Highly reflective microcrystalline/amorphous materials, and methods for making and using the same
Compositions comprising highly reflective microcrystalline/amorphous materials are provided. In some instances, the highly reflective materials are microcrystalline or amorphous carbonate materials, which may include calcium and/or magnesium carbonate. In some instances, the materials are CO 2 sequestering materials. Also provided are methods of making and using the compositions, e.g., to increase the albedo of a surface, to mitigate urban heat island effects, etc.
1. A method of enhancing the albedo of a surface of a roof shingle surface, the method comprising:
applying to the roof shingle surface a carbonate material so that the carbonate material is present only on the surface of the roof shingle, wherein the carbonate material comprises a CO 2 sequestering carbonate compound that is produced by a method comprising:
(a) contacting a CO 2 containing gas with a bicarbonate buffered aqueous medium having a pH that ranges from 8 to 10 under conditions sufficient to produce a bicarbonate rich product that comprises droplets of a liquid condensed phase (LCP) in a bulk liquid; and
(b) combining the bicarbonate rich product with a cation source under conditions sufficient to produce a solid carbonate composition comprising the CO 2 sequestering carbonate compound.
2. The method according to claim 1 , wherein the bicarbonate buffered aqueous medium has a pH that ranges from 8 to 9.
3. The method according to claim 1 , wherein the bicarbonate buffered aqueous medium is sea water.
4. The method according to claim 1 , wherein the pCO 2 of the CO 2 containing gas in contact with bicarbonate buffered aqueous medium is 10 4 Pa or higher.
5. The method according to claim 1 , wherein the droplets of a liquid condensed phase (LCP) have a diameter ranging from 10 to 100 nm.
6. The method according to claim 1 , wherein the CO 2 containing gas is contacted with the bicarbonate buffered aqueous medium in the presence of a catalyst that mediates the conversion of CO 2 to bicarbonate.
7. The method according to claim 1 , wherein the cation source is a source of divalent cations.
8. The method according to claim 7 , wherein the divalent cations are alkaline earth metal cations.
9. The method according to claim 8 , wherein the divalent alkaline earth metal cations are selected from the group consisting of Ca 2+ and Mg 2+ , and combinations thereof.
10. The method according to claim 1 , wherein the solid carbonate composition is produced without the use of an alkalinity source.
11. The method according to claim 1 , wherein the carbonate material comprises a UV absorber.
12. The method according to claim 1 , wherein the carbonate material applied onto the surface has a thickness of from 0.1 mm to 25 mm.
13. The method according to claim 1 , wherein the carbonate material comprises a granular composition.
14. The method according to claim 13 , wherein the granular composition comprises a pigment.
15. The method according to claim 13 , wherein applying comprises dispensing the granular composition onto the surface.
16. The method according to claim 13 , wherein the granular composition comprises granules ranging in size from 50 μm to 5 mm.
17. The method according to claim 1 , wherein the carbonate material exhibits a near infra-red (NIR) reflectance ranging from Rg;0=0.0 to Rg;0=1.0.
18. The method according to claim 1 , wherein the carbonate material has a hardness ranging from 3 to 8 Mohs.