Determination and analysis of solid–liquid equilibria for ternary systems Na2SO4–H2O2–H2O and Na2CO3–H2O2–H2O at 5 °C

To develop a better process for synthesizing sodium percarbonate and getting separation of the sodium salt, the equilibrium of the ternary system Na2SO4–H2O2–H2O and Na2CO3–H2O2–H2O at 5 °C was determined using the isothermal method, and the appropriate synthesis conditions for sodium carbonate from a theoretical perspective was discussed. The Na2SO4–H2O2–H2O system phase diagram contains one co-saturated point of Na2SO4·0.5H2O2·H2O and Na2SO4·10H2O. The Na2CO3–H2O2–H2O system phase diagram contains three crystal zones: Na2CO3·10H2O crystallization field, 0Na2CO3·1.5H2O2·H2O crystallization field and Na2CO3·2H2O2·H2O crystallization field. According to the phase diagram, the suitable raw material ratio of sodium percarbonate synthesis was obtained, to get the maximum of product yield, the optimal mass ratio of Na2CO3 to 30% H2O2 is 0.609.