Ozone, in its pure form, has a neutral pH of approximately 7.0. This means it is neither acidic nor basic. Importantly, this refers to ozone gas itself and not ozone dissolved in water.
Ozone and Water pH
While ozone itself has a neutral pH, its interaction with water can influence the water's pH depending on other factors present. Research indicates that ozonation, the process of introducing ozone into water, can lead to changes in the structure of organic matter in the water, impacting its overall pH. For example, studies have shown changes in the water's pH after ozonation at various pH levels (6-10). However, it's crucial to understand that ozone itself doesn't directly change the pH; the changes observed are due to the reactions of ozone with other substances in the water.
- Example: Ozonation at pH 6-10 resulted in complete oxidation of humic acids and increased the hydrophilic fraction of natural organic matter. While this changes the water's characteristics, including its pH, the pH of the ozone itself remains around 7.0.
Measuring Ozone and pH
Specialized sensors exist for simultaneously measuring residual ozone, pH, and temperature in water systems, demonstrating the importance of considering both parameters in water treatment and analysis. These measurements often comply with established standards such as USEPA 334.0 and ISO-7393.
Conclusion
The pH of ozone gas is approximately 7.0, neutral. Its effects on the pH of water are indirect and depend on the water's existing composition and the ozonation process.
