Metal-modified silica particles for reducing odor

1. A substrate for reducing odor, said substrate containing silica particles bonded to a transition metal through a covalent or coordinate bond, wherein the mole ratio of the transition metal to the silica particles is at least about 10:1, said transition metal providing one or more active sites for capturing an odorous compound; and

wherein said silica particles have an average size of less than 100 nanometers.

2. A substrate as defined in claim 1 , wherein said transition metal is selected from the group consisting of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, silver, gold, and combinations thereof.

3. A substrate as defined in claim 1 , wherein an organofunctional silane bonds said transition metal to said silica particles.

4. A substrate as defined in claim 3 , wherein said organofunctional silane is covalently bonded to silanol groups present on a surface of said silica particles.

5. A substrate as defined in claim 4 , wherein said transition metal forms a coordinate bond with said organofunctional silane.

6. A substrate as defined in claim 1 , wherein said odorous compound is selected from the group consisting of mercaptans, ammonia, amines, sulfides, ketones, carboxylic acids, aldehydes, terpenoids, hexanol, heptanal, pyridine, and combinations thereof.

7. A substrate as defined in claim 1 , wherein the substrate comprises a nonwoven, woven, or paper web.

8. A substrate as defined in claim 1 , wherein the solids add-on level of said modified silica particles is from about 0.001% to about 20%.

9. An absorbent article that comprises the substrate of claim 1 .

10. An absorbent article as defined in claim 9 , further comprising at least one liquid-transmissive layer and a liquid-absorbent core, wherein said substrate forms at least a portion of said liquid-transmissive layer, said liquid-absorbent core, or combinations thereof.

11. An absorbent article as defined in claim 10 , wherein the absorbent article includes a liquid-transmissive liner, a liquid-transmissive surge layer, a liquid-absorbent core, and a vapor-permeable, liquid-impermeable outer cover, said substrate forming at least a portion of said liner, said surge layer, said absorbent core, said outer cover, or combinations thereof.

12. A paper product that comprises the substrate of claim 1 .

13. A facemask that comprises the substrate of claim 1 .

14. A substrate as defined in claim 1 , wherein the silica particles have a surface area ranging from about 180 m 2 /g to about 240 m 2 /g.

15. A substrate for reducing odor, said substrate containing silica particles bonded to at least one copper ion through a covalent or coordinate bond, wherein the mole ratio of copper ion to the silica particles is at least about 10:1, said at least one copper ion providing one or more active sites for capturing an odorous compound; and

wherein the silica particles have a surface area ranging from about 180 m 2 /g to about 240 m 2 /g.