A filter such as an air having a reagent which chemically reacts with and removes
a gaseous component of an air stream. The reagent contains functional groups covalently
bonded to a non-volatile inorganic substrate which is incorporated in the filter.
The filter can remove gaseous components such as aldehydes. Preferred functional
groups are 3-aminopropylsilyl groups covalently bonded to silica gel (APS silica
gel). The reagent can be contained in a space in the filter or incorporated in
one or more filter elements. The reagent can be part of or coated on paper such
as filter paper or incorporated in non-paper filter elements formed from fibrous
materials such as cellulose acetate or polypropylene fibers. Other preferred reagents
include aminoethylaminopropylsilyl silica gel (AEAPS) and aminoethylaminoethylaminopropylsilyl
silica gel (AEAEAPS).
