TITLE:
Separation and Recovery of Iodine from Aqueous Solution by Permeation and Chemical Desorption (PCD) Using a Silicone Rubber Membrane
AUTHORS:
Jun Sawai, Hitomi Tomizuka, Naoki Hatanaka, Tamotsu Minami, Mikio Kikuchi, Toshimitsu Ishii
KEYWORDS:
Membrane Separation; Permeation and Chemical Desorption (PCD) Method; Diffusion Coefficient; Membrane/Aqueous Distribution Coefficient; Polydimethylsiloxane
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.2 No.4,
November
1,
2012
ABSTRACT: New technologies for iodine separation and recovery are required to decrease environmental pollution and improve iodine production. Separation and recovery of iodine (I2) in aqueous solution was achieved using permeation and chemical desorption (PCD) with a silicone rubber membrane (SRM). The SRM separated an aqueous feed solution from an alkaline or reducing recovery solution such as a mixture of sodium hydrate and sodium sulfate. The I2 crossed the membrane from the aqueous feed solution into the recovery solution, where it was converted into iodide (I–). Iodide in the recovery solution did not return to the feed solution across the SRM. An acidic feed solution promoted a high recovery of iodine. The permeation process followed first-order kinetics, allowing the overall mass-transfer coefficient and parameters related to permeation of I2 through the SRM to be determined. Permeability of I2 increased with temperature, and the apparent activation energy (Ea) for penetration of I2 through the SRM was determined. The value of Ea for I2 was of the same order of magnitude as those for phenols and anilines. The large membrane/aqueous distribution coefficient for I2 indicated that I2 had a high affinity toward the SRM. These results indicate that the PCD method is effective and powerful for separation and recovery of iodine from aqueous solutions.