Adsorption of radioactive I2 gas onto atmospheric aerosol

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 increading initial I2 concentration ranging over 10-13 to 10-9 g/cm3 at a reaction time of 31 min but was almost constant at a reaction time of 2 min. 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 x 10-2 and 2.7, respectively. Almost all experimental data were within ranges of calculated results considering the geometric standard deviation of sticking probability. (author)