Quantitative assessment of reactive surface area of phlogopite during acid dissolution

Science

Volumn 285, Issue 5429, 1999, Pages 874-876

  Rufe, Eric ^a   Hochella Jr , Michael F ^a  

^a VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

SILICATE;

DISSOLUTION; PHLOGOPITE; SILICATE; SURFACE LAYER;

ANALYTIC METHOD; ARTICLE; CHEMICAL ANALYSIS; CHEMICAL REACTION KINETICS; DISSOLUTION; HYDRATION; LEACHING; PH; PRIORITY JOURNAL; QUANTITATIVE ASSAY; REACTION ANALYSIS; SOIL POLLUTION; SURFACE PROPERTY; TEMPERATURE SENSITIVITY;

EID: 0033529532     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.285.5429.874     Document Type: Article

References (28)

1. S. L. Brantley and Y. Chen, in Chemical Weathering Rates of Silicate Minerals, vol. 31 of Reviews in Mineralogy. A. F. White and S. L. Brantley, Eds. (Mineralogical Society of America, Washington, DC, 1995), chap. 4; A. F. White and M. L. Peterson, in Chemical Modeling of Aqueous Systems II, vol. 416 of ACS Symposium Series, D. C. Melchior and R. L. Bassett, Eds. (American Chemical Society, Washington, DC, 1990), chap. 35.
2. S. L. Brantley and Y. Chen, in Chemical Weathering Rates of Silicate Minerals, vol. 31 of Reviews in Mineralogy. A. F. White and S. L. Brantley, Eds. (Mineralogical Society of America, Washington, DC, 1995), chap. 4; A. F. White and M. L. Peterson, in Chemical Modeling of Aqueous Systems II, vol. 416 of ACS Symposium Series, D. C. Melchior and R. L. Bassett, Eds. (American Chemical Society, Washington, DC, 1990), chap. 35.
3. Some authors define reactive surface area as the area occupied by high-energy sites, such as defects and dislocation outcrops [W. H. Casey, M. J. Carr, R. A. Graham, Geochim. Cosmochim. Acta 52, 1545 (1988)] . In surface complexation modeling, reactive sites consist of particular atomic arrangements where ligand adsorption and activated complex formation occur [C. M. Koretsky, D. A. Sverjensky, N. Sahai, Am. J. Sci. 298, 349 (1998)]. Microscopic studies of the mineral-solution interface indicate that coordinatively unsaturated microtopographic configurations, such as kinks and steps, consist of the most reactivè portion of a mineral surface [M. F. Hochella Jr., in Mineral Surfaces, vol. 5 of Mineralogical Society Series, D. J. Vaughan and R. A. D. Pattrick, Eds. (Chapman & Hall, New York, 1995), chap. 2]. In field-based studies, reactive surface area is the portion of the total mineral surface area that is in hydrologic contact with the system under study [J. I. Drever and D. W. Clow, in Chemical Weathering Rates of Silicate Minerals, vol. 31 of Reviews in Mineralogy, A. F. White and S. L. Brantley. Eds. (Mineralogical Society of America, Washington, DC, 1995), chap. 10].
4. Some authors define reactive surface area as the area occupied by high-energy sites, such as defects and dislocation outcrops [W. H. Casey, M. J. Carr, R. A. Graham, Geochim. Cosmochim. Acta 52, 1545 (1988)] . In surface complexation modeling, reactive sites consist of particular atomic arrangements where ligand adsorption and activated complex formation occur [C. M. Koretsky, D. A. Sverjensky, N. Sahai, Am. J. Sci. 298, 349 (1998)]. Microscopic studies of the mineral-solution interface indicate that coordinatively unsaturated microtopographic configurations, such as kinks and steps, consist of the most reactivè portion of a mineral surface [M. F. Hochella Jr., in Mineral Surfaces, vol. 5 of Mineralogical Society Series, D. J. Vaughan and R. A. D. Pattrick, Eds. (Chapman & Hall, New York, 1995), chap. 2]. In field-based studies, reactive surface area is the portion of the total mineral surface area that is in hydrologic contact with the system under study [J. I. Drever and D. W. Clow, in Chemical Weathering Rates of Silicate Minerals, vol. 31 of Reviews in Mineralogy, A. F. White and S. L. Brantley. Eds. (Mineralogical Society of America, Washington, DC, 1995), chap. 10].
5. Some authors define reactive surface area as the area occupied by high-energy sites, such as defects and dislocation outcrops [W. H. Casey, M. J. Carr, R. A. Graham, Geochim. Cosmochim. Acta 52, 1545 (1988)] . In surface complexation modeling, reactive sites consist of particular atomic arrangements where ligand adsorption and activated complex formation occur [C. M. Koretsky, D. A. Sverjensky, N. Sahai, Am. J. Sci. 298, 349 (1998)]. Microscopic studies of the mineral-solution interface indicate that coordinatively unsaturated microtopographic configurations, such as kinks and steps, consist of the most reactivè portion of a mineral surface [M. F. Hochella Jr., in Mineral Surfaces, vol. 5 of Mineralogical Society Series, D. J. Vaughan and R. A. D. Pattrick, Eds. (Chapman & Hall, New York, 1995), chap. 2]. In field-based studies, reactive surface area is the portion of the total mineral surface area that is in hydrologic contact with the system under study [J. I. Drever and D. W. Clow, in Chemical Weathering Rates of Silicate Minerals, vol. 31 of Reviews in Mineralogy, A. F. White and S. L. Brantley. Eds. (Mineralogical Society of America, Washington, DC, 1995), chap. 10].
6. Some authors define reactive surface area as the area occupied by high-energy sites, such as defects and dislocation outcrops [W. H. Casey, M. J. Carr, R. A. Graham, Geochim. Cosmochim. Acta 52, 1545 (1988)] . In surface complexation modeling, reactive sites consist of particular atomic arrangements where ligand adsorption and activated complex formation occur [C. M. Koretsky, D. A. Sverjensky, N. Sahai, Am. J. Sci. 298, 349 (1998)]. Microscopic studies of the mineral-solution interface indicate that coordinatively unsaturated microtopographic configurations, such as kinks and steps, consist of the most reactivè portion of a mineral surface [M. F. Hochella Jr., in Mineral Surfaces, vol. 5 of Mineralogical Society Series, D. J. Vaughan and R. A. D. Pattrick, Eds. (Chapman & Hall, New York, 1995), chap. 2]. In field-based studies, reactive surface area is the portion of the total mineral surface area that is in hydrologic contact with the system under study [J. I. Drever and D. W. Clow, in Chemical Weathering Rates of Silicate Minerals, vol. 31 of Reviews in Mineralogy, A. F. White and S. L. Brantley. Eds. (Mineralogical Society of America, Washington, DC, 1995), chap. 10].
7. G. Jordan and W. Ramansee, Geochim. Cosmochim. Acta 60, 5055 (1996); Y. Liang, D. R. Baer, J. M. McCoy, J. E. Amonette, J. P. LaFemina, ibid., p. 4883; A. Putnis, J. L. Junta-Rosso, M. F. Hochella Jr., ibid. 59, 4623 (1995).
8. G. Jordan and W. Ramansee, Geochim. Cosmochim. Acta 60, 5055 (1996); Y. Liang, D. R. Baer, J. M. McCoy, J. E. Amonette, J. P. LaFemina, ibid., p. 4883; A. Putnis, J. L. Junta-Rosso, M. F. Hochella Jr., ibid. 59, 4623 (1995).
9. G. Jordan and W. Ramansee, Geochim. Cosmochim. Acta 60, 5055 (1996); Y. Liang, D. R. Baer, J. M. McCoy, J. E. Amonette, J. P. LaFemina, ibid., p. 4883; A. Putnis, J. L. Junta-Rosso, M. F. Hochella Jr., ibid. 59, 4623 (1995).
10. Real-time in situ dissolution of clay particles has been observed with AFM (D. Bosbach et al., in preparation).
11. 4 tips. Several images were collected in succession and compared to check for scanner drift and tip-induced erosion. XPS measurements were performed with a PHI 5400 x-ray photoelectron spectroscopy system (Perkin-Elmer, Eden Prairie, MN) using Al Kα radiation (1466.6 eV). Measurements were collected at 0°, 55°, and 75°, corresponding to approximate depths of analysis of 8.0, 4.5, and 2.0 nm, respectively [M. F. Hochella Jr. and A. H. Carim, Surf. Sci. 197, L260 (1988)]. LEED spot patterns were collected with four-grid reverse-view LEED optics (OMICRON, Taunusstein, Germany) at beam energies between 50 and 150 eV.
12. M. Malmstrom and S. Banwort, Geochim. Cosmochim. Acta 61, 2779 (1997).
13. B. E. Kalinowski and P. Schweda, ibid. 60, 367 (1996).
14. J. G. Acker and O. P. Bricker, ibid. 56, 3073 (1992).
15. See a review by K. L. Nagy, in Chemical Weathering Rates of Silicate Minerals, vol. 31 of Reviews in Mineralogy, A. F. White and S. L. Brantley, Eds. (Mineralogical Society of America, Washington, DC, 1995), chap. 5, and references therein.
16. In a comparative study of the reactivity of different surfaces on biotite, the edges were found to dissolve ∼250 times as fast as the basal surfaces [M.-P. Turpault and L. Trotignon, Geochim. Cosmochim. Acta 58, 2761 (1994)].
17. 2O. XPS analysis shows no increase in F content of the near surface, and all atomic ratios remain the same as those of unetched phlogopite, indicating that HF is not entering the structure. The LEED pattern is consistent with freshly cleaved phlogopite.
18. -1 with a low-flow peristaltic pump. Pumping was suspended during AFM image acquisition. When not imaging, the tip was withdrawn. Image quality degrades within 24 to 48 hours at pH 5.7, precluding long-term in situ experiments at this pH.
19. M. F. Hochella Jr., J. F. Rakovan, K. M. Rosso, B. R. Bickmore, E. Rufe, in Mineral-Water Interfacial Reactions: Kinetics and Mechanisms, vol. 715 of ACS Symposium Series, D. C. Sparks and T. J. Grundl. Eds. (American Chemical Society, Washington, DC, 1998), pp. 37-56.
20. This is achieved by using standard image analysis routines to measure the area, perimeter, and volume for each etch pit imaged. [J. C. Russ, The Image Processing Handbook (CRC Press, Ann Arbor, MI, ed. 3, 1995)].
21. Etch pit dimensions and dissolution rates are available at www.sciencemag.org/feature/data/1040546.shl.
22. A. Nonaka [J. Colloid Interface Sci. 99, 335 (1984)] reports a roughness value (that is, ratio of BET surface area to geometric surface area) for mica of 1.08, so this estimate of BET-equivalent area should be reasonable.
23. A high flow rate coupled with a slow dissolution rate prevents saturation with respect to secondary phases at pH 2. Reaching saturation with respect to amorphous silica, for example, would require > 100 layers of phlogopite to dissolve in static fluid filling the 0.03-ml fluid cell.
24. At 55°, Mg/Si decreases from 1.0 to 0.25, and Al/Si decreases from 0.33 to 0.21. K 2p and F 1s peaks are not discernable above the background. Si/O increases from 0.22 to 0.49.
25. W. H. Casey and B. Bunker, in Mineral-Water Interface Geochemistry, vol. 23 of Reviews in Mineralogy, M. F. Hochella Jr. and A. F. White, Eds. (Mineralogical Society of America, Washington, DC, 1990), chap. 10.
26. H. Kaviratna and T. J. Pinnavaia, Clays Clay Miner. 42, 717 (1994).
27. M. F. Hochella Jr. and J. F. Banfield, in Chemical Weathering Rates of Silicate Minerals, vol. 31 of Reviews in Mineralogy, A. F. White and S. L. Brantley, Eds. (Mineralogical Society of America, Washington, DC, 1995), chap. 8.
28. We thank U. Becker, B. R. Bickmore, D. Bosbach, J. D. Rimstidt, J. L. Rosso, and K. M. Rosso for helpful discussions. We also thank B. R. Bickmore for developing some of the image analysis routines used in this study. The phlogopite sample was obtained from the Museum of Geological Sciences at Virginia Tech (sample HB-1246). Funding for this research was generously provided by the Petroleum Research Fund, administered by the American Chemical Society (grants PRF 31598-AC2 and 34326-AC2) and NSF (grants EAR-9527092 and EAR-9628023). This manuscript benefited from two anonymous reviewers.