adsorption isotherm data from [HMB76], ionic strength 0.002 and 0.02 M KCl, site protolysis reference [GS84] (average values from literature of various aluminium oxides); FITEQL/MICROQL; original equation: »Al-OH + H3PO4 = »Al-HPO4<1-> + H2O + H<1+> with log K = 2.56, formation constant in aqueous solution: PO4<3-> + 3H<1+> = H3PO4 logK = 21.702 [GFFGN03]