Activity and osmotic coefficients in electrolyte solutions at elevated temperatures

✍ Scribed by Alexander Apelblat

• Publisher: American Institute of Chemical Engineers
• Year: 1993
• Tongue: English
• Weight: 563 KB
• Volume: 39
• Category: Article
• ISSN: 0001-1541
• DOI: 10.1002/aic.690390523

✦ Synopsis

In this article, a numerical procedure is proposed for prediction of activity and osmotic coefficients at elevated temperatures based on the vapor pressure lowering of electrolyte splutions available at room and intermediate temperatures.

The vapor pressure lowering of electrolyte solutions can be correlated over a wide temperature range by equation, In AP=A+B/T+C(ln T-T/2TC), where A, B and C are adjustable parameters and T, is the critical temperature of pure water. The procedure is illustrated in the cases of KCI, CaCl, and especially LiCl solutions. An analytical expression for osmotic coefficients in the Meissner approach is derived by an integration of the Bjerrum equation.

Thermodynamic properties of aqueous solutions of strong electrolytes at high temperatures are of considerable importance in many areas of chemical industry, in geochemistry, in desalination and steam power generation. However, with few exceptions, the available experimental data are confined to temperatures which are not far from room temperatures. In recent years, our knowledge about activity and osmotic coefficients comes mainly from isopiestic measurements performed at elevated temperatures by the Holmes and Mesmer group. Unfortunately, these measurements constitute only a small part