27.4.1 Separation Using Anion-SR

Good recovery of I_ (as 129I~) from the Anion-SR was observed in the 3 M NaOH solution, but only minor amounts of IO3~ (as 127IO3~) were recovered (Table 27.1). The percent recoveries did not appear to be dependent on the reductant because good recoveries of I_ and poor recoveries of IO3~ were observed regardless of the presence or absence of NaHSO3. This result supports the expectation that 129I~ is extracted and ‘IO3 is not extracted by the Anion-SR, as ‘IO3 was not reduced to 127I~ by NaHSO3 in 3 M NaOH solution, and the isotopic exchange reaction between 127IO3~ and 129I~ and reduction from 127IO3~ to 127I~ were negligible at least for 1 day. It is reported that 129I in seawater offshore of Fukushima is mainly 9I regardless of the presence of large amounts of natural ‘IO3 [8].

In the diluted HCl solution at pH 2, 129I and 127I were recovered in the presence of the reductant and were not recovered without the reductant (Table 27.1). Both the isotopes behaved similarly in this case despite the difference in the initial chemical species, I and IO3 . In contrast, the experiments using 1 ^g I in the

diluted HCl solution at pH 2 without the reductant and standing, higher recovery of 127I~, 72 ± 6 %, was obtained. Although the influence of the I_ amount on recovery cannot be wholly denied, it is possible that a considerable amount of 129I~ would
be changed to another chemical species in the diluted HCl solution in a day. In addition, the changed chemical species and IO3~ were reduced to I_ by the reductant in this experimental condition. Consequently, inorganic iodine species were analyzed at pH 2 with the reductant, and only I_ was analyzed in 3 M NaOH. It is possibly to apply speciation methods to analyze I_ and IO3~, depending on the solution conditions.