Air filtration media comprising metal-doped silicon-based gel and/or zeolite materials treated with nitric acid and/or potassium persulfate
View Patent ↗A filtration system including a novel combination of at least one metal-doped silica-based gel and zeolite materials to trap and/or modify, and remove undesirable gases (such as ammonia, ethylene oxide, formaldehyde, and nitrous oxide, as examples) from an enclosed environment is provided. The gel component exhibits specific porosity requirements and density measurements; the zeolite component is generally acidic and is preferably not reacted with any salts or like substances. Also included is the presence of an oxidizing agent on the gel materials to aid in capturing nitrogen dioxide and preventing conversion of such a product to NO. Methods of using and the application within specific filter apparatuses are also encompassed within this invention.
1. A filter medium comprising at least one multivalent metal-doped silicon-based gel material and at least one pentisil zeolite material, wherein at least one of said silicon-based gel material or said pentisil zeolite material is further treated with an oxidizing material selected from the group consisting of nitric acid, potassium persulfate, and mixtures thereof.
2. The filter medium of claim 1 wherein said multivalent metal-doped silicon-based gel material exhibits a BET surface area of between 100 and 600 m 2 /g; a pore volume of between about 0.18 cc/g to about 0.7 cc/g as measured by nitrogen porosimetry; a cumulative surface area measured for all pores having a size between 20 and 40Å of between 50 and 150 m 2 /g; and wherein the multivalent metal doped on and within said silicon-based gel material is present in an amount up to 25% by weight of the total amount of the silicon-based gel material.
3. The filter medium of claim 2 wherein said multivalent metal is selected from the group consisting of cobalt, iron, manganese, zinc, aluminum, chromium, copper, tin, antimony, tungsten, indium, silver, gold, platinum, mercury, palladium, cadmium, nickel, and any combinations thereof.
4. The filter medium of claim 3 wherein said multivalent metal is copper.
5. The filter medium of claim 1 wherein said pentisil zeolite is ZSM-5.
6. The filter medium of claim 2 wherein said oxidizing material is nitric acid.
7. The filter medium of claim 5 wherein said oxidizing material is nitric acid.
8. The filter medium of claim 2 wherein said oxidizing material is potassium persulfate.
9. The filter medium of claim 5 wherein said oxidizing material is potassium persulfate.
10. The filter medium of claim 7 wherein permanganate is further present within said filter medium.
11. A filter system comprising the filter medium as defined in claim 1 .
12. A filter system comprising the filter medium as defined in claim 2 .
13. A filter system comprising the filter medium as defined in claim 3 .
14. A filter system comprising the filter medium as defined in claim 4 .
15. A filter system comprising the filter medium as defined in claim 5 .
16. A filter system comprising the filter medium as defined in claim 10 .