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Hole-transporting material (HTM) is an indispensable constituent in organic electronic devices, generally comprising a donor/dopant combination. We report that a disodium salt of substituted benzo[1,2-b:4,5-b'] dipyrrole bearing two racemic alkanediylsulfonate anion side chains (BDPSOs) serves as a neutral, nonhygroscopic, dopant-free HTM for lead perovskite (MAPbI3) solar cells. These organic/inorganic hybrid molecules are useful for tunable orbital level and controllable solubility. A fluorinated BDPSO has an energy level matched with MAPbI3, affording an inverted-structure solar cell that performs with 17.2% efficiency with minimal hysteresis. The solar cell devices fabricated using BDPSOs showed remarkable storage and operational stability. [ABSTRACT FROM AUTHOR]

Glucagon-like peptide 2 (GLP-2) is a hormone that has been shown to stimulate intestinal growth and attenuate intestinal inflammation. Despite being efficacious in a variety of animal models of disease, its therapeutic potential is hampered by the short half-life in vivo. We now describe a highly potent, stapled long-acting GLP-2 analog, peptide 10, that has a more than 10-fold longer half-life than teduglutide and improved intestinotrophic and anti-inflammatory effects in mouse models of DSS-induced colitis. [ABSTRACT FROM AUTHOR]

Capillary gel electrophoresis using sodium dodecyl sulfate (CE-SDS) is used commercially to provide quantitative purity data for therapeutic protein characterization and release. In CE-SDS, proteins are denatured under reducing or non-reducing conditions in the presence of SDS and electrophoretically separated by molecular weight and hydrodynamic radius through a sieving polymer matrix. Acceptable performance of this method would yield protein peaks that are baseline resolved and symmetrical. Nominal CE-SDS conditions and parameters are not optimal for all therapeutic proteins, specifically for Recombinant Therapeutic Protein-1 (RTP-1), where acceptable resolution and peak symmetry were not achieved. The application of longer alkyl chain detergents in the running buffer matrix substantially improved assay performance. Matrix running buffer containing sodium hexadecyl sulfate (SHS) increased peak resolution and plate count 3- and 8-fold, respectively, compared to a traditional SDS-based running gel matrix. At Bristol-Myers Squibb (BMS), we developed and qualified a viable method for the characterization and release of RTP-1 using an SHS-containing running buffer matrix. This work underscores the potential of detergents other than SDS to enhance the resolution and separation power of CE-based separation methods. [ABSTRACT FROM AUTHOR]

To promote the development of crystallization technology for recovering salt from high salinity wastewater, the effect of organic impurity on crystallization of sodium sulfate was investigated by using phenol as a representative organic impurity. The effect of phenol on crystallization thermodynamics of sodium sulfate was evaluated by measuring solubility data of sodium sulfate in water in the presence of phenol. It was found that the existence of phenol could suppress the solubility of sodium sulfate in water. The effect of organic impurity on crystal nucleation was performed by measuring the metastable zone width (MSZW) and induction time of sodium sulfate. Two models (self-consistent Nývlt-like equation and Classical 3D nucleation theory) were used to analyze the experimental data. It was found that Classical 3D nucleation theory (3D CNT) can better explain the effect of phenol on nucleation. From both MSZW data and induction time data, it was found that the existence of phenol will apparently increase the interfacial energy γ, which will result in higher nucleation Gibbs energy barrier and thus lower nucleation rate. Furthermore, the existence of phenol will increase the critical nucleus radius r* and the critical Gibbs energy ΔG*, which means that the formation of the nuclei will be more difficult in the presence of phenol. According to the above analysis, the possible mechanism of influence of organic impurity on crystallization of sodium sulfate was proposed. [ABSTRACT FROM AUTHOR]

The objective of this study is to report the solubility of cephradine form 1 in 0.5% sodium bisulfate (W/V) solution and cefprozil monohydrate in water, as a function of pH, at temperatures of 283.15, 298.15, and 308.15 K. The experiment was conducted by using a dynamic laser monitoring technique under atmospheric pressure at pH values ranging from 1.45 to 8.57. The solubility data were correlated with two transformational theoretical models. The results show that the pH value has a significant effect on the solubility; as the pH value increased, the solubility of cephradine form 1 and cefprozil monohydrate in water initially decreased before increasing. Additionally, it has a minimum value at the isoelectric point. The effect of temperature, however, was not particularly apparent; the increase of temperature from 283.15 to 308.15 K only improved the solubility slightly. The distribution curves for the species of cephradine form 1 and cefprozil monohydrate in this study were obtained. [ABSTRACT FROM AUTHOR]

Phase diagrams of aqueous two-phase systems composed of N-butylpyridinium nitrate + salt (ammonium sulfate and sodium sulfate) + water determined at (298.15, 308.15, 318.15 and 328.15) K. The binodal curves were associated with the Merchuk expression and another two empirical expressions. The influences of temperature and the type of cations were also studied, which demonstrated that lower temperature led to the expansion of the two-phase region, whereas the salting-out abilities of Na2SO4 exceeded that of (NH4)2SO4, which was proven by the Gibbs free energy of hydration of the ions. [ABSTRACT FROM AUTHOR]

Dissolved inorganic salts influence the partitioning of organic compounds into the aqueous phase. This influence is especially significant in atmospheric aerosol, which usually contains large amounts of ions, including sodium, ammonium, chloride, sulfate, and nitrate. However, empirical data on this salt effect are very sparse. Here, the partitioning of numerous organic compounds into solutions of Na2SO4, NH4Cl, and NH4NO3 was measured and compared with existing data for NaCl and (NH4)2SO4. Salt mixtures were also tested to establish whether the salt effect is additive. In general, the salt effect showed a decreasing trend of Na2SO4 > (NH)2SO4 > NaCl > NH4Cl > NH4NO3 for the studied organic compounds, implying the following relative strength of the salt effect of individual anions: SO42- > Cl[sup -] > NO3[sup -] and of cations: Na[sup +] > NH4[sup +]. The salt effect of different salts is moderately correlated. Predictive models for the salt effect were developed based on the experimental data. The experimental data indicate that the salt effect of mixtures may not be entirely additive. However, the deviation from additivity, if it exists, is small. Data of very high quality are required to establish whether the effect of constituent ions or salts is additive or not. [ABSTRACT FROM AUTHOR]

Emission from electronically excited sodium atoms (Na*) was observed when argon saturated aqueous solutions of the anionic surfactants, sodium dodecyl sulfate, sodium octyl sulfate, sodium 1-pentanesulfonate, and sodium 1-octanesulfonate were sonicated using 358 kHz ultrasound. The same emission band, centered at about 590 nm, was also obtained in aqueous NaCl solutions, although a ∼100-fold higher concentration than that used for the surfactant solutions was required to obtain an emission of comparable intensity. The results have been interpreted in terms of the surfactant adsorbing at the gas-solution interface of the bubbles generated by the ultrasound, generating an electrostatic surface potential, and attracting Na+ counterions to the bubble surface. It is reasoned that Na+ ions are simultaneously reduced and electronically excited at the bubble-solution interface during the final stages of the collapse phase of the acoustically driven bubble. It is proposed that sodium ion bound water molecules reduce interfacial Na+ under the extreme, perhaps supercritical, conditions the interface experiences on bubble implosion. [ABSTRACT FROM AUTHOR]

Standard state thermodynamic properties for completely dissociated aqueous barium sulfate, BaSO4(aq), were fixed by an ionic additivity relationship using the data from other completely dissociated electrolytes, barium chloride, sodium sulfate, and sodium chloride, from 298.15 to 598.15 K and at steam saturated pressure, psat. The solubility of barium sulfate in pure water was then predicted a priori from 273.15 to 598.15 K and pressures up to 140 MPa, and the results were compared with the literature data. These predicted solubility values for barium sulfate in pure water, when corrected for ion pair association of Ba2+(aq) ion with SO42-(aq) ion and hydrolysis of SO42-(aq) ion, are in very good agreement with the literature data to well within the uncertainties of the experimental data at all temperatures and pressures considered. Using the experimental data from this study and auxiliary data from the literature, the logarithm of the molar dissociation constants of BaSO4° associated ion pair were also calculated up to 598.15 K and up to 150 MPa. [ABSTRACT FROM AUTHOR]

Reverse osmosis (RO) plants are widely used for recovering potable water from industrial wastewater streams. The RO retentate stream is highly concentrated in salts, thereby limiting further treatment using RO due to increased scaling potential of the salts. Currently, the brine streams are disposed of in evaporation ponds in which pure salts cannot be recovered. This makes eutectic freeze crystallization (EFC) an attractive separation method for purification of such streams because it can recover both pure water and salt. However, antiscalants are present in RO and other industrial wastewater streams as impurities. These could have an effect on the thermodynamics and crystallization kinetics during EFC. This paper focuses on the effect of a phosphonate-based antiscalant on the crystallization kinetics of both ice and Na2SO4·10H2O in a continuous EFC process under subeutectic conditions. It was observed that the salt nucleation rate remained almost constant, while a general decrease in the ice nucleation rate occurred with an increase in antiscalant concentration. A general increase in the growth rates of both ice and salt was observed. A threshold antiscalant concentration in the range 350-500 mg/L was observed, beyond which the effect was reversed. The morphology of salt crystals from both the control and antiscalant-dosed solutions was monoclinic and prismatic. The morphology of ice could not be detected due to agglomeration. Product washing was very effective in removing impurities, suggesting that adsorption occurred by physisorption. [ABSTRACT FROM AUTHOR]

An interesting and tunable hydrosulfonylation of 3-cyclopropylideneprop-2-en-1-ones with sodium sulfinates and acetic acid is described. The corresponding β- or γ-addition products can be produced in good to excellent yields with high selectivities, respectively. A rationale for these transformations is proposed base on the controlled experiments. [ABSTRACT FROM AUTHOR]

Herein, we report a unique thermal synthesis method to prepare a novel two-dimensional (2D) hybrid nanostructure consisting of ultrathin and tiny-sized molybdenum disulfide nanoplatelets homogeneously inlaid in graphene sheets (MoS2/G) with excellent electrocatalytic performance for HER. In this process, molybdenum oleate served as the source of both molybdenum and carbon, while crystalline sodium sulfate (Na2SO4) served as both reaction template and sulfur source. The remarkable integration of MoS2 and graphene in a well-assembled 2D hybrid architecture provided large electrochemically active surface area and a huge number of active sites and also exhibited extraordinary collective properties for electron transport and H+ trapping. The MoS2/G inlaid nanosheets deliver ultrahigh catalytic activity toward HER among the existing electrocatalysts with similar compositions, presenting a low onset overpotential approaching 30 mV, a current density of 10 mA/cm² at ∼110 mV, and a Tafel slope as small as 67.4 mV/dec. Moreover, the strong bonding between MoS2 nanoplatelets and graphene enabled outstanding long-term electrochemical stability and structural integrity, exhibiting almost 100% activity retention after 1000 cycles and ∼97% after 100 000 s of continuous testing (under static overpotential of −0.15 V). The synthetic strategy is simple, inexpensive, and scalable for large-scale production and also can be extended to diverse inlaid 2D nanoarchitectures with great potential for many other applications. [ABSTRACT FROM AUTHOR]

The effects of CaCl2, MgCl2, and Na2SO4 on the swelling response and the thermal transition of poly(diallyldimethylammonium chloride)/poly(styrenesulfonate) (PDAC/PSS) layer-by-layer (LbL) assemblies are investigated. For MgCl2 and CaCl2, two swelling regimes are observed depending on the salt concentration of the overlying solution. Below 0.17 M MgCl2 or CaCl2, swelling appears to arise from electrostatic repulsion within the multilayer. Above 0.17 M MgCl2 or CaCl2, the multilayer swells linearly with the concentration of the overlying solution due to doping; the degree of swelling in this linear regime depends on the hydration shell of the doping ions. Alternatively, swelling with no concentration dependence was observed for Na2SO4. Unlike the swelling behavior, the thermal transition temperature observed in hydrated films shifts to higher temperatures with increasing concentration of Na2SO4. However, when hydrated with CaCl2 or MgCl2 solutions, the transition remains relatively constant within error. Results are discussed in terms of the salt ion's hydration shell and Donnan exclusion. [ABSTRACT FROM AUTHOR]

Wet-process phosphoric acid is developed with the lack of a quality mineral. More and more research focuses on the purification of wet-process phosphoric acid with solvent extraction method. Liquid-liquid equilibrium data are of important significance in the industrial reality. In this work, equilibria data have been obtained for the two quaternary systems phosphoric acid-sodium sulfate-water-tri-n-butyl phosphate and phosphoric acid-potassium sulfate-water-tri-n-butyl phosphate, which contain concentrations of components and densities and viscosities of the equilibrium phases, and also the varieties of distribution coefficient of phosphoric acid are analyzed. In different systems (phosphoric acid solution with sodium sulfate or potassium sulfate at 303.2 K), the distribution coefficient of phosphoric acid with sodium was found to be higher than that of potassium ion, which demonstrates that the extraction of phosphoric acid with sodium is greater than that with potassium ion. In addition, NRTL model and Pitzer's equation are used to correlate the experimental data. The result shows that it is suitable for both systems and obtains adjustable binary parameters of the NRTL model. [ABSTRACT FROM AUTHOR]

The synthesis of shape-controlled crystals has been a highly attractive research topic in modern materials chemistry. In this work, the growth of Li(Ni1/3Co1/3Mn1/3)O2 (NCM) crystals in molten sulfate or carbonate salts (flux) at 1000 °C was systematically studied under various conditions. In situ X-ray diffraction during the growth and thermogravimetry-differential thermal analysis revealed that the growth of NCM crystals in the flux was controlled by liquid-phase sintering according to the Ostwald ripening principle. We studied the effect of Na+ in the flux on the crystal shapes and found that Na+ was critical in forming octahedral crystals with well-developed facets. Single crystals with well-developed facets were obtained homogeneously from Na2SO4, while truncated polyhedral crystals of smaller size were obtained from Li2SO4. The shape-controlled NCM crystals showed discharge capacities approaching 160 mAh g-1 in the operating voltage range of 2.8-4.4 V vs Li/Li+ under a low current density of 0.1 C, independent of flux composition. This suggests that the Li+ and transition-metal ions in the individual NCM crystals were highly ordered into hexagonal arrangements belonging to the R3̅m space group, without cation mixing. [ABSTRACT FROM AUTHOR]

A highly efficient and generally applicable iodine-catalyzed reaction of arylacetylenic acids and arylacetylenes with sodium sulfinates for the synthesis of arylacetylenic sulfones was developed. The methodology has the advantages of a metal-free strategy, easy to handle reagents, functional group tolerance, a wide range of arylacetylenic acids and arylacetylenes, and easy access to arylacetylenic sulfones. [ABSTRACT FROM AUTHOR]

Aqueous two-phase systems can be applied to a penicillin fermentation process to extract the produced penicillin from the fermentation broth to achieve a higher production rate. Such systems contain a polymer and a salt or two polymers. In this study, the liquid-liquid equilibrium of the quinary system of polyethylene glycol 6000, sodium sulfate, glucose, penicillin G, and water at 298.15 K is investigated. The experimental partition coefficients of glucose and penicillin-G showed the high efficiency of the present extractive fermentation processes. Using the liquid-liquid equilibrium data, the parameters of the NRTL activity model were calculated for the quinary system. The average absolute relative deviation of 0.677 % between experimental and calculated mass fractions shows that the NRTL activity model has a good ability to predict the equilibrium concentrations of the present system. In addition, a simple and accurate turbidimetric method for the measurement of penicillin G is proposed. [ABSTRACT FROM AUTHOR]

Liquid-liquid equilibrium data and phase diagrams of aqueous two phase systems (ATPS) composed of polyethylene glycol (PEG) of molar mass (1500 and 4000) g•mol -1 + sodium sulfate + water were determined at temperatures of 293.15, 303.15, 313.15, and 323.15 K at pH 2. Temperature had no significant effect on the biphasic region, indicating a small enthalpic contribution in the phase separation process. The change in temperature however caused an increase in the tie line slope because water molecules were transferred from the upper phase to the lower phase. Increasing the molar mass of the polymer led to an increase in the biphasic region of the phase diagram. In determining the physical properties of the systems studied, it was observed that the increase in concentration increased the viscosity and the refraction index; while relative to temperature, the viscosity, refraction index, and density decreased. [ABSTRACT FROM AUTHOR]

Nucleation and crystal growth ofCaSO4·2H2O (gypsum) was studied under simulatedconditions of scale formationusing a reverse osmosis desalination technique. Calcium chloride andsodium sulfate were mixed with concentrated sodium chloride solution(40 g/L), and the reaction mixture turbidity was measured at differenttime intervals to determine the induction time of precipitated gypsum.Induction time was measured under different high supersaturation ratiosranging from 3.92 to 6.71. The induction time decreases exponentiallywith increasing the supersaturation. Using crystallization equationsthat relate induction times with supersaturation ratios, the freeenergy barrier and critical nuclei radius were calculated with andwithout addition of a scale inhibitor (trisodium phosphate, TSP).Rates of nucleation at a 4.47 supersaturation ratio are 0.4 ×1028and 0.5 × 1028nuclei/cm3·s with and without TSP addition, respectively. [ABSTRACT FROM AUTHOR]

The molal solubilities, density,and refractive index of the basicamino acid (l-lysine) and the neutral amino acid (l-cysteine) in aqueous solutions of potassium iodide (KI), sodiumbromide (NaBr), sodium chloride (NaCl), sodium sulfate (Na2SO4), and calcium chloride (CaCl2) at 298.15K were determined experimentally. From the values of the measuredrefractive indices, molal solubilities, and the densities, the excessrefractive indices, the molar refractions, the polarizabilities, andthe apparent molar volumes of the systems under study were calculatedand discussed. The solvation of the amino acids under study was discussedin terms of their molal solubilities, apparent molar volume, and refractiveindex data. The phase diagrams of the studied tricomponent systems(water–salt–amino acid) were also determined and discussed.The solubility of l-cysteine and l-lysine were discussedin terms of the nature of the electrolytic salts under study. Theeffect of the electrolytic solutions under study on the solubilityof l-cysteine and l-lysine was compared to thatfound in the literature of the same electrolytic solutions on theamino acids (dl-valine, dl-serine, glycine, and dl-alanine) at the same temperature. A salting-in effect ofthe electrolytic solutions under study (potassium iodide, sodium chloride,sodium bromide, calcium chloride, and sodium sulfate) and other electrolyticsolutions (potassium fluoride, potassium bromide, sodium iodide, potassiumsulfate, and barium chloride) (from literature) was observed for l-cysteine amino acid (present study), dl-valine, dl-serine, glycine, and dl-alanine (from literature)A salting-out effect of the electrolytic solutions under study (potassiumiodide, sodium bromide, sodium chloride, sodium sulfate, and calciumchloride) was observed for l-lysine amino acid (present study),and of NaF solution for amino acids; dl-alanine and dl-valine (from literature). The effect of the nature of the electrolyticsalts under study agree with that in the literature as in the followingorder: Na2SO4> NaCl, NaBr > NaCl, CaCl2> NaCl. [ABSTRACT FROM AUTHOR]

Usingdissipative particle dynamics (DPD) simulations, we explorethe specifics of micellization in the solutions of anionic and cationicsurfactants and their mixtures. Anionic surfactant sodium dodecylsulfate (SDS) and cationic surfactant cetyltrimethylammonium bromide(CTAB) are chosen as characteristic examples. Coarse-grained modelsof the surfactants are constructed and parameterized using a combinationof atomistic molecular simulation and infinite dilution activity coefficientcalibration. Electrostatic interactions of charged beads are treatedusing a smeared charge approximation: the surfactant heads and dissociatedcounterions are modeled as beads with charges distributed around thebead center in an implicit dielectric medium. The proposed modelssemiquantitatively describe self-assembly in solutions of SDS andCTAB at various surfactant concentrations and molarities of addedelectrolyte. In particular, the model predicts a decline in the freesurfactant concentration with the increase of the total surfactantloading, as well as characteristic aggregation transitions in single-componentsurfactant solutions caused by the addition of salt. The calculatedvalues of the critical micelle concentration reasonably agree withexperimental observations. Modeling of catanionic SDS–CTABmixtures show consecutive transitions to worm-like micelles and thento vesicles caused by the addition of CTAB to micellar solution ofSDS. [ABSTRACT FROM AUTHOR]

Thebinary and ternary aqueous solutions of sodium phosphate or/andsulfate were studied using the hygrometric method from dilution tosaturation in the temperature range from (298.15 to 353.15) K. Thehygrometric measurements of the binary systems were combined withreference pure water, Na3PO4(s), and Na2SO4(s) solubility data to construct a chemicalmodel that calculates solute and solvent activities from dilute tosaturated solution concentration (for (Na3PO4(s)) up to mmax= 9.00 mol·kg–1at 353.15 K; and up to mmax(Na2SO4(s)) = 3.40 mol·kg–1at 313.15 K). The constructed model was also used to calculate thermodynamicsolubility product (K°sp) of Na3PO4(s) and Na2SO4(s) in the temperature range (298.15 to 353.15) K. The excessGibbs energies of Na3PO4(aq) and Na2SO4(aq) were evaluated at various temperatures. The resultsfor these aqueous solutions were influenced by the effect of hydrationshell, with ion association or formation ion pairing. The anion solutePO4or SO4influences the hydration in an aqueoussolution; indeed the hydrogen bonding of water in the hydration shellsof PO43–anion is preeminent over thatof SO42–. The mixed electrolyte solutions{(yNa3PO4+ (1 – y)Na2SO4}(aq) were also investigatedin the temperature range from (298.15 to 353.15) K and at total molalitiesfrom dilution (0.10 mol·kg–1) to saturationfor different ionic-strength fractions (y) of Na3PO4with y= 0.20, 0.50, and 0.80.The water activity of mixed salts solutions and related propertiessuch as osmotic and activity coefficients were carried out at varioustemperatures. The osmotic coefficients data were used to evaluatethe mixing parameters of the ion interaction model θMNand ψMNXin the ternary system Na3PO4+ Na2SO4+ H2O. [ABSTRACT FROM AUTHOR]

Enthalpiesof solution and densities of glycylglycine in aqueoussolutions of NaNO3, NaClO4, and Na2SO4were measured at 298.15 K. Standard transfer enthalpies(ΔtrH0), standard transferpartial molar volume (ΔtrVϕ0), and hydrationnumbers (Nh) have been determined forglycylglycine. All of the ΔtrH0values are negative in the three salt solutions. The relativeorder of ΔtrH0in thesame concentration of 1–1 type salts is NaNO3>NaClO4. The ΔtrH0in low concentration of Na2SO4solutionsis between the corresponding values in NaNO3and NaClO4solutions. With increasing Na2SO4concentration,the ΔtrH0values exceedthat in NaNO3solutions. The ΔtrVϕ0values are positive and vary in the sequence Na2SO4> NaNO3> NaClO4. Theresultswere discussed in terms of various interactions. [ABSTRACT FROM AUTHOR]

Saline aqueous solutions at elevatedpressures and temperaturesplay an important role in processes such as supercritical water oxidation(SCWO) and supercritical water gasification (SCWG), as well as innatural geochemical processes in Earth and planetary interiors. Somesolutions exhibit a negative temperature coefficient of solubilityat high temperatures, thereby leading to salt precipitation with increasingtemperature. Using modulated FT-IR Raman spectroscopy and classicalmolecular dynamics simulations (MD), we studied the solute speciationin solutions of 10 wt % Na2SO4, at conditionsclose to the saturation limit. Our experiments reveal that ion pairingand cluster formation are favored as solid saturation is approached,and ionic clusters form prior to the precipitation of solid sulfate.The proportion of such clusters increases as the phase boundary isapproached either by decreasing pressure or by increasing temperaturein the vicinity of the three-phase (vapor–liquid–solid)curve. [ABSTRACT FROM AUTHOR]

Toseparate a salt mixture (mainly consisting of Na2CO3and Na2SO4) which is formedfrom the 4,4′-diaminostilbene-2,2′-disulfonic acid wastewatertreatment, the solubility data of Na2CO3andNaHCO3in Na2SO4–water solventmixtures were measured using a dynamic method over the 275–335K temperature range. The solute-free mass fraction of Na2SO4in the solvent mixtures extended from 0 to 0.25. Thesolubility of Na2CO3and NaHCO3inNa2SO4–water solvent mixtures decreasedwith addition of Na2SO4. With rising temperature,the solubility of NaHCO3increased while the solubilityof Na2CO3increased at first and then decreasedafter transition points. The experimental data were correlated withthe electrolyte nonrandom two-liquid model. The root-mean-square deviationsof solubility temperature varied from 0.35 to 1.50 K. Based on thesolubility data of this work, a new strategy for separating the Na2CO3and Na2SO4mixture wasproposed theoretically. [ABSTRACT FROM AUTHOR]

Sodium sulfate is known as one of the most destructive salts leading to the deterioration of porous materials, such as monuments, sculptures, and civil engineering structures. While sodium sulfate crystals are growing in a porous material, crystallization pressure will build up. In this study we have combined a nondestructive measurement of the concentration of the pore solution within a material by using NMR with an optical measurement of the expansion of the material during crystallization. These data permit calculation of the in-pore crystallization pressure during the growth of different crystalline phases induced by cooling in three different materials: fired-clay brick, Cordova Cream limestone, and Indiana limestone. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations of anionic sodium decylsulfate and nonionic pentaethylene glycol monodecyl ether micelles in water have been performed to examine the impact of hydrostatic pressure on argon solubilization as a function of pressure. The potential-of-mean force between the micelles and argon demonstrates that nonpolar gases are attracted to the interiors of both micelles. The affinity of argon for micelle interiors, however, decreases with increasing pressure as a result of the comparatively higher molar volume of argon inside assemblies. We evaluate solubility enhancement coefficients, which describe the drop in the solute chemical potential as a function of the micellized surfactant concentration, to quantify the impact of micellization on gas solubilization. While argon is similarly attracted to the hydrophobic cores of both micelles, the gas is more effectively sequestered within nonionic micelles compared with anionic micelles as a result of salting out by charged head groups and accompanying counterions. The solubility enhancement coefficients of both micelles decrease with increasing pressure, reflecting the changing forces observed in the potentials-of-mean force. An analytical liquid drop model is proposed to describe the pressure dependence of argon solubilization within micelles that captures the simulation solubility enhancement coefficients after fitting an effective micelle radius for each surfactant. [ABSTRACT FROM AUTHOR]

Inthis work, the kinetics of the reaction between sodium chlorideand sulfuric acid, in aqueous solution and in the presence of ethanolas antisolvent, was studied as a function of each reactant concentrationand temperature. The thermometric method was implemented to fit theexperimental data obtained in an adiabatic batch reactor. The initialreaction rate methodology was applied to determine the order of reactionas well as the specific reaction rate constants. The reaction ratecorresponded to an elementary reaction. Good agreement between experimentaland simulation temperature profiles was achieved (absolute averagedeviation (AAD) of ∼1.15%). The reactive crystallization processwas found to be very selective to anhydrous Na2SO4, with yields higher than 95 wt %. [ABSTRACT FROM AUTHOR]

Animportant part of the protein folding process is the consolidationof the protein core through the formation of specific, directionalcontacts after the initial hydrophobic collapse. Here, we simultaneouslymonitor formation of core contacts and assembly of secondary structurethrough salt-induced folding by using resonance Raman spectroscopy.Unfolded barstar at pH 12 was refolded by gradual addition of sodiumsulfate salt. Altered spectral characteristics of the Trp53 residuesuggest that the core of the protein attains a CH−π interactionat a low concentration of the salt, with an increase in the packingdensity. Further increase in salt concentration produces a reductionin the solvent accessibility of the core. These data provide evidencethat the core of the protein becomes rigid upon the addition of 0.6M sodium sulfate. This is the first time that the formation of a CH−πinteraction has been directly monitored during the folding of a protein. [ABSTRACT FROM AUTHOR]

Thethermodynamics and kinetics of crystallization of sodium sulfatewith a tripodal tris-urea receptor (L1) from aqueous alkaline solutionshave been measured in the 15–55 °C temperature range fora fundamental understanding of the elementary steps involved in thissulfate separation method. The use of radiolabeled Na235SO4provided a practical way to monitor the sulfateconcentration in solution by β liquid scintillation counting.Our results are consistent with a two-step crystallization mechanism,involving relatively quick dissolution of crystalline L1 followedby the rate-limiting crystallization of the Na2SO4(L1)2(H2O)4capsules. We foundthat temperature exerted relatively little influence over the equilibriumsulfate concentration, which ranged between 0.004 and 0.011 M. Thiscorresponds to 77–91% removal of sulfate from a solution containing0.0475 M initial sulfate concentration, as found in a typical Hanfordwaste tank. The apparent pseudo-first-order rate constant for sulfateremoval increased 20-fold from 15 to 55 °C, corresponding toan activation energy of 14.1 kcal/mol. At the highest measured temperatureof 55 °C, 63% and 75% of sulfate was removed from solution within8 and 24 h, respectively. These results indicate the capsule crystallizationmethod is a viable approach to sulfate separation from nuclear wastes. [ABSTRACT FROM AUTHOR]

Residual contamination contained in lower permeability zones is difficult to remediate and can, through diffusive emissions to adjacent higher permeability zones, result in long-term impacts to groundwater. This work investigated the effectiveness of oxidant delivery for reducing diffusive emissions from lower permeability zones. The experiment was conducted in a 1.2 m tall × 1.2 m wide × 6 cm thick tank containing two soil layers having 3 orders of magnitude contrast in hydraulic conductivity. The lower permeability layer initially contained dissolved methyl ferf-butyl ether (MTBE) and benzene, toluene, ethylbenzene, and p-xylenes (BTEX). The treatment involved delivery of 10% w/w nonactivated sodium persulfate (Na2S2O8) solution to the high permeability layer for 14 days. The subsequent diffusion into the lower permeability layer and contaminant emission response were monitored for about 240 days. The S2O82- diffused about 14 cm at 1% w/w into the lower permeability layer during the 14 day delivery and continued diffusing deeper into the layer as well as back toward the higher-lower permeability interface after delivery ceased. Over 209 days, the S2O82- diffused 60 cm into the lower permeability layer, the BTEX mass and emission rate were reduced by 95-99%, and the MTBE emission rate was reduced by 63%. The overall treatment efficiency was about 60-110 g-S2O82- delivered/g-hydrocarbon oxidized, with a significant fraction of the oxidant delivered likely lost by back-diffusion and not involved in hydrocarbon destruction. [ABSTRACT FROM AUTHOR]

Predicting and controlling nanostructure formation during nucleation can pave the way to synthesizing novel energy materials via crystallization. However, such control over nucleation and crystallization remains challenging due to an inadequate understanding of critical factors that govern evolving atomistic structures and dynamics. Herein, we utilize coordination number as a reaction coordinate and rate theory to investigate how sodium sulfate, commonly known as a phase-change energy material, nucleates in a supersaturated aqueous solution. In conjunction with ab initio and force field-based molecular dynamics simulation, the rate theoretical analysis reveals that sodium sulfate from an initially dissolved metastable state transits to a heterogeneous mixture of prenucleated clusters and finally to a large cylindrical zigzag morphology. Measurements of Raman spectra and their ab initio modeling confirm that this nucleated morphology contains a few waters for every sulfate. Rate processes such as solvent exchange and desolvation exhibit high sensitivity to the evolving prenucleation/nucleation structures, providing a means to distinguish between critical nucleation precursors. Desolvation and forming the first-shell interionic coordination structure via monomer-by-monomer addition around sulfates are found to explain the formation of large nuclei. Thus, a detailed understanding of the step-by-step structure formation across scales has been achieved. This can be leveraged to predict nucleation-related structures and dynamics and potentially control the synthesis of novel phase-change materials for energy applications.

In the present study, we have investigatedthe effect of sodiumsulfate (Na2SO4) buffer on the antifreeze activityof DAFP-1, the primary AFP in the hemolymph of the beetle Dendroides canadensis. In contrast to previous studies,we found evidence that sodium sulfate does not suppress antifreezeactivity of DAFP-1. Terahertz absorption spectroscopy (THz) studieswere combined with molecular dynamics (MD) simulations to investigatethe change in collective hydrogen bond dynamics in the vicinity ofthe AFP upon addition of sodium sulfate. The MD simulations revealedthat the gradient of H-bond dynamics toward the ice-binding site iseven more pronounced when adding sodium sulfate: The cosolute dramaticallyslows the hydrogen bond dynamics on the ice-binding plane of DAFP-1,whereas it has a more modest effect in the vicinity of other partsof the protein. These theoretical predictions are in agreement withthe experimentally observed increase in THz absorption for solvatedDAFP-1 upon addition of sodium sulfate. These studies support ourpreviously postulated mechanism for AF activity, with a preferredice binding by threonine on nanoice crystals which is supported bya long-range effect on hydrogen bond dynamics. [ABSTRACT FROM AUTHOR]

The optimal activity of Bacillus sp. TB-90 urate oxidase (BTUO) is 45 °C, but this enzyme is one of the most thermostable urate oxidases. A marked increase (>10 °C) in its thermal stability is induced by high concentrations (0.8-1.2 M) of sodium sulfate. Calorimetric measurements and size exclusion chromatographic analyses suggested that sulfate-induced thermal stabilization is related to the binding of a sulfate anion that repressed the dissociation of BTUO tetramers into dimers. To determine the sulfate binding site, the crystal structure was determined at 1.75 Å resolution. The bound sulfate anion was found at the subunit interface of the symmetrical related subunits and formed a salt bridge with two Arg298 residues in the flexible loop that is involved in subunit assembly. Site-directed mutagenesis of Arg298 to Glu was used to extensively characterize the sulfate binding site at the subunit interface. The network of charged hydrogen bonds via the bound sulfate is suggested to contribute significantly to the thermal stabilization of both subunit dimers and the tetrameric assembly of BTUO. Knowledge of the mechanism of salt-induced stabilization will help to develop new strategies for enhancing protein thermal stabilization. [ABSTRACT FROM AUTHOR]

Solid–liquid equilibrium (SLE) and solution density data for the (Na2SO4+ H2NCH2CH2SO3H + H2O) system from (288.15 to 328.15) K were measured by use of the method of isothermal dissolution. From the experimental data, a set of polynomial equations were derived to calculate the solubility of taurine as a function of sodium sulfate mass fraction in the equilibrium solution, and two phase diagrams at (293.15 and 318.15) K were constructed. In general, the density of the equilibrium solution regularly increases with the sodium sulfate concentration. Furthermore, at low temperatures the equilibrium solid phase is Na2SO4·10H2O, whereas at high temperatures the equilibrium solid phase is Na2SO4. All of these data will provide a better understanding of the separation of taurine from Na2SO4 aqueous solutions through crystallization. [ABSTRACT FROM AUTHOR]

The mean activity coefficients ofNaBr in the NaBr + Na2SO4+ H2O ternarysystem were determined atthe total ionic strength ranging from (0.0500 to 3.0000) mol·kg–1at 298.15 K by potential difference measurementsfrom the galvanic cell without liquid junction: Na–ISE|NaBr(m1), Na2SO4(m2)|Br–ISE. The mean activity coefficients of NaBrwere compared with those different ionic strength fractions yBof Na2SO4with yB= (0.8, 0.6, 0.4, 0.2, and 0). The experimentalresults showed that Na–ISE and Br–ISE in this work hada good Nernst response, and the mean activity coefficients of NaBrin NaBr + Na2SO4+ H2O mixtures werecalculated using the Nernst equation. Mixing interaction parametersof θBr–·SO42–and φNa+·Br–·SO42–in Pitzer’s equation, whichhad not been previously reported, were evaluated from the presentmeasurements of the mean activity coefficients of NaBr. In addition,the osmotic coefficients, water activity, and the excess Gibbs energyof this system were calculated by the Pitzer’s equations. [ABSTRACT FROM AUTHOR]

Thesolubility of sodium vanadate(V) and sodium sulfate(VI) inthe system NaVO3+ Na2SO4+ H2O within a temperature range from (293.15 to 323.15) K wasmeasured with the method of isothermal saturation of solutions. Theconcentration of ions in solutions was determined using the EDXRFmethod. The part of the polythermal solubility surface for the investigatedsystem was plotted based on the obtained data. Additionally, the solutiondensity and viscosity was investigated. Knowledge of these data isnecessary to evaluate the possibility of the use of vanadium compoundsfrom a spent vanadium catalyst for the production of Na2CO3, and to assess the possibility of selective precipitationof vanadium compounds from a solution after leaching the waste. [ABSTRACT FROM AUTHOR]

The chemistry and kinetics of NOremoval by aqueous solutions of sodium persulfate (Na2S2O8) simultaneously activated by temperature andFe2+were studied in a bubble reactor. Reaction pathwayswere proposed and a mathematical model utilizing the pseudo-steady-state-approximationtechnique and film theory of mass transfer were developed. The modelwas solved numerically using the fourth order Runge–Kutta methodin Matlab to obtain species concentrations; correlate experimentaldata; and estimate mass transfer and kinetic rate parameters. Themodel was used to investigate the effects of Na2S2O8(0.01–0.2 M), Fe2+(0–0.1M), gas-phase NO (500–1000 ppm) concentrations and temperatures(23–90 °C), and is a follow-up to an experimental study,which demonstrated that Fe2+activation further improvedNO conversion by ∼10% at all temperatures. The model results,which appeared to fit those of the experiments remarkably well, werediscussed and predicted kinetic data compared with available literaturevalues. [ABSTRACT FROM AUTHOR]

Six new ATPSs were prepared by combiningpolyethylene glycol PEG600with potassium citrate, dipotassium hydrogen phosphate, sodium formate,potassium formate, sodium sulfate, and lithium sulfate. Complete phasediagrams, including the binodal curve and three tie-lines, were determinedat 23 °C. The experimental data obtained for the binodal curvewere successfully adjusted to the Merchuk equation, and the reliabilityof tie-line data was confirmed using the equations suggested by Othmer–Tobiasand Bancroft. The ability of each ion to induce ATPS formation wasinvestigated. Na+proved to be more effective in ATPS formationthan K+and Li+. For potassium salts, the orderobserved for the effectiveness of the anions was: HPO42–> C6H5O73–> HCO2–. Regardingthe sodium salts,it was found that SO42–is clearly moreeffective than HCO2–. The position ofthe ions in the Hofmeister series and their free energy of hydration(ΔGhyd) were used to explain theability of the ions to induce PEG salting-out. Furthermore, the effectiveexcluded volume (EEV) of the salts was determined and the followingorder was found: Na2SO4> K2HPO4> Li2SO4> K3C6H5O7> NaCHO2> KCHO2. Similar order was obtained when analyzing the size of theheterogeneousregions, suggesting the practical use of EEV as a comparison parameterbetween different ATPSs. [ABSTRACT FROM AUTHOR]

Thesolubility of sodium 2,4-diaminobenzenesulfonate in binaryNaCl + H2O, Na2SO4+ H2O, and C2H5OH + H2O solvent mixtureswere measured at elevated temperatures from 273.15 K to 323.15 K bya steady-state method. The results of these data were correlated bya modified Apelblat equation. [ABSTRACT FROM AUTHOR]

The influence of ascorbic acid onthe micellar, thermodynamic,and volumetric properties and viscometric and aggregation behaviorof anionic surfactant sodium dodecylsulfate, cationic surfactant cetylpyridiniumbromide, and nonionic surfactant hexadecylpoly[oxyethylene(20)] alcoholwas studied. Micellar and surface thermodynamic data were obtainedfrom the temperature dependence of critical micelle concentration.The apparent molar volumes, standard partial volumes, and standardtransfer volumes for surfactant–ascorbic acid–watersystems were calculated. On the basis of dependence of the relativeviscosities on concentration, the viscosity B-coefficientsof the Jones–Dole semiempirical equation were calculated forboth premicellar and postmicellar regions. From the fluorescence-quenchingmeasurements it was found that both the hydrodynamic radius and themicellar aggregation number decreased with the increase of ascorbicacid concentration. This study allowed us to conclude that ascorbicacid solubilized in micelles. [ABSTRACT FROM AUTHOR]

Thesolubility and density of the thermodynamic phase equilibriaternary system (Na2SO4+ Li2SO4+ H2O) at (288 and 308) K were determined usingthe isothermal dissolution method. According to the experimental resultsof the ternary system at (288 and 308) K, the phase diagrams and thediagrams of density versus composition were plotted. In the ternarysystem at 308 K, four crystallization regions corresponding to thenardite(Na2SO4, Th), two congruent double salts ofLi2SO4·3Na2SO4·12H2O (Db1) and Li2SO4·Na2SO4(Db2), and lithium sulfate monohydrate (Li2SO4·H2O, Ls) were found, whereas onlythree crystallization regions corresponding to Ls, one incongruentdouble salt of Db1, and mirabilite (Na2SO4·10H2O, Mir) were found in the system at 288 K. No solid solutionwas found at either temperature. When the experimental phase diagramat 308 K was compared with that at 288 K, it shows that (1) a newphase region of double salt Db2 was formed and the mineral of Mirtransformed into Th with the increase of temperature from (288 to308) K and (2) the area of the crystallization region of sodium sulfatewas decreased sharply and those of the crystallized regions of Li2SO4·H2O and double salt Db1 increasedobviously. The solution densities of the ternary system both at (288and 308) K change regularly with increasing lithium sulfate concentrationin solution. Based on the Pitzer model and its extended Harvie-Weare(HW) model, the mixing triple interaction parameter of ΨLi,Na,SO4at (288 and 308) K and the solubility equilibriumconstants Kspof solid phases Ls, Db1,Db2, Th, and Mir at (288 and 308) K, which are not reported in theliterature, were acquired by fitting the experimental solubility dataof the ternary system (Li2SO4+ Na2SO4+ H2O) by the lease-square method. A comparisonbetween the calculated and experimental results at (288 and 308) Kfor the ternary system shows that the predicted solubilities obtainedwith the extended HW model agree well with experimental data. [ABSTRACT FROM AUTHOR]

The ability of a single sodium dodecylsulfate (SDS) molecule topromote the formation of CO2clathrate hydrates in water(as it does for methane) has been investigated at the microscopiclevel. For this purpose, the components of the related force fieldwere carefully formulated and assembled following the procedure previouslyadopted for methane. The properties of the whole system (as well asthose of its components) were analyzed by carrying out extended moleculardynamics calculations. Contrary to what happens for methane, the calculationssingled out the propensity of CO2(pure) water clustersto form clathrate hydrate-like structures and the disappearance ofsuch propensity when a single SDS molecule is added to the clusters.This feature was found to be due to the strong interaction of carbondioxide with the additive that makes the SDS molecule lose its shapetogether with its ability to drive water molecules to form a suitablecage. [ABSTRACT FROM AUTHOR]

In this article, the impact of differentneutral polymers on thekinetic stability of charge-stabilized poly(diallyldimethylammoniumchloride) (PDADMAC)/sodium dodecylsulfate (SDS) colloidal dispersionsis analyzed using dynamic light scattering, electrophoretic mobility,turbidity, and coagulation kinetics measurements. Poly(ethyleneoxide)(PEO), poly(vinylpyrrolidone) (PVP), and dextran of comparable molecularmasses as well as a higher-molecular-weight dextran sample were testedas nonionic additives. The light scattering and mobility data indicatethat the PEO and PVP molecules may adsorb on the surface of the PDADMAC/SDSnanoparticles formedin the presence of excess surfactant. The primary effect of theseadditives is manifested in enhanced coagulation of the PDADMAC/SDSnanoparticles due to bridging at lower polymer concentrations anddepletion flocculation at higher polymer concentrations. These findingsare in sharp contrast to the earlier published effect of the samenonionic polymers on the poly(ethyleneimine) (PEI)/SDS colloidal dispersions,which can be sterically stabilized at appropriate PEO or PVP concentrations.However, the adsorption of the investigated dextran samples is negligibleon the PDADMAC/SDS nanoparticles. Therefore, dextran molecules maycause only depletion flocculation in the PDADMAC/SDS system in thevicinity of the critical overlap concentration. [ABSTRACT FROM AUTHOR]

Acidorange 7 acidity constants were determined in water, in sodiumchloride, and in sodium sulfate solutions, from spectrophotometricmeasurements, within the temperature range (278.15 to 333.15) K. Thesalt molalities were lower than (2 and 0.7) mol·kg–1for sodium chloride and sodium sulfate solutions, respectively.Stoichiometric acidity constants were determined in those ionic mediato assess the influence of those two salts on the acid–baseequilibrium. Deviations from ideal behavior were estimated by theevaluation of the activity coefficients of the ions that take partin the chemical equilibria by means of the Debye–Hückeltheory. Expanded Debye–Hückel equations showed a goodfit to the experimental data within the considered temperature range.The results also indicate the formation of dye aggregates at highionic strength which is more evident as the temperature decreases. [ABSTRACT FROM AUTHOR]

In this study, aged (iron oxide coated) Fe0 was applied to the degradation of trichloroethylene (TCE) in seawater. It was found that while the aged Fe0 was inactive with regard to TCE degradation in Milli-Q water, more than 95% of the TCE present was degraded in real and synthetic seawater solutions after exposure to aged Fe0 for 21 days. Results with individual salts from the synthetic seawater revealed that no significant TCE degradation was observed in the presence of Na2SO4, CaCl2, and NaHCO3. Partial TCE degradation (28.4%) was observed in 500 mM NaCl after 21 days, while a similar extent of degradation to that found in the seawater solutions was observed in 50 mM solutions of magnesium salts (MgCl2 and MgSO4). Results of open circuit potential analysis suggested that the Fe0 corrosion potential was not a key determinant of extent of TCE reduction since the corrosion potential decreased to levels similar to that of Fe0/Fe2+ in the presence of all salts examined. Lower final pH values and higher dissolved Fe(II) concentrations were observed in the presence of magnesium salts compared to other salts. Formation of the surface complex >FeOMg+ was identified as being critical to protonation of surface sites, reductive dissolution of the passivating Fe(III) oxyhydroxide layer coating the underlying Fe0 and enhancement in extent of TCE reduction. These findings provide insight into the molecular-scale mechanism of depassivation of aged Fe0 by inorganic salts with particular implications for the Fe0-mediated degradation of contaminants in saline natural waters such as seawater and saline groundwaters. [ABSTRACT FROM AUTHOR]

In order to develop a new processfor concentrating and separatingsodium sulfate (Na2SO4) and magnesium sulfate(MgSO4) of the bloedite based on tetrahydrofuran (THF)hydrate method, the equilibrium of the ternary systems THF–Na2SO4–H2O and THF–MgSO4–H2O and the quaternary system THF–Na2SO4–MgSO4–H2O were measured at 5 °C, and the phase digrams of these threesystems were investigated. It showed that the mass percentage of Na2SO4(MgSO4) in equilibrium liquid washigher than in feed and we could obtain Na2SO4·10H2O and MgSO4·7H2Oin turn. It proved that THF hydrate could be used to the concentrationand separation of Na2SO4and MgSO4. The extended Pitzer model of the electrolyte–electrolyte–nonelectrolyte–watersystem was derived and applied into THF–Na2SO4–MgSO4–H2O system andits subsystems. The necessary thermodynamic parameters had been derivedfrom a least-squares optimization program. The model calculation valuewas in good agreement with experimental solubility for ternary andquaternary mixtures, which indicated that the Pitzer model could besuccessfully used to predict the phase equilibrium of the electrolyte–electrolyte–nonelectrolyte–watersystems containning THF hydrate. [ABSTRACT FROM AUTHOR]

The main objective of this study was to test the possibility that graphene-based nanomaterials can mediate environmentally relevant abiotic redox reactions of organic contaminants. We investigated the effect of graphene oxide (GO) on the reduction of nitrobenzene by Na2S in aqueous solutions. With the presence of GO (typically 5 mg/L), the observed pseudofirst-order rate constant (kobs) for the reduction of nitrobenzene was raised by nearly 2 orders of magnitude (from 7.83 × 10-5 h-1 to 7.77 × 10-3 h-1). strongly suggesting reaction mediation by GO. As reflected by the combined spectroscopic analyses, GO was reduced in the beginning of the reaction, and hence the reduced GO (RGO) mediated the reduction of nitrobenzene. It was proposed that the zigzag edges of RGO acted as the catalytic active sites, while the basal plane of RGO served as the conductor for the electron transfer during the catalytic process. Furthermore, changing the pH (S.9- 9.1) and the presence of dissolved humic acid (10 mgTOC/L) were found to greatly influence the catalytic activity of RGO. The results imply that graphene-based nanomaterials may effectively mediate the reductive transformation of nitroaromatic compounds and can contribute to the natural attenuation and remediation of these chemicals. [ABSTRACT FROM AUTHOR]

Equilibriadata for the Na+,NH4+∥SO42–,Cl––H2Oquaternary system at (10, 20, 30, 50, 90, and 100) °Cwere measured, and the phase diagrams at (10, 50, and 100) °Cwere constructed. Furthermore, the crystallization zones in the phasediagrams are discussed in detail. [ABSTRACT FROM AUTHOR]