Experimental Study of Mass Transfer of Iodine Vapor from Air in Sodium Hydroxide Solution in a Packed Column

Caustic scrubbing is the normally adopted method to absorb radio iodine from the off-gas of nuclear recycle facilities and radioisotope separation facilities. An experimental study was conducted in a lab-scale packed scrubber to find the mass transfer coefficient of iodine from air into sodium hydroxide (NaOH) solution under different gas and liquid flow rates and also in the presence of NOx gases. It was found that the overall mass transfer coefficient in a packed column is a strong function of the gas-phase Reynolds number and flow rate (ReG0.91 to ReG1.15) and is almost entirely controlled by gas-phase resistance. A removal factor in the range of 32–190 was obtained for iodine in the experimental scrubber under different operating conditions and can be scaled appropriately for industrial standards to get similar results. The effect of NOx up to 5000 ppm in air on the mass transfer coefficient of iodine was found to be negligible.