Bleaching with Ozone:

Ozone is a very powerful oxidizing agent and having very good bleaching agent. It is very common for bleaching of  wood pulp. Following are some facts and properties of Ozone:

i)             Ozone is prepared by passing electric discharge through cold and dry oxygen and is highly unstable, thus liberates [O]. The nascent oxygen is a powerful oxidizing agent. It oxidizes organic matter and kills bacteria. Ozone acts as a sterilizer. When 2—3  of ozone is injected into the water, the water gets sterilized within 10-15 min. The only disadvantage of this method is that it is very expensive.

                                              Ozone sterilizer

ii)            Ozone is a pale blue gas, slightly soluble in water and much more soluble in inert non-polar solvents such as carbon tetrachloride or fluorocarbons, where it forms a blue solution. Most people can detect about 0.01 ppm of ozone in air where it has a very specific sharp odor.

iii)           Ozone is one of the strongest oxidizing agents known, exceeded in electronegative oxidation potential by F₂ and the oxygen atom, far stronger than O₂ .

iv)           Ozone is formed from oxygen in a strongly  endothermic reaction and decomposes easily into molecular and atomic oxygen, with a half-life of about half an hour in atmospheric conditions. Ozone can be generated from oxygen, air or from other N2/O2 mixtures. The first step towards ozone formation in gas discharges is the dissociation of O2 molecules by electron impact

In the commercial production, ozone generator, in which cylindrical discharge tubes are used.  Large ozone generators use several hundred discharge tubes.  Large ozone generating facilities produce several hundred kg ozone per hour at a power consumption of several megawatts. The capacity of a big ozone generator is up to 100 kg/h. The main applications are in water treatment and in pulp bleaching

Denim Jean bleaching using Ozone:

Reduce chemical cost. Does not damage denim Short process time Reduce the operational cost  Does not leave any chemical residue on the surface.