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ION_EXCHANGE_RXN

Specifies parameters for an ion exchange reaction.

Required Cards:

ION_EXCHANGE_RXN

Opens the block.

CEC <float>

Cation exchange capacity in (1) equivalents per volume of mineral [eq/m³_mineral] (if a MINERAL card is present) or (2) equivalents per bulk volume [eq/m³_bulk] (if a MINERAL card is not present)

CATIONS

Opens the CATIONS block for listing cations participating in the reaction.

<Cation species Name> <float> <REFERENCE for reference cation only>

Name of cation and associated selectivity coefficient. One must select a reference cation with a selectivity coefficient of 1 and convert all the selectivity coefficients to be relative to the reference species selectivity coefficient. The REFERENCE card must be appended to the reference cation (see examples).

Optional Cards

MINERAL <string>

Name of the mineral to which the cations sorb.

Examples

SORPTION
  ION_EXCHANGE_RXN
    MINERAL Halite
    CEC 750.  ! eq/m^3
    CATIONS
      Na+   1.  REFERENCE
      Ca++  0.2953
      Mg++  0.1666
    /
  /
END