大気エアロゾルに対する放射性元素状ヨウ素ガスの吸着特性

抄録

Laboratory scale experiments on the adsorption of radioactive elemental iodine (I₂) gas onto atmospheric aerosol showed that the adsorption reached an equilibrium state in about twelve minutes at high initial I₂ concentrations. The proportion of iodine which was adsorbed on the aerosol gradually decreased with increasing initial I₂ concentration ranging over 10^-13 to 10^-9g/cm³ at a reaction time of 31min but was almost constant at a reaction time of 2min. A fraction of iodine desorbed from particulate iodine as mainly I₂ gas. An adsorption isotherm of atmospheric aerosol for I₂ gas was estimated from the experimental data of long reaction time and high I₂ concentrations. Using this adsorption isotherm, a theoretical equation, which was similar to our previous equation, was derived to explain the experimental results. A geometric mean and standard deviation of sticking probability in the equation were estimated to be 1.2×10^-2 and 2.7, respectively. Almost all experimental data were within ranges of calculated results considering the geometric standard deviation of sticking probability.