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-O<1-> + K<1+> = »Fe-O-K logK = 3.0 (2.6) »Fe-OH = »Fe-O<1-> + H<1+> pK2 = -logK = 12.3 sum »Fe-OH + K<1+> = »Fe-O-K + H<1+> logK=3.0(2.6)-12.3 = -9.3(-9.7)