Ozone

WHAT IS OZONE?

Ozone is a molecule based on three oxygen atoms (O3), equipped with a negative electrical charge. Ozone molecule is very unstable and it has a short halving time .For this reason it will decay after a certain time into its original form: oxygen (O2, according to the following reaction) 2O3 ? 3O2

Essentially ozone is nothing else that oxygen (O2), with a supplementary oxygen atom which has a high electrical charge. In nature ozone is originated by some chemical reactions. The most familiar example is, of course, the ozone layer in which ozone is created by (UV) ultraviolet rays of the sun. Ozone can be also produced during storms and by falls. Extremely high tensions which can be reached during storms produce ozone from oxygen. The special “fresh and clean, the smell of spring rain” scent is a result of ozone produced in nature. Ozone derives from the Greek word ozein which means “to smell”.
Ozone is originated only in extreme conditions but it can be produced by ozone generators.

HOW DOES OZONE WORK?

Ozone acts according to the oxidation principle. When the statically charged molecule of ozone (O3) gets in touch with something which can be oxidized, the charge of the ozone molecule flows directly on it. This happens why ozone is very unstable and tends to transforms itself in its original form (O2). Ozone can react with all kinds of materials but also with odors and microorganisms such as viruses, mildews and bacteria. The supplementary oxygen atom is released by the ozone molecule and links itself to the other material. At the end only the pure and stable molecule of oxygen remains.

Ozone is one of the strongest available oxidation technic to oxidize solutes. The supplementary oxygen atom will link itself (=oxidation) in one second to each component which gets in contact with ozone.
Ozone can be used in a great deal of purification processes. For the major part it is used in the municipal sewage water and for the treatment of drinkable water (for its disinfection). On the other hand ozone is increasingly used in industry. In food production chain it is used for disinfection and in textile and paper industry it is used to oxidize waste water. The most important advantage of ozone is its environment friendly feature as it oxidizes only materials and almost not giving origin to by-products. As ozone has a distinctive smell even very little concentration can be detected. This makes safe to work with it.

HOW IS OZONE PRODUCED?

Ozone can be artificially produced following the same phenomenon as in nature, that is to say UV light (ozone layer) or through crown effect (high tensions, lightning). With both methods the link among oxygen molecules is broken and oxygen radicals are originated, which link themselves to a an oxygen molecule in O3 (ozone).  The crown effect system is the most used method of production such as low production costs and long lasting life. For the food chain production natural air as well as pure oxygen can be used. By using pure oxygen a higher concentration of ozone can be produced.

WHAT IS HALVING TIME OF OZONE

For water and air purification ozone must be produced on place. Because of its rapid halving time, ozone decays once it is produced. Halving time of ozone in water is about 30 minutes and this means that every half an hour its concentration  halves itself in comparison to the initial one. For example, if you have 8 g/l the concentration reduces every 30 minutes as follows: 8; 4; 2; 1 a.s.o.. In practice halving time can be shorter as many other elements can alter it. These factors are temperature, pH, concentration and type of solutes. As ozone reacts together with every type of component its concentration will reduce very rapidly. As soon as the greatest part of components is oxidized, residual ozone remains and its concentration reduces slowly.

IS OZONE DANGEROUS AND WHICH ARE ITS EFFECTS?

To the highest concentration  ozone can be dangerous for human health if inhaled. Many agencies such as the European Agency for Safety and Health at Work (OSHA) suggest MAC value for ozone. A MAC value is the maximal acceptable concentration to which a human being can be exposed for a certain period of time and for a determined agent. For ozone MAC value is 0,06 ppm (parts per million) for 8 hours a day, 5 days a week . For a maximum of 15 minutes a MAC value of 0,3 ppm is applied. Above mentioned limits are higher that the smell limit to which ozone can be detected and for this reason critical concentration can rapidly noticed. When people are exposed to high ozone concentrations symptoms can vary from mouth dryness, cough, headache and thoracic restriction. Near to mortal limits there are more severe symptoms. When big ozone production plants are used, ozone destruction plants can be used to destroy residual ozone.

HOW CAN BE OZONE LEVEL DETECTED?

There are many measurement instruments available to define the quantity of ozone in air and water. These instruments are based on different principles and they can measure concentration from ppm (parts per million) to ppb (parts per billion). These instruments can be used to control and command the ozone generator.