High-pressure phase equilibrium aqueous solutions

Previous work in the area of high-pressure phase equilibrium of aqueous solutions of organic compounds with supercritical fluids... 

High-pressure phase equilibrium (HPPE) data of aqueous polymer solutions... 

HIGH-PRESSURE PHASE EQUILIBRIUM (HPPE) DATA OF AQUEOUS POLYMER SOLUTIONS... 

The Supplement will be divided again into the seven chapters as used before in the former Handbook. (1) Introduction, (2) Vapor-Liqitid Equilibrium (VLE) Data of Aqueous Polymer Solutions, (3) Liquid-Liquid Eqitilibriitm (LLE) Data of Aqueous Polymer Solutions, (4) High-Pressure Phase Equilibrium (HPPE) Data of Aqueous Polymer Solutions, (5) Enthalpy Changes for Aqueous Polymer Solutions, (6) PVT Data of Polymers and Aqueous Polymer Solutions, and (7) Second Virial Coefficients (A2) of Aqueous Polymer Solutions. Finally, appendices quickly route the user to the desired data sets. 

Experimental results are presented for high pressure phase equilibria in the binary systems carbon dioxide - acetone and carbon dioxide - ethanol and the ternary system carbon dioxide - acetone - water at 313 and 333 K and pressures between 20 and 150 bar. A high pressure optical cell with external recirculation and sampling of all phases was used for the experimental measurements. The ternary system exhibits an extensive three-phase equilibrium region with an upper and lower critical solution pressure at both temperatures. A modified cubic equation of a state with a non-quadratic mixing rule was successfully used to model the experimental data. The phase equilibrium behavior of the system is favorable for extraction of acetone from dilute aqueous solutions using supercritical carbon dioxide. 

The system carbon dioxide - acetone - water was investigated at 313 and 333 K. The system demonstrates several of the general characteristics of phase equilibrium behavior for ternary aqueous systems with a supercritical fluid. These include an extensive LLV region that appears at relatively low pressures. Carbon dioxide exhibits a high selectivity for acetone over water and can be used to extract acetone from dilute aqueous solutions. 

The law of mass action is widely applicable. It correctly describes the equilibrium behavior of all chemical reaction systems whether they occur in solution or in the gas phase. Although, as we will see later, corrections for nonideal behavior must be applied in certain cases, such as for concentrated aqueous solutions and for gases at high pressures, the law of mass action provides a remarkably accurate description of all types of chemical equilibria. For example, consider again the ammonia synthesis reaction. At 500°C the value of K for this reaction is 6.0 X 10 2 F2/mol2. Whenever N2, H2, and NH3 are mixed together at this temperature, the system will always come to an equilibrium position such that... 

This section considers the Donnan equilibrium which is established by the equilibrium distribution of a simple electrolyte between an aqueous protein-electrolyte mixture and an aqueous solution of the same simple electrolyte, when the two phases are separated by a semipermeable membrane. A difference in osmotic pressure is estabhshed across the membrane permeable to all other species but proteins. This difference is measurable and provides important information about the protein-protein interaction in solution [37, 109-112, 116]. The principal goal of the theory is to explain how factors such as protein concentration, pH, protein aggregation, salt concentration and its composition, influence the osmotic pressure. At the moment this goal seems to be too ambitious these systems are often complicated mixtures of highly concentrated electrolytes and protein molecules, and the principal forces are not easy to identify [117]. 

Carbonated drinks are bottled under high CO2 pressure, permitting the gas to dissolve into aqueous solution. When the bottle is opened, the partial pressure of CO2 in the gas phase rapidly decreases to the value in the atmosphere, and the gas bubbles out of solution. When the bottle is closed again, CO2 gas pressure builds until a saturated solution at equilibrium is again obtained. The solubility of gases in a liquid also increases in the bloodstream of deep-sea divers when they experience high pressures. 

U.v.-Visible Absorption Spectroscopy.—A review of currently available u.v.-visible spectrophotometers and accessories has been compiled by Tayler, Several sample cells have been reported allowing absorption spectra to be recorded under non-ambient sample conditions. A high-temperature cell, designed for a Cary model 15 spectrophotometer, has been employed in an investigation of the octahedral-tetrahedral equilibrium in aqueous solutions of cobalt(ii) compounds. A cell for a double-beam instrument (Beckman Acta M-VII) enabled studies of aqueous systems with temperatures up to 325 °C at maximum pressures of 12 MPa.Sample pressure and temperature variation was also possible in a study of volatile uranyl complexes in the gas phase using a home-built spectrophotometer. ... 

There are about 850 newly published referenees containing about 150 new vapor-liquid equilibrium data sets and some new tables containing classical Henry s coefficients, about 600 new liquid-liquid equilibrium data sets and some new high-pressure fluid phase equilibrium data, 10 new enthalpic data sets, 20 new data sets describing PVT-properties of polymers, and 120 new data sets with densities or excess volumes. There are also new results on second osmotic virial coefficients of about 45 polymers in aqueous solution. So, in comparison to the original handbook, the new supplementary volume contains even a larger amoimt of data and will be a useful as well as necessary completion of the origirral handbook. 

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