4. METHOD OF SOLUTION
The program draws information from a thermodynamic data base consisting of solubility products and complex formation constants for all known species, and standard electrode potentials, at 25 C, corrected for ionic strength effects. By minimising the free energy of the system through a series of iterations, a precipitating solid phase is predicted which limits the solubility, and the concentration of the main aqueous species are calculated as a function of pH.
Initially the program evaluates only hydroxide and carbonate species, but the effect of sulphate, phosphate and fluoride anions can also be included.
The program is simple to use, requiring inputs of:
2. pH range
3. Ionic strength
4. Redox conditions
5. Ligand concentrations
Functions are included to calculate the distribution of the protonated and unprotonated forms of carbonate and phosphate and the value of Eh as a function of pH under disposal conditions as required.
The program can further evaluate the role of free calcium ions.