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+> + CN<1-> = »Fe-OH2-CN logK = 2.8(2.4)) »Fe-OH + H<1+> = »Fe-OH2<1+> -pK1 = logK = 6.8 sum »Fe-OH+CN<1->+H<1+> = »Fe-OH2-CN logK = 2.8(2.4)) + 6.8 = 9.6(9.2)