V. Baratharaj
July 5, 2016

Poly propylene belongs to a class of plastics that are termed Thermoplastic materials. The other group of plastics is the thermosetting plastics. They find numerous uses in Industries and each type of plastics are used for different purposes dependent on the physical and chemical properties of each.

The effects of ozone on each of these materials will depend totally on the configuration of the polymers that make up the plastics. Crossed linked plastics such as poly propylene, poly- ethylene, poly-vinyl chloride and silicon or fluorine combined plastics are sufficiently impervious to ozone to enable their use in direct contact.

Most of the mineral water plants all over the world use plastics in some form or the other and the knowledge of each of these will help understand the likely effects with the use of ozone.

Studies have revealed that some forms of polymers are readily attacked by ozone and are not recommended, there are other forms that are quite resistant and take a longer time for effects of ozone.

For example, silicon, teflon is some materials that are used safely with ozone. However the long terms effects of these are normally later than the useful life of the materials. Hence all the ozone generator parts that are in contact with ozone are normally made up of these materials.

Since most of the mineral water manufacturers prefer residual ozone, and they invariably use PET bottles, poly-carbonate jars, PP filters, that are all polymer materials, the question of whether they are safe with ozone is frequently asked. The effects of ozone in the long run (several years) could unzip some of these polymers to form by-products, but they are all dose, concentration and time related, and that invariably the effects are noted after the useful life of these materials are surpassed.

For example poly-carbonate has been shown to be very resistant to UV and like water is classified as a universal solvent. Ozone can also be classified as a universal reactant - the only question is how much does it reacts. Through practical experience, it is very insignificant. For that matter, ozone is also supposed to be corrosive to stainless steel. But the corrosion is concentration and time related and therefore stainless steel is regarded safe with the use of ozone. In fact many ordinary plastics that give out smell (the popular PVC tank) can also be held suspicious, more than ozone which imparts no flavor to the water. The action of ozone on plastics also depends on whether ozone is used as a gas or solution. Nylon appears to break down faster when in contact with ozone-air mixture than ozone solution.

In fact the use of chlorine as a disinfectant produces more harmful by-products in the water which are proven carcinogen, but we rarely question this fact as we believe that chlorine cannot be substituted. In spite of this knowingly chlorine is still being used. There are reported incidences that chlorine by products are still present in the water in-spite of the use of the best activated carbon filters .The use of ozone therefore is much safer in as much as many of its by-products have not been identified and proven toxic. The benefits of the use of ozone outweigh some of the reported and unproven toxic effects.

V. Baratharaj V. Baratharaj is Head, Ozone Technologies & Systems India Pvt Ltd. He can be reached at, and +91 44 4211 8266.

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