Influence of dissolved carbon dioxide on the sound velocity and adiabatic compressibility in aqueous solutions with saccharose and ethanol

Alcoholic fermentation fluids are containing various sugars, ethanol and carbon dioxide in aqueous solution. Precondition for the concentration determination with ultrasound based methods is a calibration model describing the dependency of typical ultrasound parameters like the sound velocity from the concentration of the dissolved components and the temperature. For this reason, the sound velocity c in aqueous solutions with CO2, CO2+saccharose, CO2+ethanol and CO2+saccharose+ethanol in dependence of the temperature in a range of 2°C up to 30°C and constant CO2-pressures of 2.01∙105Pa and 3.01∙105Pa was measured and compared with the data in equivalent solutions without a carbon dioxide fraction. Carbon dioxide induces, like the components saccharose and ethanol, an increase Δc of the sound velocity. The density ρ of the investigated fluids was calculated by the interpolation of literature data combined with several approximation approaches. The adiabatic compressibility κ, which can be determined from the relationship κ=1/(c2∙ρ), is decreased by all investigated solutes, showing a linear dependency from their mole fractions χ. Different values ∂κ/∂χ can be explained by the molecular structure of the investigated molecules. It could be shown, that the overall decrease ΔκSa+Et+CO2 of the compressibility induced by saccharose, ethanol and CO2 can be depicted as a sum ΔκSa+ΔκEt+ΔκCO2 of contributions generated in solutions containing only one of the three components. Regression functions ΔcSa+Et+CO2(χSa, χEt, χCO2, T), ΔκSa+Et+CO2(χSa, χEt, χCO2, T) have been calculated for the change of the sound velocity and compressibility respectively.     «

Alcoholic fermentation fluids are containing various sugars, ethanol and carbon dioxide in aqueous solution. Precondition for the concentration determination with ultrasound based methods is a calibration model describing the dependency of typical ultrasound parameters like the sound velocity from the concentration of the dissolved components and the temperature. For this reason, the sound velocity c in aqueous solutions with CO2, CO2+saccharose, CO2+ethanol and CO2+saccharose+ethanol in depende...     »