Here are more chemical facts associated with Chlorine Dioxide.
1. Chlorine dioxide (ClO2) is a synthetic, green-yellowish gas with a chlorine-like, irritating odor. Chlorine dioxide is a neutral chlorine compound. Chlorine dioxide is very different from elementary chlorine, both in its chemical structure as in its behavior. Chlorine dioxide is a small, volatile and very strong molecule. In diluted, watery solutions chlorine dioxide is a free radical. At high concentrations it reacts strongly with reducing agents. Chlorine dioxide is an unstable gas that dissociates into chlorine gas (Cl2), oxygen gas (O2) and heat. When chlorine dioxide is photo-oxidized by sunlight, it falls apart. The end-products of chlorine dioxide reactions are chloride (Cl-), chlorite (ClO-) and chlorate (ClO3-).
2. One of the most important qualities of chlorine dioxide is its high water solubility, especially in cold water. Chlorine dioxide does not hydrolyze when it enters water; it remains a dissolved gas in solution. Chlorine dioxide is approximately 10 times more soluble in water than chlorine. Chlorine dioxide can be removed by aeration or carbon dioxide.
3. As an oxidizer chlorine dioxide is very selective. It has this ability due to unique one-electron exchange mechanisms. Chlorine dioxide attacks the electron-rich centers of organic molecules. One electron is transferred and chlorine dioxide is reduced to chlorite (ClO2- ).
4. The following comparisons show what happens when chlorine dioxide reacts. First, chlorine dioxide takes up an electron and reduces to chlorite:
ClO2 + e- ® ClO2-
The chlorite ion is oxidized and becomes a chloride ion:
ClO2- + 4H+ + 4e- ® Cl- + 2H2O
5. Chlorine dioxide remains gaseous in solution. The chlorine dioxide molecule is powerful and has the ability to go through the entire system. Chlorine dioxide can penetrate the slime layers of bacteria, because chlorine dioxide easily dissolves, even in hydrocarbons and emulsions. Chlorine dioxide oxidizes the polysaccharide matrix that keeps the bio film together. During this reaction the chlorine dioxide is reduced to chlorite ions. These are divided up into pieces of bio film that remain steady. When the bio film starts to grow again, an acid environment is formed and the chlorite ions are transformed into chlorine dioxide. This chlorine dioxide removes the remaining bio film.
6. Chlorine dioxide is a powerful disinfectant for bacteria and viruses. The byproduct, chlorite (ClO2-), is a weak bactericidal agent. In water chlorine dioxide is active as a biocide for at least 48 hours, its activity probaly outranges that of chlorine.
Chlorine dioxide prevents the growth of bacteria in the drinking water distribution network. It is also active against the formation of bio film in the distribution network. Bio film is usually hard to defeat. It forms a protective layer over pathogenic microorganisms. Most disinfectants cannot reach those protected pathogens. However, chlorine dioxide removes bio films and kills pathogenic microorganisms. Chlorine dioxide also prevent bio film formation, because it remains active in the system for a long time.
7. The use of chlorine dioxide instead of chlorine prevents the formation of harmful halogenated disinfection byproducts, for example trihalomethanes and halogenated acidic acids. Chlorine dioxide does not react with ammonia nitrogen, amines or other oxidizable organic matter. Chlorine dioxide removes substances that can form trihalomethanes and improves coagulation. It does not oxidize bromide into bromine. When bromide containing water is treated with chlorine or ozone, bromide is oxidized into bromine and hypobromous acid. After that these react with organic material to form brominated disinfection byproducts, for example bromoform.
8. Chlorine dioxide and its disinfection byproducts chlorite and chlorate can create problems for dialysis patients.