Ethylene Glycol pH: Understanding Changes & Factors

Pure ethylene glycol has a neutral pH (~7). However, pH can shift due to:

1. Environmental Conditions

Ethylene glycol is hygroscopic—it absorbs moisture and atmospheric CO₂, slightly lowering pH (more acidic).

2. Contaminants

Impurities (metal ions, acids, bases) can significantly alter pH. Iron/copper ions catalyze oxidation, forming acidic byproducts that reduce pH.

3. Temperature and Storage

Extreme temperatures or prolonged storage can degrade ethylene glycol, producing acidic compounds and lowering pH.

pH stability depends on concentration, exposure, contaminants, and storage conditions. Properly stored pure ethylene glycol maintains stable pH, but regular monitoring and testing are recommended for quality assurance.