Frequently Asked Questions

What Are the Characteristics of Chlorine Dioxide?

Chlorine Dioxide is a small, power molecule consisting of 1 Chlorine atom and 2 oxygen atoms. Abbreviated to ClO2, chlorine dioxide exists as a free radical in dilute solutions • It has a molecular weight of 67.45.

  • It is a gas at normal temperatures and pressures.
  • It has a melting point of -59oC.
  • It has a boiling point of 11o C [230 F].
  • It is yellowish/green and has an odor similar to that of Chlorine.
  • It is denser than air and is water-soluble at standard temperatures and pressures up to 5000 ppm.
  • It can explosive in air at concentrations > 10% [100,000 ppm].
  • Because it is often prohibited from road and sea transport in its concentrated form and is normally generated at the point of the application using 2 precursor chemicals.
  • It will decompose in the presence of UV, high temperatures, and high alkalinity (>pH12).

What are the By-Products Produced by Chlorine Dioxide?

The DBPs of chlorine dioxide reactions are chlorite (ClO2-) and chlorate (ClO3-), and eventually chloride (Cl-). The fate of any disinfection by-products depends largely on the conditions at the time, such as concentration, temperature, and the presence of other molecules.

  • Unlike ozone (O3), chlorine dioxide does not oxidize bromide (Br-) ions into bromate ions (BrO3-). Additionally, chlorine dioxide does not produce large amounts of aldehydes, ketones, or other disinfection by-products that originate from the ozonization of organic substances.

Are SVS Aqua Technology Products the Same as Chlorine or Hypochlorite?

Although they have similar names and elements they are very dissimilar. The commonality of the name arises from the fact that they all contain the element chlorine, but their properties are quite different.

Chlorine and Hypochlorite are very powerful oxidizing agents but more importantly, their reaction with organic matter can lead to unacceptable concentrations of chlorinated organic compounds via substitution reactions. Some of these compounds such as the by-products of reactions with phenolic compounds are either odoriferous (such as 2, 6-dichlorophenol) or extremely carcinogenic like dioxin.

Chlorine Dioxide on the other hand is incapable of causing such chemical transformations. Chlorine Dioxide is non-mutagenic, non-carcinogenic, and relatively non-irritating, unlike Chlorine and Hypochlorite.

Is Chlorine Dioxide as Dependent on pH as Bleach?

Because chlorine dioxide is a dissolved gas, it does not ionize to form weak acids (as elemental chlorine and bromine do) in aqueous solutions. This allows ClO2 to be effective over a wide pH range from Acidic to Alkaline (4-10), where bleach, as an example is only effective in the near-neutral pH range of 5-7.

What is the Oxidizing Action that Takes Place between ClO2 and Organic Matter?

The predominant oxidation reaction mechanism for chlorine dioxide (and for ozone as well) proceeds through a process known as free radical electrophilic (i.e.: electron-attracting) abstraction rather than by oxidative substitution or addition (as in chlorinating agents such as chlorine or hypochlorite). It has this ability due to unique one-electron exchange mechanisms.
One electron is transferred and chlorine dioxide is reduced to chlorite (ClO2-). The term “oxidation strength” is used to describe how strongly an oxidizer reacts with an oxidizable substance. Ozone is generally regarded as having the highest oxidation strength and reacts with every substance that can be oxidized. In practical terms, this is often undesirable since several side reactions can take place causing undesirable disinfection byproducts. Chlorine dioxide has a lower oxidation strength than ozone but is more powerful than chlorine. Less chlorine dioxide is normally required to obtain an active residual disinfectant. Unlike ozone, ClO2 can also be used when a large amount of organic matter is present.

How is Chlorine Dioxide Superior to Ozone & Peroxide?

For one, ozone is so powerful oxidizing agent, that in acidic environments its oxidizing power is almost as powerful as fluorine, which dissolves glass! Ozone will corrosively react with most substances at 25° C, and accidental skin or eye contact would lead to immediate, irreparable tissue damage. Plus, it has only a half-life of 2 minutes so must be produced where you want to use it and cannot be stored. It is generally manufactured as a dilute water solution, on-site, and production cost is very high.

Hydrogen Peroxide on the other hand is very stable if correctly handled. However, contact with even trace amounts of metal ions (Mn+2, Fe+2) can cause rapid, explosive decomposition. Preparation and dilution with anything other than distilled or de-ionized water will lead to unstable and less reactive solutions. Because it is also a powerful oxidizing agent, accidental contact would again result in immediate, irreparable tissue damage.

Chlorine Dioxide has the highest of all Oxidizing Potential, but is nowhere near as powerful oxidizing (corrosive) agent, making it the best of all oxidizing biocides.

  – It is safe for all uses and contact with skin will cause no damage. 

  – It is used as a mouthwash and pet deodorizer. 

For the more chemically minded, the oxidation potential of chlorine dioxide is only 0.954 EoV,

compared with 

  – Acidic Ozone 2.07, 

  – Hydrogen Peroxide 1.77, 

  – Hypochlorite 1.48 and 

  – Chlorine 1.36.

How is it that Chlorine Dioxide May be Used at Lower Levels than other Oxidizers?

Peroxide and Hypochlorite may be considered more powerful oxidizers than Chlorine Dioxide, but in reality, that is their problem.

Every other oxidizer can be characterized as non-selective and is hence easily consumed by all manner of materials present in the environment. As a result, large quantities must be used to ensure there is sufficient residue to act as a biocide.

Chlorine Dioxide is in comparison a weak oxidizing agent, but highly selective – reacting ONLY with its organic targets. Beyond that, it only reacts with some sulfur compounds; selected amines, and other reduced organic compounds. As a result, low levels can be used to eliminate microorganisms, as it is not consumed attacking non-target compounds.

How Does Chlorine Dioxide Inactivate Microorganisms?

When the cell wall is penetrated by chlorine dioxide, organic substances within cells and on the surface of cell membranes react with chlorine dioxide, causing bacterial, fungus, and protozoan cell metabolism to be disrupted. Chlorine dioxide also reacts directly with amino acids and the RNA in the cells of viruses, arresting their parasitic activities. This reaction is not dependent on reaction time or concentration. Unlike non-oxidizing disinfectants like quaternary-ammonium compounds, chlorine dioxide kills microorganisms even when they are inactive.

Finally, Chlorine Dioxide is unique in that there has been no evidence to show that microorganisms can build up resistance to chlorine dioxide.

Is There Any Comprehensive List of the Organisms Against Which ClO2 is Effective?

Yes, this marvelous, comprehensive and thoroughly footnoted document may help you become confident in the full efficacy of Chlorine Dioxide. 

What More can be said about the Biocidal Action of Chlorine Dioxide?

ClO2 is an oxidizing biocide. It deactivates microorganisms by attacking and penetrating their cell wall, disrupting the transport of nutrients across the cell wall and inhibiting protein synthesis. Since this action occurs regardless of the metabolic state of the organism, this method of oxidizing biocides is uniquely effective against dormant organisms and spores (Giardia Cysts and Poliovirus).

How Effective is Chlorine Dioxide in Breaking Down Defensive Biofilm?

Many biocides have particular problems in penetrating this biofilm, due to the polysaccharide “glue” that is secreted by the bacteria to hold the biofilm together. Unlike most biocides, chlorine dioxide can quickly and effectively penetrate biofilm to eliminate its protective coating from the bacteria.

Furthermore, chlorine dioxide kills viruses by preventing protein formation. ClO2 reacts with peptone, a water-soluble substance that originates from the hydrolysis of proteins to amino acids.

Is there free chlorine in CDD 5000 or CDL 7500?

No, there is no free Chlorine in CDD 5000 or CDL 7500, and minimally so in Chloritab

Although Chlorine Dioxide has the word Chlorine in its name, the two chemicals have completely different chemical structures making chlorine dioxide a truly revolutionary formula.

The additional oxygen atom radically changes the molecule and creates a completely different chemical, with different behaviors and by-products. Consider this illustration: hydrogen, a highly explosive gas, when combined harmoniously with oxygen, creates di-hydrogen oxide – commonly called water.

What makes CDD 5000/CDL 7500 an Excellent Choice for Healthcare Facilities?

ClO2 is an oxidizing biocide. It deactivates microorganisms by attacking and penetrating their cell wall, disrupting the transport of nutrients across the cell wall and inhibiting protein synthesis. Since this action occurs regardless of the metabolic state of the organism, this method of oxidizing biocides is uniquely effective against dormant organisms and spores (Giardia Cysts and Poliovirus).

What makes CDD 5000/CDL 7500 an Excellent Choice for Wastewater Treatment?

Chlorine dioxide safely oxidizes phenols, cyanides, aldehydes, and mercaptans, reduced sulfur compounds and some pesticides. It is useful in both waste-water treatment and scrubber systems. Chlorine dioxide is an Eco-friendly oxidant that is preferred by many regulating water utilities and supply authorities for final discharge disinfection.

What makes CDD 5000/CDL 7500 an Excellent Choice for Ultra Pure Water?

Ultra Purification water is used to process pharmaceuticals and WFI (water for injection), to rinse silicon microchips, and to feed high-pressure boilers and turbines in power plants and chemical processing installations.
Ultra-pure water delivered at the process level must have between 99.9% and 99.99% of typical freshwater impurities removed. In addition to other contaminants, process-piping systems must be free of bacteria and biofilm.

What makes All our Products an Excellent Choice for the Environment?

There are many reasons why Chlorine Dioxide is safe and friendly. Environmentally, the by-products formed when using Chlorine Dioxide are benign. Compare this to chlorinated by-products formed when using Chlorine or Hypochlorite and you can see why so many Pulp and Paper Mills use Chlorine Dioxide. They have virtually eliminated trichloromethanes, chloroacetic acids, chlorinated dioxins, and furans from their waste streams, all of which used to pose significant risks in the environment. In its reaction, Chlorine Dioxide oxidizes (removes electrons) other compounds and is itself reduced (gains electrons) to the Chlorite anion (CLO2). Toxicological studies have shown the Chlorine Dioxide and its disinfection by-product, Chlorite, pose no significant risk to human, animal, or fish health. Chlorine Dioxide was first introduced for drinking water disinfection in 1944 at Niagara Falls. Today over 1000 municipal water treatment processes use Chlorine Dioxide.