|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
1 Department of Geological Sciences, 4044 Derring Hall, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, U.S.A.
2 Institut für Mineralogie, Universität Münster, Corrensstrasse 24, 48149 Münster, Germany
3 Environmental Geochemistry Group, L.G.I.T., B.P. 53, F-38041 Grenoble Cedex 9, France
The dissolution behavior of two smectite minerals, hectorite (trioctahedral) and nontronite (dioctahedral), was observed in situ, in acid solutions, using atomic force microscopy. As expected, the crystallites dissolved inward from the edges, and the basal surfaces appeared to be unreactive during the timescale of the experiments. The hectorite (010) faces appeared to dissolve about 6x more slowly than the lath ends, usually broken edges. The edges visibly dissolved on all sides, and appeared to roughen somewhat. On the other hand, the (010), (110), and (1
0) faces on nontronite crystals were exceptionally stable, so that any dissolution fronts originating at broken edges or defects would quickly become pinned along these faces, after which no more dissolution was observable. These observations can be explained by using periodic bond chain theory to predict the topology of the surface functional groups on the edge faces of these minerals. If a certain amount of predicted surface relaxation is allowed on the (110) and (10) faces of nontronite, an important difference between the exceptionally stable faces and the others becomes apparent. That is, the oxygen sites connecting the octahedral and tetrahedral sheets are all fully bonded on the nontronite (010), (110), and (10) edge faces, whereas all hectorite edge faces and nontronite broken edges would have coordinatively unsaturated connecting O atoms. This explanation for the differential reactivity of these crystal faces implies that the rate limiting step of the dissolution process is the breaking of bonds to connecting O atoms.
This article has been cited by other articles:
|
|
 |
|
  Y. Kuwahara In situ observations of muscovite dissolution under alkaline conditions at 25-50 {degrees}C by AFM with an air/fluid heater system American Mineralogist, July 1, 2008; 93(7): 1028 - 1033. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. FERRAGE, G. SEINE, A.-C. GAILLOT, S. PETIT, P. DE PARSEVAL, A. BOUDET, B. LANSON, J. FERRET, and F. MARTIN Structure of the {001} talc surface as seen by atomic force microscopy: comparison with X-ray and electron diffraction results European Journal of Mineralogy, August 1, 2006; 18(4): 483 - 491. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Kuwahara In-situ AFM study of smectite dissolution under alkaline conditions at room temperature American Mineralogist, July 1, 2006; 91(7): 1142 - 1149. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. MEUNIER Why are clay minerals small? Clay Minerals, June 1, 2006; 41(2): 551 - 566. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Pieper, D. Bosbach, P. J. Panak, T. Rabung, and T. Fanghanel Eu(III) COPRECIPITATION WITH THE TRIOCTAHEDRAL CLAY MINERAL, HECTORITE Clays and Clay Minerals, February 1, 2006; 54(1): 45 - 53. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Yokoyama, M. Kuroda, and T. Sato ATOMIC FORCE MICROSCOPY STUDY OF MONTMORILLONITE DISSOLUTION UNDER HIGHLY ALKALINE CONDITIONS Clays and Clay Minerals, April 1, 2005; 53(2): 147 - 154. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. V. Guidotti, F. P. Sassi, P. Comodi, P. F. Zanazzi, and J. G. Blencoe SLATY CLEAVAGE: DOES THE CRYSTAL CHEMISTRY OF LAYER SILICATES PLAY A ROLE IN ITS DEVELOPMENT? Can Mineral, February 1, 2005; 43(1): 311 - 325. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. P. S. Krekeler, E. Hammerly, J. Rakovan, and S. Guggenheim MICROSCOPY STUDIES OF THE PALYGORSKITE-TO-SMECTITE TRANSFORMATION Clays and Clay Minerals, February 1, 2005; 53(1): 92 - 99. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M.-C. Jodin, M.-C. Jodin, F. Gaboriaud, and B. Humbert Repercussions of size heterogeneity on the measurement of specific surface areas of colloidal minerals: Combination of macroscopic and microscopic analyses American Mineralogist, October 1, 2004; 89(10): 1456 - 1463. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Aldushin, K. Aldushin, G. Jordan, M. Fechtelkord, W. W. Schmahl, H.-W. Becker, and W. Rammensee ON THE MECHANISMS OF APOPHYLLITE ALTERATION IN AQUEOUS SOLUTIONS. A COMBINED AFM, XPS AND MAS NMR STUDY Clays and Clay Minerals, August 1, 2004; 52(4): 432 - 442. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. P. S. Krekeler, S. Guggenheim, and J. Rakovan A MICROTEXTURE STUDY OF PALYGORSKITE-RICH SEDIMENTS FROM THE HAWTHORNE FORMATION, SOUTHERN GEORGIA, BY TRANSMISSION ELECTRON MICROSCOPY AND ATOMIC FORCE MICROSCOPY Clays and Clay Minerals, June 1, 2004; 52(3): 263 - 274. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. R. Bickmore, B. R. Bickmore, K. M. Rosso, K. L. Nagy, R. T. Cygan, and C. J. Tadanier AB INITIO DETERMINATION OF EDGE SURFACE STRUCTURES FOR DIOCTAHEDRAL 2:1 PHYLLOSILICATES: IMPLICATIONS FOR ACID-BASE REACTIVITY Clays and Clay Minerals, August 1, 2003; 51(4): 359 - 371. [Abstract] [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
