Eutonic Solutions Research Articles

Optimization of Liquid Complex Fertilizer Formulations Using Phase Diagrams of Multicomponent Systems

The paper describes a method for the optimization of liquid complex fertilizer (LCF) formulations using phase diagrams of multicomponent water–salt systems. The chosen optimization criteria are the concentration of solution and the set of salts that provide the most concentrated fertilizer at the set ratio N : P2O5 : K2O. The opportunities of the method are shown for exemplary three- and four-component systems. The compositions of eutonic solutions and the ratios of nutrients calculated for them are given. Experimental data confirm the influence of the salt set and a solubilizer (urea) on the solution concentration. The number of optimal compositions becomes greater as the number of components in the system increases. Phase diagrams help to determine whether the liquid fertilizer composition belongs to the 15 homogeneous regions and thereby to guarantee its long-term storage stability.

Composition for rock grouting based on insoluble calcium salts for groundwater protection

Importance to reduce permeability of rocks arises safety of mining operations and protecting the soil and underground water in the area of industrial waste storage with high contents of water-soluble salts. Disadvantage of the existing methods of grouting rocks by soluble salts is either their dissolution with changing of the composition or diluting of the contacting solution. The paper considers the composition of the grouting mixture for the deposition of insoluble calcium salts and its effectiveness in laboratory conditions. The eutonic solution of a four-component KCl–NaCl–CaCl2–H2O system was used as the initial solution, while saturated solutions of sodium sulfate and carbonate, and sulfuric acid were applied as the precipitators. Efficiency of rock grouting was estimated according to the water or solution filtration rate through the rock (sand, sylvinite, and halite) before and after calcium salt crystallization. Laboratory experiments showed that the precipitation of calcium sulfate responds to the challenge of plugging rocks. The paper proposes some recommendations of protective screens at the bed of the salt tailing piles and slurry storage facilities.

Specifics of Phase Equilibria Studies in the NH4H2PO4–(NH4)2HPO4–(NH4)2SO4–NH4Cl–H2O at 25°C System by the Optimized Sections Method

Phase equilibria in the NH4H2PO4–(NH4)2HPO4–(NH4)2SO4–NH4Cl–H2O five-component water–salt system and in its boundary systems have been studied at 25°С by an optimized sections method. The efficiency of the algorithm for predicting the compositions of eutonic solutions in the system has been shown. The methodology of experimental design and its implementation in studies of in-, mono-, di-, and invariant equilibria by the optimized sections method is described. The system under study is a simple eutonic type; its eutonic solution is saturated with the initial salt components. Monovariant equilibrium lines and salt cocrystallization surfaces have been studied. Experimental data have been used to plot the phase diagram of the system and its projection on the salt base. The boundaries of areas where one, two, three, or four salts crystallize together have been designated on the salt projection.

ОПРЕДЕЛЕНИЕ ФАЗОВЫХ РАВНОВЕСИЙ И ПОСТРОЕНИЕ ДИАГРАММЫ СИСТЕМЫKH2PO4–KNO3–KCl–K2SO4–H2O ПРИ 25°C

Phase equilibria in the KH2PO4 – KNO3– KCl – K2SO4 – H2O at 25 ° C five-component water-salt system and its boundary systems have been studied at 25 °C by an optimized sections method. The compositions of saturated solutions of the three boundary systems have been obtained in the experiment.The efficiency of the algorithm for predicting the compositions of eutonic solutions in the multi-component systems has been shown. According to the experimental data, the phase diagram has been drawn. Monovariant equilibria lines and the areas of all four salts crystallize have been designed on the phase diagram. The values of N, P2O5, K2O have been calculated for the saturated solutions of the system.

Modeling of the composition of the eutonic solution in the NaCl–AlCl3−SrCl2–HCl–H2O system at 25°С and its experimental confirmation

The solubility was studied in the system NaCl–AlCl3−SrCl2–HCl–H2O of the eutonic type at 25°C in the section 28 wt % HCl. It was determined that it is possible to derive equations of the solubility surface of crystallizing salts and to calculate the composition of the eutonic solution.

The NaCl–AlCl3–HCl–H2O system at 25°С

Solubility was studied in the system NaCl–AlCl3–HCl–H2O at 25°C in the section 28 wt % HCl. The system is of the eutonic type and has an extensive sodium chloride crystallization region. The composition of the eutonic solution is the following, wt %: NaCl, 0.47; AlCl3 • 6H2O, 8.88; HCl, 25.38; and H2O, 65.27. The lines of saturated solutions were approximated by polynomial equations.

Solubility in the LaCl3-LnCl3-HCl-H2O (Ln = Pr, Nd) Systems at 25°C

The solubility in the quaternary water-salt systems LaCl3-NdCl3-HCl-H2O (1) and LaCl3-PrCl3-HCl-H2O (2) at 25°C was studied in the section of 40 wt % hydrochloric acid, a system with a eutonic discontinuity. The composition at the point of discontinuity for the eutonic solution is the following. In system 1: 4.67 wt % LaCl3 · 7H2O, 0.37 wt % PrCl3 · 7H2O, 37.98 wt % HCl, and 56.98 wt % H2O; in system 2: 4.37 wt % LaCl3 · 7H2O, 0.93 wt % NdCl3 · 6H2O, 37.88 wt % HCl, and 56.82 wt % H2O.

Solubility in the NaCl-ZrOCl2-HCl-H2O system at 25, 50, and 75°C

Solubilities were studied in the NaCl-ZrOCl2-HCl-H2O water-salt system along the 28 wt % HCl section at 25, 50, and 75°C. This is a eutonic system. The compositions of the eutonic solution are as follows (wt % NaCl, ZrOCl2 · 8H2O, HCl, and H2O, respectively): at 25°C, 0.26, 1.88, 27.4, and 70.46; at 50°C, 2.82, 2.68, 26.46, and 68.04; and at 75°C, 1.9, 16.1, 22.96, and 59.04.

A combined method for investigating solubility and determining the composition of equilibrium solid phases saturating eutonic solutions in a NaCl-Na2SO4-Na2CO3-H2O system at 50°C

The composition of equilibrium solid phases NaCl, Na2SO4, Na2CO3 · 2Na2SO4 (berkeyite) and NaCl, Na2CO3 · H2O, Na2CO3 · 2Na2SO4 (without preparative determination), saturating E1 and E2 eutonic solutions respectively, was established via nonvariant area boundary determination in a NaCl-N2SO4- Na2CO3-H2O system at 50°C with the use of a combined method.

Physicochemical properties of eutonic aqueous solutions of zinc and copper tetraammoniates in the range 293–323 K

The density, viscosity, surface tension, and conductivity of subeutonic and eutonic solutions in the CuO-ZnO-NH3-NH4Cl-H2O system at ammonia concentrations in the range 1.16–13.36 mol/l are determined experimentally in the temperature range 293–323 K. The expansion coefficient, the activation energy of viscous flow, the parachor, the orthochor, the degree of dissociation, and the equilibrium constant are calculated.

Solubility in the LaCl3-YbCl3-HCl-H2O System at 25°C

Solubility has been studied in the LaCl3-YbCl3-HCl-H2O water-salt system at 25°C along the (40 ± 0.2)% HCl section; this is a eutonic-type system. The composition of the eutonic solution is as follows (wt %): LaCl3 · 7H2O, 4.67, YbCl3 · 6H2O, 0.37; HCl, 37.98; and H2O, 56.98.

Solubility in the systems AlCl3-SrCl2-HCl-H2O and NaCl-SrCl2-HCl-H2O at 25°C

Solubility in quaternary water-salt systems AlCl3-SrCl2-HCl-H2O (I) and NaCl-SrCl2-HCl-H2O (II) at 25°C along the 28% HCl section of the eutonic-type systems has been investigated. The compositions of eutonic solutions are the following (wt %): in system I, 3.11 AlCl3 ·6 H2O, 7.57 SrCl2 · 6H2O, 22.21 HCl, and 57.11 H2O; and in system II, 2.3 SrCl2 · 6H2O, 1.7 NaCl, 26.88 HCl, and 69.12 H2O.

Hygroscopic growth of ammonium sulfate/dicarboxylic acids

Recent studies have shown that tropospheric sulfate aerosols commonly contain 50% by mass organic species. The influence of these organics on the chemical and physical properties of sulfate aerosols is not fully established. We have measured the water activity of pure dicarboxylic acids and eutonic mixtures of ammonium sulfate/dicarboxylic acids at 25°C and have calculated van't Hoff factors for each individual system. We have also used the vapor pressure data to determine the hygroscopic growth curves for pure dicarboxylic acids and eutonic mixtures and provide power law fits to the data. For the systems studied we find that the presence of soluble dicarboxylic acids at the eutonic proportion depresses hygroscopic growth when compared to pure ammonium sulfate. In addition, we find that the presence of low‐solubility dicarboxylic acids at the eutonic proportion has no effect on the hygroscopic growth when compared to pure ammonium sulfate. To model the hygroscopic growth curves of the eutonic solutions, we employed the Zdanovskii, Stokes, and Robinson method. It was found that this approximation was accurate to within 17% for all the systems studied.

The Influence of the Degree of Organization of Saturated Solutions on the Shape of the Solubility Isotherm

Abstract Special features of solubility isotherms of salt hydrates have been observed, from which the evidence of strong organization of saturated solutions of hydrates may be deduced. Often observed low contents of the non saturating component in the eutonic solution limiting the crystallization branch of hydrated salts is put into connection with this result. The composition of the respective eutonic solutions exhibits a correlation with the hydration entropy of the ions present in the ternary saturated solution.

Solubility in the system NiCl2–ZnCl2–H3BO3–H2O at 15, 20 and 25 °C

Solubility in the system NiCl2–ZnCl2–H3BO3–H2O for a limited concentration range of ZnCl2(up to 13.5 wt %) has been investigated at 15, 20 and 25 °C. In the ternary system NiCl2–ZnCl2–H2O no formation of solid solutions takes place, contrary to similar systems of sulphates or nitrates of both cations: only nickel chloride hexahydrate, NiCl2· 6H2O, has been found as the coexisting solid phase in the mentioned concetration and temperature range. The ternary system NiCl2–H3BO3–H2O belongs to a simple system in which each of both components crystallizes in a pure from form mixed saturated solutions, with the exception of eutonic solutions, with which both solid components coexist together. In the quaternary system, the solubility of NiCl2 decreases slightly with increasing content of ZnCl2 and H3BO3. Similar trends have been observed for the solubility of H3BO3 dependent on the content of NiCl2 or ZnCl2, respectively. The solubility dependence of the crystallizing component on the content of other components (in wt % and mol kg–1) and on the temperature have been expressed numerically.