Share thisNot all chlorine dioxides are created equally. The use of pure chlorine dioxide gas successfully decontaminated an imaging laboratory — with the equipment in place.
In November 2008, an imaging laboratory was decontaminated using chlorine dioxide. The laboratory was filled with analytical and imaging equipment which is regularly used. After the decontamination, the analytical and imaging equipment in the laboratory worked just like before.
This was just another example of chlorine dioxide gas being used to decontaminate an area containing sensitive equipment. However, there still exists a stigma amongst many in the research field that chlorine dioxide is inherently corrosive. This impression is based on experience and fact, but it is still not necessarily true.Many people are familiar with some of the liquid chlorine dioxides on the market and have seen corrosion after using them, which is how their perceptions came about. Not all chlorine dioxides are created equally though, with pure chlorine dioxide much gentler than the corrosive liquid chlorine dioxide solutions which have been on the market for years. The use of pure chlorine dioxide gas is what made decontaminating the imaging laboratory a success.
Background Information
Chlorine dioxide is an oxidizer, as is hydrogen peroxide, ozone, and oxygen among many other agents. Oxidation/reduction potential is a measure of the tendency of a chemical species to gain electrons and oxidize other chemical species. A higher oxidation/reduction potential means that the species is more likely to gain electrons and is a stronger oxidizer. This gives a numerical value as to how corrosive the agent is.
Chlorine dioxide has an oxidation/reduction potential of 0.95V, which is lower than another commonly known decontaminating agent, hydrogen peroxide, as well as the lesser used agent, ozone. The reason that chlorine dioxide has a worse reputation concerning corrosion is due to byproducts created in the method of generation of some common liquid chlorine dioxide solutions that have been used for many years.
Generation Method
The generation method of chlorine dioxide is where the difference in corrosiveness can be found. There are many different methods of generation for chlorine dioxide. Many of the liquid methods are created by mixing an acid and a base which then forms an acidified chlorine dioxide solution. A common generation method for liquid chlorine dioxide is:
mixture of base + water + activator = acidified sodium chlorite + chlorous acid + chlorine dioxide
The production of two acidic components, acidified sodium chlorite and chlorous acid, is where the corrosive properties come from. The pH of these solutions is typically around 3. This liquid is then fogged or sprayed throughout the room, and onto sensitive materials. Some institutions perform a follow up water rinse upon completion of the decontamination when using liquid chlorine dioxide. This follow up rinse does remove leftover corrosive materials from easy to reach places. This lessens the impact that the corrosive solution would have as it is removed from staying in contact with surfaces for a long period of time. However, it does not eliminate the risk of corrosion completely, as the acidic solution did contact materials during the decontamination itself. It also does not remove any acidic solution from unreachable areas, such as behind grills and inside of electronics.