In order to understand the fixation mechanism of IO
3- in ettringite, we studied the desorption behavior of IO
3- from the IO
3- sorbed ettringite and the IO
3- type synthesized ettringite which was prepared by using IO
3- instead of SO
42-. Desorption behavior of IO
3- was discussed by using distilled water, KOH (pH10.6) solution, 20 mM-K
2SO
4+KOH (pH10.6) solution, 20 mM-K
2SO
3+KOH (pH10.6) solution, and ettringite equilibrium solution, and it was found that the ettringite-like structure was preserved during the desorption reactions and that desorption fractionation of IO
3- was about 1 to 7 % of total amounts of IO
3- sorbed in ettringite. Change in the lattice constants of ettringite-like structure was evaluated for the the IO
3- sorbed ettringite when IO
3- was desorbed by 0.4 M-K
2SO
4+KOH (pH10.6) solution for one day, and the good correlation between the lattice constant change and the desorption amount of IO
3- was observed.
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