A model for the thermal regeneration of ion-exchange resins, Part I

1971 ◽  
Vol 24 (10) ◽  
pp. 1979 ◽  
Author(s):  
SD Hamann
Keyword(s):  
Ion Exchange ◽  
Weak Acid ◽  
Ion Exchange Resins ◽  
Equilibrium Conditions ◽  
Thermal Regeneration ◽  
Equilibrium Relationship ◽  
Acid And Base ◽  
Temperature And Pressure ◽  
Exchange Resins ◽  
Ionization Of Water

A theoretical model has been developed to describe the thermal regeneration of ion-exchange resins in the Sirotherm process1-10 for desalting water. It assumes that the thermal effect is primarily due to the large increase that occurs in the ionization of water when the temperature is raised. The hydrogen and hydroxyl ions compete with salt for exchange sites in the resins and for that reason water, itself, acts as a regenerating acid and base. ��� Calculations have been made of the equilibrium conditions, column behaviour, and titration behaviour of mixtures of weak-acid and weak-base resins with aqueous solutions of 1 : 1 and 2 : 2 electrolytes, assuming the systems to obey Donnan's equilibrium relationship. There is satisfactory agreement between the calculated and observed effects of both temperature and pressure.

A model for the thermal regeneration of ion-exchange resins, Part II

1971 ◽  
Vol 24 (12) ◽  
pp. 2439 ◽  
Author(s):  
SD Hamann
Keyword(s):  
Ion Exchange ◽  
Functional Groups ◽  
Ionization Constant ◽  
Ion Pairs ◽  
Ion Exchange Resins ◽  
Thermal Regeneration ◽  
Degree Of Ionization ◽  
Titration Curves ◽  
Two Factors ◽  
Exchange Resins

The model described in Part I1 has been extended to allow for two factors which may explain the abnormally flat titration curves of some amine ion-exchange resins. They are (a) the possible formation of ion pairs within a resin and (b) a possible increase in the ionization constant of the functional groups in a resin as its degree of ionization increases. It is suggested that the change (b) may occur if the di- electric constant of a resin is increased sufficiently by the absorption of ions and water as titration proceeds. ��� Calculations have been made of the influence of both effects on thermal regeneration equilibria.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

Sign in / Sign up

Export Citation Format

Share Document