Separation and Recovery of Iodine from Aqueous Solution by Permeation and Chemical Desorption (PCD) Using a Silicone Rubber Membrane

Abstract

New technologies for iodine separation and recovery are required to decrease environmental pollution and improve iodine production. Separation and recovery of iodine (I 2 ) 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 I 2 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 I 2 through the SRM to be determined. Permeability of I 2 increased with temperature, and the apparent activation energy (E a ) for penetration of I 2 through the SRM was determined. The value of E a for I 2 was of the same order of magnitude as those for phenols and anilines. The large membrane/aqueous distribution coefficient for I 2 indicated that I 2 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.

Denitrification Combined with Diazotization of Anilines and the Synthesis of 4′-Chlorobiphenyl-2,5-diamine and 1-Chloro-4-iodobenzene

“…In all reactions (entries 1–5), chlorobenzene resulting from hydrogen abstraction by the aryl radical could be identified as the only side-product . The conversion of 2a into the iodide 5 is particularly valuable due to its metal-free nature, the possibility to recycle the excess iodide from the reaction mixture, and the manifold options to employ aryl iodides in transition metal-catalyzed coupling reactions…”

Antibacterial Properties of Silicone Membranes after a Simple Two-Step Immersion Process in Iodine and Silver Nitrate Solutions

“…Although these methods could produce effective antimicrobial-finished silicone materials, they required high energy, long reaction times, or complicated preparation steps. Iodine molecules can accumulate at high concentrations in silicone membranes according to studies on the separation of iodine using these membranes Sawai et al, 2012a. Nakamura et al 2011 prepared iodinereleasing silicone membranes using an adsorption process, which produced membranes with high antibacterial activity.…”