Phase Equilibrium for the Ternary System NaH2PO4 + Na2SO4 + H2O in Aqueous Solution at 298.15 K

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• 作者：Xi-Zhou Chen ; Jian-Hua Tang ; Ya-Nan Cui ; Mei Liu ; Dun Mao
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2014
• 出版时间：February 13, 2014
• 年：2014
• 卷：59
• 期：2
• 页码：481-484
• 全文大小：197K
• ISSN：1520-5134

文摘

The ternary system (NaH₂PO₄ + Na₂SO₄ + H₂O) at 298.15 K was investigated by using an isothermal solution saturation method. The solubilities and densities of the solution were determined. According to the experimental results, the phase diagram and the diagram of densities versus composition were plotted. The phases of the equilibrium solids were analyzed by X-ray diffraction (XRD), and crystalline regions of both solid phases were determined. It was found that there were two invariant points (NaH₂PO₄路2H₂O + Na₂SO₄; Na₂SO₄ + Na₂SO₄路10H₂O), three univariant curves, and three crystallization regions corresponding to sodium dihydrogen phosphate dihydrate (NaH₂PO₄路2H₂O), sodium sulfate (Na₂SO₄), and sodium dihydrogen phosphate decahydrate (Na₂SO₄路10H₂O; also known as Glauber鈥檚 salt) in this ternary system. The system belonged to a simple eutectic type, and neither double salts nor solid solutions were formed. This research provided missing information of the phase diagram in this ternary system, which in turn can provide fundamental data for industry and future study. These fundamental data could be useful for separation and crystallization processes in chemical industry.