Does the pH level in ethylene glycol change over time?

The pH of pure ethylene glycol is typically around 7, which is neutral. However, the pH level of ethylene glycol can change over time due to several factors, including:

1. Environmental Conditions: Ethylene glycol is hygroscopic, meaning it readily absorbs moisture from the surrounding environment. When exposed to air, it can absorb carbon dioxide (CO2) from the atmosphere, which can cause a slight decrease in pH, making it more acidic.

2. Contaminants: If ethylene glycol comes into contact with certain impurities or contaminants, such as metal ions, acids, or bases, the pH can change significantly. For instance, the presence of iron or copper ions can catalyze oxidation reactions, leading to the formation of acidic byproducts and a decrease in pH.

3. Temperature and Storage Conditions: The pH of ethylene glycol may also be influenced by temperature and storage conditions. Extreme temperatures or prolonged storage can lead to the degradation of ethylene glycol, resulting in the formation of acidic compounds and a decrease in pH.

It's important to note that the rate of pH change in ethylene glycol depends on various factors, including the concentration of ethylene glycol, the extent of exposure to environmental conditions, the presence of contaminants, and the temperature and storage conditions. In general, properly stored and pure ethylene glycol should exhibit a stable pH over time, but monitoring and regular testing are recommended to ensure its quality and suitability for specific applications.