Ion Exchange

File → New → Sorbing Surfaces → ion-exchange → Gaines-Thomas Aqueous species are drawn from a thermo dataset to create surface reactions You balance reactions on the exchanging cations. In the Gaines-Thomas convention, the activity of the sorbed ion is its equivalent fraction of the sorbing sites.

Basis… → Na + Choose a basis species from the list, typically an abundant monovalent cation. Right click → add TEdit automatically fills in all entries. Click Apply

Basis… → Ca ++ Choose basis or redox species to create exchange reactions. Right click → add Exchange reaction automatically written using Gaines-Thomas convention. TEdit automatically fills in all entries except the selectivity coefficient, which you supply.

File → New → Sorbing Surfaces → ion-exchange → Vanselow The Vanselow convention is like Gaines-Thomas, except that the sorbed ion activity is the molar fraction of the sorbing sites.

File → New → Sorbing Surfaces → ion-exchange → Gapon In the Gapon convention, you balance reactions on the sites rather than on the ions. The sorbed ion activities can be expressed as equivalents or molar fractions.

Basis… → Na + Right click → add TEdit automatically fills in all entries. Click Apply Choose a basis species from the list, typically an abundant monovalent cation.

Basis… → Ca ++ Choose basis or redox species to create exchange reactions. Right click → add Exchange reaction automatically written using Gapon convention. TEdit automatically fills in all entries except the selectivity coefficient, which you supply.