Formation and Production of Ozone in Nature; It is formed when ultraviolet rays from the sun break apart oxygen in the atmosphere, converting them into ozone molecules.

Technologically, it is produced by splitting oxygen in the air using electrical energy or from pure oxygen.

In plate-type generators

In CD-type generators

In UV-type lamps

Ozone gas is the only natural disinfectant with commercial use. After completing its task, it always converts back into its raw material, oxygen.

Ozone gas is inversely proportional to temperature. It is a gas with a very high oxidation power and one of the strongest disinfectants known. Its high oxidation power plays a crucial role in the elimination of microorganisms.

Ozone disinfection destroys microorganisms by breaking down their cell membranes. Ozone gas, when used in water, provides disinfection after approximately 4-10 minutes of contact. Around 0.1-0.5 mg/L ozone kills almost all microorganisms.

Under the same conditions, ozone has 3100 times stronger disinfecting effect than chlorine. Due to ozone's unstable structure, it converts back into oxygen within 30 minutes in an open environment or 8-12 hours in a sealed package, leaving no residue after the disinfection process.

In a report published by the World Health Organization in 1979, ozone disinfection was recommended. After ozone gas was classified as a safe gas (GRAS) in 1997, its use in food began to increase. The Turkish Food Code has also made HACCP (Hazard Analysis Critical Control Points) studies mandatory for safe food production.

Due to its strong oxidizing and highly effective disinfecting properties, ozone is used as a microorganism killer in water purification plants that provide drinking water worldwide.

The high oxidation power of ozone plays a full role in the destruction of bacteria.

Additionally, since ozone is obtained by splitting oxygen in the air, it always converts back into oxygen, its raw material, after completing its disinfection task due to its unstable structure.

The fact that ozone gas does not leave residue after disinfection makes it more advantageous than other disinfectants, especially in the food industry.

For ozone to dissolve in water, the temperature must be low, and the applied pressure must be high.

Formation Mechanism

The formation and production of ozone occur in the stratosphere layer of the atmosphere, where ozone is formed due to ultraviolet radiation, while at the same time, it is also destroyed. The air mass in the stratosphere is continuously affected by the ultraviolet radiation coming from the sun. At this stage, almost all of the Ultraviolet-B (UV-B) rays, which pose a great danger to life on Earth, are absorbed by the ozone in the stratosphere.

This process occurs as:

O3 + h υ → O2 + O reaction (λ = wavelength < 243 nm). As a result of this reaction, the ozone molecule breaks down, releasing one oxygen molecule and one oxygen atom. Here, h represents Planck's constant, and υ is the frequency of the UV-B rays.

Ozone Molecule Formation Mechanism

The new free oxygen molecule formed in the above reaction reacts with an oxygen atom in the ozone layer, reforming an ozone molecule (O3).

O2 + O + M → O3 + M

Here, M is a third molecule that carries the energy released during the reaction.

Destruction Mechanism

When an ozone molecule (O3) is exposed to ultraviolet radiation, it breaks down into O2 and O. During the breakdown, atomic and molecular oxygen gain kinetic energy, which increases the heat and causes the atmospheric temperature to rise.

Ozone production is provided by ultraviolet radiation with wavelengths shorter than 240 nm. Ozone decomposition occurs when exposed to ultraviolet radiation with wavelengths longer than 320 nm and between 400 and 700 nm. Longer wavelength photons are more easily absorbed into the atmosphere in the creation of the ozone production and decomposition region. Even if an ozone molecule absorbs low-energy ultraviolet radiation, it can break down into oxygen molecules and free oxygen atoms.

The main chemical substances that destroy ozone are compounds containing hydrogen, nitrogen, chlorine, and bromine. If one of the roots, such as HOx, ClOx, NOx, or BrOx, is removed, the general reaction destroying ozone can be shown as:

X + O3 → XO + O2
XO + O → X + O2
— --
O + O3 → O2 + O2

It should be noted that a single catalyst can destroy thousands of ozone molecules. Especially, the catalytic effect of ClOx and BrOx plays a major role in ozone destruction in the lower stratosphere.

Br

O + ClO → Br + Cl + O2
Br + O3 → BrO + O2
Cl + O3 → ClO + O2
— --
2O3 → 3O2

The mechanism by which chlorine (Cl) atoms break down and destroy ozone molecules.

Major Chemical Compounds That Destroy Ozone and Their Properties

The main chemical compounds that destroy ozone are chlorofluorocarbons (CFC2), carbon tetrachloride, methyl chloroform, methane, and nitrogen oxides, which are widely used in industry (Table 2). Their usage, share, and atmospheric lifespans are provided in the following table.

The thinning of the ozone layer means that more UV radiation reaches the Earth's surface. Therefore, ozone absorbs most of the UV-B radiation and protects the biosphere, playing a vital role in our environment.

All theoretical and experimental studies show that...