Details
| Original language | English |
|---|---|
| Pages (from-to) | 5406-5411 |
| Number of pages | 6 |
| Journal | Applied Surface Science |
| Volume | 256 |
| Issue number | 17 |
| Publication status | Published - 4 Jan 2010 |
| Externally published | Yes |
Abstract
We have carried out streaming current measurements of sapphire c-plane single crystals in contact with the solutions containing the Al 13 -ε-Keggin ions at different pH values. We followed the evolution of the zeta-potential as a function of time and pH. The Keggin ions were synthesised and characterised by ESI-MS in two different laboratories, and the results showed that nearly 100% of Al was in the form of Al 13 cluster. The streaming current measurements were carried out to investigate whether Al 13 clusters would (i) be adsorbed to the surface and (ii) remain stable. Close to the isoelectric point of the sapphire c-plane (around pH 4) it was found that the Al 13 ions were adsorbed and stable in the systems for an extended period. After some time the conductivity of the solution strongly increased and the zeta-potential declined, indicating that the clusters were destroyed (certainly in solution, as indicated by the conductivity reading, but potentially also at the surface). ESI-MS measurements at various dilution factors or decreased pH also showed disintegration of the clusters resulting in a multitude of smaller Al species, in agreement with the conductivity measurements during the streaming current measurements. Additions at higher pH showed clear adsorption of the clusters but resulted in stability over the complete observation period as inferred from the conductivity measurements.
Keywords
- ESI-MS, Isoelectric point, Sapphire c-plane, Single crystals, Speciation, Zeta-potential
ASJC Scopus subject areas
- Chemistry(all)
- General Chemistry
- Physics and Astronomy(all)
- Condensed Matter Physics
- Physics and Astronomy(all)
- General Physics and Astronomy
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Materials Science(all)
- Surfaces, Coatings and Films
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In: Applied Surface Science, Vol. 256, No. 17, 04.01.2010, p. 5406-5411.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Adsorption of Al 13 -Keggin clusters to sapphire c-plane single crystals
T2 - Kinetic observations by streaming current measurements
AU - Lützenkirchen, J.
AU - Kupcik, T.
AU - Fuss, M.
AU - Walther, Clemens
AU - Sarpola, A.
AU - Sundman, O.
PY - 2010/1/4
Y1 - 2010/1/4
N2 - We have carried out streaming current measurements of sapphire c-plane single crystals in contact with the solutions containing the Al 13 -ε-Keggin ions at different pH values. We followed the evolution of the zeta-potential as a function of time and pH. The Keggin ions were synthesised and characterised by ESI-MS in two different laboratories, and the results showed that nearly 100% of Al was in the form of Al 13 cluster. The streaming current measurements were carried out to investigate whether Al 13 clusters would (i) be adsorbed to the surface and (ii) remain stable. Close to the isoelectric point of the sapphire c-plane (around pH 4) it was found that the Al 13 ions were adsorbed and stable in the systems for an extended period. After some time the conductivity of the solution strongly increased and the zeta-potential declined, indicating that the clusters were destroyed (certainly in solution, as indicated by the conductivity reading, but potentially also at the surface). ESI-MS measurements at various dilution factors or decreased pH also showed disintegration of the clusters resulting in a multitude of smaller Al species, in agreement with the conductivity measurements during the streaming current measurements. Additions at higher pH showed clear adsorption of the clusters but resulted in stability over the complete observation period as inferred from the conductivity measurements.
AB - We have carried out streaming current measurements of sapphire c-plane single crystals in contact with the solutions containing the Al 13 -ε-Keggin ions at different pH values. We followed the evolution of the zeta-potential as a function of time and pH. The Keggin ions were synthesised and characterised by ESI-MS in two different laboratories, and the results showed that nearly 100% of Al was in the form of Al 13 cluster. The streaming current measurements were carried out to investigate whether Al 13 clusters would (i) be adsorbed to the surface and (ii) remain stable. Close to the isoelectric point of the sapphire c-plane (around pH 4) it was found that the Al 13 ions were adsorbed and stable in the systems for an extended period. After some time the conductivity of the solution strongly increased and the zeta-potential declined, indicating that the clusters were destroyed (certainly in solution, as indicated by the conductivity reading, but potentially also at the surface). ESI-MS measurements at various dilution factors or decreased pH also showed disintegration of the clusters resulting in a multitude of smaller Al species, in agreement with the conductivity measurements during the streaming current measurements. Additions at higher pH showed clear adsorption of the clusters but resulted in stability over the complete observation period as inferred from the conductivity measurements.
KW - ESI-MS
KW - Isoelectric point
KW - Sapphire c-plane
KW - Single crystals
KW - Speciation
KW - Zeta-potential
UR - http://www.scopus.com/inward/record.url?scp=77953131294&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2009.12.095
DO - 10.1016/j.apsusc.2009.12.095
M3 - Article
AN - SCOPUS:77953131294
VL - 256
SP - 5406
EP - 5411
JO - Applied Surface Science
JF - Applied Surface Science
SN - 0169-4332
IS - 17
ER -