Solubility Curves Research Articles

Experimental Determination and Thermodynamic Model of Solid–Liquid Equilibria in the Ternary System (LiCl + SrCl2 + H2O) at 273.15 K and Its Application in Industry

Solubilities, densities and refractive indices of the ternary system (LiCl + SrCl2 + H2O) at 273.15 K were determined using the isothermal dissolution equilibrium method. The phase diagram of the system consists of two invariant points, three univariant solubility curves and three crystallization areas corresponding to LiCl·2H2O, SrCl2·2H2O and SrCl2·6H2O. Applying the Pitzer and Harvie–Weare model, the Pitzer mixing parameters and the solubility product constants (Ksp) of solid phases were fitted to the solubility data; then, the solubilities of this ternary system were predicted. A comparison shows that the calculated solubilities agree well with the experimental results. The phase diagram and Pitzer model for the ternary system at 273.15 and 298.15 K were then used to conduct a computer simulation of brine separation. Lithium chloride and strontium chloride salts can be separated completely by six steps in the brine separation process. This result of the simulation of brine separation can be used as a theoretical reference guideline for salt separation and purification of brine systems.

Hole Transport Property of α-phenyl-4'-(diphenylamino)stilbene Single Crystal Prepared Based on Solubility and Supersolubility Curves

Hole Transport Property of α-phenyl-4'-(diphenylamino)stilbene Single Crystal Prepared Based on Solubility and Supersolubility Curves

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

The formation process of LDHs (layered double hydroxides) coating on magnesium alloy by the CO2 pressurization method was studied. The micro-structure was observed by OM, SEM and GAXRD. The weighted gain curve, apparent activation energy, and CO2 solubility curve were all calculated by equations. The potentiodynamic polarization curve, hydrogen evolution data, and immersion were analyzed by an electrochemical method. The results show that the LDHs coating was formed layer-by-layer. The formation positions were initially on the α-Mg phase, and then on the β-Mg17Al12 phase. It was found to be the most compact after 30 min. The LDHs coating began to appear to have severe cracks and holes over time. The formation process of the LDHs coating can be divided into three stages: a rapid growth stage (0–10 min), slow growth stage (10–20 min), and periodic growth stage (30 min, 1 h). The apparent activation energies in each of the three stages are 21.78, 31.86 and 34.92 kJ mol−1, respectively. The LDHs coating has a compact micro-structure and better anti-corrosion at a pressure of 3 MPa, a temperature of 50 °C and a time of 30 min. The CO2 pressurization promotes a formation reaction rate and achieves a high formation efficiency and good formation stability under the condition of zero pollution.

Deposition of ZnO Thin Films by Chemical Bath Technique: Physicochemical Conditions and Characterization

Zinc oxide (ZnO) was synthesized by chemical bath deposition (CBD) technique at two temperatures (70°C and 90°C). Chemical analysis was carried out on the Zn-NH3-OH zone growth using the species distribution diagrams and the solubility curves in order to determine the parameters to obtain good quality ZnO films. Results show that ZnO films can be obtained when the pH solution is up than 7. Three different pH zones between 7 and 12 were selected for deposition. ZnCl2, NH4NO3, and KOH were the chemical reagents used for the bath. The morphology of the deposited films shows a strong dependence on the pH range of the solution. When the samples are prepared into the Zn(NH3)42+ complexes zone, nano-flowers structures were obtained; whereas, if they are prepared in the zone where the Zn(OH)n2-n ions dominate, nano-flakes were formed. ZnO films deposited at 90°C present highly oriented hexagonal structure (zincite) and a [Zn]/[O]≈1 stoichiometry. While samples deposited at 70°C show degradation in their properties when the pH of the solution increases. By controlling the growth parameters, deposition of the ZnO films and their physical properties can be regulated for determined applications.

ÊA simple approach for THE DETERMINATION AND CHARACTERIZATION OF TERNARY PHASE DIAGRAMS of aqueous two-phase systems composed of water, poly(ethylene) glycol and sodium carbonate

In this work, a simple experimental protocol to determine liquid-liquid phase diagrams of aqueous two-phase systems (ATPS) on a Chemical Engineering course is described. Throughout this laboratory set of experiments, the liquid-liquid ternary phase diagrams, tie-lines, tie-line lengths and critical points of ATPS will be determined. Ternary liquid-liquid phase diagrams composed of water, polyethylene glycol (PEG 200, 400 and 600 g·mol-1) and sodium carbonate (Na2CO3) were obtained by cloud-point titration method at room temperature. The respective tie-lines, tie-line lengths and critical points were also determined. Phase diagrams were represented both as conventional ternary phase diagrams and orthogonal phase diagrams. Through the analysis of the results obtained it was identified a higher ability to form ATPS with the increase of the polymer molecular weight. The interpretation of phase diagrams, particularly the most complex, the orthogonal ones, is not always easy to grasp by students, so this novel 3-hour-class educational approach could be potentially used to teach and help understanding 3-component liquid-liquid equilibrium and the formation of biphasic systems to undergraduate students, without requiring the use of volatile organic solvents.

Calcium/Phosphate Solubility Curves for Premasol and Trophamine Pediatric Parenteral Nutrition Formulations.

Calcium and phosphate incompatibility in parenteral nutrition formulations remains a critical concern for patient safety. This study examined calcium phosphate solubility for 2-in-1 admixtures prepared using 2 commercially available pediatric amino acid solutions (Premasol, Baxter Healthcare Corp; or Trophamine, B. Braun Medical Inc), applying identical test methods, storage conditions, and acceptance criteria. Parenteral 2-in-1 admixtures included amino acid; dextrose; static concentrations of sodium, potassium, and magnesium, and varying concentrations of calcium (0-60 mEq/L), phosphate (15-50 mmol/L), and cysteine. Three replicate samples were stored for 48 hours at 40°C ± 2°C and then visually inspected for particulate matter, evaluated for subvisible particulate matter, when particulate matter was noted, microscopic examination was performed to confirm the presence of calcium phosphate crystals. Pass criteria were: all replicates free of visible particulate matter related to calcium phosphate crystals and particle counts below US Pharmacopeia <788> limits. Premasol and Trophamine generated identical calcium phosphate curves for 2% amino acid formulations containing 20% dextrose with/without cysteine, and similar curves for the 1% or 3% amino acid formulations containing 10% or 20% dextrose with/without cysteine. Calcium phosphate particles were identified in failed samples by scanning electron microscopy/energy dispersive X-ray spectroscopy. Calcium phosphate solubility was higher in formulations containing cysteine 40 mg/g amino acid vs. cysteine 20 mg/g amino acid and in cysteine 20 mg/g amino acid vs. no cysteine. Admixtures made with 1%, 2%, or 3% Premasol or Trophamine have essentially equivalent calcium phosphate solubility curves when tested with identical methods, storage conditions, and acceptance criteria.

Prediction of Maximum Pit Sizes in Elevated Chloride Concentrations and Temperatures

Calculated maximum pit sizes for stainless steel 304L (SS304L) are presented for atmospheric conditions with elevated chloride concentrations and temperatures. These calculations were carried out by experimentally determining the pit stability product ((i · x)sf), repassivation potential (Erp), and cathodic kinetics. These results were aided by determination of a solubility curve as a function of temperature for a stoichiometric metal salt mixture of iron chloride (FeCl2), chromium chloride (CrCl3), and nickel chloride (NiCl2). Based on these newly measured saturation concentrations, metal ion diffusivities were calculated. Overall, it was found that (i · x)sf decreases with increasing chloride concentration and increases with increasing temperature. Erp was determined to decrease with increasing concentration and increase with increasing temperature. When incorporated into the maximum pit size model, these experimental results yielded a small increase in maximum pit size with increasing bulk chloride concentrations and/or increasing temperature.

Influence of fluorides on phase relations in the molten systems MI2O-Р2О5 Mn2O3/MIIO, МI – Li, Na, K; MII – Ni, Co

Addition of alkaline fluorides to molten phosphates with a composition MI2O-Р2О5-Mn2O3 and MI2O-Р2О5-MIIO (МI – Li, Na, K) gradually changes the solubility of polyvalent metals oxides and shifts the crystallization areas in the corresponding melts. The results obtained are based on solubility curves found for Mn2O3, СоО and NiO in the fluxes of MI2O-Р2О5 -MF and MI2O-Р2О5 -MF (where МI – Li, Na, K) and X-Ray diffraction, IR spectroscopy and thermal analysis. The presence of 10 and 20 % mass of fluorides provides molten polyphosphates depolymerization and yields pyro- Li2MnP2O7, K2CoP2O7, Na2CoP2O7and orthophosphates Na2Mn3(P2O7)2, NaMnPO4, NaNiPO4 single crystals growth.

Influence of Water-soluble polymers on Epalrestat ternary complexation by kneading

The study reported in this current work objected to demonstrate the formation of binary and ternary inclusion complexes of Epalrestat (EP), a poorly water-soluble acidic type drug, with s-cyclodextrin (CD) and with water-soluble polymers PVP K30 and HPMC E4. The solid systems of EP with s-CD and water-soluble polymers were obtained by kneading and characterized for phase solubility, saturation solubility, dissolution, stability studies. FTIR, DSC, PXRD and SEM data indicated the positive influence of s-CD and hydrophilic polymers on EP solubility and dissolution. Phase solubility studies were carried out to evaluate the solubilizing power of CD, with regards to EP in combination with water-soluble polymers, and to determine the apparent stability constants (Ks) and complexation efficiency (CE) of the complexes. Phase solubility studies showed AL (linear) type of solubility curve for the ternary complexes it also showed amelioration in Ks value for ternary complexes. The CE of s-CD towards EP was promoted by water-soluble polymers signifying its use as a ternary component. The dissolution rate of EP and solubility were undoubtedly improved by complexation with s-CD as compared to model drug EP alone. Ternary complexes incorporated with PVP K 30 and HPMC E4 proved better than binary complex. Hence, the water-soluble carrier could be exploited as a ternary component to improve the solubility of EP via s-CD complexation.

Thermodynamic properties in ternary system of NH4HCO3–H2O–ethanol based on antisolvent method to strengthen crystallization of carbonized ammonia

One of the main challenges of the ammonia-based CO2 capture process is how to further reduce the regeneration energy consumption. An antisolvent crystallization method was proposed to strengthen the crystallization process of carbonized ammonia, and heating the crystal products instead of rich solution can greatly reduce renewable energy consumption. The main component of the crystal product was NH4HCO3 analyzed by X-ray diffraction. Therefore, it is very important to study the thermodynamic properties of ammonium bicarbonate in the ternary system of NH3–H2O–ethanol. In this paper, the solubility curves under different temperature and solvent compositions were determined by static method and the mathematical model of solubility was established. The effects of the addition of ammonium carbamate which was produced in the initial stage of the CO2 absorption process and the addition of ammonia on the solubility in ternary system of NH4HCO3–H2O–ethanol were studied. The dissolution heat was also calculated in the end. The research of this article has a guiding significance for the antisolvent method to strengthen the crystallization of carbonized ammonia of ammonia-based carbon capture technology. It is helpful to further strengthen the crystallization process of low carbonized ammonia and improve the crystallization yield.

Possibility of pressure crossover prediction by classical DFT for sparingly dissolved compounds in scCO2

A new method of solubility estimations, applied to sparingly dissolved compounds in supercritical carbon dioxide has been introduced in this paper. The method is based on determination of solubility contributions along the thermodynamic path consisting of sublimation and solvation processes. The contribution of the sublimation process is taken from the experiment, while the free energy of solvation is calculated from the classical density functional theory based on the fundamental measure theory. The parameterization of potential was performed using the Weeks-Chandler-Anderson procedure, where the Lennard-Jones parameters were obtained from the thermodynamics data of solute and solvent critical points. The introduced method can efficiently predict the pressure crossover on solubility curve of sparingly dissolved compounds in supercritical carbon dioxide.

Temperature dependent control of the solubility of gallium nitride in supercritical ammonia using mixed mineralizer

Using a mass-loss method, we investigated the solubility change of gallium nitride (GaN) in supercritical ammonia with mixed mineralizers [ammonium chloride (NH4Cl) + ammonium bromide (NH4Br) and NH4Cl + ammonium iodide (NH4I)]. The solubilities were measured over the temperature range 450–550 °C, at 100 MPa. The solubility increased with NH4Cl mole fraction at 450 °C and 100 MPa. The temperature dependence of the solubility curve was then measured at an equal mole ratio of the two mineralizers. The slope of the solubility–temperature relationship in the mixed mineralizer was between those of the individual mineralizers. These results show that the temperature dependence of the solubility of GaN can be controlled by the mineralizer mixture ratio. The results of the van’t Hoff plot suggest that the solubility species were unchanged over the investigated temperature range. Our approach might pave the way to realizing large, high-quality GaN crystals for future gallium-nitride electronic devices, which are increasingly on demand in the information-based age.

Measurement of Mineral Solubilities in the Ternary Systems NaCl–PbCl2–H2O and MgCl2–PbCl2–H2O at 373 K

In this paper, isothermal solubility equilibrium method was used to study the mineral solubilities of two ternary systems sodium chloride-lead chloride-water and magnesium chloride-lead chloride-water at 373 K. The solubilities of the salt minerals and the densities of saturated solution in these systems were measured at 373 K. Based on the determined equilibrium solubility data and the corresponding equilibrium solid phase, the isothermal solubility diagrams of the ternary systems were shown, respectively. The results show that both the two ternary systems are simple total saturated at 373 K that neither double salt nor solid solution produced under the condition. Besides, the isothermal solubility diagrams of the two ternary systems at 373 K are both constituted of a eutectic point, two isothermal solubility curves and two solid crystalline phase regions. The two equilibrium solid phases corresponding to the eutectic point of the sodium chloride-lead chloride-water ternary system are NaCl and PbCl2. The two equilibrium solid phases corresponding to the eutectic point of the magnesium chloride-lead chloride−water ternary system are MgCl2 · 6H2O and PbCl2. The experimental result of density was simply discussed.

Enhanced dissolution and solubility of Epalrestat with β-Cyclodextrin ternary complex using Arginine

The objective of present is work to achieve improvement in solubility and dissolution using Epalrestat with β-cyclodextrin ternary complex with addition of L-arginine. Kneading method with and without incorporation of L-arginine was used to obtain the solid systems (binary and ternary complex) of Epalrestat with β-cyclodextrin and characterized for DSC, PXRD, SEM. Phase solubility, saturation solubility, dissolution and stability studies were carried out. The effect of L-arginine was investigated on complexation efficiency of β-cyclodextrin towards Epalrestat in an aqueous media through phase solubility according to Higuchi and Connors. Phase solubility studies showed AL (linear) type of solubility curve in presence of L-arginine, the complexation efficiency and association constant of β-cyclodextrin towards Epalrestat were promoted by L-arginine signifying its use as a ternary component. Dissolution rate of Epalrestat and solubility were significantly improved by complexation with β-cyclodextrin as compared to Epalrestat alone. Ternary complex incorporated with L-arginine proved better than binary complex. Hence, L-arginine could be exploited as a ternary component to improve the solubility of Epalrestat via β-cyclodextrin complexation.&#x0D; Keywords: Epalrestat, solubility enhancement, inclusion complexes, β-cyclodextrin, L-arginine.

Oxygen Solubility in Titanium-Containing Melts of the Ni–Co System

Thermodynamic analysis is performed for the oxygen solutions in titanium-containing melts of the Ni–Co system. The equilibrium constants of the reactions of titanium with oxygen, activity coefficients at infinite dilution, and interaction parameters in melts of various compositions at 1873 K are determined for the first time. The titanium contents at the equilibrium points between the oxide phases TiO2, Ti3O5, and Ti2O3 are determined. The dependences of the oxygen solubility on the titanium content in the studied melts are calculated. The deoxidation ability of titanium decreases with an increase in the cobalt content to 40% and then increases as the cobalt content in the melt further increases. The titanium contents at the minimum points on the curves of the oxygen solubility and the corresponding minimum oxygen contents are determined.

First-principles investigation of activity and solubility of Si in Mo solid solution

The activity and solubility of Si in Mo solid solution were studied by the first-principles calculations and quasi-harmonic approximation. The lattice constants, bulk modulus, and formation enthalpies of Mo-Si intermetallics were investigated, and the thermodynamic properties of Mo were also calculated. The Si activity coefficient [Formula: see text] is approximately 10[Formula: see text] at 100 K, while it increases by about 15 orders of magnitude over the investigated temperature range (100–2000 K). It is clear that Si activity coefficient in Mo solid solution increased rapidly with the increasing temperature, which should be ascribed to the Si–Mo interaction being evidently stronger than Mo–Mo interaction. According to the calculated thermodynamic properties, the solubility curve of Si in Mo solid solution was also predicted. The solubility limit of Si in Mo solid solution is [Formula: see text]5.5 at.%, which agrees well with the other experiment and assessed results.

Continuous-Flow Tubular Crystallization To Discriminate between Two Competing Crystal Polymorphs. 1. Cooling Crystallization

A laminar-flow tubular crystallizer was used for seedless continuous flow crystallization of an active pharmaceutical ingredient, namely, Brivaracetam, which has a polymorphic behavior: rod-shaped crystals and a pseudo-polymorphic solvated, needle-like crystal. The combination of fast cooling at 20 °C/s and high supersaturation values between 4 and 11 resulted in the discrimination of nucleation and growth of only the desired crystalline form even though its solubility curve is very close to the one of the undesired needle shape. Crystal nucleation and the start of crystal growth occur inside the tubular crystallizer; high flow rates prevent clogging of the crystallizer. Further crystal growth may be, if desired, stopped via immediate filtration. In this way, an industrially applicable continuous crystallizer is proposed. It is also demonstrated that the presence of restrictions in the tubing drastically increases the nucleation rate. A literature survey points out that induced turbulence can occur under ...

The aqueous solubility of common organic groundwater contaminants as a function of temperature between 5 and 70 °C

High-temperature thermal energy storage in shallow aquifers can potentially increase ambient groundwater temperatures up to 70 °C or even more. Since an increase in temperature is expected to influence contaminant mass flux into groundwater monitoring the spreading of organic contaminants located in the subsurface is crucial. In numerous former studies, the NAPL solubility, one major parameter controlling mass flux on field scale, was measured at temperatures up to 70 °C for a broad spectrum of organic substances. However, quantitative calculations of solubilities as a function of temperature considering a compiled database are largely missing. Aiming to examine the reliability of existing solubility-temperature relationships, to describe them functionally and further to identify knowledge gaps, previously published data on solubilities of 42 different organic groundwater contaminants were evaluated in this study. By using a common temperature regression function, the calculated solubility curves from compiled solubility data for 5–70 °C show relative changes between a few percent (CHCs and BTEX) and up to 2000% (PAHs). As published temperature-dependent solubilities for chlorinated ethylenes are contradictory in parts, solubilities of tetrachloroethylene, trichloroethylene, 1,2-cis-dichloroethylene and 1,2-trans-dichloroethylene were additionally investigated in more detail using batch experiments between 5 and 70 °C. The results show distinctive solubility minima at medium temperatures (20–40 °C) with concentrations decreasing from 5 °C to the minimum by 10–20%. The measured and calculated temperature-dependent solubilities enable a more reliable assessment of thermal energy storage at contaminated sites, of existing thermal remediation approaches and of combinations of underground heat storage with groundwater remediation.

Experimental measurements and simulation of the fouling phenomena of natural proteins

Fouling, a mass transfer phenomenon that depends on the solubility of the proteins, in food industry is a severe problem causing loss of efficiency of heat exchangers. In this work, ovalbumin and β-lactoglobulin fouling was studied through of protein solubility curves. Mathematical simulation using artificial neural networks with several configurations containing independent variables (velocity, convection heat and mass transfer coefficients, temperature, potential of Hydrogen and molecular descriptors) and dependent variables (percentage of fouling removed and the reduction of free flow area) was made. Results showed that the thickness of the fouled deposit is inversely and directly proportional to the Reynolds number and the inlet temperature, respectively. For transient and turbulent flows, egg white fouls faster than milk. The fouling was greater at pH 5.0, for β-lactoglobulin. Results obtained by the artificial neural networks were successful performance for simulating the fouling phenomenon for both natural proteins for the architecture 5-20-2, where the input layer has 5 neurons, the hidden layer has 20 neurons and the output layer has 2 neurons.

Investigation of the Dependence of the Flory–Huggins Interaction Parameter on Temperature and Composition in a Drug–Polymer System

The Flory-Huggins (F-H) solubility equation has been widely used to describe the solubility of a small-molecule drug in a polymeric carrier and thus determine the design space available for formulating a stable amorphous solid dispersion. The F-H interaction parameter (χ) describes the thermodynamic properties of drug-polymer solutions and accounts for any enthalpic and entropic changes in solubility. Many studies have found that for a limited compositional range, χ varies proportionally to the inverse of the melting temperature of the drug. We explored this relationship using a highly sensitive DSC technique to detect remaining residual crystalline active pharmaceutical ingredients (APIs) following annealing of ball milled mixtures of crystalline itraconazole (ITZ) and either Soluplus or hydroxypropyl methylcellulose phthalate (HPMCP) at temperatures near the estimated solubility curve. Depending on the experimental approach taken, the measurement of drug-polymer solubility can be restricted to mixtures with a high proportion of drug, but in this study, solubility was experimentally determined for mixtures with API content as low as 10 wt %. Results suggest that the proposed linear relationship does not extend to compositions with smaller amounts of API, instead indicating that χ was both temperature- and composition-dependent for the systems studied. The feasibility of this technique to measure interactions in a ternary system containing itraconazole and both polymers was also determined; ITZ-HPMCP exhibited the most favorable values of χ, while ITZ-Soluplus and ITZ-Soluplus-HPMCP demonstrated similar interaction parameters.