Desorption of IO₃^- from IO₃^- sorbed ettringite and IO₃^- type synthesized ettringite

Abstract

  In order to understand the fixation mechanism of IO₃^- in ettringite, we studied the desorption behavior of IO₃^- from the IO₃^- sorbed ettringite and the IO₃^- type synthesized ettringite which was prepared by using IO₃^- instead of SO₄^2-. Desorption behavior of IO₃^- was discussed by using distilled water, KOH (pH10.6) solution, 20 mM-K₂SO₄+KOH (pH10.6) solution, 20 mM-K₂SO₃+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 IO₃^- was about 1 to 7 % of total amounts of IO₃^- sorbed in ettringite. Change in the lattice constants of ettringite-like structure was evaluated for the the IO₃^- sorbed ettringite when IO₃^- was desorbed by 0.4 M-K₂SO₄+KOH (pH10.6) solution for one day, and the good correlation between the lattice constant change and the desorption amount of IO₃^- was observed.