Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes

Area of Science:

• Environmental Science
• Polymer Science
• Water Quality

Background:

• Organic compounds in soil and groundwater pose risks to drinking water safety.
• Thermoplastic pipes, like high-density polyethylene (HDPE), are widely used but can be permeable to contaminants.

Purpose of the Study:

• To estimate permeation parameters of benzene in HDPE pipes.
• To investigate factors influencing benzene permeation through HDPE pipes.

Main Methods:

• Utilized a permeation model combining equilibrium partitioning and Fick's diffusion.
• Measured benzene permeation data in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 HDPE pipes.
• Simulated permeation curves for different HDPE pipe sizes and thicknesses.

Main Results:

• Determined concentration-dependent diffusion coefficients for benzene (2.0×10⁻⁹ to 2.8×10⁻⁹ cm²/s) and a solubility coefficient (23.7).
• Smaller diameter HDPE pipes (SIDR 9 and SIDR 7) showed greater vulnerability to benzene permeation.
• Increased pipe thickness retarded benzene breakthrough and decreased permeation flux.

Conclusions:

• HDPE pipe diameter and thickness are critical factors in benzene permeation.
• Permeation characteristics differ between instantaneous and continuous contaminant sources.
• Aquifer properties, such as dispersion coefficients, influence benzene transport through HDPE pipes.