Zelinsky S. The pressure and temperature influence on thermodynamically properties in glycerol-water solution

The thesis concerns the research of thermodynamic properties and their connection with structure of water, glycerol and glycerol-water solutions in wide range of temperature and pressure. We make next steps for decision of this task: The density of glycerol-water solutions containing from 0.22 to 0.55 mole fraction of glycerol were measured by using the picnometer method in the range of temperature from 293 K to 357K along of the coexistence curve. The same measurements were carried out for double distilled water and single-component glycerol. The P-V-T data of water rich solutions has been made by the bellow method in the wide temperature range (from 293К to 375К) and pressure range (from 0.1 MPa to 103 MPa). We obtain the value of modulus of elasticity, isobaric coefficient of thermal expansion, the increments of the entropy, Gibbs energy, whole inner energy and enthalpy by numerical differentiation and integration in the investigation range of temperature and pressure. We carried out the molecular dynamic simulation on liquid water, liquid glycerol and glycerol-water solution with concentration of 0.27 mole fraction of glycerol at temperature Т=300К and Т=354К and pressure 0.1MPa and 100MPa. The result shows that the jump of density exists on the coexistence curve. The position of this jump located at 0.33 mole fraction of glycerol. The position of the density jump is the same for all investigated temperatures. This behavior we explain by integration of two molecules of water into molecule of glycerol. We observed the maximum of modulus of elasticity from temperature if concentration of glycerol in glycerol-water solution is less that 0.33 mole fraction of glycerol at 320K. Also we have found the singularity of isobaric coefficient of thermal expansion in this range of concentration. It was found that in water rich solutions below the boundary concentration (0.33 mole fraction of glycerol) the behaviors of modulus of elasticity and isobaric coefficient of thermal expansion are determinate only by structural singularity of water. This boundary concentration decrease if increase pressure. The number of hydrogen bonds, value of hydrogen bond angles and pair atom-atom correlation functions was determined in water, glycerol and 0.27mole fraction of glycerol by method of MD simulation. It was demonstrated that when pressure and concentration of glycerol are increasing then the number of hydrogen bond and value of hydrogen bonds angles are decreasing and that the network of hydrogen bond are destroyed in water. But this behavior didn’t common for all hydrogen bonding liquids, because when pressure increase the number of hydrogen bond in glycerol is increasing. The Tait equation of state is applicable to describe the P-V-T data of our solution. This equation describes a behavior of modulus of elasticity and isobaric coefficient of thermal expansion completely.