Carbon nanocomposite sorbent and methods of using the same for separation of one or more materials from a gas stream

1. A promoted carbon nanocomposite sorbent made by a method comprising:

contacting a carbon precursor and a substrate material, wherein the carbon precursor comprises a carbohydrate, wherein the substrate material comprises diatomaceous earth, clay, zeolite, or a combination thereof, to provide a nanocomposite starting material;

heating the nanocomposite starting material, to provide a carbon nanocomposite sorbent; and

promoting at least a portion of the carbon nanocomposite sorbent by chemically reacting the portion of the carbon nanocomposite sorbent with a halogen or halide promoter, wherein the halogen or halide promoter is NH 4 Br, NaBr, CaBr 2 , HBr, or a combination thereof, to form the promoted carbon nanocomposite sorbent;

wherein the carbon nanocomposite sorbent and the promoted carbon nanocomposite sorbent are multiphase solid materials having at least one phase having at least one dimension that is about 1-1000 nm or having a repeat distance separating at least some of the phases of about 1-1000 nm.

2. The promoted nanocomposite sorbent of claim 1 , wherein the carbon precursor comprises brown sugar, barley sugar, caramel, cane sugar, corn syrup, molasses, starch, a sugar waste product, or a combination thereof.

3. The promoted nanocomposite sorbent of claim 1 , wherein the heating comprises heating at about 100° C. to about 1200° C.

4. The promoted carbon nanocomposite sorbent of claim 1 , wherein the halogen or halide promoter is in a form comprising a vapor form, a solid form, in a solvent, or a combination thereof.

5. The promoted carbon nanocomposite sorbent of claim 1 , wherein the halogen or halide promoter comprises at least one of Group V halide, Group VI halide, or a mixture thereof.

6. The promoted carbon nanocomposite sorbent of claim 1 , wherein a promoter precursor transforms into the halogen or halide promoter that reacts with the carbon nanocomposite sorbent.

7. The promoted carbon nanocomposite sorbent of claim 1 , wherein about 1 g to about 30 g of promoter is used per about 100 g of carbon nanocomposite material.

8. The promoted carbon nanocomposite sorbent of claim 1 , wherein the promoted carbon nanocomposite sorbent comprises binding sites formed by reaction or impregnation with the halogen or halide promotor, wherein the binding sites are pollutant-absorbant.

9. The promoted carbon nanocomposite sorbent of claim 1 , wherein the promoted carbon nanocomposite sorbent is pollutant-absorbent in a pollutant-containing gas.

10. The promoted carbon nanocomposite sorbent of claim 9 , wherein the promoted carbon nanocomposite sorbent comprises binding sites that are pollutant-absorbant.

11. The promoted carbon nanocomposite sorbent of claim 9 , wherein the pollutant is mercury.

12. The promoted carbon nanocomposite sorbent of claim 11 , wherein the promoted carbon nanocomposite sorbent is configured to absorb at least about 70 wt % of the mercury present in the mercury-containing gas.

13. A method for reducing the pollutant content of a pollutant-containing gas, comprising:

contacting at least part of the promoted nanocomposite sorbent of claim 1 with the pollutant, to form a pollutant-sorbent composition; and

separating at least some of the pollutant-sorbent composition from the pollutant-containing gas, to give a cleaned gas.

14. The method of claim 13 , wherein at least one of the promoting, the contacting, or the separating occurs in an aqueous scrubber.

15. The method of claim 14 , wherein the promoting occurs in the scrubber, wherein the scrubber comprises an aqueous slurry that comprises the promoter.

16. A promoted carbon nanocomposite sorbent made by a method comprising:

contacting a carbon precursor and a substrate material, to provide a nanocomposite starting material, wherein the carbon precursor comprises a carbohydrate, wherein the substrate material comprises diatomaceous earth, clay, zeolite, or a combination thereof;

heating the nanocomposite starting material, to provide a carbon nanocomposite sorbent; and

promoting at least a portion of the carbon nanocomposite sorbent by chemically reacting the portion of the sorbent material with a halogen or halide promoter, wherein the halogen or halide promoter is NH 4 Br, NaBr, CaBr 2 , HBr, or a combination thereof, to form a promoted carbon nanocomposite sorbent;

wherein

the promoted carbon nanocomposite sorbent is mercury-absorbent in a gas comprising mercury, and

the carbon nanocomposite sorbent and the promoted carbon nanocomposite sorbent are multiphase solid materials having at least one phase having at least one dimension that is about 1-1000 nm or having a repeat distance separating at least some of the phases of about 1-1000 nm.