Process for high concentration cation exchange metathesis

摘要

Provided is a method for high concentration cation exchange metathesis of divalent ions such as calcium with univalent ions such as sodium or potassium. Due to the difference between ionic valences between the exchanged ions, the provided process behavior is strongly dependent upon the selection of resin properties and to total solution normality. A combination of resin properties and solution normality is provided to achieve the cation exchange.

主权项

1. A method of resin evaluation, comprising:
(a) loading a known volume of water-washed divalent cation loaded resin with a known activity into a test column; (b) passing a solution with known concentration of univalent counter ion to be exchanged over the resin for an initial period of time; (c) repeating steps (a) and (b) for a different period of time than the initial period of time; (d) calculating the resin conversion X; (e) calculating a univalent counter ion tau value using the equations:t=τNa⁡(1-3⁢(1-X)23+2⁢(1-X))(Eq.⁢13)where⁢:⁢⁢τNa=KdCNa=ρCa⁢R26⁢bDe⁢CNa(Eq.⁢14) where t is the time it takes to achieve a given resin conversion X, in minutes; ρCa is the molar density of divalent cation loaded resin in meq/mL; R is the resin particle radius; De is the interparticle diffusion coefficient; and CNa is the concentration of univalent counter ion in the feed solution; (f) loading a known volume of water-washed univalent cation loaded resin with a known activity into a test column; (g) passing a solution with known concentration of divalent counter ion to be exchanged over the resin for an initial period of time; (h) repeating steps (f) and (g) for a different period of time than the initial period of time; (i) calculating the resin conversion X; (j) calculating a divalent counter ion tau value using the equations:t=τCa⁡(1-3⁢(1-X)23+2⁢(1-X)) where t is the time it takes to achieve a given resin conversion X, in minutes; ρNa is the molar density of univalent cation loaded resin in meq/mL; R is the resin particle radius; De is the interparticle diffusion coefficient; and CCa is the concentration of divalent counter ion in the feed solution; and (k) calculating a ratio τNa/τCa.