Investigation of the formation of wegscheiderite, Na2CO3· 3NaHCO3

Abstract

The reaction of sodium carbonate with water vapour and carbon dioxide has been studied in the temperature range 343–368 K in pure carbon dioxide, and at pressures of water vapour between 1 × 10⁴ and 5 × 10⁴ N m^–2. The products of reaction, sodium hydrogencarbonate and/or wegscheiderite, vary with temperature and pressure, and stability fields are presented. Reaction mechanisms for the formation of wegscheiderite are probably diffusion controlled but are complicated by side reactions. The rate of formation of wegscheiderite is very dependent on the partial pressure of water vapour: analysis of this dependence suggests that sodium carbonate monohydrate is the most likely intermediate.