Probing size-dependent electrokinetics of hematite aggregates
Karolina Kedra-Królik1, Kevin M Rosso2, Piotr Zarzycki1
1Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
Journal of Colloid and Interface Science
|November 12, 2016
Summary
This study reveals that particle size significantly impacts electrostatic surface potential in aqueous suspensions. Analyzing electrophoretic mobility distributions provides new insights into particle electrokinetics and acidity.
Area of Science:
- Surface chemistry
- Colloid and interface science
- Materials science
Background:
- Aqueous particle suspensions are stabilized by surface electrostatic potentials.
- The relationship between particle size and surface potential is not fully understood.
- Zeta Potential Analyzers (ZPAs) measure electrophoretic mobility but typically report only peak values.
Purpose of the Study:
- To develop a method for analyzing electrophoretic mobility and hydrodynamic diameter histograms from ZPAs.
- To investigate the dependence of electrokinetic potential (ζ-potential) on particle size.
- To explore the impact of particle size on the surface chemistry of iron (III) oxide (hematite).
Main Methods:
- Developed a histogram inter-correlation mapping procedure.
- Applied the method to aqueous suspensions of iron (III) oxide (hematite, α-Fe2O3).
- Analyzed the distribution of surface site types as a function of aggregate size.
Main Results:
- Electrophoretic mobility and ζ-potential showed a linear relationship with aggregate size.
- Site coordination increased with increasing aggregate diameter.
- Particle acidity decreased with increasing particle size.
Conclusions:
- The proposed mapping procedure extracts valuable information from ZPA spectra beyond peak values.
- Increased site coordination with particle size explains the observed decrease in acidity.
- This work provides a new approach to understanding particle size-dependent electrokinetics.
