Chlorine Dioxide - A Technical View
What is Chlorine Dioxide?
Like ozone and chlorine, chlorine dioxide is an oxidizing biocide and not
a metabolic toxin. This means that chlorine dioxide kills microorganisms
by disruption of the transport of nutrients across the cell wall, not by
disruption of a metabolic process.
How does it work?
Of the oxidizing biocides, chlorine dioxide is the most selective oxidant.
Both ozone and chlorine are much more reactive than chlorine dioxide, and
they will be consumed by most organic compounds. Chlorine dioxide however,
reacts only with reduced sulphur compounds, secondary and tertiary amines,
and some other highly reduced and reactive organics. This allows much lower
dosages of chlorine dioxide to achieve a more stable residual than either
chlorine or ozone. Chlorine dioxide, generated properly (all chlorine dioxide
is not created equal), can be effectively used in much higher organic loading
than either ozone or chlorine because of its selectivity.
How effective is it?
The affectivity of chlorine dioxide as a gas or when dissolved in water
is at least as high as chlorine, though at lower concentrations. But there
are more and important advantages.
- Chlorine dioxide is clearly superior to chlorine in the destruction of
spores, bacteria's, viruses and other pathogen organisms on an equal residual
- Chlorine dioxide can be used as a gas like ozone but not chlorine but
without the destructive oxidizing side effects of ozone.
- The required contact time for ClO2 is lower;
- Chlorine dioxide has better solubility in water;
- No corrosion associated with high chlorine concentrations. Reduces long
term maintenance costs;
- Chlorine dioxide does not react with NH3 or NH4+;
- It destroys THM precursors and increases coagulation;
- ClO2 destroys phenols and has no distinct smell;
- It is better at removing iron and magnesia compounds than chlorine, especially
When used in its gaseous form, provides all the benefits of ClO2 dissolved
in water with the clear advantage that there is no water to contend with
and it can infiltrate areas that water based ClO2 can not reach or be used.
In the past producing ClO2 gas required large and expensive machinery but
with the introduction of OdorXit ClO2 Dry Media design no machinery is required.
The packets once exposed to water or humid air produce low levels of ClO2
gas. The Fast Release version produces enough gas per hour to raise ClO2
levels high enough to require that people and pets be removed from the area
being treated (usually 24 hours or less). The Extended Release version produces
much smaller amounts of gas per hour for 20 to 30 days. Used as advised,
ClO2 levels never exceed .01 ppm which is considerably below levels that
are considered an irritant or dangerous.
In its gaseous state, ClO2 works very well even at extremely low concentrations.
We have seen evidence that suggest that the Extended Release version of the
product actually does better at killing bacteria, mold and mold spores than
the Fast Release version.
General Background Information On Chlorine Dioxide
Chlorine dioxide is effective at low concentrations across a wide range of
pH (roughly 4 to 9), and, because it is a gas in its natural state, dissipates
upon exposure to sunlight As a consequence, it is known widely as one of
the most effective inhibitors of algae, yeast, mold, fungi and viruses. However,
because transporting the gas is prohibited in all but frozen forms, pure
chlorine dioxide has heretofore been limited to use in large concerns that
employ chemical generators, such as pulp mills (controlling slime) and municipal
water systems (water purification applications).
Similarly, in cleaning and antimicrobial knockdown applications, pure chlorine
dioxide has previously been unavailable, and only with "stabilized" solutions
or acidified sodium chlorite, which are corrosive and produce significant
chemical residues, could any of the advantages of chlorine dioxide be realized.
Dry Media Chlorine Dioxide (dmClO2™)
The OdorXit ClO2 package design created a truly portable
ClO2 delivery system
called “Dry Media Chlorine Dioxide (dmClO2™)”. dmClO2™ is easy to use for many types of small-
and medium- sized applications and requires no electricity to generate a
pure solution of ClO2. Dry
media chlorine dioxide significantly expands opportunities for the safe use
of chlorine dioxide while reducing associated costs in many applications.
In some uses, dry media chlorine dioxide can eliminate the need for chlorine
dioxide generators, multiple chemical requirements, and greatly reduce shipping
and storage costs while increasing ease of use and safety considerations. The
simplicity and inherent safety of the dmClO2™ may
also reduce requirements for costly technical personnel.
The Dry Media design products are simple, efficient delivery systems based
on portable engineered pouches ideal for multiple point-of-use applications
of ClO2. These portable pouches are small enough to be easily stored
but capable of generating up to several thousand gallons of sanitizing and
disinfecting solutions and gasses.
Most commercial disinfectants are manufactured in solution containing large
volumes of water resulting in costly transportation, storage and end-use
costs. The dry-media chlorine dioxide (dmClO2™)
technology only requires moisture activation to produce a ready-to-use liquid
solution of ClO2 or to produce low concentrations
of ClO2 gas in the air. Active
solutions of ClO2 can be used in multiple industrial
and institutional applications ranging from potable water disinfection to
dmClO2 Generation Mechanism
The dmClO2™ device combines the utilization of membrane
technology with a custom made heat-sealing procedure resulting in a defined
space called the Membrane Micro Reactor (M2R™), where
the reaction takes place. Within the M2R™, the conversion
of sodium chlorite to chlorine dioxide is governed by the
- transport phenomenon of water and/or moisture into the M2R™
- dissolution rate of the ClO2 precursors
- reaction kinetics of ClO2 generation
- controlled release of ClO2 gas or ClO2 in solution.
The design of the M2R™ provides a defined physical
space having a favorable environment for an efficient conversion of sodium
chlorite to chorine dioxide. This conversion results in an economical process
for the production of chlorine dioxide with minimum amounts of un-reacted
species and undesired by-products.
Other devices currently available rely on the mixture of un-separated reactants
in one device or the mixture of solutions of the reactants. In either case,
the conversion and therefore the cost effectiveness is not economically attractive;
these methods yield ClO2 with a high level of by-products.
Avoiding THMs with Chlorine Dioxide
One of the major advantages in using ClO2 is that it does not form chlorinated
organic byproducts. ClO2 is structurally different than chlorine and
reacts with organic matter through different pathways. Chlorine chlorinates
organic matter, forming chlorinated byproducts.
Many chlorinated organic compounds have been found to be carcinogenic, such
as trihalomethanes (THMs). Alternatively, ClO2 reacts with organic matter
through an oxidation-reduction reaction. ClO2 oxidizes the organic
matter and is itself reduced to the chlorite ion, and eventually to the chloride
ion. Thus, disinfection with ClO2 does not result in carcino.
Recently, studies linking THMs to health problems have caused concern over
the presence of THMs in drinking water. As Total THM (TTHM) regulations
become stricter, it is anticipated that more water treatment facilities will
turn to ClO2 to lower THM levels in treated water.
The Development Of MRSA And Its Increasing Resistance To Antibiotics
Staphylococcus aureus (SA)-Antibiotic Resistance (General): Throughout history,
Staphylococcus aureus (SA) has been a dangerous pathogen once it has successfully
breached the normal defense system. The first effective antibiotic against
SA, penicillin, became available in the 1940s. Soon after, SA evolved resistance
to penicillin, and by the late 1950s, 50 percent of all SA strains were resistant.
Today, fewer than 10 percent of SA infections can be cured with penicillin.
The next weapons against SA, methicillin and cephalosporin, became available
in the 1960s and 1970s. By the late 1970s, some strains of SA had evolved
resistance to these drugs. Today, as many as 50 percent of SA strains isolated
from U.S. hospitals are resistant to methicillin. (Source:
National Institutes of Health)
New MRSA Bacteria Killer Registered by EPA
Main Category: MRSA
/ Drug Resistance News
Article Date: 04 Sep 2005 - 10:00 PDT The EPA (Environmental Protection Agency)
has recently registered a new product for preventing and eliminating methicillin-resistant
Staphylococcus aureus (MRSA), which causes potentially deadly infections
commonly known as "staph" infections. The MRSA "super bug" is
typically contracted in hospitals, in other healthcare environments, and
in health clubs and locker rooms.
The EPA has registered chlorine dioxide dissolved in water for use as a disinfectant
on hard, non-porous surfaces and instruments, including those used within
hospitals and other medical settings. As a no-wipe, no-rinse spray, hydrated
chlorine dioxide can also be used on hard, non-porous surfaces in health
clubs, spas, public places and swimming facilities as a treatment against
MRSA. The EPA has also registered hydrated chlorine dioxide as a disinfectant
for vancomycin-resistant Enterococcus faecalis, athlete's foot, Mycobacterium
bovis (TB) and other pathogens that spread in many environments.
Though this product was not OdorXit ClO2 Dry Media, OdorXit ClO2 Dry Media
has been registered with the EPA as well and uses the same ClO2 technology
plus the gas version of the technology.
MRSA is usually spread by direct physical contact with those already infected
or through indirect contact by touching objects (towels, clothes, sports
equipment, etc.) that infected skin has contaminated. Consequently, any heavily
trafficked area can be a source of infection.
According to a report by the BBC News, "Staphylococcus aureus is the
leading cause of human infections in the skin and soft tissues, bones and
joints, abscesses and normal heart valves. It flourishes in the hospital
setting, producing bloodstream and surgical wound infections, including MRSA." (news.bbc.co.uk/1/hi/health/4671585.stm)
How OdorXit ClO2 Kills MRSA And Other Deadly Pathogens
Chlorine dioxide is an ideal biocide because of its ability to kill viruses,
bacteria, fungi, and algae at low saturation levels (parts per million) in
a manner that does not allow pathogens to build resistance to the compound.
The gas generating form of the product can easily and safely be used in locker
rooms, inside lockers, bathrooms, equipment storage rooms, bins, and carry
Prior to OdorXit ClO2, healthcare and health club environments were limited
to using substances like bleach and quaternary ammonium compounds that can
leave residue and require higher concentrations than does chlorine dioxide
to achieve the same antimicrobial efficacy.
Chlorine dioxide can be produced as a pure gas where in can disinfect all
surfaces and materials or in water and sprayed, mopped, or sponged onto surfaces
that require disinfection.
After application of the liquid product, the solution is left on target surfaces
and does not require rinsing. Due to the comparatively low application concentrations
required to kill pathogens, hydrated ClO2 is compatible with most materials.
Gaseous ClO2 requires not rinsing or cleanup of any kind since there is not
residual build up.
Air quality is equally as important as water quality and has received considerable
attention in the last few years by consumers as well as regulatory and governmental
agencies. The market is literally flooded with deodorizers, which basically "mask" the
odor with some sort of fragrance.
Odors can be caused by a number of factors and often are associated with
bacterial presence and action, food processing, smoke, and industrial processes.
The list of chemical substances causing odor is very extensive but most odor-causing
compounds are derived from sulfur and nitrogen compounds such as amines,
cyanides, hydrogen sulfide, mercaptans, aldehydes and phenols.
Odor problems are not only affected by the source of the pollutant but also
by environmental conditions such as humidity, temperature and air movement.
Ventilation systems play a key role in the control of odors in confined spaces
such as buildings, storage rooms, processing areas, homes and residences.
The most effective methods of eliminating odor-causing compounds are air
scrubbing and chemical destruction. Air scrubbers are normally used in industrial
settings and in processes which involve a continuous release of air-borne
pollutants. Air scrubbing involves sophisticated and well-engineered systems
requiring substantial capital, maintenance and training.
One of the key properties of ClO2 is its ability to selectively oxidize chemical
compounds. In addition, ClO2 has the ability to inhibit and kill bacteria,
viruses, and protozoa. The combination of selective oxidation and bacterial
inhibition make ClO2 a powerful tool to control odors in confined spaces.
The OdorXit ClO2 Dry Media design controls odor-causing bacteria, mold, mildew,
and chemical odors. This product is based on the generation of ClO2 gas and
is capable of generating a controlled concentration of ClO2 in the air based
on specific ratios of relative humidity and temperature.
The OdorXit ClO2 Dry Media products are designed to produce specific concentrations
of ClO2 in a given air volume while meeting the current OSHA permissible
exposure limit (PEL) of 0.1 ppm as an 8-hour time-weighted average. Choosing
the proper sized product is key to the safe and affective use in a well defined
History of Chlorine Dioxide
The chemistry of chlorine dioxide (ClO2) has been known since the early 1800’s,
when it was discovered by Sir Humphrey Davy.
ClO2 proceeded to gain recognition as a disinfectant and an oxidant, and
in the 1950’s, ClO2 attained widespread commercial use as a bleaching
agent in the pulp and paper industry. In 1967, the USEPA registered the liquid
form of ClO2 as a disinfectant and sanitizer. Subsequently, in the 1970’s,
the use of ClO2 as a disinfectant for drinking water was developed.
In 1988, the USEPA registered ClO2 gas as a sterilant. Recently growing
concern about Trihalomethanes (THMs), a carcinogenic disinfection byproduct,
has caused researchers to focus on ClO2 as an alternative drinking water
While chlorine, hypochlorite, and other chlorine-related disinfectants produce
carcinogenic chlorinated organic byproducts, disinfection with ClO2 does
Today, ClO2 is used in 700-900 US drinking water facilities, mainly for taste
and odor control as well as to meet increasingly strict THM regulations.
Chlorine dioxide is perhaps the most versatile disinfectant in terms of its
capacity to destroy and kill most pathogenic microorganisms.
While ClO2 has chlorine in its name, ClO2 reaction chemistry is radically
different from that of chlorine. Chlorine dioxide is a stable free radical
and functions via an oxidative rather than a chlorinating reaction.
Chemistry of Chlorine Dioxide
Chlorine dioxide’s oxidative power allows it to disrupt the cell membranes
of microorganisms, so that nutrients cannot be transported into the cell. Many
commonly used disinfectants are not effective against the cell membrane and
instead interrupt the metabolism of the microorganism.
Over time, the microorganisms can develop resistance to disinfectants. With
ClO2, however, the microorganism does not have a chance to develop resistance
because it is killed upon contact with ClO2.
Some oxidizers can be too powerful in their oxidation. ClO2 is unique
because, although it is highly oxidative, it is also highly selective.
This means that ClO2 does not react with whatever material is present; it
selectively oxidizes and destroys certain microorganisms and is not wasted
on benign matter. Due to its oxidizing power, ClO2 has excellent capability
to penetrate biofilms where certain bacteria such as Legionella hide and
cannot be killed by most disinfectants including chlorine.
If you have questions, call the odor experts at 1-877-636-7948.