sodium sulfate

It can form heptahydrate and decahydrate forms; the heptahydrate (Na2SO4·7H2O) is a white orthorhombic crystal. It turns into an anhydrous form when heated to 24.4°C. Sodium sulfate is reduced to sodium sulfide when it reacts with carbon at high temperatures. 　Sodium sulfate decahydrate is also known as mirabilite; its chemical formula is Na2SO4·10H2O. It is also called Glauber’s salt. It belongs to the monoclinic crystal system and usually appears in granular or massive forms, though it can also be found in crusty or coated forms. Colorless and transparent; impurities cause it to turn gray, gray-green, light yellow, milky white, black, etc. Glassy luster. Streak is white. Hardness 1.5–2.0. Specific gravity 1.48. It has a slightly bitter and salty taste. It loses its crystalline water at 100°C. It gradually loses water in dry air to turn into white powdery anhydrous mirabilite, and its flame turns dark yellow when burned. Soluble in water and glycerin, but insoluble in ethanol. Temperature range: Crystalline state – 0–32.38 °C: crystallizes as Na2SO4·10H2O; 32.38–241 °C: crystallizes as Na2SO4 (rhombic); above 241 °C: crystallizes as Na2SO4 (monoclinic)

Does sodium sulfate crystallize in every temperature range? ? ?

I’m confused by your question. Normally, in the case of a sodium sulfate solution, at the aforementioned temperature, crystals will form as long as the solution reaches saturation.

Oh, does it crystallize only at saturation, or does it crystallize at low temperatures as well? ? ?

Sodium sulfate can be concentrated, crystallized, separated, and dried, right?

Flash crystallization, with low energy consumption, is the basis for the current approach of nitrate removal in a single step.

A fairly clear answer has already been given for the second floor. Crystallization occurs whenever a solution reaches saturation, but at different temperatures, the crystal water contained in the crystals or their crystal structure varies. Take another look in detail at the relevant parameters found on the second floor.

Sodium sulfate is also known as Glauber’s salt, anhydrous mirabilite, or anhydrous natron. Small crystals or powder in the white monoclinic crystal system. Relative density is 2.68, and the melting point is 884°C. It is soluble in water, and its aqueous solution is neutral. Soluble in glycerol, insoluble in ethanol; when exposed to air, it readily absorbs moisture to form aqueous sodium sulfate. It is a homopolycrystalline substance according to Chemicalbook; it exists in a rhombic structure at temperatures between 32.4 and 223°C, while at higher temperatures it forms monoclinic crystals, and at 241°C it transforms into hexagonal crystals. When crystallized from a solution, it shows affinity for iron, iron compounds, and various organic substances; high-purity, fine-grained anhydrous sodium sulfate is known as Glauber’s salt.