Effects of temperature and solution composition on evaporation of iodine as a part of estimating volatility of iodine under gamma irradiation

As a part of evaluating the volatility of iodide ions subjected to gamma irradiation, $I_2$ evaporation experiments were performed with $I_2$ and $I^-$ mixed solutions in the temperature range $26-80^{\circ}C$ in an open, well-ventilated space. The evaporation of $I_2$ was observed to follow primarily first order kinetics, depending on the $I_2$ concentration. The evaporation rate constant increased rapidly with increase in temperature. The presence of $I^-$ slightly reduced the evaporation rate of $I_2$ by forming relatively stable $I_3^-$. The effect of $Cl^-$ at <1.0 wt% on $I_2$ evaporation was insignificant. The evaporation rate constants of $I_2$ were $1.3{\times}10^{-3}min^{-1}\;cm^{-2}$, $2.4{\times}10^{-2}min^{-1}\;cm^{-2}$, and $8.6{\times}10^{-2}min^{-1}\;cm^{-2}$, at $26^{\circ}C$, $50^{\circ}C$, and $80^{\circ}C$, respectively.