A microfibrous matrix with embedded supporting particulates/fibers and chemically reactive materials is provided as a filtration system for the removal of contaminants and other harmful agents from liquid and gaseous streams. Such materials may include chemically reactive materials as high surface area carbons, zeolites, silicas, aluminas, inorganic metal oxides, polymer resins, ZnO, ZnO/Carbon, Pt/.gamma.-Al.sub.2O.sub.3, PtCo/.gamma.-Al.sub.2O.sub.3, ZnO/SiO.sub.2 and various other catalysts, sorbents or reactants. The invention may be used to protect the intolerant anodes and cathodes of fuel cells from damaging H.sub.2S while simultaneously aiding the selective conversion of CO to CO.sub.2 in fuel streams predominated by hydrogen, to provide a highly efficient gas and/or liquid separation and purification methodology for gas masks, building filtration systems, and/or as polishing media located downstream of traditional packed bed filtration systems.