Abstract
The properties of clays and oxides govern many environmental processes, consequently, ongoing effort is invested in developing non-destructive, in-situ analytical tools that reflect these properties. Herein, the physicochemical properties of montmorillonite (MMT) and iron-oxide coated montmorillonite (FeOx-MMT) were characterized using common analytical techniques, and the results were compared to spectral induced polarization (SIP) measurements. FeOx-MMT particles showed a lower CEC, higher pH dependency of the surface charge, and lower suspension stability. Also, the size of the primary particles increased following iron-oxide deposition. SIP measurements over a range of salinities showed that the effective polarization length of the clays was in the order of several microns, suggesting the measurements of aggregates (not primary particles). Moreover, FeOx-MMT particles were more compact than MMT, and their size decreased with increasing salinity due to compaction of the EDL and arrangement of primary particles in the aggregate. The SIP-response to pH changes agreed with zeta potential measurements; at low pH values, MMT exhibited higher polarization due to the higher CEC. However, at a high pH, the differences diminish due to deprotonation of the Fe-OH surface groups. These findings suggest that SIP is a sensitive method that can detect changes in the surface chemistry of soil particles.
Original language | American English |
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Pages (from-to) | 173-180 |
Number of pages | 8 |
Journal | Journal of Colloid and Interface Science |
Volume | 577 |
DOIs | |
State | Published - 1 Oct 2020 |
Bibliographical note
Funding Information:This work was supported by the Ministry of Energy and Water Resources Ministry of Israel, Grant # 217-17-022.
Publisher Copyright:
© 2020 Elsevier Inc.
Keywords
- Aggregation
- Clay minerals
- Complex conductivity
- Electrical double layer
- Impedance spectroscopy
- Iron oxides
- Montmorillonite
- Spectral induced polarization