Dissolution Kinetics of Epitaxial Cadmium Carbonate Overgrowths on Dolomite
[1];
[2];
[3];
[2];
[4];
- Univ. of Illinois at Chicago, Chicago, IL (United States); Univ. of California, Los Angeles, CA (United States)
- Argonne National Lab. (ANL), Lemont, IL (United States)
- Univ. of Chicago, Chicago, IL (United States)
- Univ. of Delaware, Newark, DE (United States)
- Univ. of Illinois at Chicago, Chicago, IL (United States)
Thin films grown on mineral surfaces can immobilize toxic metals in natural systems, but the effects of epitaxy and film thickness on dissolution rates of the overgrowth are typically unknown. To explore these effects, otavite (CdCO3) films were grown on dolomite (104) surfaces from aqueous solutions containing [Cd] = [Ca] = [CO3] = 0.2 mM for 1–48 h and then dissolved in deionized water. Films of various thicknesses and strain states were obtained by varying the growth reaction time. Growth for up to 3 h produced strained thin films with Cd coverages of <4.3 ± 0.6 equivalent monolayers (ML) (corresponding to a thickness of up to 17 Å), whereas reaction times of up to 48 h produced thicker films with as many as 114 ± 14 equivalent ML of Cd. Intrinsic dissolution rates were measured as a function of otavite film thickness by a combination of synchrotron X-ray fluorescence, specular X-ray reflectivity, and atomic force microscopy. As a result, the initial dissolution rates for unstrained films were comparable to those reported for synthetic otavite powders, whereas the thinnest films (<3.1 ± 1.1 ML) dissolved at a 50% slower rate, indicating that epitaxial strain effectively enhanced their stability. We discuss potential reasons for this difference.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1496224
- Journal Information:
- ACS Earth and Space Chemistry, Vol. 3, Issue 2; ISSN 2472-3452
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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