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-> + Tl<1+> = »Fe-O-Tl logK = 5.3 (5.0) »Fe-OH = »Fe-O<1-> + H<1+> pK2 = -logK = 12.3 sum »Fe-OH + Tl<1+> = »Fe-O-Tl + H<1+> logK=5.3(5.0)-12.3 = -7.0(-7.3)