Use of Iodine for Disinfection

IODINE weight of possesses the four the halogens highest atomic and is weight of the four halogens and is the least soluble in water (and the least hydrolyzed by water) ; it has the lowest oxidation potential, and reacts least readily with organic compounds. Although these somewhat negative characteristics might at first sight appear to be limiting factors with respect to iodine's use for the disinfection of water, just the reverse is the case. Taken collectively, the characteristics mean that low iodine residuals should be more stable and, therefore, persist longer in the presence of organic (or other oxidizable) material than corresponding residuals of any of the other halogens. The high chemical reactivity of chlorine and its ability to react with organic material by oxidation, by substitution, or by addition, constitutes perhaps the greatest drawback to its effectiveness for water disinfection. The ideal water disinfectant would be some material that is chemically weak and unable to participate in such reactions, but, at the same time, possessing bactericidal, cysticidal, and viricidal properties equal or superior to those of chlorine.