1. Two-layer datasets

2. File → New → Sorbing Surfaces → two-layer
Enter a unique identifier for the sorbing surface.
You can optionally set a constant potential or capacitance for your surface.
Aqueous species are drawn from a thermo dataset to create surface reactions

3. Uncomplexed, uncharged strongly sorbing site Right click → add
Two-layer datasets must have one or more sorbing sites – the Basis species
Uncomplexed, uncharged strongly sorbing site
Right click → add
Compose new Basis species >(s)FeOH from elements.

4. Add surface protonation, deprotonation, and complexation reactions.
Deprotonated strong sorbing site.
Right click → add
Equilibrium constant for deprotonation reaction.
Supply reaction coefficients
Add uncomplexed sites and aqueous species to construct a surface complex.

5. Fe(OH)3(ppd) selected from list of minerals in thermo dataset.
Associate surface sites with minerals from a thermo dataset and set their site density.
Fe(OH)3(ppd) selected from list of minerals in thermo dataset.
Asp
Right click → add
Each sorbing mineral can contain one or more of the sorbing sites (the surface basis species).