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Colloid (Nano- and Micro-Particle) Transport and Surface Interaction in Groundwater

Publication year: 2023
Number of pages: 161
ISBN: 978-1-77470-070-9

Authors:
William P. Johnson: University of Utah, USA
Eddy F. Pazmiño: Escuela Politécnica Nacional, Ecuador

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Released: 4 August 2023

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Colloid (Nano- and Micro-Particle) Transport and Surface Interaction in Groundwater

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Description

The means by which colloid size particles (e.g., pathogens, clays, nanomaterials, nanoplastics, microplastics) move through groundwater—to deeper horizons and longer distances—is an important field of study. Field scale transport and spatial distribution of colloids in groundwater depends on nanoscale interactions with grain surfaces and pore-scale forces such as fluid drag, diffusion, and gravity.

This text provides  both basic and advanced information regarding these interactions and forces. The authors examine how colloid movement can be understood using simulations at nano to field scales. Exercises that utilize numerical modeling freeware are incorporated into the text to allow both newly initiated and advanced researchers to explore the concepts presented by the authors. This book is an important addition to the growing literature on colloid transport in groundwater.

Contents

1 Scope of this Book

1.1 The Need for Multiple Scales

1.2 Knowledge and Misperceptions

1.3 Our Approach

1.4 Our Objectives for this Book

2 Introduction to Groundwater Colloids

2.1 Colloids Defined (The What)

2.2 Colloid Significance (The Why and Where)

2.3 Colloid Transport (The How... and the Rest of this Book)

3 Sizes, Scales, Forces, and Energies

3.1 Sizes and Scales

3.2 Forces and Energies

4 Nanoscale Interactions

4.1 Nanoscale: Solute Interaction with Colloids

4.2 Nanoscale Colloid Interactions with Surfaces

4.2.1 Nanoscale Colloid-Surface Interaction Under Favorable Conditions
4.2.2 Nanoscale Colloid-Surface Interaction Under Unfavorable Conditions
4.2.3 Zone of Colloid-Surface Interaction (ZOI)
4.2.4 DLVO and xDLVO Interactions in Detail

5 Pore Scale Colloid Transport Processes

5.1 Experimentally Observed Pore-Scale Transport Processes

5.1.1 Colloid Motion in Near Surface Fluid Domain in Pore Scale Experiments
5.1.2 Collector Efficiencies in Pore Scale Experiments
5.1.3 Detachment in Pore Scale Experiments
5.1.4 Roughness Impacts in Pore Scale Experiments

5.2 Simulating Pore Scale Colloid Transport

5.2.1 Simulating Pore Scale Colloid Delivery to Surfaces via Mechanistic Force and Torque Balance
5.2.2 Simulating Pore Scale Colloid Attachment (Arrest) via In Contact Torque Balance
5.2.3 Simulating Pore Scale Colloid Detachment
5.2.4 Simulating Pore Scale Colloid Transport Under Unfavorable Conditions
5.2.5 Impacts of Colloid Shape (and Type)

5.3 Short cuts to Pore Scale Colloid Transport Simulation

5.3.1 Correlation Equations as a Shortcut to Collector Efficiency (η)
5.3.2 Perfect Sink Boundary Condition as a Shortcut to In-Contact Torque Balance
5.3.3 Comparison of Arresting and Mobilizing Energies as a Shortcut to Mechanistic Pore Scale Simulations
5.3.4 Retention in and Re-entrainment from Secondary Minima
5.3.5 Straining as a Shortcut Pore-Scale Mechanism for Colloid Retention
5.3.6 Attachment Efficiency (α) as a Shortcut to Unfavorable Collector Efficiencies

5.4 Solute Versus Colloid Transport at the Pore Scale

6 Continuum Scale (Pore Network) Colloid Transport

6.1 Experimentally Observed Continuum-Scale Colloid Transport

6.1.1 Inferring Operating Mechanisms
6.1.2 Macroscale Physical and Chemical Heterogeneity
6.1.3 Experimentally Observed Impacts of Favorable Versus Unfavorable Conditions at the Continuum Scale
6.1.4 Practical Implications of Continuum Scale Experimental Observations

6.2 Simulating Continuum Scale Colloid Transport

6.2.1 Simulated Continuum-Scale Hydrodynamic Processes
6.2.2 Simulated Continuum Scale Reactive Transport Using Rate Coefficients
6.2.3 Mechanistic Linking of Rate Coefficients to Pore- and Nanoscale Processes: Getting under the Hood of Rate Coefficients

7 Wrap Up

8 Exercises

9 References

10 Boxes

Box 1 - Development of Expressions for Hydrodynamic Retardation Factors

Box 2 - Derivation of Colloid Translational Velocity From Rolling on Surface in Response to Arresting and Mobilizing Torques

11 Exercise Solutions

12 Notation List

13 About the Authors

Interview with Author