IOA-EA3G Conference in Geneva
on Ozone & related oxidants: solutions for emerging pollutants of concern to the water and the environment (April 28th - 30th, 2010 - Geneva, Switzerland) Call for papers & 1st announcement >>
Ozone is essential for life on Earth
The Chemist Christian Friedrich SCHOENBEIN discovered
ozone as chemical entity in 1840.
Ozone properties
Ozone is a colorless
to bluish gas with a characteristic pungent odor. The
ozone molecule contains three oxygen atoms (O3).
It is unstable and readily reacts with other substances.
Ozone is
a powerful oxidizing agent.
Molecular weight
48,00 g/mol
Enthalpy of formation
142,12 kJ/mol
Boiling temperature
-111,9°C (1 atm)
Standard redox potential
+2,076 V
Gas density
2,144 g/l (0°C, 1 atm)
Solubility in water
1370 mg/l
Ozone
in the environment
Ozone naturally occurs in the environment. It is constantly formed in the earth's atmosphere by action of ultraviolet light emitted by the sun on oxygen molecules. Ozone thus constitutes in the stratosphere a shield that prevents the ultraviolet radiation, which causes biological damage (skin cancer) from passing to the earth's surface.
Without
ozone in the upper atmosphere, life on earth would not
have evolved and could not exist today.
The
hole in the ozone layer. About 90 % of ozone in the earth's atmosphere is in the stratosphere (12 to 50 km of altitude). It forms a layer where its concentration is higher than anywhere but low ranging from 1 to 20 ppm compared with the oxygen concentration of about 210000 ppm. The ozone layer is what makes the sky blue. Ozone concentration in this layer depends on the latitude, the season, the weather conditions and the pollutants released from human activity (for example, CFC). The latter can involve complex reactions that decompose ozone. This explains the hole in the ozone layer over the poles.
The
ozone smog. The other 10% of the ozone found in the earth's atmosphere are in the troposphere (earth's surface to 12 km up). Ozone is naturally created during thunder and lightning storms but mainly results from hydrocarbons and nitrogen oxides released by automobiles and industry. Ozone concentration reaches excessive levels (0,3 ppm) when these emissions, sunlight, moisture and temperature combine the right conditions for smog. Ozone in troposphere at such concentration can cause damage to human health like eyes irritation, coughing, difficulty in breathing. The characteristic sharp, irritating odor is readily detectable by human nose at low concentration (0,02 ppm). However, ozone in the troposphere is one of the greenhouse gases that make earth habitable for life. Ozone purifies the air that we breathe by reacting with noxious compounds responsible for or issued from its formation. Ozone monitoring in large cities during smog days lead to the general confusion: ozone is smog. Ozone is a key ingredient in smog and a powerful and natural greenhouse gas.
The use of ozone
was made possible through the development of ozone generators
mainly based on corona discharge applied to oxygen-containing
gas. The latter directly installed on the use site permit
to make the most of the oxidizing properties of ozone
in various fields since the beginning of nineties.
In 1973,
the professionals from industry and research sectors
created the International Ozone Association as network
dedicated to support the growth of ozone application
in all fields.
Ozone can serve in any case where an effective oxidizing action is required on natural, organic, inorganic, mineral, biological, gaseous, liquid or solid substances: disinfection (destruction of pathogenic germs in water, gas, equipment, packaging...), pollutants removal with biodegradability increase, decolorization, COD abatment, VOCs elimination, reduction in toxicity, degradation of specific compounds (from water, air, surface...), conversion and purification of products (chemicals, natural products), therapy purpose...
Water purification: drinking water, bottled water, swimming pools, industrial wastewaters cooling towers, groundwater remediation, wastewater re-use. Air
purification: gas emissions from industry, conditioning
system. Pulp
bleaching for chlorine-free production of paper. Organic
synthesis. Aquaculture
and fish farming. Food
processing: rinsing water, food preservation. Surface
treatment: semiconductor manufacture, inorganics production. Medicine
and esthetics: ozonotherapy, surgery, dental care, optical
care, manufacture of pharmaceuticals and beauty products.
Ozone based process
Ozone
is generated using air or pure oxygen and electric energy.
Typical ozone plant includes system for air or oxygen
supply, generator, reactor equipped with gas diffusion
device, equipment for monitoring and destruction of
ozone in excess into oxygen.
Key-publications
The following selection of papers published in Ozone:
Science & Engineering illustrates the knowledge
in ozone science and the expertise degree of professionals
that you can meet through IOA.
FREE articles are available in Adobe Acrobat
format.
Molecular weight 
