Separation factor for counterion i with respect to ion j Separation factor for counterion i with respect to ion k The different separation factors for an ion with respect to the other are calculated with formula (2): (2) Relation (1) can be written regarding the selectivity of the resin for the different ions in our water sample: (1) The resin prefers much more ions with a high valence. So at equilibrium the ions do not occupy the same amount of resin.
The resin has different preferences for the ions in the water.
Separation factor for anion i exchanging with Cl - onto resin Table 6: Selectivity coefficient and separation factor for a strong base anionic resin AnionĮxplanation of the selectivity coefficient and separation factor notation: selectivity coefficient for anion i exchanging with Cl - onto resin In the Literature 1 you can find the following values for selectivity coefficients and separation factors (Table 6). The resin has a standard exchange capacity of 1,4 eq/L and a density of 0,7 kg/L. We want to eliminate anions from the water so we have to use an anionic resin. Table 5: Composition of the water used in this example Anion Lets take water with the following composition: Determine the percentile distribution of the occupied sites in the resin by the different ions.Determine the maximum amount of water that can be treated per liter of resin before breakthrough occurs.
Determine the equilibrium composition of the resin, thus calculating how much of the Exchange capacity is used by the different ions.Determine the separation factor for an ion with respect to the other ions in the water.The following points are treated in the example: There is an example under the calculation tables to show how the calculations are made by the calculator.Įxample calculation to illustrate the equations used by the calculator: But again be careful, the calculations are based on theoretical formulas and are not corrected with results from real ion exchange water treatment plants. The calculator also shows some calculations that are needed for the sizing of an ion exchange installation. This calculator is based on theoretical calculations and explains how to use selectivity coefficients, separation factors and how to determine the maximum volume of water that can be treated with a resin before breakthrough happens. › ► Purolite Ion Exchange Design Calculation Programs
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