Solubility Of Mercury Research Articles

Mercury solubility and its modeling in an artificial natural gas at high pressures

Getting to know of mercury (Hg) behavior will contribute to proper handling and removal of Hg in natural gas processing facilities. Hg solubility was measured in an artificial natural gas, composed of 88.80 vol. % methane, 5.10 vol. % ethane, and 6.10 % vol. % carbon dioxide, by a flow-type apparatus up to 6.031 MPa at (268 to 303) K. The Hg mole fraction ranged from 4.991 × 10–9 to 8.125 × 10–7 in the vapor phase. The Hg solubilities decreased with increasing pressure, and the pressure dependencies were similar to that in pure methane. The experimental data were correlated with the Peng–Robinson equation of state (PR-EOS) developed in the previous studies, where the attractive parameter of Hg was evaluated from the saturated vapor pressure, and binary parameters among the other constituents of the artificial natural gas determined from the VLE data available in the literature. The calculation results were acceptable and agreed with the experimental data without any additional corrections. The maximum and the minimum the absolute relative deviation (ARD) and the average absolute relative deviation (AARD) were 9.72, 0.0542, and 3.20 %, respectively.

Predicting the Solubility of Mercury in Hydrocarbons

SummaryElemental mercury (Hg0) is a common trace contaminant associated with corrosion of infrastructure impacting exploration, production, and processing of commercial hydrocarbons. Presently lacking is a model for the quantitative prediction of Hg concentration in reservoir fluids, sufficiently reliable for process engineering applications and design of mitigation strategies to ameliorate the potential risk of Hg presence.In this paper, we present a thermodynamic equilibrium mineral-based model for predicting the solubility of mercury in hydrocarbons, Hg0(org), at in-situ reservoir conditions. The model is based on literature experimental data on the solubility of Hg0 in a mixture of alkanes, in equilibrium with Hg0, H2S, O2, cinnabar (HgS), and water. As the model inputs are based on the chlorite-pyrite-H2S model, its application should primarily be limited to clastic hydrocarbon-bearing reservoirs. A global data set of Hg in hydrocarbons reveals a remarkably strong association with the presence of humic coal in subsurface formations.Assuming that pure stoichiometric cinnabar (HgS) is stable at the reducing conditions typical of hydrocarbon reservoirs (i.e., aHgS = 1) results in an overestimation of Hg0(org) solubility by up to three orders of magnitude relative to globally reported concentrations of mercury in natural hydrocarbons. A statistically robust match between model and observed concentrations of Hg0(org) was achieved using an aHgS of 0.003, consistent with reported concentrations of Hg0 from pyrite (FeS2) in coals and hydrocarbon reservoirs. The model has been validated in a case study of reservoir Hg reported in the Gorgon North-1 well, North West Shelf (NWS), Australia.The dominant process of cinnabar precipitation is by oxidation, particularly in the near-surface environment where reduced Hg0-bearing hydrocarbons mix with shallow oxygenated or acidic surface waters. Such processes are typical of the environments where most downhole fluid samples are collected during drilling, sampling, and cleanup of exploration and development wells. This leads to the invariable conclusion that much of the particulate mercury species, specifically HgS, collected with hydrocarbon fluid samples, are metastable with respect to the dissolved Hg0(org) in hydrocarbons at reservoir conditions and should not be included in the estimation of total Hg (i.e., THg) in hydrocarbons.This hypothesis has been confirmed by an extended well test in the Minami-Nagaoka gas condensate field, where it was observed that Hg dissolved in produced water decreased to negligible levels over time, while the Hg0(org) in the condensate liquid reached a stable value like what the new Hg0(org) solubility model would predict for in-situ reservoir conditions.

Measurement and Modeling of Mercury Solubility in Methanol, Glycols, and N-methyldiethanolamine

Measurement and Modeling of Mercury Solubility in Methanol, Glycols, and N-methyldiethanolamine

Calculating the chemical and phase equilibria of mercury in natural gas

Thermodynamic models and algorithms that can accurately describe the chemical and phase equilibria of mercury in natural gas are of paramount importance. In this work, a multiphase flash algorithm is implemented for calculating the solubility of elemental mercury in typical natural gas fluids. The algorithm can handle three- and even four-phase systems (vapor-liquid hydrocarbon-water-mercury), while a free-mercury assumption is proposed to accelerate solution speed. In addition, a simultaneous chemical and phase equilibrium algorithm is employed for studying a theoretical reaction between mercury and H2S that can lead to solid HgS formation in natural gas. Both algorithms are coupled with the UMR-PRU model, and new interaction parameters are estimated for groups Hg and H2S with CO2, N2, and hydrocarbons, yielding very satisfactory results. Despite the lack of experimental data for comparison, the study of mercury solubility and reaction in natural gas with the proposed algorithms leads to very useful qualitative results, which agree with field observations.

Elemental mercury partitioning in high pressure fluids part 2: Model validations and measurements in multicomponent systems

A good understanding of the solubility of elemental mercury over wide ranges of temperature, pressure and composition is an important issue to assess the possibility of mercury dropping out in gas processing streams. In this work, new mercury solubility in three multicomponent systems with methane content varying between 89 – 26 mol% have been measured over a wide range of temperature (243.15 to 323.15 K) and pressure and up to 20 MPa. A group contribution method for the Peng-Robinson equation of state has been used to allow calculation of binary interactions between mercury and saturated hydrocarbons, aromatic hydrocarbons, nitrogen and carbon dioxide. The parameters of the group contribution have been adjusted using mercury solubility previously measured in single components. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model.

Elemental mercury partitioning in high pressure fluids part 1: Literature review and measurements in single components

Mercury in its elemental form is naturally present in most reservoir fluids. The presence of mercury can lead to serious operational and safety/health problems. Knowledge of the maximum solubility of elemental mercury with temperature and pressure in reservoir fluids is important to avoid mercury dropping out during processing operations, as mercury is naturally present in hydrocarbon deposits.In this work, a new experimental approach is presented to determine the mercury content in high pressure gas and liquid systems. Mercury solubility in methane, ethane, propane, nitrogen and carbon dioxide over a wide range of temperature and pressure (243.15–323.15K and up to 20 MPa) have been measured. An extensive literature review has been conducted on the solubilities of mercury in gases and liquid hydrocarbons. A critical evaluation of the literature data has been conducted to identify any inconsistencies in the reported data. The new experimental data generated in this work along with the literature data have been used to tune the binary interaction parameters of the Peng-Robinson and the Soave-Redlich-Kwong equations of state between mercury and the mentioned compounds.

Mercury solubility measurements in natural gas components at high pressure

Saturated vapor pressure of elemental mercury (Hg) and Hg solubility in compressed gaseous methane, ethane, and carbon dioxide were investigated. The apparatus designed for this study was based on a flow method and equipped with a cold vapor atomic absorption survey meter to measure Hg concentration in gas phase. The saturated Hg vapor pressure ranged from 4.579 × 10−2 to 2.757 × 10−1 Pa at 278–298 K. The Hg solubility was measured up to 6.042 MPa for methane, 3.533 MPa for ethane, and 2.070 MPa for carbon dioxide at 268–303 K. The Hg mole fraction ranged from 4.842 × 10−9 to 8.683 × 10−7 in the vapor phase. The Hg solubility decreases with increasing pressure, and the pressure dependencies are similar in the three gases. The activation energy of Hg solubility was determined from the Arrhenius plot at the 1.55 and 3.55 MPa isobars. The activation energy at 1.55 MPa is about 60 kJ/mol·K for the three gases, similar to that at the saturated Hg vapor pressure. At 3.55 MPa the activation energy has the same value for methane but decreases to around 60 kJ/mol·K for ethane. The Peng–Robinson equation of state (PR-EOS) was used to correlate the saturated Hg vapor pressure and the Hg solubility in the vapor phase. The attractive parameter in the PR-EOS was fitted with the saturated Hg vapor pressure, and its temperature dependence was investigated using the van der Waals one-fluid mixing rule. The average absolute deviations were 0.322, 0.265 and 0.197 % for Hg solubility in gaseous methane, ethane and carbon dioxide, respectively. This investigation contributes to predicting mercury partitioning in natural gas processing facilities.

The behavior of mercury in water, alcohols, monoethylene glycol and triethylene glycol II. Elemental mercury solubility in alcohols, ethers and acetone; gas plant mercury distribution; and speciation in monoethylene glycol solution

This short communication provides elemental mercury equilibrium solubilities in 1-hexanol, 1-decanol, 2-propanone (acetone), 2-[(propan-2-yl)oxy]propane (diisopropyl ether), and 1-butoxybutane (dibutyl ether) over the approximate temperature range, 255–333 K. Exponential expressions of the solubility are presented in the form: Solubility (ng/g) = Aext, where t is in ⁰C. In a low temperature separator at a gas field, mercury partitioning has been modelled. At separator temperature and pressure conditions of 263–267 K and 2600–3100 kPa, ∼94 wt% of the mercury is calculated to report to the vapor phase, whilst ∼3 wt% each reports to the condensate and aqueous phases. The aqueous phase consists of H2O-rich monoethylene glycol (36 wt% MEG) used to inhibit gas hydrate formation. Sampling and analysis show that the H2O-rich and H2O-lean MEG streams contain predominantly particulate mercury. The use of this technical information is critical to planning for mercury removal, decontamination and waste minimization.

Экогеохимия ртути в почвах и углях юга Кузбасса

Assessment for content of mercury as a toxic component of coal combustion by-product in rocks and deposit environments is aimed at identification of risks caused by impact of hazardous activities on the environment in full concordance with green chemistry concept. In this paper have been presented results of mercury content determination for the South Kuzbass coals and soils of the coal-mining area. The mercury contents in soils (30 samples) and coals (30 samples) were determined by atomic absorption method on the RA‑915+ mercury analyzer with pyrolytic attachment. The mercury content in Mezhdurechensk strip mines’ coals varies from 0.13 to 2.46 mg/kg with the average concentration of 0.57±0.10 mg/kg. The determined content exceeds the Clarke of mercury in coals by factor of 1.3 to 24.6. The mercury content in soil samples varies from 0.012 to 0.173 mg/kg with the average value of 0.057±0.007 mg/kg, which is by 1.7 times more than the average mercury content in the Earth crust. There are five locations within Mezhdurechensk city area where the mercury content in the soil exceeds 3.1–5.3 times the Clark value. During past 25 years the average mercury content in the soil has been decreased by 2.8 times. The solubility of mercury from technogenic landscapes’ soils has been studied by methods of successive acetate-ammonium and hydrochloric acid extracts. The solubility of mercury in aqueous extracts from Mezhdurechensk soils is by 2.2–2.9 times higher than the ones taken from undisturbed landscapes, in acetate-hydrochloric acid and alkaline extracts it is within the limits of content in natural soils; in strongly acidic extracts has been found the maximum solubility of mercury (30.6–84.8% from the total amount). Based on the major contribution of coal dust in the gross input of mercury into the environment of Mezhdurechensk, it is possible to expect the increasing of mercury background in and around the city caused by the growth of coal mining in the area without implementation of modern and effective methods for dust suppression.

Thiosulfate amendment reduces mercury accumulation in rice (Oryza sativa L.)

Thiosulfate addition increases the solubility of mercury (Hg) in soil and Hg uptake by plants under oxic conditions. However, anoxic conditions could dominate the biogeochemical processes of Hg cycling during rice cultivation. The present study aimed to determine whether thiosulfate, a sulfur-containing fertilizer, could be used for Hg immobilization in paddy soil. A pot experiment was conducted using soil newly spiked with Hg and different doses of thiosulfate. Total Hg concentrations in rice tissues, Hg speciation in roots, and geochemical fraction of Hg in soils were investigated. Hydroponic cultivation was conducted to determine the subcellular distribution of Hg in root tissues. Thiosulfate application significantly reduced Hg concentration in rice plants. It increased the percentage of organic-bound Hg, but decreased the percentage of iron/manganese oxide-bound Hg. Thiosulfate enhanced iron plaque formation and Hg adsorption on the iron plaque. Its application increased the percentage of Hg forms similar to HgS and decreased those similar to Hg-glutathione [Hg(GS)2]. Thiosulfate amendments had a remarkable inhibitory effect on Hg accumulation in rice plants in newly Hg-spiked soil. This occurred because thiosulfate reduced Hg mobility in the rhizosphere and root tissues, promoted the formation of iron plaque, and facilitated more Hg adsorption by the iron plaque. Our findings suggest that appropriate thiosulfate treatment could be used as Hg-immobilizing agents in paddy soil.

Measurement of Elemental Mercury Solubility in Natural Gas Dehydrating Solvents

Mercury pollution and emission from natural gas processing industry has gradually received worldwide concern. Basic data and references are important for pollution control and environmental risk management. For this purpose, the solubility and the dissolving characteristics of mercury in the natural gas dehydrating solvents (methanol, mono-ethylene glycol and tri-ethylene glycol in particular) were studied at a temperature range from 253K to 373K. The dissolution experiments were carried out in the dissolving kettle and mercury concentration was analyzed by cold-vapor atomic absorption technique (CVAAS). The experimental results indicated that the solubility of mercury in these solvents showed an increasing trend with increased temperature, whereas decreased with decreasing solvent concentration. The results would be useful for the research on the distribution of mercury in the natural gas processing and provide basis for the prevention and control of mercury pollution.

Modelling of elemental mercury solubility in natural gas components

Elemental mercury is a natural occurring trace component of fossil fuels, which poses significant health and safety risks during oil and gas processing due to its highly toxic and corrosive nature. In order to anticipate and control the distribution of mercury during industrial processes, there is a necessity for thermodynamic models, which can accurately predict its partitioning in the various phases. In this work, the UMR-PRU model is extended to systems that contain elemental mercury and is employed for predicting its solubility in hydrocarbons, compressed gases, water and methanol. A comparison is also made between UMR-PRU and the two most widely used equations of state, Soave-Redlich-Kwong and Peng-Robinson, with modified attractive terms. The results reveal that all three models can accurately describe the solubility of mercury in the aforementioned compounds, with UMR-PRU being the most accurate.

Electrocrystallization and solubility of mercury in alkaline solution

The chemical thermodynamics of mercury in aqueous sodium hydroxide solution has been investigated through electrochemical polarisation and solubility experiments. A review of thermodynamic data allowed determination of the Hg/HgO electrode potential. Cyclic voltammetry revealed a complex anodic reaction beginning with aqueous dissolution of elemental mercury and subsequent electrocrystallization of mercuric oxide. Cathodic sweeps showed dual reduction reactions, attributed to the presence of aqueous mercury and mercuric oxide. The solubility and hence activity of elemental mercury in sodium hydroxide solution was determined, otherwise known as the Sechenov salt effect. Sodium hydroxide salted mercury out of solution.

Predicting phase behavior of metallic mercury in liquid and compressed gaseous hydrocarbons II: Further examination of CP-PC-SAFT in the light of new data

This short communication confirms that the CP-PC-SAFT equation of state attached by a universal value of k12=0.3 is a generally robust estimator of solubility of metallic mercury in liquid and vapor phases of various hydrocarbons at different temperatures and pressures. The considered predictive approach demonstrates that in spite of the divergence of phase behavior in these systems, they exhibit a fundamental regularity, namely the nearly identical ratio between solubility in saturated vapors and liquids expressed in mol/dm3 and plotted versus the reduced pressures of various solvents. In other words, according to this model, the distribution of metallic mercury between saturated vapors and liquids of different compounds actually displays similar patterns of behavior. This observation can be partly confirmed by the novel experimental data.

Thermodynamic Modeling of the Solubility and Chemical Speciation of Mercury and Methylmercury Driven by Organic Thiols and Micromolar Sulfide Concentrations in Boreal Wetland Soils.

Boreal wetlands have been identified as environments in which inorganic divalent mercury (HgII) is transformed to methylmercury (MeHg) by anaerobic microbes. In order to understand this transformation and the mobility and transport of HgII and MeHg, factors and conditions in control of the solubility and chemical speciation of HgII and MeHg need to be clarified. Here we explore the ability of thermodynamic models to simulate measured solubility of HgII and MeHg in different types of boreal wetland soils. With the input of measured concentrations of MeHg, sulfide, eight low molecular mass thiols and thiol groups associated with natural organic matter (NOM), as determined by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and Hg LIII-edge extended X-ray absorption fine structure spectroscopy (EXAFS), the model could accurately predict porewater concentrations of MeHg in the wetlands. A similar model for HgII successfully predicted the average level of its concentration in the porewaters, but the variability among samples, driven mainly by the concentration of aqueous inorganic sulfide, was predicted to be larger than measurements. The smaller than predicted variability in HgII solubility is discussed in light of possible formation of colloidal HgS(s) passing the 0.22 μm filters used to define the aqueous phase. The chemical speciation of the solid/adsorbed and aqueous phases were dominated by NOM associated thiol complexes for MeHg and by an equal contribution from NOM associated thiols and HgS(s) for HgII.

The behavior of mercury in water, alcohols, monoethylene glycol and triethylene glycol

The oil and gas industry is becoming aware of the effects of produced mercury on hydrocarbon processing systems, and that produced mercury contaminates processing equipment. The use of technical information is critical to planning for decommissioning, decontamination and waste minimization. To this end, the solubility of mercury in the polar solvents - water, alcohols, monoethylene glycol (MEG) and triethylene glycol (TEG) have been determined from approximately 243 to 373K. Elemental mercury solubility in MEG and TEG is somewhat higher than that reported previously in the literature when a mass of mercury was agitated for several days in the respective solvent. Elemental mercury was nearly quantitatively stripped from water by natural gas in a small laboratory stripping column, and in a distillation experiment, about 75% of Hg0 in 40vol%MEG partitioned to the distillate phase. Elemental mercury is present in process inlet flow lines and can drop out.This is expected if the reservoir is both hot and saturated with elemental mercury (common), and the pipeline is colder (common). However, in the inlet separator, any dissolved mercury is removed by the drop in pressure and the flashing of C1-C4 hydrocarbons. These light hydrocarbons are very effective in stripping Hg0 from the crude and condensate. What remains in the crude and condensate is particulate metacinnabar, β-HgS. In amine treaters and glycol dehydrators a portion of the Hg0 in the gas can react with traces of oxygen to form heat-stable salts. These can further react to form Hg-rich sludges. The success of the experiments will be useful to the industry in understanding the behavior of mercury in polar solvents, gas hydrate inhibition and in glycol and amine contactors.

A group contribution method for predicting the solubility of mercury

Mercury is a toxic and corrosive element, and understanding its partitioning within ecosystems and industrial processes is of vital importance. The solubility of mercury in normal alkanes, aromatics, water and alcohols is predicted using widely used Soave-Redlich-Kwong equation of state in combination with a group contribution method to estimate binary interaction parameters. The interaction parameters between elemental mercury and seven other molecular groups were determined in this work by fitting available solubility data for mercury. The solubility in the studied solvents was accurately described. This work allows the prediction of the thermodynamic behavior of elemental mercury in a wide variety of solvents, solvent mixtures, and operating conditions where experimental data are unavailable.

Solubility of Mercury in Liquid Hydrocarbons and Hydrocarbon Mixtures

Two experimental methods were developed to determine the solubility of mercury in liquid methane, propane, pentane, octane, and toluene at temperatures from 173 K to 419 K at pressures to 2.1 MPa. For solubility measurements with T > 298 K, a conventional absorption spectroscopic technique at λ = 253.6 nm was used for propane, pentane and octane. Measurements at T < 298 K, however, were made using a laser-based technique utilizing two photon excitation at λ = 320.782 nm and subsequent fluorescence detection of the excited electronic state at λ = 546 nm with a photomultiplier. In both methods a literature value for the solubility of mercury in either hexane or toluene at 298 K was used for calibration. The reliability of this new method was verified by comparison of the results referenced with literature data for the solubility of mercury in pentane and octane at T > 298 K. The two-photon technique was also used for measurements on toluene as aromatic hydrocarbons absorb at the 253.6 nm adsorption peak of mercury, the wavelength normally used for mercury analysis. For both methane and propane at T ≈ 175 K the solubility s was ≈1·10–9 mol·dm–3. These values are higher than expected from a generalized plot of log s against 1/T. Values would be expected to be lower than that predicted from the generalized plot as mercury is a solid at T < 233 K.

Reduction of mercury bioaccessibility using dietary strategies

Food is the main source of mercury for most people. To promote its toxic effect, ingested mercury must be solubilised during digestion and absorbed. The present work aimed to seek dietary components that reduce the quantity of soluble (bioaccessible) mercury after digestion.The effect of 28 compounds on solubility of inorganic mercury and methylmercury in aqueous solution after in vitro gastrointestinal digestion was evaluated. Compounds that reduced mercury solubility were assayed in seafood subjected to gastrointestinal digestion. Lignin (95% CI: 77–88%), tannic acid (95% CI: 61–75%), pectin (95% CI: 48–65%), hydroxypropylmethylcellulose (95% CI: 40–59%), methylcellulose (95% CI: 44–53%) and carboxymethylcellulose (95% CI: 34–51%) produced the highest reductions in mercury bioaccessibility from food. Apart from tannic acid, lignin, pectin and methylcellulose, which reduced Fe bioaccessibility, they did not affect bioaccessibility of essential cations. This information may be useful for defining dietary strategies to reduce mercury bioavailability, although in vivo studies are required to confirm their suitability.

Green waste compost as an amendment during induced phytoextraction of mercury-contaminated soil.

Phytoextraction of mercury-contaminated soils is a new strategy that consists of using the higher plants to make the soil contaminant nontoxic. The main problem that occurs during the process is the low solubility and bioavailability of mercury in soil. Therefore, some soil amendments can be used to increase the efficiency of the Hg phytoextraction process. The aim of the investigation was to use the commercial compost from municipal green wastes to increase the efficiency of phytoextraction of mercury-contaminated soil by Lepidium sativum L. plants and determine the leaching of Hg after compost amendment. The result of the study showed that Hg can be accumulated by L. sativum L. The application of compost increased both the accumulation by whole plant and translocation of Hg to shoots. Compost did not affect the plant biomass and its biometric parameters. Application of compost to the soil decreased the leaching of mercury in both acidic and neutral solutions regardless of growing medium composition and time of analysis. Due to Hg accumulation and translocation as well as its potential leaching in acidic and neutral solution, compost can be recommended as a soil amendment during the phytoextraction of mercury-contaminated soil.