NaCl H2O Solutions Research Articles

An accurate model for the solubilities of anhydrite in H2O–NaCl solutions at temperatures up to 1073 K, pressures up to 14,000 bar, and mole fractions of NaCl up to 0.3

An accurate density-based solubility model is established for anhydrite in H2O–NaCl solutions, which is valid for temperatures up to 1073 K, pressures up to 14,000 bar, and mole fractions of NaCl (xNaCl) up to 0.3. The isobaric linear dependence of the mineral solubility logarithm on the solvent density logarithm should be a common phenomenon similar to isothermal linear dependence, particularly at relatively high pressures. The terms about P in the equations of the density-based model are rational and necessary to elevate the accuracy of mineral solubility models. This model reproduces the complicated changing trends of anhydrite solubility with temperature, pressure, and xNaCl. Compared to numerous experimental data, the average relative deviations of calculated anhydrite solubilities in water and the aqueous NaCl solution are 3.52% and 9.64%, respectively, which are within experimental uncertainties. According to this model, the anhydrite deposition would result from any salinity variation departing from the specified xNaCl in skarn- or porphyrite-type iron ore-forming hydrothermal fluids.

Fluid origin and evolution of the Pusangguo Cu–Pb–Zn skarn deposit in Tibet: Constraints from fluid inclusions and isotope compositions

he Pusangguo Cu–Pb–Zn skarn deposit is a representative Co-bearing deposit in the Gangdese metallogenic belt. The mineralization mainly has a close relationship with the biotite granodiorite. Here we identified four paragenetic stages during the ore formation: prograde skarn stage (stage 1) dominated by garnet and less diopside, retrograde stage (stage 2) which is characterized by epidote, chlorite and actinolite, quartz polymetallic sulfide stage (stage 3) featured by chalcopyrite, sphalerite, galena with minor cobaltite and aikinite, and quartz calcite stage (stage 4). In this study, fluid inclusion, H–O, He–Ar, S and Pb isotope compositions were determined to constrain the sources and evolution of the ore-forming fluids, metal deposition mechanisms and metallogenetic model for the Pusangguo deposit. The He–Ar isotopic compositions (3He/4He = 0.39–0.55 Ra, 40Ar/36Ar = 299–366) show that the ore-forming fluids predominantly derived from crust source with minor mantle input. The H–O isotopic analysis results (δ18OH2O = −13.3 to + 4.9 ‰, δD = −168 to −79.5 ‰) suggest that the ore-forming fluids were sourced from a magmatic origin that mixed with some meteoric water. The S–Pb isotopic results suggest that the ore-forming materials were mostly derived from the upper crust with a minor amount of mantle materials and the biotite granodiorite magma contributed most of the lead and possibly other metals. Fluid inclusion petrography and microthermometry results show that the fluid inclusion assemblages developed in the different mineralization stages of Pusangguo deposit changed from type II (vapor-rich two-phase fluid inclusions) + type III (daughter mineral-bearing three-phase fluid inclusions) to type I (liquid-rich two-phase fluid inclusions) + type II + type III + type IV and eventually evolved into type II. Correspondingly, the ore-forming fluids mainly belonged to H2O-NaCl solutions and changed from high temperature (413–532 °C), moderate–high salinity (15.5–53.1 wt% NaCl equiv.) fluid system in stage 1 to a lower-temperature (176–234 °C) and lower-salinity (0.7–4.2 wt% NaCl equiv.) meteoric water during stage 4. Fluid boiling and mixing were likely the vital factors controlling the metal precipitation.

A New Density Model of Quartz Solubility in H2O-CO2-NaCl Ternary Systems up to High Temperatures and High Pressures

A novel density model for computing quartz solubility in H2O-CO2-NaCl hydrothermal fluids applicable to wide ranges of temperature and pressure is proposed. Based on the models of Akinfiev and Diamond (2009) and Wei et al. (2012), the effective partial molar volume of water (VH2O∗) is replaced by the partial molar volume of water (V¯H2O) by implementing an empirical correction, and water molar fraction (xH2O) is modified with water activity (aH2O), in addition to a series of changes to the model coefficient forms. The absolute values of averaged relative deviation of this model compared to the experimental data sets in pure water, H2O-CO2, and H2O-NaCl solutions are 5.74%, 6.69%, and 7.09%, respectively, which are better than existing models in the literature. The model can be reliably used for computing quartz solubilities in pure water from 0°C to 1000°C, from 0 bar to 20,000 bar, and in CO2- and/or NaCl-bearing solutions from 0°C to 1000°C, from 0 bar to 10,000 bar (with slightly lower accuracy at 5000-10,000 bar in H2O-NaCl systems) in the single liquid region. Moreover, the trends and overall ranges of this model may probably be more accurate in the H2O-CO2-NaCl fluid mixtures compared to the limited experimental data. In addition, a bisection algorithm for deriving the isopleths of quartz solubilities based on this new model is first proposed, and application perspectives are discussed for various geologic settings including subduction zone, lower crust-upper mantle, migmatite, pegmatite, porphyry, and orogenic deposits.

Influence of NaCl and temperature on the interaction between cephradine monohydrate and surfactants: Conductivity and UV–visible measurements

The formulation of drug considering the body fluid ingredients is important and therefore study of the interaction of drug-surfactant in fluid ingredients medium is very significant. Herein, we applied a conductivity technique to insight the interaction of cephradine monohydrate (CDM) drug with cationic surfactant- cetyltrimethylammonium bromide (CTAB) and anionic surfactant- sodium dodecyl sulfate (SDS)) while UV–visible spectroscopic was employed to observe the interaction of CDM with non-ionic surfactant, triton X-100 (TX-100). The experimental temperature ranges were 303.15–328.15 K and 293.15–323.15 K for CDM + CTAB and CDM + SDS systems respectively in the case of the conductivity study whereas for UV–visible spectroscopic study the temperature was kept in the range of 298.15–318.15 K. The values of critical micelle concentration (CMC) of CDM + CTAB and CDM + SDS systems were analyzed from their conductivity data in H2O and aqueous NaCl solution. The CMC values were found to be lower for CDM + CTAB and CDM + SDS systems as compared to corresponding pure surfactants. The CMC values were found to be influenced by the variation of experimental temperature. The micellization of CDM + CTAB and CDM + SDS systems was favored in the presence of NaCl and augmentation of NaCl concentration generates a more favorable condition for micellization of studied systems. The values of counter ion dissociation (α) were found to be temperature and additives dependent. The free energy of micellization (∆Gmo) indicates that micellization of CDM + CTAB and CDM + SDS systems was thermodynamically spontaneous which further augmented with the boost of NaCl concentration. The computed enthalpy and entropy values exhibit a linear relationship in all cases for CDM + CTAB and CDM + SDS systems. The binding constant (Kb) between CDM and TX-100 was found to be increased with the augmentation of CDM concentration and exhibit U-like variation as temperature increases. The binding between CDM and TX-100 was also thermodynamically spontaneous.

Diopside, enstatite and forsterite solubilities in H2O and H2O-NaCl solutions at lower crustal and upper mantle conditions

The interaction of fluids with rock-forming minerals plays an important role in the chemical evolution of mafic and ultramafic rocks in the lower crust and upper mantle. Recent work highlights the importance of salt-rich fluids in element transport in settings such as the mantle wedge above subduction zones and high-grade granulite facies metamorphism. Forsterite (Mg2SiO4), enstatite (MgSiO3) and diopside (CaMgSi2O6) are key rock-forming minerals in these settings in the system CaO-MgO-SiO2. We determined experimentally the solubilities of diopside, enstatite and forsterite in H2O-NaCl fluids at a range of pressures and temperatures. Forsterite solubility was determined at 1 GPa, 800 and 900 °C, in pure H2O and in H2O-NaCl solutions. Forsterite dissolved congruently at nearly all conditions. Its solubility in pure H2O is low, but increases greatly with rising NaCl concentration in the fluid. Enstatite solubility was investigated in H2O-NaCl solutions at 1 GPa, 800 and 900 °C. Enstatite dissolved incongruently to yield forsterite at all conditions. Addition of excess silica led to suppression of forsterite and showed that fluids in equilibrium with enstatite with or without forsterite are strongly enriched in Si relative to Mg, though Mg solubility is significant at high salinity. Diopside solubility was determined in pure H2O at 650–900 °C and 0.7–1.5 GPa, and in H2O-NaCl solutions at 800 °C and 1 GPa, with NaCl concentrations approaching halite saturation. Diopside dissolves incongruently yielding residual forsterite at all conditions investigated. The solubility of diopside in pure H2O increases with increasing pressure, temperature and salinity. Diopside dissolution in H2O-NaCl solutions displays a dependence on fluid salinity similar to that of forsterite and wollastonite. The results of forsterite solubility experiments in H2O-NaCl solutions were used to calculate the compositions of fluid coexisting with enstatite or diopside where forsterite was present. The concentration of solutes coexisting with enstatite decreases with rising NaCl, similar to quartz. In contrast, bulk solutes coexisting with diopside increase with NaCl, similar to wollastonite and forsterite. These patterns imply complexing among rock-forming components and fluid components, that Ca-chloride species are substantially more stable than Mg-chloride species, and that hydrous Na-silicate complexes are important components of deep H2O-NaCl fluids. The results show that salt-bearing brines have substantial metasomatic power and may exert significant control on the chemical evolution of lower crustal and upper mantle mafic and ultramafic rocks.

The effect of sodium chloride concentration on the mutarotation and structure of d-xylose in water: Experimental and theoretical investigation

The effect of NaCl concentration on the structure of d-xylose in H2O was studied. It was found that NaCl could prolong the equilibrium time between the two main configurations, α-xylopyranose and β-xylopyranose. The proportion of α-xylopyranose was slightly increased in NaCl–H2O solution than that in H2O, and the alteration of NaCl on α-xylopyranose and β-xylopyranose was different. Theoretical calculations demonstrated that NaCl was more favorable to stabilize the structure of α-xylopyranose. Na+ had attraction with O atoms (α: O6; β: O6 and O1), with the outflow of electron from C atom to O atom on the C1–O6 bond, which was beneficial to the transformation between chain form and pyran forms. Cl− had interaction with the hydroxyl groups of xylose. The interaction between xylose and NaCl, was also evidenced by the variation of 35Cl and 23Na NMR spectra. The findings could provide guidance for understanding the conformational change and design of xylose conversion ways. It also provided valuable information for making efficient use of hemicellulose.

A model for the solubility of minerals in saline aqueous fluids in the crust and upper mantle

Quantifying and predicting the solubility of minerals in saline aqueous fluids across wide ranges of pressure, temperature and salinity is critical for interpreting geologic processes. Here, we define a new thermodynamic model for mineral solubility in saline aqueous fluids. The model is based in part on coupling two previous models: one for the solubility of minerals in pure H2O fluids as function of temperature and fluid density (Dolejs and Manning, 2010), with the additional effects of salinity modeled based in part on Akinfiev and Diamond (2009), with some modifications and additions. Specifically, the new model adopts a modified version of the approach by Akinfiev and Diamond (2009) to incorporate the effect salinity on solvent density, with additional expressions added for the equilibrium constants of reactions involving explicit sodium and/or chloride species. The new generic model is applicable to the solubility of minerals that dissolve as hydrous species, sodium and/or chloride species, and combinations thereof. The model has been calibrated according to experimentally determined solubilities for six common rock-forming minerals – quartz, calcite, corundum, fluorapatite, fluorite, and rutile – in H2O-NaCl solutions at temperatures up to 1100 °C and pressures up to 20 kbar. Data and trends in experimental measurements are well reproduced by the model, and the accuracy is within experimental uncertainty. In the case of pure H2O fluids (zero salinity), the model is implicitly equivalent to that of Dolejs and Manning (2010). This thermodynamic model, accounting for dissolution reactions in saline fluids over an extreme range of pressure, temperature and salinity, will allow for robust modeling of reactions and mass transport in natural systems.

Characterization and Assessment of a Novel Plate and Frame MD Module for Single Pass Wastewater Concentration-FEED Gap Air Gap Membrane Distillation.

Membrane distillation (MD) is an up and coming technology for concentration and separation on the verge of reaching commercialization. One of the remaining boundaries is the lack of available full-scale MD modules and systems suitable to meet the requirements of potential industrial applications. In this work a new type of feed gap air gap MD (FGAGMD) plate and frame module is introduced, designed and characterized with tap water and NaCl–H2O solution. The main feature of the new channel configuration is the separation of the heating and cooling channel from the feed channel, enabling a very high recovery ratio in a single pass. Key performance indicators (KPIs) such as flux, gained output ratio (GOR), recovery ratio and thermal efficiency are used to analyze the performance of the novel module concept within this work. A recovery rate of 93% was reached with tap water and between 32–53% with salt solutions ranging between 117 and 214 g NaCl/kg solution with this particular prototype module. Other than recovery ratio, the KPIs of the FGAGMD are similar to those of an air gap membrane distillation (AGMD) channel configuration. From the experimental results, furthermore, a new MD KPI was defined as the ratio of heating and cooling flow to feed flow. This RF ratio can be used for optimization of the module design and efficiency.

Fluid characteristics from shallow magmatic environments: A contribution to danburite bearing Luc Yen pegmatites, northern Vietnam

Danburite as a member of the Luc Yen pegmatite mineral assemblage has been studied using fluid inclusion microthermometry and Raman spectroscopy. Data characterize well-preserved fluid inclusions which originate from primary large tubular inclusions as result of necking down. Same modifications underwent a second inclusion generation that evolved during healing of a later crack. Both generations of fluid inclusions show the same chemistry (H2O-CO2) characterizing 3-phase inclusions with additional solids (calcite, sassolite and danburite). Inclusions consist of pure CO2 and H2O with additional NaCl ± KCl comprising a salinity of about 4.5 mass%. Internal fluid inclusion pressures as well as bulk inclusion densities have been calculated using the fermi diad split method of pure CO2 at clathrate melting temperatures of the system and total homogenization temperatures, respectively. Mean internal pressures of ca. 4.5 MPa as well as a bulk density around 0.60 g/cm3 represent a low-dense fluid with XH2O~0.86 and XCO2~0.14 in composition that was present during formation of danburite. Data characterize danburite as a late stage crystallization member of the pegmatite in a shallow magmatic environment.ReferencesAnovitz L.M. and Grew, E.S., 1996. Mineralogy, petrology and geochemistry of boron: An introduction. In L.M. Anovitz and E.S. Grew, Eds., Boron: Mineralogy, Petrology, and Geochemistry, Reviews in Mineralogy, Vol. 33, Mineralogical Society of America, Washington DC, USA, 1–40.Bakker, R.J., 1997. Clathrates: computer programs to calculate fluid inclusion V–X properties using clathrate melting temperatures. Computer & Geosciences, 23, 1-18.Bakker R.J., Diamond L.W., 2000. Determination of the composition and molar volume of H2O–CO2 fluid inclusions by microthermometry. Geochimica et Cosmochimica Acta, 64, 1753-1764.Bodnar R.J., 1993. Revised equation and table for determining the freezing point depression of H2O-NaCl solutions. Geochimica et Cosmochimica Acta, 57, 683-684.Chauviré B., Rondeau B., Fritsch E., Ressigeac P., Devidal J.-L., 2015. Blue spinel from the Luc Yen District of Vietnam. Gems & Gemology, 51, 1, 2–17.Diamond L., 2003. Glossary: Terms and symbols used in fluid inclusion studies, In: Samson, I., Anderson, A., Marshall, D. (Eds.), Fluid Inclusions: Analysis and Interpretation. Mineralogical Association of Canada Short Course Series, 32, 365-374.Duan Z., Møller N., Weare J.H., 1996. A general equation of state for supercritical fluid mixtures and molecular dynamics simulation of mixture PVTX properties. Geochimica et Cosmochimica Acta, 60, 1209-1216.Davis D.W., Lowenstein T.K., Spencer R.J., 1990. Melting behavior of fluid inclusions in laboratory-grown halite crystals in the systems NaCl-H2O, NaCl-KCl-H2O, NaCl-MgC12-H2O, and NaCl-CaCl2-H2O. Geochimica et Cosmochimica Acta, 54, 591-601.Fall A., Tattrich B., Bodnar R.J., 2011. Combined microthermometric and Raman spectroscopic technique to determine the salinity of H2O-CO2-NaCl fluid inclusions based on clathrate melting. Geochimica et Cosmochimica Acta, 75, 951-964.Garnier V., Ohnenstetter D., Giuliani G., Maluski H., Deloule E., Phan Trong T., Pham Van L., Hoang Quang V., 2005. Age and significance of ruby bearing marble from the Red River shear zone, northern Vietnam. Canadian Mineralogist, 43(4), 1315-1329.Goldstein R.H., Reynolds T.J., 1994. Systematics of fluid inclusions in diagenetic minerals. SEPM Short Course, 31.Kurshakova L.D., 1982. Temperature regime and geochemical conditions of formation of danburite. International Geology Review 24, 3, 367–371.Roedder E. 1984. Fluid Inclusions. Reviews in Mineralogy, 12, 646.Tattitch B.C., Candela P.A., Piccoli P.M., Bodnar R.J., 2015. Copper partitioning between felsic melt and H2O-CO2 bearing saline fluids. Geochim.

Effect of boiling on the acidity of hydrothermal solutions

Natural seawater and H2O–NaCl solutions were equilibrated along the two-phase (liquid–vapor) curves between 150 and 390 °C to re-examine the effect of liquid–vapor phase separation on element fractionations between saline brines and vapor phases. The experimental setup allows vapor and brine to be sampled separately at in situ P–T conditions. Experimental vapor pressure is constrained by temperature and the electrolyte concentration of the brines. With increasing temperature, dissolved electrolytes react with increasing temperature to hydroxides and HCl, in both seawater and H2O–NaCl solutions. The extent of hydrolysis is more pronounced in seawater than in H2O–NaCl solutions because seawater contains, in addition to NaCl, a range of other electrolytes capable of hydrolysis. Associated HCl has a great affinity to fractionate to the vapor phase when phase separation occurs. At 365 °C, halite-saturated vapor phases have a pH25 (pH after condensation to 25 °C) of 1.8 (seawater) and 2.8 (H2O–NaCl brines). Our data suggest that boiling of hydrothermal solutions followed by mixing of vapor condensates with seawater can impose pH25 values as acidic as the most acidic natural hydrothermal solutions vented on the ocean floor.

Metasomatic Replacement of Albite in Nature and Experiments

Replacement of albite by sodium-rich, secondary phases is a common phenomenon, observed in different geological settings and commonly attributed to alkaline metasomatism. We investigated growth of nepheline and sodalite on albite in time series experiments between two and 14 days. A total of 42 hydrothermal experiments were performed in cold-seal hydrothermal vessels at a constant pressure of 4 kbar and 200–800 °C in the system SiO2–Al2O3–NaCl–H2O. To allow for fluid flow and material transport, a double-capsule technique was used; hereby, a perforated inner Pt capsule was filled with cleavage fragments of natural albite, whereas the shut outer Au capsule was filled with γ-Al2O3 and the NaCl–H2O solution. Complete overgrowth of albite by sodalite and nepheline occurred after just two days of experiments. At high salinity (≥17 wt % NaCl) sodalite is the stable reaction product over the whole temperature range whereas nepheline occurs at a lower relative bulk salinity than sodalite and is restricted to a high temperature of ≥700 °C. The transformation of albite starts along its grain margins, cracks or twin lamellae. Along the reaction front sodalite crystallizes as small euhedral and highly porous grains forming polycrystalline aggregates. Coarse sodalite dominates in the outermost domains of the reaction zones, suggesting recrystallization. Sodalite may contain fluid inclusions with trapped NaCl-rich brine, demonstrating that the interconnected microporosity provides excellent pathways for fluid-assisted material transport. Highly porous nepheline forms large, euhedral crystals with rectangular outline. Sodalite and nepheline in natural rock samples display only minor porosity but fluid and secondary mineral inclusions, pointing to coarsening of a previously present microporosity. The reaction interface between sodalite and albite in natural rock samples is marked by open channels in transmission electron microscopy. In many of the experiments, a zone of Si–H-rich, amorphous material is developed at the reaction front, which occurs at a temperature of up to of 750 °C as nanometer to 350 µm wide reaction zone around albite. This change in composition corresponds with the abrupt termination of the crystalline feldspar structure. The presence of sodalite as micro- to nanometer-sized, euhedral crystals within the amorphous zone demonstrates, that both the sodalite reaction rim and the amorphous material allow for fluid-assisted material transport between the crystalline albite (release of Si, Al) and the bulk fluid (H2O, Na, Cl). This texture, moreover, suggests that the amorphous phase represents a metastable interstage reaction product, which is progressively replaced by sodalite and nepheline. Remarkably, product sodalite, nepheline, and the amorphous material largely inherit the trace element budget of the respective ancestor albite, indicating that at least part of the trace elements remained fixed during the reaction process. The observed reaction textures in both natural and experimental samples indicate an interfacial dissolution–reprecipitation mechanism. Results of our study bear important implications with respect to mineral replacement in the presence of a fluid phase, especially regarding the interpretation of trace element patterns of the product phases.

The hydrothermal Waterberg platinum deposit, Mookgophong (Naboomspruit), South Africa. Part II: Quartz chemistry, fluid inclusions and geochronology

AbstractThe historic Waterberg platinum deposit, ~15 km WNW of Mookgophong (formerly Naboomspruit), Limpopo Province, South Africa, is a rare fault-bound hydrothermal vein-type quartz-hematite-platinum-group mineralization. As a continuation of the geochemistry and ore mineralogy studies (Part I, Oberthür et al., 2018), this paper concentrates on the ore-bearing quartz and on the age constraints of ore formation. The state-of-the-art methods used include cathodoluminescence microscopy, electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) of trace elements, stable isotope (δ18O) analysis and fluid-inclusion studies. U-Pb and (U-Th)/He radiometric age determination gave ages of 900–1075 Ma suggesting platinum-group element (PGE) mineralization as a result of upwelling fluids with connection to the Bushveld complex during Kibaran tectonic movements along the Thabazimbi–Murchison Lineament. Felsic fragments containing Qtz-1 were cemented by different quartz generations (Qtz-2 to Qtz-4) and enable the characterization of the changing physicochemical parameters during multistage mineralization and cooling. The PGE minerals are associated with the earliest hydrothermal stage represented by botryoidal radial-fibrous quartz aggregates (Qtz-2a) which formed on brecciated felsite. The other quartz types are essentially barren. Cathodoluminescence studies of quartz indicate very high Al, Fe and K concentrations as confirmed by EPMA and LA-ICP-MS, whereas Ti is always very low. The varying Al concentrations in the quartz mainly indicate pH fluctuations, the high Fe3+ points at high oxygen fugacity. Micro-inclusions of iron oxide are associated with Pt ore (Fe, Pt, Pd, Au, W, Sb, As), rutile, kaolinite and muscovite. The hydrothermal activity must have been characterized by low saline (<10 wt%) H2O–NaCl solutions. These fluids mixed with original high-saline NaCl ± CaCl2 ± CO2 brines in the brecciated felsite (Qtz-1). According to the quartz-hematite geothermometer the ore depositional temperatures were ~370–330°C (Qtz-2a), whereas the successive quartz veins formed during cooling towards ~295°C. The transport of PGE must have been facilitated by strongly oxidizing chloride complexes of relatively low salinity and moderate acidity.

The Effect of Si and Mn on Microstructure and Selected Properties of Cr-Ni Stainless Steels

Abstract Cast stainless steel of the Cr-Ni duplex type is used, among others, for the cast parts of pumps and valves handling various chemically aggressive media. Therefore, the main problem discussed in this article is the problem of abrasion wear resistance in a mixture of SiC and water and resistance to electrochemical corrosion in a 3% NaCl-H2O solution of selected cast steel grades, i.e. typical duplex cast steel, high silicon and manganese duplex cast steel, and Cr-Ni austenitic cast steel (type AISI 316L). The study shows that the best abrasion wear resistance comparable to Ni-Hart cast iron was obtained in the cast duplex steel, where Ni was partially replaced with Mn and N. This cast steel was also characterized by the highest hardness and matrix microhardness among all the tested cast steel grades. The best resistance to electrochemical corrosion in 3% NaCl-H2O solution showed the cast duplex steel with high content of Cr, Mo and N. The addition of Ni plays rather insignificant role in the improvement of corrosion resistance of the materials tested.

On the ionic strength and electrical conductivity of crustal brines

An empirical model has been developed to depict the ionic strength of concentrated NaCl aqueous solutions at high temperatures and pressures. The model adopts the solvation properties of electrolyte-bearing aqueous solutions that link ionic strength with relative permittivity:ÂĪ=1/ϵsol–1/ϵH2Owhere Ī denotes for ionic strength, ϵH2O and ϵsol are the dielectric constants of H2O and NaCl-H2O solution respectively. Aqueous speciation calculations reveal that the parameter  is strongly dependent on the density of H2O (ρH2O, gcm−3):lnÂ102=aÂ−bÂρH2Owith aÂ=6.95±0.18kgmol−1 and bÂ=9.51±0.12kgcm3mol−1g−1.The dielectric constant of the saline solution has been determined by employing the activity coefficient of SiO2(aq), which emerged from published experimental data on quartz solubility in the NaCl-H2O system (0.01–0.4 XNaCl) at 500–900°C and 5–15kbar that correspond to H2O density conditions of 0.69–1.0gcm−3 (Newton and Manning, 2000). Accordingly, thermodynamic calculations integrate the extent of quartz solubility with the ϵH2O and ϵsol of saline fluids, and result in formulating the dielectric constant of NaCl(aq) as a function of pressure (P, kbar), ϵH2O and ρH2O:ϵNaClaq=ϵH2O−expφP−3ρH2OP2−Ψ2with Ψ=2.6kbar and φ=22.4±0.3kbarcm3g−1.When compared to the Helgeson-Kirkham-Flowers equations of state, the empirical Ī–ϵH2O–ϵsol model appears to better constrain the effect of ion-pairing and multi-ion complexation towards approximating the true ionic strength of highly concentrated NaCl solutions at elevated pressures and temperatures. In effect, the ionic strength conditions depicted by this model exhibit a strong linear correlation with the electrical conductivity (σf) of the electrolyte-bearing aqueous fluids. This relationship is expressed as:σf=csĪwith cs=79.5±0.4kgSmol−1m−1. This linear regression is applicable within the temperature and pressure range of 500–800°C, 6–12kbar and for NaCl concentrations ranging from 0.01 to 0.4 XNaCl. Following this approach, both the electrical conductivity and the ionic strength of crustal brines can be readily predicted at conditions applicable to the Earth's lower crust and upper mantle.

Hydrous albite magmas at lower crustal pressure: new results on liquidus H2O content, solubility, and H2O activity in the system NaAlSi3O8–H2O–NaCl at 1.0 GPa

The system albite–H2O serves as an important model for the generation of granitic magmas, yet relatively few experimental investigations have focused on phase relations at high pressure. This study reports new experimental results, at 1.0 GPa and 690–1050 °C, on the temperature and liquid composition at vapor-saturated melting, the H2O content of undersaturated silicate liquids in equilibrium with albite, the solubility of albite in H2O–NaCl fluids immediately below the solidus, and the activity of H2O in hydrous NaAlSi3O8 liquids along the liquidus. Albite melts and dissolves congruently at all temperatures and salinities. In the NaCl-absent system, the temperature of vapor-saturated melting of low albite, confirmed by X-ray diffraction, is 695 ± 5 °C and the liquid composition is 18.14 ± 1.35 wt% H2O. The temperature dependence of the fluid-undersaturated liquidus curve in the system NaAlSi3O8–H2O varies with H2O wt% (\(w_{{{\text{H}}_{2} {\text{O}}}}\)) according to $$T = - 2.0331 \times 10^{ - 3} w_{{{\text{H}}_{2} {\text{O}}}}^{3} + 1.6497w_{{{\text{H}}_{2} {\text{O}}}}^{2} {-} 58.963w_{{{\text{H}}_{2} {\text{O}}}} + 1235.5\,^{ \circ } {\text{C}}$$ indicating positive curvature in temperature-composition coordinates and a dry melting temperature of ~1235 °C. At 690 °C, immediately below the solidus, albite solubility decreases drastically with NaCl content of the fluid phase, from 8.8 ± 0.6 wt% in the NaCl-free fluid to ˂2 % at NaCl concentration of only 10 mol%. Experiments determining the activity of H2O (\(a_{{{\text{H}}_{2} {\text{O}}}}\)) in liquids at vapor-saturated melting exploited low Cl solubility in liquids and low albite solubility in the presence of H2O–NaCl fluids. The maximum Cl content of quenched glasses, only 0.95 wt%, and very low albite solubility together make possible H2O activity measurement in melts equilibrated with NaCl–H2O solutions. When combined with activity data for H2O–NaCl fluids, experimentally determined \(a_{{{\text{H}}_{2} {\text{O}}}}\) along the liquidus is described by $$T = - {469.16a_{{H_{2} O}}^{L}}^{{\frac{1}{2}}} {-} 93.382a_{{H_{2} O}}^{L} + 1235.5\;^\circ C.$$ At 1 GPa, H2O activities in hydrous albitic melts in H2O–NaCl fluids agree with those in the presence of H2O–CO2 fluids, provided appropriate fluid mixing data are used. Our results constrain an asymmetric regular solution model for the mixing of Na1/8Al1/8Si3/8O and H2O, yielding Margules parameters of W Ab = 25.56 ± 0.54 and \(W_{{{\text{H}}_{2} {\text{O}}}} = \, 10.50\; \pm \;0.74{\text{ kJ}}/{\text{mol}}\). The results imply critical mixing of liquid and vapor at ~1100 °C. Using existing speciation models, our results imply that H2O dissolved in hydrous albitic liquids is almost entirely in the form of molecular H2O (OH− concentration is negligible) at temperatures near vapor-saturated melting. The results provide a more complete experimental foundation for modeling the system NaAlSi3O8–H2O at high pressure.

Thermodynamic description of H2S–H2O–NaCl solutions at temperatures to 573 K and pressures to 40 MPa

Reliable experimental results were selected from the literature (using over 700 data) to develop a thermodynamic model for calculating the solubility of hydrogen sulfide (H2S) in pure water and in aqueous NaCl solutions between 283 and 573K, 0.1–40MPa and ms 0–6mol·kg−1. Thermodynamic properties of the pure components were calculated using highly accurate multiparametric equations of state for H2S (Lemmon and Span, 2006) and for H2O (Wagner and Pruss, 2002). Thermodynamic properties of H2S(aq) at infinite dilution were based on the Henry's law constants generated from the SOCW model (Sedlbauer et al., 2000) and reported by Majer et al. (2008). The determined activity coefficients of H2S in pure water and in NaCl solutions were treated using the Pitzer interaction model. The Pitzer parameters for H2S in binary and ternary solutions were newly determined while those for NaCl(aq) in the H2S-free system were adopted from the review of Archer (1992). The experimental solubilities selected for correlation are reproduced by the model with mean relative deviations of 5.2% and 6.1% for the H2S–H2O and for H2S–H2O–NaCl systems, respectively. These values are comparable to the experimental uncertainty of the solubility data. The new model allows a thermodynamically consistent description of numerous other properties of the liquid phase in the ternary H2S–H2O–NaCl system, including the activity coefficients of H2S and NaCl, the osmotic coefficients, the Setchenow constants, and the molar volume and density of the bulk liquid. These properties can be calculated for any H2S and NaCl concentrations up to halite saturation. The model is available as a computer code that is freely distributed.

Ultrashort-laser-pulse-induced thermal lensing effect in pure H2O and a NaCl–H2O solution

Using the Z-scan technique with 82 MHz 18 femtosecond (fs) laser pulses at 820 nm, we explore the thermal lensing effect induced in pure H2O and a NaCl–H2O solution. We verify the contributions of thermal and mass diffusions in NaCl–H2O.

Volumetric Properties of Na2SO4–H2O and Na2SO4–NaCl–H2O Solutions to 523.15 K, 70 MPa

The densities of aqueous solutions in the systems Na2SO4–H2O and Na2SO4–NaCl–H2O were determined experimentally at temperatures from (298.15 to 523.15) K and pressures up to 70 MPa, and over a wide range of salt concentrations (up to 5 mol·kg–1 of NaCl and up to 1.2 mol·kg–1 of Na2SO4). The measurements were conducted in vibrating-tube densimeters permitting density determinations with an accuracy varying from (2.8·10–5 to 1.0·10–4) g·cm–3 depending on temperature. The Pitzer equation for the apparent molar volume was parametrized on the basis of the newly obtained experimental data and data from literature. The resulting model for binary Na2SO4–H2O and ternary Na2SO4–NaCl–H2O solutions can be applied across the entire range of temperatures, pressures, and compositions covered by this study. Most importantly, it is the first model capable of calculating the mean apparent molar volume of the mixed solutes and, consequently, the density of solution in aqueous system Na2SO4–NaCl–H2O at elevated temperatures ...

The relationship between environmental abundant electromagnetic fields and packaging shape to their effects on the 17O NMR and Raman spectra of H2O–NaCl

In this study, two identical groups of four containers with different packaging shapes made of polymethyl methacrylate (PMMA) were used to store H2O–NaCl solution for seven days at ambient room temperature (25°C). Faraday shield was used to shield one group. The surrounding electromagnetic fields were measured during the storage period by using R&S®TS-EMF EMF measurement system. Samples of H2O–NaCl were collected at the end of the storage period and examined by 17Oxygene nuclear magnetic resonance spectroscopy (17O NMR) and Raman spectroscopy. Electromagnetic simulation was used to explore the relationship between the packaging shape of H2O–NaCl containers and the environmentally abundant electromagnetic fields to their effects on the cluster size of water. The study showed variations in the cluster size of water stored inside the two groups of containers. It was observed that the cluster size of water stored in the unshielded containers was lower than that of the shielded containers. The cluster size of water stored in the unshielded pyramidal container was lower than the cluster size of water stored in the unshielded rectangular, square, and cylindrical containers. The EM simulation results showed significant variations in the total specific absorption rate SAR and maximum point SAR values induced in the H2O–NaCl solution in the unshielded container models at 2400MHz for both vertical and horizontal polarization. It can be concluded that the variations in the values of SAR induced in H2O–NaCl solution are directly related to the variations in the cluster size of the stored water.

C-2022: Monitoring of the residual cryoprotectant concentration with electrical conductivity measurements during cryoprotectant removal

Cryoprotective agents (CPA) should be added to cell suspension before freezing and removed after thawing. Nowadays people mainly apply centrifugation for CPA removal. This method may cause many problems. Meanwhile, a fast, easy and cheap method to monitor the residual CPA concentration remains an unfilled need. In this work, real-time monitoring of residual CPA concentration with electrical conductivity (EC) measurements was proposed and tested. It was found that CPA concentration is correlated with the EC of the solution. The standard data of “CPA concentration—EC of the solution” for a few widely used CPA solutions were obtained. A “dilution–filtration” system based on a hollow fiber dialyzer, three peristaltic pumps and some well-designed tubing connections was applied to remove CPA. Me2SO solutions (Me2SO–NaCl–H2O solutions with or without 5% BSA) were selected as representative examples. The results showed that CPA can be removed effectively by the “dilution–filtration” system. The ECs of waste solution (filtration product) and “cell suspension” were almost identical after a short period of processing, which were validated by osmolality measurements with an osmometer. EC readings of waste solution can convey the instant residual CPA concentrations in cell suspension. This validates the feasibility of a safe (no contamination), easy and cheap way to real-time monitoring of CPA concentration in cell suspension by measuring the EC of the waste solution. Compared to other CPA removal methods that are applied traditionally (centrifugation) or proposed recently (microfluidic device), the “dilution–filtration” method may offer advantages of low time and labor consumption, low injury to the cells, high effectiveness, ease of controlling the final suspension volume and low risk of contamination. The configuration of the “dilution–filtration” system can also be modified easily to achieve CPA addition and volume control of cell suspension (concentration or dilution of the cell suspension).