Transfer of iodine through graphite in aqueous iodide solutions

✍ Scribed by Paolo Silvestroni; Francesco Rallo

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 498 KB
• Volume: 28
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(83)87016-9

✦ Synopsis

A polycrystalline graphite diaphragm separating two aqueous KI solutions containing different amounts of I, is a bipolar electrode and (he whole system behaves like a short-circuited concentration cell in which the graphite diaphragm is the bipolar electrode and it acts in the meantime also as the separatory diaphragm. Transfer of iodine from the more. concentrated to the more diluted side of the diaphragm is accomplished by electrochemical reduction of I; to I _ on the side facing the concentrated solution and simultaneous oxidation of I-to I; on the other side. The overall transfer process results to be much faster than a simply diffusive phenomenon, because it is driven by electrical potentials and it is not simply related to the concentration gradient. The transfer rate seems to be mainly dependent from the electrical mobility of the positive ions in the solution contained in the graphite pores.