equilibrium constants in this study refer to site-occupancy standard state with hypothtical 1.0 M ionic strength (K°) and values for N' = 10 * 10^18 m^-2 and A' = 10 m²/g using the equation: K = K°(Ns * As/N' * A'), where Ns represents the SSD = 8.0 sites/nm² from [HS73] and As the SSA = 100.0 m²/g from [HS73]; regression of proton surface charge data reported in [S05]; pH(ZPC): low ionic strength isoelectric point from [HS73]