Ozone

Ozone is an unstable allotropic form of oxygen that is made up of three oxygen atoms instead of two; the trio of oxygen atoms is relatively unstable and makes ozone one of the strongest oxidising agents, second only to the free hydroxyl radical (-OH). Ozone (O3) is formed from dioxygen (O2) with ultraviolet light acting as a catalyst.

Principle of disinfection

Ozone disinfects fluids and surfaces in a similar manner to advanced oxidation processes, namely, by the generation of free hydroxyl radicals. The process of ozone decomposition is driven by either direct reaction with the water or air, or by the use of hydroxyl radicals; the use of ultraviolet (UV) light privileges the latter, which makes ozone an effective disinfectant. As hydroxyl radicals are highly reactive they voraciously combine with free organic and inorganic particles in the fluid or surface.

Ozone is also produced to effectively de-odourise air. As the half-life of ozone is relatively short it has a natural tendency to donate its extra oxygen atom and revert to its pure form. The free oxygen atom combines with the organic vapours and reduces them to mineral salts and water.

Applications of ozone disinfection and odour removal

Industrially, ozone has conventionally been used to disinfect substances and materials, deodorise air, inactivate bacteria on surfaces, sanitise large bodies of water, kill and remove insects, yeast, mould, chemically bind with compounds in water such as iron, arsenic, hydrogen sulphide, nitrites, and for bleaching.

Characteristics of ozone

Ozone is a rather environmentally friendly method of disinfection when compared with other chemical methods such as chlorination or hypochlorites. In addition, ozone and advanced oxidation processes require relatively little contact time when compared with the aforementioned chemical processes.