Ion exchange equilibria in a ternary system

Abstract

A study has been made of the cation exchange equilibria between Dowex 50W-X8 resin and aqueous solutions of copper nitrate, nitric acid, and sodium nitrate in binary and ternary mixtures. Experiments were carried out a t room temperature with solutions having total cation concentrations of approximately O.lN, 0.05N, and 0.01N. It was found that the equilibria for any two ions were essentially the same in binary and ternary mixtures. Moreover single valued selectivity coefficients were determined which characterize these data quite well for all three concentration levels. This mokes possible the complete description, for engineering purposes, of I more accessible binary exchange reactions, as ternary equilibria in terms of the simpler and previously suggested (7).One of the controlling factors governing the use of ion exchange separations is the equilibrium distribution of ions, between resin and solution phases, which can be achieved in any given system. For this reason ion exchange equilibria have been widely studied in recent years. [See for example Kitchener (2), Kunin ( 3 ) , or Nachod and Schubert ( 4 ) .] With but ii few exceptions however all of the previous work has dealt with exchanges in binary systems, that is those which contain only two exchanging species, or wjth multicomponent systems containing ions in only trace amounts.In view of the frequent occurrence oi' multicomponent ionic systems in practical situations it seems desirable to extend basic equilibrium studies to systems containing more than two ions. The recent work of Dranoff and Lapidus (1) and of Smith ( 5 ) with ternary cation systems represents a start in this direction. Both of these studies demonstrated the feasibility of representing ternary equilibrium data in terms of binary systems, but only with rather limited data. The present investigation was initiated in order to test this approach more thoroughly over a reasonable concentration range. It is hoped that this will serve as a reliable guide to the eventual treatment of more complex multicomponent exchange systems. THEORYThe theory of equilibrium in ion exchange reactions has been widely studied. It has been shown (2, 3 ) that in most cases the equilibria may be described in terms of either Donnan membrane equilibrium theory or standard mass action chemical equilibrium. When rigorously applied to include resin swelling and solution nonideality these two approaches lead to different equilibrium expressions ( 2 ) . Page 42perimental data adequately for engineering purposes. For this reason this type of approach was used for analysis of the present data.When a ternary system is considered, it is convenient to describe the exchange reactions and equilibria in terms of the various pairs of ions in the system (1). Thus tor the case of the H -Na+-Cut+ system, one may write the following reactions:H,' + Na,' e Hs+ + Nalt+ ( 4 a ) to resin swelling and hydration, they yield the same relationships.In particular for a binary reaction of the form ~H R ' C U~" + 2Hs+ + Curtt+ (4b) ( 4~) b...

Recovery of vanillin from Kraft lignin oxidation by ion-exchange with neutralization

“…In this reversible equilibrium, both the ion-exchanger and the solution contain both competing counterion species, Na + and H + . The reversible ion-exchange reaction between the liquid and resin phases resulting in an equilibrium constant K Na-H for the binary system [24]:…”

Prediction of multicomponent ion exchange equilibria for the ternary system SO‐NO‐Cl from data of binary systems

“…Pieroni and Dranoff (1963) report that the ternary system H+-Na+-CaZ+ may be treated in terms of the binaries, and that, effectively, the third component is ignored in the graphical presentation. This limitation is restrictive.…”

Correlation between data of adsorption from binary and multicomponent liquid mixtures on solid surfaces

“…Equation (6) has been introduced and tested experimentally by Dranoff and Lapidus (1957), and Pieroni and Dranoff (1963) who studied ternary ion exchange systems. However, the relationship (7) has been proved by Minka and Myers (1973).…”