Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

The water - urea - ammonium sulfamate ternary system was investigated by means of experimental methods and thermodynamic modelling. Experimental part of the work includes (i) DSC measurements of liquidus and solidus of the urea - ammonium sulfamate, the water - ammonium sulfamate subsystems with the estimation of eutectic point position and a set of experiments on the phase boundaries in the ternary system; (ii) vapor pressure measurements in the binary water - ammonium sulfamate and ternary water - ammonium sulfamate - urea systems at 298.15 K in a wide concentration range. Excess Gibbs energies of the water - ammonium sulfamate - urea system and its binary subsystems were described by the Pitzer- Simonson-Clegg model which is reduced to polynomial formalism in case of nonelectrolyte systems. Results of the water - urea subsystem reassessment are given.