What is Chlorine Dioxide?

Chlorine dioxide is a selective oxidant and reacts with several components of microbial cells. Made up of one chlorine atom and two oxygen atoms, this chemical is used as both a dilute liquid (aqueous) and gaseous solutions. Chlorine dioxide commonly presents in a yellow-green color and is used in a variety of industries including Water Treatment, Food Safety, Oil & Gas, and Healthcare to name a few!

Chlorine Dioxide Formula

Chlorine Dioxide is made of one chlorine atom and two oxygen atoms. ClO2!

Why Chlorine Dioxide Treatment is Effective

A helpful way to understand why chlorine dioxide treatment is effective is to think of non-oxidizing biocides as ‘bacterial poisons’.  Reaction rates of these non-oxidizing biocides are slow when compared to chlorine dioxide. Chlorine dioxide can be thought of as an agent that gives bacteria a ‘heart attack’. The inactivation and reaction rate is short, and early researchers have said the vast majority of bacteria are inactivated within the first minute while non-oxidizing biocides have longer reaction rates.

While non-oxidizing biocides also kill microorganisms, they can only kill them when the microorganisms are active. Since microorganisms spend most of their time in a dormant state, non-oxidizing biocides must be used at much higher concentrations and more frequently to effectively kill microbial pollutants. In addition, microorganisms become resistant to non-oxidizing biocides over time.

Chlorine dioxide is an oxidizing biocide that penetrates the cell wall readily, inactivating vital processes that involves the sulfhydryl (-RSH) functional group of a vital enzyme; because of the extremely rapidly reaction of chlorine dioxide with reduced sulfur. Chlorine dioxide is an especially effective biocide because bacteria can not develop a resistance to it.

Chlorine (not chlorine dioxide!) is very reactive and will react with most organic compounds. As a result, it must be used in much larger doses to maintain a residual effect sufficient to kill microorganisms. But chlorine’s greatest drawback is that it can produce dangerous disinfection by-products (DBPs) which are unacceptable according to new standards established by the Environmental Protection Agency. Ozone is similar and can produce dangerous brominated organics if a bromide ion is present. In contrast, chlorine dioxide is far less reactive. Regardless of its concentration or contact time, chlorine dioxide penetrates the walls of microorganisms.

Finally, chlorine dioxide and its primary by-products—chlorite and chlorate—all break down to sodium chloride. This, along with failure to form toxic and carcinogenic chlorination by-products and produce a build-up of toxic organic or inorganic by-products like bromates, makes chlorine dioxide the most eco-friendly biocide that can be used.

Chlorine Dioxide Properties

Melting Point-74°F (-59 °C)
Boiling Point52°F (11 °C)
OdorSimilar to Chlorine
ColorYellow-green, becomes more red at
higher concentrations
Density2.4x heavier than air

Aqueous Chlorine Dioxide Properties

Melting Point~32°F
Boiling Point~212°F
OdorSimilar to Chlorine
ColorPale-yellow to yellow liquid

What is Chlorine Dioxide Gas?

Chlorine dioxide gas is the gaseous form of the chlorine dioxide molecule, and is a strong oxidizing agent that has broad and high biocidal effectiveness, and has about 2.5 times the oxidation capacity of chlorine. Chlorine dioxide gas penetration ability can be greater than that of liquid, and chlorine dioxide gas has been surveyed to be even more effective for surface treatment than aqueous chlorine dioxide.

What is Stabilized Chlorine Dioxide?

While the term stabilized chlorine dioxide may be commonplace among businesses to describe their chemical products, the term in and of itself is actually misleading. Stabilized chlorine dioxide is essentially an aqueous solution of buffered sodium chlorite, but not true chlorine dioxide. Depending on the activation of stabilized chlorine dioxide, results in the use of treatment can vary significantly.

What Are Common Chlorine Dioxide Uses?

A growing number of industries are relying on the oxidation properties of chlorine dioxide. Chlorine dioxide is quickly becoming the preferred bleaching agent in the pulp and paper industry because it minimizes the environmental impact of the bleaching process.

Chlorine dioxide is also used to not only treat municipal and drinking water supplies, but also control the water’s taste, odor and color. In the food industry, chlorine dioxide treats water used to clean equipment and preparation surfaces, wash fruits and vegetables, and prevent salmonella and e-coli from contaminating meat and poultry.

In commercial and institutional applications, chlorine dioxide is used to prevent the spread of Legionella in hospitals and universities. Industrially, chlorine dioxide is an effective membrane treatment, as well as a biocide for cooling and wastewater. It is used in the production of ethanol, microelectronics, nitrogen and ammonia.

The following facilities, businesses, and functions are all candidates of using chlorine dioxide: Air Washers, Clinical Laboratory Waste, Cooling Tower Cleaning, Cooling Towers, Cruise Ships, Dental Water Systems, Dialysis Clinics, Emergency Drinking Water, Grocery Store Produce Misting Machines, Health Club Spas, Medical Waste, Medical/Dental/Vet Instrument Cleaning, Ornamental Fountains, Retirement Homes, ‘Sick’ Buildings, Small DRinking Water Plants, Swimming Pools, Third World Drinking Water, Waste Water, and many more!

Is Chlorine Dioxide Safe?

In a consumer setting, chlorine dioxide can be found in toothpastes, mouthwashes, vegetable and fruit washes, and is used to treat municipal drinking water supplies. Both the EPA and FDA have approved the use of products whose active ingredient is chlorine dioxide for use in these instances, but consumers must follow the instructions as approved by the governing bodies.

Like many over-the-counter chemicals, following instructions from governing bodies’ guidance (EPA/FDA) and the product label is necessary for the end-user. When using chlorine dioxide according to the labeled instructions approved by governing bodies, the end-user should feel confident in handling and using chlorine dioxide for its intended purpose. Depending on the concentration of the solution at play, there may be hazard statements that the consumer has to heed warning to.

In a business or industrial setting, generators are typically utilized to create chlorine dioxide on-site in larger quantities. Only experts or those who have in-depth knowledge of the properties of chlorine dioxide and the main precursor chemical of sodium chlorite should be trusted to make and use it safely. Larger scale generation of aqueous chlorine dioxide should only be conducted by experts, knowledgeable parties, and by generators or equipment made be chlorine dioxide experts.

Safety incidents that occur in chlorine dioxide generation within industrial settings like the oil patch typically revolve around handling and storage of sodium chlorite, misapplications, improper generation, and an attitude that ignores the need for specialized knowledge of chlorine dioxide generation. With proper knowledge and expertise, the handling and generation of chlorine dioxide can be executed correctly with marvelous benefits to the business – such as treating frac water in the oil field!

Is Chlorine Dioxide the Same as Chlorine?

They are not the same! Chlorine dioxide (ClO2) is also not the same as bleach (NaClO). While they share in name a chlorine atom, the resulting chemicals are different. Shown above is a video that shows the different effects of chlorine dioxide and chlorine on biofilm. You will notice how the chlorine dioxide will inhibit and eliminate the biofilm while chlorine does not.

A few examples of the difference between chlorine dioxide and chlorine include:

  • Chlorine has a higher corrosion potential than chlorine dioxide on equipment and piping.
  • Chlorine is known to produce carcinogenic trihalomethanes and haloacetic acids when treating water systems while chlorine dioxide does not.
  • Chlorine does not inhibit biofilm at normal operating conditions, while chlorine dioxide inhibits biofilm.
  • The US Federal government is phasing out the use of chlorine in pulp and paper mills as the use of chlorine dioxide has virtually eliminated dioxin in mill wastewater, leading to significant improvements in surrounding ecosystems.

PureLine Chlorine Dioxide Generators and Chemicals

PureLine specializes in designing and implementing chlorine dioxide solutions utilizing our broad line of proven chlorine dioxide (ClO2) generators and pre-cursor chemicals. Our solutions are supported by experienced engineers and technicians focused on the goal of building long term, successful partnerships. Our nearly three decades of successful experience in generating chlorine dioxide make PureLine the chlorine dioxide experts.

PureLine’s manufactured equipment is used within Hospitals, Municipal Water Systems, large Industrial Water systems, Oil & Gas applications in the United States and the Middle East, and at Food Processing Plants.

PureLine’s chlorine dioxide chemicals are used within the Food and Beverage industry, Healthcare, Mold and Mildew Remediation, Odor Removal, Restaurants, Schools, Gyms, and more!

PureLine’s exclusive patented chlorine dioxide technologies offers superior benefits including:

  • Environmentally Friendly
  • EPA/RMP & OSHA PSM Compliance
  • Efficacy Over Broad pH Range
  • Iron & Manganese Reduction
  • Taste & Odor Control
  • Removes Color
  • TOC Reduction
  • CT Credit
  • Low Capital & Operating Costs