Chlorine dioxide kills pathogens by a chemical process known as oxidation. It breaks down walls of microbes, effectively disintegrating them. Oxidized organic molecules cease to perform their functions and when the damage is widespread, death of the organism is inevitable. In contrast to chlorine, the oxidation occurs merely by electron transfer, chlorine dioxide does not 'halogenate' the molecules it oxidizes.
Resistant to resistance
Pathogenic (disease causing) microorganisms, like all living things, can evolve. They can develop mechanisms to overcome adverse conditions and survive. It is well-known how diseases caused by certain bacteria can no longer be treated with the same antibiotics that used to be so effective against them. This phenomenon is referred to as 'resistance', and such bacteria are called 'resistant'. The emergence of resistant strains of microbes is a major health concern.
Microorganisms do not have well-developed biochemical processes to deal with oxidizing agents. In other words, they are unable to produce effective reducing agents to prevent themselves from the damage that results from oxidative attack. This means, despite their ability to evolve, they cannot become resistant to chlorine dioxide, which is a powerful oxidizing agent. Chlorine dioxide, therefore, is resistant to microbial resistance.
Chlorine dioxide is very fast. While you may have to wait for at least an hour after application for other disinfectants to be fully effective, chlorine dioxide does its work in seconds to minutes. Here are several examples of our EPA-approved recommended instructions for chlorine dioxide use to illustrate this:
- Formula may be used to sanitize and disinfect non-food contact surfaces at a dilution ratio of 20 ppm and an exposure time of 5 minutes.
- Effective food contact surface sanitizer at an exposure time of 1 minute at a dilution of 5 ppm.
- This product may be used for 1 minute at a dilution of 5 ppm in food processing facilities in order to control spoilage microorganisms on raw agricultural commodities.
Chlorine dioxide is specific in what it will target and what it should not. Let's compare this with two other well-known disinfectants: chlorine and ozone. The problem with both of them is that they are just too reactive. In addition to harmful microorganisms, they will react with most of the organic matter they come in contact with. They will also react with ammonia present in water. The result is that they are used up fairly quickly and not much of them is left when bacteria begin to reestablish. Moreover, this undue reactivity leads to the formation of unnecessary and, often, unwanted by-products. Chlorine dioxide is more selective and much less reactive. It goes after the pathogens and leaves out other organic matter. This makes it more efficacious.
Effective at low concentrations
There are two aspects to this:
Low concentrations are effective
This is related to chlorine dioxide's powerful oxidizing action. Even low concentrations are enough to kill pathogenic bacteria and viruses. The short time it requires to destroy microbes is proof of its potency.
Lower amounts are required
This refers to its selective action. It isn't wasted in unwanted reactions with incidental organic matter. For example, an equivalent amount of another disinfectant such as chlorine will be much less effective as most of it would be lost in undue reactions, reducing the amount of available active disinfectant.
Effective at varied pH
To understand this, let's use chlorine for comparison. Chlorine reacts with water to form hydrochloric acid and hypochlorous acid. As pH rises, more of the hypochlorous acid converts into the hypochlorite ion which is a much weaker disinfectant. Therefore, chlorine loses its effectiveness with increasing pH levels (alkaline conditions). Chlorine dioxide does not react with water and remains a true gas in solution at different levels of pH. This means it is as effective at a lower to neutral pH as it is in an alkaline pH. In fact, it may be more effective at a higher pH. This property makes chlorine dioxide ideal for cooling towers with an alkaline pH or with no pH-control mechanisms in place.
This can be explained on the basis of chlorine dioxide's selective action, lower reactivity, and greater effectiveness at low concentrations. When chlorine dioxide is used for disinfection, it will not react with any organic molecules it isn't aimed at. This means more of it will remain available (the residual) to inhibit regrowth of bacterial colonies. Furthermore, even if it gets diluted or partially used up, any little amount left will adequately keep guard against regrowth because it is still highly effective at low concentrations. Another reason for its longer efficacy is that bacteria cannot develop resistance against it over time.
Chlorine dioxide is not known to cause corrosion when used at the recommended concentration levels. This is yet another beneficial characteristic which sets it apart from other disinfectants. This is especially applicable when disinfection of water is required that flows in metal pipes such as in cooling towers or potable water. It does not react with silica and phosphate which are present in potable water to inhibit corrosion. Chlorine dioxide disintegrates biofilms, which are a contributing factor to corrosion.
Chlorine dioxide ends up releasing oxygen and forming NaCl (salt) in water. These are harmless by-products. This is in stark contrast to chlorine which has been extensively documented to form trihalomethanes (THMs) such as chloroform, and halogenated organic compounds. It also reacts with ammonia and amines. THMs and halogenated hydrocarbons are not easily biodegradable and have been implicated in causing cancer, i.e., they are carcinogenic. These are the exact considerations which convinced the EPA in 1983 to recommend chlorine dioxide as the ideal disinfectant for potable water treatment, as it does not produce THMs and other harmful by-products.
This is based on at least two facts:
No harmful by-products
Chlorine dioxide does not produce harmful by-products such as THMs and halogenated hydrocarbons, which are possibly carcinogenic. Therefore, it does not pollute the environment.
Lower amounts are required
Due to its potent action as well as its long-lasting effects, considerably lower amounts of chlorine dioxide are needed, compared to other disinfectants, for the same level of disinfection requirements. This ensures minimal by-products and contributes to its status as an environment-friendly disinfectant.
PERFORMACIDE® is an EPA registered Disinfectant, Sanitizer, Tuberculocide, Virucide*, Fungicide, Algaecide, Slimicide, & Deodorizer. PERFORMACIDE® is registered for use on hard non-porous surfaces, with many applications, including hospitals, laboratories, veterinary hospitals, diagnostic centers, first-responder facilities and equipment.
Ounce for ounce, chlorine is cheaper but the question is: is it economical? When you bring pertinent facts into the equation you realize chlorine dioxide is far more economical. For instance, chlorine dioxide
- Is more potent so lower amounts are required for the same level of disinfection. Lower amounts mean lower costs.
- Has long-lasting action, so longer treatment cycles are possible which cut costs.
- Is environment friendly, hence no hidden costs to human health and the environment in the long run.