Effect of Temperature on HTO-Dissociation Determined by Ion Exchange Resins

Abstract

In order to reveal the effect of temperature on (i) the dissociation equilibrium of tritiated water (HTO water) and (ii) the reactivity of each anion-exchange resin, the OT-for-OH exchange reaction between each anion-exchange resin and HTO water was studied within the range of 20°C to 80°C in the equilibrium state. In addition, the apparent dissociation constant (pK′) for each resin was estimated by the method of pH-titration. From the observation of the OT-for-OH exchange reaction between each of the following anion-exchange resins and HTO water, the next three items have been found: (1) in the case of acryl-type anion-exchange resin, the effect of temperature on OT-for-OH exchange reaction is larger than that on the reaction in the case of styrene-type one; (2) the radioactivity incorporated into weakly basic anion-exchange resin (OH^--form) by the isotope exchange reaction is smaller than that into strongly basic one; (3) in the case of the weak-ly basic anion-exchange resin, the amount of radioactivity incorporated into Cl^--form resin by the hydrolysis is larger than the amount of radioactivity incorporated into OH^--form resin by the isotope exchange reaction.