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What is ozone?
Ozone is an allotrope of oxygen.
What's an allotrope of oxygen?
Allotrope means; "another form". Put correctly,
ozone is triatomic oxygen. An ozone molecule, O3, contains
three atoms of oxygen. A highly unstable molecule with a very
short half-life (22 minutes on average), it prefers to revert
back to its more stable state, O2. In order to return to that
diatomic state, O2, it must release one atom of oxygen. Ozone’s
desire to release a lone molecule of oxygen is referred to
by chemists as its power to oxidize. This natural oxidizing
tendency is what makes it such an attractive industrial disinfectant.
Why is ozone such a strong industrial disinfectant?
The unpaired oxygen atom that ozone releases will attach
itself to other compounds in water, thus, oxidizing them into
different compounds. That single oxygen atom will oxidize
virtually all organic and many inorganic compounds. Once oxidized,
they will proceed to precipitate out of the water.
Because ozone will break down, oxidize, almost anything that
it contacts, it is an enormously powerful disinfectant and
oxidizer. In fact, ozone is 150% stronger in terms of oxidation
potential than chlorine, and is the second strongest, commercially
available chemical in the water treatment industry, after
the hydroxyl free radical. Ozone kills organisms and viruses
by cell lysis, the rupturing of a cell’s wall, a process,
according to the EPA, “to which microorganisms cannot
develop immunity.” On the other had, some parasitic
species have shown resistance to low doses of chlorine, including,
ococysts of Cryptosporidium parvum, cysts of Endamoeba histolytica
and Giardia Lamblia, and eggs of parasitc worms. By contrast,
“residual ozone concentrations of as little as 0.1 mg/L
will reduce populations of Legionella pneumophilia in cooling
towers to 80%.
Why do we use ozone?
We use ozone because it is a safe and environmentally friendly
tool for treating and disinfecting water. Because it is such
a powerful oxidizer, little else is needed to clean condenser
water, chilled water, cooling towers, tube bundles, and pipes.
Compared to the cost of storage and labor required to apply
chemical, not to mention the danger, ozone is a comparatively
cheaper alternative.
Its exceptional oxidizing power aside, one of the strongest
motors propelling ozone’s increased use is the fact
that it’s use does not harm our planet like chlorine
does. Chlorine is a carcinogen, that is, it causes cancer,
whereas, ozone is not a carcinogen. In fact, chlorine’s
carcinogenic presence in our drinking water is, according
to the EPA, one of the largest causes of cancer in America.
Chlorine became so popular years ago because of its ability
to disperse itself across nearly 100% of a body of water,
and, therefore, kill many microorganisms. This same ability
to diffuse so completely makes it nearly impossible to remove,
meaning that blowdown or discharge water from a chlorine treated
cooling tower or wastewater plant still contains chlorine
when it returns to the environment where it continues to kill
organisms in our ecosystems and bio-accumulate in fish and
mammals: from shrimp to salmon to bears, etc. and eventually
in human beings. In fact, chlorine and organochlorines have
even managed to contaminate arctic mammas like reindeer that
live thousands of miles from the nearest chlorine treated
water plant. Chlorine persists in our environment, where,
ironically it is not even found naturally. Ozone on the other
hand is nature’s disinfectant. Pure oxygen is its sole
ingredient, and when its done disinfecting it reverts back
into pure oxygen, on average after only 22 minutes. In other
words, there is no harmful residual. It is the environmental
and responsible alternative.
Is Ozone Generation a brand-new technology?
No. In fact, it is quite old. Wener von
Siemens, a German and a co-founder of the modern-day technology
giant Siemens AG, discovered a method or producing ozone artificially
in the 19th century. His technique led to the first use of
ozone disinfection in water treatment in 1906. Given its superior
strength and effectiveness as an oxidant, virucide, and biocide,
ozone has become one of the dominant water treatment technologies
in Europe. Its popularity and use is increasing in America
as Americans become increasingly cognizant of its superior
disinfecting and oxidizing power and of the malicious effects
of chlorine on public health, the environment, and air quality.
Extensive research into the generation of ozone has produced
an array of viable systems, many producing large quantities
of ozone gas for injection into water. It’s use has
become so widespread that today it treats the water in the
world’s largest aquarium in Hualien, Taiwan and the
drinking water for the city of Los Angeles.
PHYSICAL PROPERTIES OF OZONE
Ozone (O3) is the triatomic, allotropic form of oxygen (O).
It is an unstable gas with a pungent odor.
Since ozone is unstable, it must be generated at the point
of application.
The ozone molecule, having a molecular weight of 48, is made
up of three oxygen atoms bound by equal oxygen-oxygen bonds
at an obtuse angle of 116°49'. This structure is inherently
unstable and is the reason for ozone's powerful oxidizing
ability. Ozone has approximately 150% the oxidizing potential
of chlorine. The physical properties of ozone and comparative
oxidizing potentials for other chemical oxidants are presented
in Table 1 and Table 2, respectively.
TABLE 1: PHYSICAL CONSTANTS OF OZONE
| Molecular Weight |
48.0 |
| Boiling Point, °Celsius |
111.9 |
| Melting Point, °Celsius |
-193 |
| Gas Density, 0°C grams/liter |
2.144 |
| Critical Temperature, °C |
-12.1 |
| Critical Pressure, atm |
54.6 |
| Critical volume, cm3/mole |
111 |
TABLE 2: COMPARATIVE OXIDIZING POTENTIALS, 25°C
| COMPOUND |
Volts |
| Flourine (F2) |
2.87 |
| Ozone (O3) |
2.07 |
| Hydrogen Peroxide (H2O2) |
1.78 |
| Potassium Permanganate (KMnO4) |
1.70 |
| Hypobromous Acid (HOBr) |
1.59 |
| Hypochlorous Acid (HOCl) |
1.49 |
| Chlorine (Cl2) |
1.36 |
| Chlorine Dioxide (ClO2) |
1.27 |
| Oxygen (O2) |
1.23 |
| Chromic Acid (H2Cr2O4) |
1.21 |
| Bromine (Br2) |
1.09 |
| Nitric Acid (HNO3) |
0.94 |
| Iodine (I2) |
0.54 |
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