Chemistry of sulfate chloride perhydrates. Part 1. — Thermal decomposition of 4Na2SO4·NaCl·2H2O2 and the formation of Na2SO4(III)

Abstract

Thermal treatment of the perhydrate, 4Na₂SO₄NaCl2H₂O₂ , results in the evolution of H₂O₂ . Combined thermogravimetry (TG) and mass spectrometry (MS) confirms that at least a portion of the H₂O₂is released intact. TG, together with differential scanning calorimetry (DSC), suggests that the release of H₂O₂occurs in two stages. The isothermal decomposition of the perhydrate at 88 °C has been monitored by powder X-ray diffraction (PXRD), IR spectroscopy, available oxygen content (AVOX) and thermogravimetry. The resulting solid consists of an intimate mixture of Na₂SO₄(III) and NaCl. An explanation for the formation of this particular polymorphic form of Na₂SO₄ is proposed.