Abstract
Some of the problems associated with the application of the existing thermodynamics of ion exchange for the description of ion adsorption on variable charge soils are discussed. A major problem is the difficulty in saturating the surface functional groups of variable charge materials with ions other than H+ or OH−, i.e., the difficulty in obtaining complete exchange isotherms. It was shown that this difficulty could be overcome by choosing appropreate standard states of exchanger phase components. A set of equations that relate the exchanger phase activity coefficients and thermodynamic equilibrium constant to the selectivity coefficient were derived based on a nonconventional asymmetric reference system. The terms related to adsorbed water activity that appear in the derived equations were found to be non-significant for some variable charge materials.
Original language | English |
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Pages (from-to) | 191-200 |
Number of pages | 10 |
Journal | Soil Science and Plant Nutrition |
Volume | 37 |
Issue number | 2 |
DOIs | |
Publication status | Published - Jun 1991 |
All Science Journal Classification (ASJC) codes
- Soil Science
- Plant Science