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-> + Rb<1+> = »Fe-O-Rb logK = 3.0 (2.7) »Fe-OH = »Fe-O<1-> + H<1+> pK2 = -logK = 12.3 sum »Fe-OH + Rb<1+> = »Fe-O-Rb + H<1+> logK=3.0(2.7)-12.3 = -9.3(-9.6)