret, methylallophanate and cyanourea.CMI salt reacted with methylamine to give methylguanylurea salt in good yield, but no reaction occurred with aniline.Carbamoylmelamine was obtained by the reaction of CMI with biguanide at room temperature, and cyanoguanylurea was obtained with cyanamide in good yield in the same manner.

Übergangsmetallchalkogenverbindungen. Study of formation and relative reaction rates of different thioanions of molybdenum and tungsten

AbstractThe formation of thioanions of mlybdnum and tungsten in the reaction between MoO and WO, respectively, with H2S in aqueous solution is spectrophotometrically investigated under identical conditions. The qualitatively found reaction rates are compared.