Formation of double salt hydrates I. Hydration of quenched Na2SO4CaSO4 phases

✍ Scribed by D. Freyer; St. Fischer; K. Köhnke; W. Voigt

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 402 KB
• Volume: 96
• Category: Article
• ISSN: 0167-2738
• DOI: 10.1016/s0167-2738(96)00612-1

✦ Synopsis

The formation of double salts in the system Na,SO,-CaSO,-H,O has been investigated by solid-gas reactions. The hydration processes of the quenched phases 2Na,SO,. CaSO, and (Na, ,Ca,,,),SO, have been monitored by thermogravimetry and X-ray diffraction in the presence of a definite water vapour pressure. Hydration of the metastable phase 2Na,SO,. CaSO, leads to the formation of glauberite and thenardite, preceded by an intermediate formation of the 'labile salt' (ZNa,SO, . CaSO, .2H,O). The second quenched phase, (Na,,,Ca,, ,),SO,, reacts to hydroglauberite (3Na,SO,. SCaSO, + 6H,O) and thenardite, [Na,SO, (V)].