System NH4Cl Research Articles

Solid–Liquid Phase Equilibrium of the Ternary System NH4Cl-(NH2)2CO-H2O at Multiple Temperatures

Solid–Liquid Phase Equilibrium of the Ternary System NH4Cl-(NH2)2CO-H2O at Multiple Temperatures

Study on the phase equilibria and solid solution in the ternary systems NH4Cl–NH4Br–H2O and NH4Cl–NH4Br–CH3OH at 298.15 K

Aiming at utilizing bromine resource in bittern after magnesium extraction, the solubilities of the ternary systems NH4Cl–NH4Br–H2O and NH4Cl–NH4Br–CH3OH at 298.15 K were studied by means of isothermal dissolution equilibrium, and the phase diagrams were depicted. It was found that two phase diagrams are similar, and the solid solution was defined two types, NH4(Brx, Cl1−x) rich of NH4Br and NH4 (Cl1-y, Bry) rich of NH4Cl (x and y are mole fractions of Br− in solid solutions). The phase diagram of water system was delimited two single-phase crystallization zones and contains one invariant point. Under the effect of methanol, a large two-phase cocrystallization area exists in the phase diagram of methanol system. According to the Pitzer model, the solubilities of the ternary NH4Cl–NH4Br–H2O system at 298.15 K were evaluated without the consideration of the ion-interaction parameters θ and ψ, and the results basically coincide with the measured values. Compared with the XRD patterns of the mixture of two salts, the characteristic peaks of the solid solution are weaker and shifted. The thermogravimetry differential scanning calorimetry (TG-DSC) showed that the difference between the solid solutions formed in aqueous solution and methanol is not significant.

Study on the Phase Equilibria and Solid Solution in the Ternary Systems Nh4cl–Nh4br–H2o and Nh4cl–Nh4br–Ch3oh at 298 K

Study on the Phase Equilibria and Solid Solution in the Ternary Systems Nh4cl–Nh4br–H2o and Nh4cl–Nh4br–Ch3oh at 298 K

Solid-liquid phase equilibrium determination and correlation of ternary systems NH4Cl+AlCl3+H2O, MgCl2+AlCl3+H2O and SrCl2+AlCl3+H2O at 298 K

The equilibrium data (solubility, density and refractive index) of three aqueous ternary systems NH4Cl + AlCl3+H2O, MgCl2+AlCl3+H2O, and SrCl2+AlCl3+H2O at 298 K were measured by isothermal dissolution method, and the corresponding diagrams were plotted. The phase diagram shows that these three systems are simple eutectic type, and neither double salt nor solid solution formed. Three ternary systems all have one ternary invariant point, two isothermal dissolution curves and two crystallization fields. The equilibrium thermodynamics data of three aqueous ternary systems at 298 K were correlated by using the Pitzer thermodynamic model. Result shows that the calculated values are consistent well with the experimental ones.

Measurement and Correlation of Phase Equilibria of Ammonium, Calcium, Aluminum, and Chloride in Aqueous Solution at 298.15 K

The equilibrium data on the aqueous quaternary system NH4Cl–CaCl2–AlCl3–H2O at 298.15 K were investigated by using the isothermal dissolution method, and the corresponding diagrams were constructed...

Solid-liquid phase equilibria of quaternary system NH4+//C1−, SO42−, H2PO4−–H2O and its subsystems NH4+//C1−, SO42−–H2O, NH4+//C1−, H2PO4−–H2O at 313.15 K

Solid–liquid phase equilibrium and physical properties of ternary systems NH4Cl-NH4H2PO4-H2O, NH4Cl-(NH4)2SO4-H2O and quaternary system NH4Cl-(NH4)2SO4-NH4H2PO4-H2O at 313.15K and atmospheric pressure were obtained by means of an isothermal solution method. The solid phases formed in the systems studied were determined by the Schreinemaker wet residue method. Based on the measured data, corresponding phase diagrams and the diagrams of physical properties versus composition were plotted. Neither complex salt nor solid solution is found in these systems at 313.15K. The ternary phase diagram of NH4+//C1−, H2PO4−–H2O contains one invariant point, and three crystallization regions (NH4H2PO4, NH4Cl, and (NH4Cl+NH4H2PO4)). The ternary phase diagram of NH4+//C1−, SO42−–H2O is similar to the previous one, also contains one invariant point, three crystallization regions ((NH4)2SO4, NH4Cl, and (NH4Cl+(NH4)2SO4)). The quaternary phase diagram of NH4+//C1−, SO42−, H2PO4−–H2O contains one quaternary invariant point, three crystallization regions ((NH4)2SO4, NH4Cl, and NH4H2PO4), and crystallization field of NH4H2PO4 is the largest one of them. All results obtained in this work can be used for the stripping process of solvent extraction in the production of potassium dihydrogen phosphate.

Solid–Liquid Metastable Phase Equilibria in the Ternary Systems KCl + NH4Cl + H2O and NH4Cl + MgCl2 + H2O at 298.15 K

The metastable phase equilibria in the ternary systems KCl + NH4Cl + H2O and NH4Cl + MgCl2 + H2O were investigated at 298.15 K using an isothermal evaporation method. The metastable phase diagrams and the physicochemical properties versus composition diagrams were constructed on the basis of the experimental data. In the phase diagram of the ternary system KCl + NH4Cl + H2O, there are three invariant points and five crystallization fields, corresponding to potassium chloride (KCl), ammonium chloride (NH4Cl), a solid solution based on potassium chloride [(K, NH4)Cl], a solid solution based on ammonium chloride [(NH4, K)Cl], and a crystallization field of two kinds of solid solution [(K, NH4)Cl + (NH4, K)Cl] precipitation. Comparisons between the metastable and stable phase diagrams at 298.15 K show that the crystallization forms of salts are all the same, whereas the size of crystallization regions has slight changes. The ternary system NH4Cl + MgCl2 + H2O is a complex type system with a double salt ammonium carnallite (NH4Cl·MgCl2·6H2O) formed at 298.15 K. Comparisons between the metastable and the stable phase diagrams at 298.15 K and 323.15 K show that the crystallization forms have not changed, while the crystallization fields have slight changes. The density coefficient Ai and refractive index coefficient Bi of salts KCl, NH4Cl, and MgCl2 at 298.15 K were obtained by fitting. The calculated values of densities and refractive indices agree well with the experimental values, with a maximum relative error better than 0.010.

Phase change materials in the ternary system NH 4Cl+CaCl 2+H 2O

Solubility isotherms of the ternary system (NH 4Cl+CaCl 2+H 2O) were elaborately determined at T = (273.15 and 298.15) K by using the isothermal method. In the equilibrium phase diagram, there are two solubility branches corresponding to the solid phases CaCl 2⋅6H 2O and NH 4Cl. Invariant point compositions are 36.32 wt% CaCl 2 and 3.4 wt% NH 4Cl at 273.15 K, and 45.86 wt% CaCl 2 and 5.22 wt% NH 4Cl at 298.15 K. A Pitzer–Simonson–Clegg thermodynamic model was applied to represent the thermodynamic properties of this ternary system and to construct a partial phase diagram of the ternary system at temperatures between (273.15 and 323.15) K. It was found in the predicted solubility phase diagram that the double salt 2NH 4Cl⋅CaCl 2⋅3H 2O, found by other authors at (323.1 and 348.1) K, will disappear at temperatures below 298.15 K. Besides, it was found that there are two peritectic points in the ternary system with peritectic temperatures at 299.65 K and 298.15 K, and the former peritectic point falls just on the line between the composition points of NH 4Cl and CaCl 2⋅6H 2O. According to phase rule, a solution made of this point will begin to crystallize at 299.65 K and end at 298 K and therefore can be acted as a “pseudo eutectic” phase change material (PCM). A heat storing and releasing experiment of 50 grams of the PCM was carried out, obtaining a satisfying result.

Thermodynamic Properties of Quaternary Aqueous Solutions of Chlorides Charge-type 1-1*1-1*2-1: NH4Cl + NaCl + YCl2 + H2O with Y ≡ Mg2+, Ca2+, and Ba2+

Thermodynamic properties of quaternary aqueous solutions of mixed chlorides of 1-1*1-1*2-1 charge type with the cations (Na+, NH4 +; Mg2+, Ca2+, Ba2+) were determined using the hygrometric method. The quaternary systems NH4Cl + NaCl + MgCl2 + H2O, NH4Cl + NaCl + CaCl2+ H2O, and NH4Cl + NaCl + BaCl2 + H2O have been studied at 25 °C. The water activities were measured at total molalities from 0.44 mol⋅kg−1 to saturation for different ionic-strength fractions y of NH4Cl, y=(0.20,0.50,0.80), and different ionic strength ratios z for other solutes, z=(0.20,0.50 and 0.80) for each value of y. The obtained data allows the calculation of osmotic coefficients. A new parameterization of the ion interaction model approach has been established from the relevant laboratory measurements for quaternary systems. This ion interaction model was developed and the ionic mixing parameters φ and χ for the studied quaternary systems were determined. From these results, the parameters φ and χ are used to predict the solute activity coefficients in the mixtures. A correlation of the behavior of quaternary aqueous solutions of alkaline-earth metal + ammonium + sodium chlorides is reported and the results show that ionic interactions are more important for system containing Mg2+ or Ca2+ than for Ba2+.

Thermodynamic properties on quaternary aqueous solutions of chlorides charge-type 1-1*2-1*2-1: XCl + MgCl 2 + CaCl 2 + H 2O with (X ≡ Na +; NH 4+)

In this investigation, the quaternary aqueous solutions of chlorides charge-type 1-1*2-1*2-1 with a cation (Na +; NH 4 +; Mg 2+; Ca 2+) have been studied using the hygrometric method at 298.15 K. The water activities of the systems NH 4Cl + MgCl 2 + CaCl 2 + H 2O and NaCl + MgCl 2 + CaCl 2 + H 2O are measured at total molalities from 0.60 mol kg −1 to saturation for different ionic-strength fractions NH 4Cl or NaCl, y = 0.20, 0.50, 0.80, and z ratio ionic-strength for other solutes, with z = 0.20, 0.50 and 0.80 for each y. The obtained data allow the deduction of osmotic coefficients. The ionic interaction model with our approach is developed and evaluated the mixing ionic parameters φ and χ for quaternary systems. From these measurements, newly quaternary parameters φ and χ are determined and used to predict the solute activity coefficients in the mixtures. The results are compared with experimental data.

Osmotic Coefficients of the System NH4Cl + (NH4)2SO4 + H2O at 298.15 K and Calculation of Onsager Transport Coefficients

Osmotic coefficients are reported for the system NH4Cl + (NH4)2SO4 + H2O at 298.15 K over a wide range of concentrations. Scatchard’s mixed electrolyte equation is used to fit these data with six fitting parameters, bij. For comparison, we insert extended Debye−Huckel equations and separately Pitzer’s equations as the necessary binary salt equations within Scatchard’s equation. Three sets of the six bij are obtained in each case from fits with two subsets and the full set of the osmotic coefficients. We examine the consequence of including different binary osmotic coefficient expression equations and applying different data ranges in these fits. The results are combined with available ternary diffusion coefficients to calculate and report solvent frame thermodynamic transport coefficients, (Lij)0. These are intercompared relative to the Onsager Reciprocal Relations requirement. Finally, we use Pitzer’s mixed electrolyte equation to calculate thermodynamic properties of the ternary system directly and to c...

Thermodynamic properties of aqueous mixed ternaries { y NH 4Cl+(1− y) BaCl 2 } (aq) and { y NH 4Cl+(1− y) CaCl 2 } (aq) at 298.15 K

Hygrometric measurements of the water activity are reported for the thermodynamic properties of the mixed aqueous electrolyte systems of ammonium–calcium chloride and ammonium–barium chloride at 298.15 K. The measurements were made at a large number of total molalities, varying from 0.4 mol kg −1 to saturation at three ionic-strength fractions ( y ) of NH 4Cl for the systems NH 4Cl–CaCl 2 (aq) and NH 4Cl–BaCl 2 (aq) with y = 0.20 , 0.50 and 0.80. The experimental data are reported as water activities and osmotic coefficients at various molalities, along with derived values of the activity coefficients of both solutes. The ranges of water activities a w are 0.800–0.989 for ammonium–barium chlorides and a w = 0.560 – 0.989 for ammonium–calcium chlorides. The activity coefficients were calculated by means of a thermodynamic model based on a variant of the Pitzer ion-interaction equations with extended binary parameters. However, the results were also compared for the precision of the presentation of the osmotic coefficients using an extended model with the calculations of the Zdanovskii–Stokes–Robinson, Kusik and Meissner, Robinson and Stokes, Lietzke and Stoughton, Reilly, Wood and Robinson, and Pitzer models.

Dendritic array growth in the systems NH 4Cl–H 2O and [CH 2CN] 2–H 2O: steady state measurements and analysis

Dendrite array dimensions have been measured under steady state growth conditions in the transparent material systems, ammonium chloride–water and succinonitrile–water. The measurements were made as functions of growth rate, V, and temperature gradient, G, and the results compared with the current analysis of Hunt and Lu. Close agreement with the analysis was found for the system [CH 2CN] 2–H 2O, but less so for the system NH 4Cl–H 2O in which the volume fraction of solid is very small. The data are presented as a reference base for subsequent examination of array behavior under transient conditions following deceleration.

Dendritic array growth in the systems NH 4Cl–H 2O and [CH 2CN] 2–H 2O: dendrite tip behavior and the origin of side arm evolution

Dendrite side arms evolve from perturbations behind primary dendrite tips and develop with exponentially increasing amplitudes before coalescence and ripening begin. Measurements of the spacings and amplitudes of these initial perturbations extrapolate to small finite displacements at the primary tips, compatible with small oscillatory fluctuations in the mean growth velocity. The frequency of these oscillations correspond to the initial side arm spacings and this oscillatory mode is an intrinsic characteristic of dendritic growth.

Dendritic array growth in the systems NH 4Cl–H 2O and [CH 2 CN] 2–H 2O: the detachment of dendrite side arms induced by deceleration

Dendrite array adjustments have been measured in transparent material during the transient conditions attending deceleration. There is considerable hysteresis between the responses of dendrite tip radii and primary spacings to velocity changes and this promotes the dissolution of the necked regions, where side arms attach themselves to primary stems. Simple analyses of the transient dendritic dimensions are offered to illustrate a detachment mechanism. This phenomenon is relevant to the development of an equiaxed zone in metal castings.

Nucleation of KCl, NH 4Cl and BaCl 2: the influence of additives on supercoolings

The nucleation phenomena in inorganic salt solutions were studied by measuring distributions of supercoolings with an automated apparatus. Secondary and primary (heterogeneous) nucleation could be observed. The linearity of the experimental data (nucleation rate) in a Pound plot (1n( JVΔ t) versus 1 (ΔT) 2 ) was examined. The influence of additives (1000 ppm related to the weight of water-free salt) was also studied. Some systems ( KCl PbCl 2 , KCl K 4[Fe(CN) 6]) and KCl K 3[Fe(CN) 6]) showed a shift of the supercoolings to higher values (retarding effect), while in the system NH 4Cl PbCl 2 an accelerating effect was observed. Most of the used additives did not influence the nucleation supercoolings significantly. The method is a short screening test to examine the influence of additives (impurities) in a crystallization process.

Double salts of indium trichloride with the alkali chlorides, with ammonium chloride, and with indium sulfate

From a determination of the phase diagrams, at 25 °C, the following double salts were shown to exist: 3LiCl•InCl3•8H2O in the system LiCl–InCl3–H2O, 2KCl•InCl3•H2O and 3KCl•InCl3•2H2O in the system KCl–InCl3–H2O, 2RbCI•InCl3•H2O in the system RbCl–InCl3–H2O, 2CsCl•InCl3•H2O in the system CsCl–InCl3–H2O, 2NH4Cl•InCl3•H2O in the system NH4Cl–InCl3–H2O, In2(SO4)3•InCl3•(17 ± 1)H2O in the system In2(SO4)3–InCl3–H2O. No double salt was found in the system NaCl–InCl3–H2O, studied previously (1). All the double salts except the two involving potassium chloride are congruently saturating at 25 °C.

Phase diagram of the solid solution system NH 4Cl 1-xBr x as determined by optical methods

The phase diagram of NH 4Cl 1- x Br x has been determined by means of optical anisotropy and transmission measurements using solution-grown single crystals. It is shown that the change from the parallel to the anti-parallel orientational ordering of the NH 4-tetrahedra already takes place at X tr ≈ 0.08. In NH 4Br, the γ - δ transition temperature decreases rapidly with slowly increasing substitution of chloride for bromide. From the hysteresis along the β-δ and β-γ transition lines the existence of a tricritical point at X tc ≈ 0.25 is concluded. The relation between the x- T phase diagram and the p- T diagram of the ammonium halides is discussed.

Electron Spin Resonance of Mn2+ in the Ternary System NH4Cl–MnCl2–H2O

Solid solutions grown from the ternary system NH4Cl–MnCl2–H2O with Mn2+ concentrations up to 8% by weight show a change of structure from cubic to tetragonal in the vicinity of 4% Mn2+. Electron spin resonance at X band shows an extraordinarily complex spectrum for the series, and a change in hyperfine structure intensity with change of structure. Previous workers have shown by x-ray diffraction that the tetragonal phase, which occurs at high concentrations of manganese, is due to ordered arrangement of NH4Cl double cells in which the manganese ion is interstitial. It is deduced from the electron spin resonance results that the double cell structure also holds at low concentrations, the bcc phase shown by x-ray diffraction being due to a lack of order among such double cells. A Q-band spectrum yields an exceptionally large axial parameter D=0.150 cm—1, and a small cubic parameter a=2.8×10—4 cm—1 in the spin Hamiltonian.