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-> + Na<1+> = »Fe-O-Na logK = 3.2 (2.6) »Fe-OH = »Fe-O<1-> + H<1+> pK2 = -logK = 12.3 sum »Fe-OH + Na<1+> = »Fe-O-Na + H<1+> logK=3.2(2.6)-12.3 = -9.1(-9.7)