Probing size-dependent electrokinetics of hematite aggregates
Abstract
Aqueous particle suspensions of many kinds are stabilized by the electrostatic potential developed at their surfaces from reaction with water and ions. An important and less well understood aspect of this stabilization is the dependence of the electrostatic surface potential on particle size. Surface electrostatics are typically probed by measuring particle electrophoretic mobilities and quantified in the electrokinetic potential (f), using commercially available Zeta Potential Analyzers (ZPA). Even though ZPAs provide frequency-spectra (histograms) of electrophoretic mobility and hydrodynamic diameter, typically only the maximal-intensity values are reported, despite the information in the remainder of the spectra. Here we propose a mapping procedure that inter-correlates these histograms to extract additional insight, in this case to probe particle size-dependent electrokinetics. Our method is illustrated for a suspension of prototypical iron (III) oxide (hematite, a-Fe2O3). We found that the electrophoretic mobility and f-potential are a linear function of the aggregate size. By analyzing the distribution of surface site types as a function of aggregate size we show that site coordination increases with increasing aggregate diameter. This observation explains why the acidity of the iron oxide particles decreases with increasing particle size.
- Authors:
- Publication Date:
- Research Org.:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 1372971
- Report Number(s):
- PNNL-SA-125768
Journal ID: ISSN 0021-9797; 47824; KC0302060
- DOE Contract Number:
- AC05-76RL01830
- Resource Type:
- Journal Article
- Journal Name:
- Journal of Colloid and Interface Science
- Additional Journal Information:
- Journal Volume: 488; Journal Issue: C; Journal ID: ISSN 0021-9797
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Environmental Molecular Sciences Laboratory
Citation Formats
Kedra-Królik, Karolina, Rosso, Kevin M., and Zarzycki, Piotr. Probing size-dependent electrokinetics of hematite aggregates. United States: N. p., 2017.
Web. doi:10.1016/j.jcis.2016.11.004.
Kedra-Królik, Karolina, Rosso, Kevin M., & Zarzycki, Piotr. Probing size-dependent electrokinetics of hematite aggregates. United States. https://doi.org/10.1016/j.jcis.2016.11.004
Kedra-Królik, Karolina, Rosso, Kevin M., and Zarzycki, Piotr. 2017.
"Probing size-dependent electrokinetics of hematite aggregates". United States. https://doi.org/10.1016/j.jcis.2016.11.004.
@article{osti_1372971,
title = {Probing size-dependent electrokinetics of hematite aggregates},
author = {Kedra-Królik, Karolina and Rosso, Kevin M. and Zarzycki, Piotr},
abstractNote = {Aqueous particle suspensions of many kinds are stabilized by the electrostatic potential developed at their surfaces from reaction with water and ions. An important and less well understood aspect of this stabilization is the dependence of the electrostatic surface potential on particle size. Surface electrostatics are typically probed by measuring particle electrophoretic mobilities and quantified in the electrokinetic potential (f), using commercially available Zeta Potential Analyzers (ZPA). Even though ZPAs provide frequency-spectra (histograms) of electrophoretic mobility and hydrodynamic diameter, typically only the maximal-intensity values are reported, despite the information in the remainder of the spectra. Here we propose a mapping procedure that inter-correlates these histograms to extract additional insight, in this case to probe particle size-dependent electrokinetics. Our method is illustrated for a suspension of prototypical iron (III) oxide (hematite, a-Fe2O3). We found that the electrophoretic mobility and f-potential are a linear function of the aggregate size. By analyzing the distribution of surface site types as a function of aggregate size we show that site coordination increases with increasing aggregate diameter. This observation explains why the acidity of the iron oxide particles decreases with increasing particle size.},
doi = {10.1016/j.jcis.2016.11.004},
url = {https://www.osti.gov/biblio/1372971},
journal = {Journal of Colloid and Interface Science},
issn = {0021-9797},
number = C,
volume = 488,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}