Vapor aqueous polyelectrolyte solutions

Experimental Data for the Vapor-Liquid Equilibrium of Aqueous Polyelectrolyte Solutions... 

FIGURE 10.1 Schematic representation of a membrane crystallization system a high concentrated stripping solution (usually an aqueous solution of polyelectrolyte salt) is used to induce the solvent to migrate—in vapor phase—from the retentate compartment (a solution of biomolecules). The progressive removal of solvent drives the retentate solution toward... 

MAU Maurer, G., Lammertz, S., and Schafer, L.N., Aqueous solutions of polyelectrolytes Vapor-hquid equilibrium and some related properties, Adv. Polym. Sci., 238, 67, 2011. 

Aqueous Solutions of Polyelectrolytes Vapor-Liquid Equilibrium... 

Abstract This chapter reviews the thermodynamic properties of aqueous solutions of polyelectrolytes, concentrating on properties that are related to phase equilibrium phenomena. The most essential phenomena as well as methods to describe such phenomena are discussed from an applied thermodynamics point of view. Therefore, the experimental findings concentrate on the vapor liquid phase equilibrium phenomena, and the thermodynamic models are restricted to expressions for the Gibbs energy of aqueous solutions of polyelectrolytes. 

Keywords Aqueous solutions Counterion condensation Excess Gibbs energy Osmotic coefficient Polyelectrolytes Salt effects Thermodynamics Vapor liquid equilibrium... 

Because polyelectrolytes are nonvolatile, the most important thermodynamic property for vapor + liquid phase equilibrium considerations is the vapor pressure of water above the aqueous solution. Instead of the vapor pressure, some directly related other properties are used, e.g., the activity of water a, the osmotic pressure 71, and the osmotic coefficient < . These properties are defined and discussed in Sect. 4. Membrane osmometry, vapor pressure osmometry, and isopiestic experiments are common methods for measuring the osmotic pressure and/or the osmotic coefficient. A few authors also reported experimental results for the activity coefficient y i of the counterions (usually determined using ion-selective electrodes) and for the freezing-point depression of water AT p. The activity coefficient is the ratio of activity to COTicentration ... 

Tables 3 6 give a survey of literature data for the vapor-liquid equilibrium of aqueous solutions of a single polyelectrolyte with various counterions. Abbreviations (shown in Table 2) are used to characterize the polyelectrolyte and the experimental procedures (MO membrane osmometry DMO differential membrane osmometry VO vapor pressure osmometry ISO isopiestic experiments EMF electromotive force measurements including also measurements with ion-selective electrodes as well as titration FPD freezing point depression GDM gel deswelling investigations). Table 3 gives a survey for aqueous solutions of poly(styrene sulfonic acid).

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