US EPA

7443679 

Journal Article 

Ion concentrations in the CO2-NH3-H2O system from C-13 NMR spectroscopy 

Holmes, PE; Naaz, M; Poling, BE 

1998 

Yes 

Industrial and Engineering Chemistry Research
ISSN: 0888-5885
EISSN: 1520-5045 

American Chemical Society 

37 

8 

3281-3287 

English 

10.1021/ie9707782 

WOS:000075213700046 

A method was developed to determine the concentrations of the ionic species present in the CO2-NH3-H2O system. The 13C NMR spectra of these solutions contain two peaks, one for the carbamate and one for the carbonate and bicarbonate. The method uses the area ratio and the position of the latter peak to determine concentrations. Ion concentrations were determined at 17 different concentrations for total NH3 and CO2 and at two different temperatures, 25 and 35 °C. All measurements were for solutions in which the total concentration of NH3 was greater than that of CO2. A comparison of three different thermodynamic models showed that although the models overpredicted the amount of carbonate, all were in reasonable agreement with experiment when the total ammonia concentration was less than 3 mol/L of solvent. At the higher concentrations, all the models badly underpredicted the amount of carbamate formed and overpredicted the amount of carbonate. © 1998 American Chemical Society. 

Ammonia; Carbon dioxide; Carbonates; Composition effects; Ions; Mathematical models; Nuclear magnetic resonance spectroscopy; Thermodynamic properties; Water; Carbamates; Mixtures