ION EXCHANGE Update 16 Oct 2012

Approximate selectivity scales
SBA resins

Data only typical, i.e. approximate, but relative order should be right.

The values may vary according to porosity of resin (primary and secondary cross-linking). For instance, the chloride selectivity value varies from about 15 to more than 30 for different SBA type 1 resins.

Conventional SBA resins
SBA resin Type 1 Type 2
Amberlite example IRA402 IRA410
Ion Selectivity
HSiO3 < 1.0 < 1.0
OH (reference) 1.0 1.0
F 1.6 0.3
CH3COO 3.2 0.5
HCOO 4.6 0.5
IO3 5.5 0.5
HCO3 6.0 1.2
Cl 22 2.3
NO2 24 3
BrO3 27 3
HSO3 27 3
CN 28 3
HSO4 35 9
Br 50 6
NO3 65 8
ClO3 74 12
SO42– 150  
I 175 17
SeO42– 280  
ClO4 > 500  
CrO42– 1700  
C6H5SO3 > 500 75

For these resins, as shown above, the order of selectivity is:

SO4= > NO3 > Cl > HCO3 > OH > F

There is thus no practical way to remove only chloride from water without removing other anions as well.


Nitrate selective resin
Ion Amberlite PWA5
Cl 1.0
NO3 5.8
ClO4 440
HCO3 0.21
SO42– 0.019

With such a product, you can remove nitrate with the resin in the chloride form.

From an unknown source: selectivity scale of a SBA resin at pH 9 to 10:

V2O74– > UO2(CO3)34– > MoO42– > SO42– > CO32– > NO3 > Cl > HCO3

See also cation selectivity values.

© François de Dardel