Interception History Drives Colloid Transport Variance in Porous Media

Area of Science:

• Environmental science
• Biomedical engineering
• Physical chemistry

Background:

• Colloid transport in porous media traditionally uses exponential decay models based on grains passed.
• Repulsive barriers inhibit attachment, causing nonexponential colloid concentration decay, which current models cannot predict.
• Observed nonexponential trends across experiments indicate a fundamental, yet unaddressed, transport process.

Purpose of the Study:

• To propose a paradigm shift in colloid transport modeling.
• To develop a predictive framework for nonexponential colloid decay.
• To enhance colloid transport prediction in environments with repulsive barriers.

Main Methods:

• Revising the principle of fractional removal from 'per grain passed' to 'per grain interception'.
• Incorporating the history of grain interceptions into the transport model.
• Validating the new framework against experimental data exhibiting nonexponential decay.

Main Results:

• The proposed model accurately predicts nonexponential colloid concentration decay with distance.
• The framework successfully accounts for the influence of repulsive barriers on colloid transport.
• A simple and predictive approach is established by considering interception history.

Conclusions:

• A shift to modeling fractional loss per interception, rather than per grain passed, provides a more accurate colloid transport prediction framework.
• This new perspective enables accurate colloid transport prediction in previously challenging environments, such as those with repulsive barriers.
• The findings have significant implications for groundwater protection and drug delivery systems.