Measurement and correlation on stable phase equilibria of ternary system NaBr−Na2SO4−H2O at 273.2 K and 308.2 K and its application for sodium sulfate separation from underground brines

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The heavy metal lead will cause serious effects on human living environment and personal health when it enters the ecosystem, and the wastewater produced during the production of lead−chromium pigments may cause lead pollution to the environment. The heavy metals in wastewater can be further treated by studying the thermodynamic properties and phase diagrams of the NaNO 3 and Pb(NO 3 ) 2 systems. The cell potential method and the Pitzer model were used to evaluate the activity coefficients of the NaNO 3 -Pb(NO 3 ) 2 -H 2 O system at 298.2 K. The Pitzer mixed ion parameters were fitted by the activity coefficient data and solubility data, and the theoretical prediction of the solubility of the NaNO 3 -Pb(NO 3 ) 2 -H 2 O system at 298.2 K was made based on the obtained parameters (θ Na,Pb = 0.0462, ψ Na,Pb,NO3 = −0.0056). Phase diagrams predict better results. From the phase diagram, an isothermal evaporation process can be designed to separate NaNO 3 . By conservation calculations, the percentage of NaNO 3 recovered was 71.07%, where NaNO 3 solution can be used to produce KNO 3 products, and the solution after isothermal evaporation has a high Pb(NO 3 ) 2 content, which can be reused in the production of lead−chromium pigments.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Activity Coefficients, Phase Diagrams of the NaNO₃-Pb(NO₃)₂-H₂O System at 298.2 K, and Its Applications

Tan,

Sang,

Zhu

et al. 2024

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“…In known reports, the phase diagram of the ternary NH 4 Br–NaBr–H 2 O system at 298.15 K has only one invariant point and three crystallization regions . Sang et al reported the phase diagram of the ternary NaBr–Na 2 SO 4 –H 2 O system at 298.15 to 373.15 K and found that NaBr existed in the form of NaBr·2H 2 O at 298.15 to 323.15 K. When the temperature was between 348.15 and 373.15 K, NaBr·2H 2 O is converted to NaBr. − Rivett and Zhang et al measured the phase equilibrium data of the quaternary Na 2 SO 4 –NaCl–(NH 4 ) 2 SO 4 –NH 4 Cl–H 2 O system at 273.15 to 373.15 K and found that the double salt appeared at 273.15 to 323.15 K, and the crystallization region of the double salt disappeared at 333.15 K. The ternary subsystems of this quaternary system (Na + , NH 4 + //SO 4 2– –H 2 O, Na + , NH 4 + //Br – –H 2 O, and Na + //Br – , SO 4 2– –H 2 O) have been reported at 298.15 and 323.15 K. ,,− There are no reports on the ternary NH 4 Br–(NH 4 ) 2 SO 4 –H 2 O system and the quaternary Na 2 SO 4 –NaBr–NH 4 Br–(NH 4 ) 2 SO 4 –H 2 O system. In view of this, the phase equilibrium data of the quaternary Na 2 SO 4 –NaBr–NH 4 Br–(NH 4 ) 2 SO 4 –H 2 O system and its ternary NH 4 Br–(NH 4 ) 2 SO 4 –H 2 O system at 298.15 and 323.15 K were determined using the isothermal method.…”

Section: Introductionmentioning

confidence: 99%

Study on the Phase Equilibrium of the Quaternary Na₂SO₄–NaBr–NH₄Br–(NH₄)₂SO₄–H₂O System at 298.15 and 323.15 K

Xi,

Li,

Tian

et al. 2024

In order to provide a theoretical basis for the comprehensive utilization of bittern resources, the phase equilibrium data of the ternary NH 4 Br−(NH 4 ) 2 SO 4 −H 2 O system and quaternary Na 2 SO 4 −NaBr−NH 4 Br−(NH 4 ) 2 SO 4 −H 2 O system at 298.15 and 353.15 K were determined by the isothermal method, and the phase diagrams were depicted. It was found that the phase diagrams of the ternary systems at 298.15 and 323.15 K were similar, with one invariant point, two univariant curves, and three crystallization regions. The phase diagram of the quaternary system at 298.15 K included four invariant points, six crystallization regions, and nine invariant curves. At 323.15 K, the phase diagram of the quaternary system comprised three invariant points, five crystallization regions, and seven invariant curves. According to the Pitzer and HW models, the experimental values of the ternary system at 298.15 K were used to fit the ion interaction parameter ψ NHd 4 −SOd 4 −Br by the least-squares method. The solubility of the quaternary system at 298.15 K was calculated using the known Pitzer parameters and interaction parameters, and the calculated values were basically consistent with the experimental values.

“…Bromine compounds are widely used and can be used in medical and industrial fields, but industrial production remains relatively outdated, making it necessary to strengthen the comprehensive development and utilization of bromine resources in brine. Zhou et al had measured the activity coefficient of NaBr in NaBr–SrBr 2 –H 2 O at 298.15 K, Zhong et al had studied the activity of NaBr in a NaBr–Na 2 SO 4 –H 2 O mixed electrolyte solution at 298.15 K, and Zeng et al had reported the stable phase equilibria of the NaBr–Na 2 SO 4 –H 2 O ternary system at 273.2 and 308.2 K. There is no report about the activity coefficient of the NaBr–Na 2 SO 4 –H 2 O ternary system at low temperatures; hence, this work studies the activity coefficient of NaBr in the NaBr–Na 2 SO 4 –H 2 O ternary system at 278.2 and 288.2 K, and the activity coefficient of Na 2 SO 4 , the osmotic coefficient, water activity, and excess Gibbs free energy are obtained. This paper also investigates the phase equilibria of the NaBr–Na 2 SO 4 –H 2 O ternary system at 288.2 K and predicts the phase equilibria of the NaBr–Na 2 SO 4 –H 2 O ternary system at 278.2 and 288.2 K.…”

Section: Introductionmentioning

confidence: 99%

Mean Activity Coefficients and Phase Equilibria of the NaBr–Na₂SO₄–H₂O Ternary System at 278.2 and 288.2 K

Feng,

Sang,

Song

et al. 2024

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In this paper, the cell potential method is used to determine the activity coefficients of the NaBr−Na 2 SO 4 −H 2 O ternary system at 278.2 and 288.2 K. The cell potentials of NaBr− H 2 O solutions are measured using a cell without a liquid junction composed of ion-selective electrodes. According to the measured cell potentials of NaBr-H 2 O solutions, the response curve can be obtained by combining the Nernst equation. The measured cell potentials of NaBr−Na 2 SO 4 −H 2 O mixed solutions are combined with the Nernst equation to determine the activity coefficients, and the mixed ion interaction parameters θ Br,SOd 4 and ψ Na,Br,SOd 4 of the Pitzer model are obtained by applying the activity coefficients and the programming solver. Then, other thermodynamic parameters are calculated using Pitzer equations, such as the activity coefficient of Na 2 SO 4 (γ Nad 2 SOd 4 ), the osmotic coefficient ( ), water activity (a w ), and excess Gibbs free energy (G E ). In addition, the phase equilibria of the NaBr−Na 2 SO 4 −H 2 O ternary system at 288.2 K were investigated using the isothermal dissolution equilibrium method, and phase equilibrium predictions were made for the NaBr− Na 2 SO 4 −H 2 O ternary system at 278.2 and 288.2 K. The experimental values of the system at 288.2 K are in good accordance with the predictions, and therefore, the fitted parameters have good applicability.