Details
| Original language | English |
|---|---|
| Pages (from-to) | 150-160 |
| Number of pages | 11 |
| Journal | Colloids and Surfaces A: Physicochemical and Engineering Aspects |
| Volume | 431 |
| Publication status | Published - Aug 2013 |
Abstract
The effect of grain water repellency on transport and deposition of hydrophilic colloids was studied by analyzing the breakthrough behavior of carboxylate-modified microspheres in water-saturated wettable and hydrophobic sand columns at different ionic strengths. Interaction free energies calculated from zeta (ζ)-potential and contact angle data were used to explain the specific colloid breakthrough behavior. Experimental breakthrough data could be well described with the finite-element code HYDRUS-1D using a one kinetic site model with attachment and detachment kinetics. Higher colloid deposition rates found for the hydrophobic sand could primarily be explained by its small electron-donor component of surface free energy (γs-=1.6×10-2mJm-2, compared to γs-=64.1mJm-2 for the wettable sand), leading to strongly attractive acid-base interactions at separation distances<5nm. Increasing ionic strength reduced the repulsive electrostatic interactions and generally increased colloid deposition with the effect being more pronounced in the hydrophobic sand. It can be concluded that grain water repellency tends to increase the deposition of negatively charged hydrophilic colloids, which can be ascribed to specific acid-base interactions. However, our results further revealed that the calculated interaction free energy profiles should be considered only as an approximation showing general trends because surface chemical heterogeneity as detected by atomic forces microscopy impeded the determination of the actual interaction energy conditions, resulting in an overestimation of electrostatic repulsion.
Keywords
- Acid-base interaction, Carboxylate-modified microspheres, Colloid breakthrough, Interaction free energy, Surface free energy components, Wettability
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Chemistry(all)
- Physical and Theoretical Chemistry
- Chemical Engineering(all)
- Colloid and Surface Chemistry
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In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 431, 08.2013, p. 150-160.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Water repellency enhances the deposition of negatively charged hydrophilic colloids in a water-saturated sand matrix
AU - Goebel, Marc O.
AU - Woche, Susanne K.
AU - Abraham, Priya M.
AU - Schaumann, Gabriele E.
AU - Bachmann, Jörg
N1 - Funding Information: Financial support provided by the German Research Foundation DFG (Priority program SPP 1315, BA1359/9 and SCHA849/8) for this study is greatly appreciated. We also would like to thank three anonymous reviewers for their constructive comments and valuable suggestions on an earlier version of the manuscript. Copyright: Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2013/8
Y1 - 2013/8
N2 - The effect of grain water repellency on transport and deposition of hydrophilic colloids was studied by analyzing the breakthrough behavior of carboxylate-modified microspheres in water-saturated wettable and hydrophobic sand columns at different ionic strengths. Interaction free energies calculated from zeta (ζ)-potential and contact angle data were used to explain the specific colloid breakthrough behavior. Experimental breakthrough data could be well described with the finite-element code HYDRUS-1D using a one kinetic site model with attachment and detachment kinetics. Higher colloid deposition rates found for the hydrophobic sand could primarily be explained by its small electron-donor component of surface free energy (γs-=1.6×10-2mJm-2, compared to γs-=64.1mJm-2 for the wettable sand), leading to strongly attractive acid-base interactions at separation distances<5nm. Increasing ionic strength reduced the repulsive electrostatic interactions and generally increased colloid deposition with the effect being more pronounced in the hydrophobic sand. It can be concluded that grain water repellency tends to increase the deposition of negatively charged hydrophilic colloids, which can be ascribed to specific acid-base interactions. However, our results further revealed that the calculated interaction free energy profiles should be considered only as an approximation showing general trends because surface chemical heterogeneity as detected by atomic forces microscopy impeded the determination of the actual interaction energy conditions, resulting in an overestimation of electrostatic repulsion.
AB - The effect of grain water repellency on transport and deposition of hydrophilic colloids was studied by analyzing the breakthrough behavior of carboxylate-modified microspheres in water-saturated wettable and hydrophobic sand columns at different ionic strengths. Interaction free energies calculated from zeta (ζ)-potential and contact angle data were used to explain the specific colloid breakthrough behavior. Experimental breakthrough data could be well described with the finite-element code HYDRUS-1D using a one kinetic site model with attachment and detachment kinetics. Higher colloid deposition rates found for the hydrophobic sand could primarily be explained by its small electron-donor component of surface free energy (γs-=1.6×10-2mJm-2, compared to γs-=64.1mJm-2 for the wettable sand), leading to strongly attractive acid-base interactions at separation distances<5nm. Increasing ionic strength reduced the repulsive electrostatic interactions and generally increased colloid deposition with the effect being more pronounced in the hydrophobic sand. It can be concluded that grain water repellency tends to increase the deposition of negatively charged hydrophilic colloids, which can be ascribed to specific acid-base interactions. However, our results further revealed that the calculated interaction free energy profiles should be considered only as an approximation showing general trends because surface chemical heterogeneity as detected by atomic forces microscopy impeded the determination of the actual interaction energy conditions, resulting in an overestimation of electrostatic repulsion.
KW - Acid-base interaction
KW - Carboxylate-modified microspheres
KW - Colloid breakthrough
KW - Interaction free energy
KW - Surface free energy components
KW - Wettability
UR - http://www.scopus.com/inward/record.url?scp=84878376705&partnerID=8YFLogxK
U2 - 10.1016/j.colsurfa.2013.04.038
DO - 10.1016/j.colsurfa.2013.04.038
M3 - Article
AN - SCOPUS:84878376705
VL - 431
SP - 150
EP - 160
JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects
JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects
SN - 0927-7757
ER -