Table 5. The extent of divalent cation substitution into the first layer of calcite and the resulting contact angle change (using Eqs 7 and 8), assuming an initial contact angle of 120°.
| Ion | % substituted ions first layer CO2 [10−3.5 to 1 bar] | Δθ (°) CO2 [10−3.5 bar] | % substituted ions first layer CO2 [10−2 bar] and H2S [10−3.5 bar] | Δθ (°) CO2 [10−2 bar] and H2S [10−3.5 bar] |
|---|---|---|---|---|
| Mg2+ | 2 | −6 | 2 | −6 |
| Mn2+ | 25 | −38 | 25 | −38 |
| Fe2+ | 25 | −47 | 12 | −24 |
| Co2+ | 25 | −10 | 0 | 0 |
| Ni2+ | 25 | −68 | 0 | 0 |
| Cu2+ | 25 | −55 | 0 | 0 |
| Zn2+ | 25 | −70 | 0 | 0 |
The pH in the simulations was 7.5 (Fig. 4b). More than 25% sorption might occur for Mn, Fe, Co, Ni and Zn but our DFT set up capped substitution at 1 of the 4 available cation surface sites.