calculation from literature values with standard SSA and SSD at ionic strength of 1M, log K for pHzpc 8.4-8.6 in brackets for pHzpc 9-9.5 »Fe-OH2<1+> + I<1-> = »Fe-OH2-I logK = 3.6(2.9) »Fe-OH + H<1+> = »Fe-OH2<1+> -pK1 = logK = 6.8 sum »Fe-OH + I<1->+ H<1+> = »Fe-OH2-I logK= 3.6(2.9)+6.8 = 10.4(9.7)