Air filtration media comprising metal-doped silicon-based gel and zeolite materials
An environmental control for use in air handling systems that provides highly effective filtration of noxious gases is provided. Such a filtration system utilizes a novel combination of at least one metal-doped silica-based gel and zeolite materials to trap and/or modify, and remove such undesirable gases (such as ammonia, ethylene oxide, formaldehyde, and nitrous oxide, as examples) from an enclosed environment. 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. The novel combination of such gels and zeolites permits highly effective noxious gas filtration such that excellent breakthrough results are attained, particularly in comparison with prior media filtration products. Methods of using and specific filter apparatuses are also encompassed within this invention.
1 . An air filtration medium comprised of a combination of at least two distinct materials, one comprising a silica-based material, the other comprising a zeolite material, wherein said air filtration medium exhibits an ammonia breakthrough of at least 35 when the challenge concentration of ammonia is 1,000 mg/m 3 at 25° C. and the breakthrough concentration of ammonia is 35 mg/m 3 at 25° C., wherein said air filtration medium exhibits an ethylene oxide breakthrough of at least 35 when the challenge concentration of ethylene oxide is 1,000 mg/m 3 at 25° C. and the breakthrough concentration of ethylene oxide is 1.8 mg/m 3 at 25° C., and wherein said air filtration medium does not exhibit any appreciable capacity to capture nitrous oxide without further converting it to nitrogen oxide.
2 . The air filtration medium of claim 1 wherein said silica-based material is a silicon-based gel material.
3 . The air filtration medium of claim 2 wherein said silicon-based gel material is metal-doped.
4 . The air filtration medium of claim 1 wherein said zeolite material is a pentisil zeolite.
5 . The air filtration medium of claim 2 wherein said zeolite material is a pentisil zeolite.
6 . The air filtration medium of claim 3 wherein said zeolite material is a pentisil zeolite.
7 . A filter system comprising the filter medium as defined in claim 1 .
8 . A filter system comprising the filter medium as defined in claim 2 .
9 . A filter system comprising the filter medium as defined in claim 3 .
10 . A filter system comprising the filter medium as defined in claim 4 .
11 . A filter system comprising the filter medium as defined in claim 5 .
12 . A filter system comprising the filter medium as defined in claim 6 .
13 . A method of filtering air comprising the steps of providing the filter system of claim 7 and permitting air to be moved through said filter system to remove contaminants therein.
14 . A method of filtering air comprising the steps of providing the filter system of claim 8 and permitting air to be moved through said filter system to remove contaminants therein.
15 . A method of filtering air comprising the steps of providing the filter system of claim 9 and permitting air to be moved through said filter system to remove contaminants therein.
16 . A method of filtering air comprising the steps of providing the filter system of claim 10 and permitting air to be moved through said filter system to remove contaminants therein.
17 . A method of filtering air comprising the steps of providing the filter system of claim 11 and permitting air to be moved through said filter system to remove contaminants therein.
18 . A method of filtering air comprising the steps of providing the filter system of claim 12 and permitting air to be moved through said filter system to remove contaminants therein.