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 = 12.5 sites/nm² from [JF86] and As the SSA = 20.6 m²/g from [JF86]; regression of proton charge data in the present study; low ionic strength isoelectric point from [JF86]