Determination and Analysis of Solid–Liquid Equilibria for Quaternary System Na₂CO₃–Na₂SO₄– H₂O₂–H₂O at 5 °C

In order to develop a better process for synthesizing sodium percarbonate and getting separation of sodium salt, the equilibrium of the quaternary Na2SO4–Na2CO3–H2O2–H2O at 5 °C was determined using the isothermal method. Five types of solid phases such as Na2CO3·1.5H2O2·H2O were determined. Based on the phase diagram, the influence of sodium sulfate and hydrogen peroxide input on the yield of sodium percarbonate product was discussed when the sodium carbonate content in the sample red mud was constant. In order to get the maximum of product yield, the optimal mass ratio of H2O2 to Na2SO4 is 7.24–8.12. According to the dry salt diagram and water diagram, the amount of water added was analyzed when the content of sodium percarbonate product precipitated in the sample is the highest.