Proposed is a multi-layer filtration system including a metal catalyst filter unit, a carbon filter unit, and an inorganic compound filter unit. The metal catalyst filter unit includes at least one among metals including Ni, Co, Fe, Cu, Cr, Mg, Zn, Ba, Au, Ag, Pd, Pt, Ru, Mn, and Ti, oxides thereof, and mixtures thereof. The carbon filter unit includes at least one of activated carbon or activated carbon fiber. The inorganic compound filter unit includes an inorganic compound capable of adsorbing toxic gas. The multi-layer filtration system has good removal effect for toxic gas. A filter module including the multi-layer filtration system and a gas mask including the multi-layer filtration system are also proposed.

The objective of the present invention is to provide a method for effectively and easily reducing an amount of a specific impurity in a liquid. The method for reducing an amount of a nucleic acid in a liquid according to the present invention is characterized in comprising the steps of contacting the liquid with a water-insoluble magnesium compound to adsorb at least a part of the nucleic acid on the water-insoluble magnesium compound. Also, the objective of the present invention is to provide an adsorbing filter useful for purifying a useful substance, such as an antibody and an antibody-like molecule, used as a purification material for effectively removing an impurity with easily maintaining the yield of the target substance due to excellent adsorption ability to a nucleic acid and low adsorption ability to an antibody, an antibody-like molecule or the like. The adsorbing filter is characterized in comprising the layer comprising a water-insoluble magnesium compound.

A filter bag is disclosed that comprises a porous membrane having a strength in the transverse direction to improve durability. There is a filter assembly for filtering particulates from a gas stream comprising a support substructure and a filter bag at least partially surrounding the support substructure. The filter bag comprises a porous membrane having a upstream surface exposed to the gas stream. The porous membrane is lightweight and has a structure to collect the particulates on the upstream surface. In particular, the porous membrane has a bubble point of 0.06 MPa or more and has a strength in a transverse direction that is 100 N/m or more. Other filter bags disclosed comprise a laminate comprising a porous membrane having a bubble point of 0.06 MPa or more and a second layer that acts as a sacrificial material.

The present disclosure provides a filtration media for filtering one or more airborne particles. The filtration media may comprise a membrane comprising one or more polymeric layers to filter the airborne particles. The filtration media may have high filtration efficiency and high breathability. Additionally, the present disclosure provides devices (e.g., face masks) comprising the filtration media which may be used to filter airborne particles (e.g., bacteria, viruses) and to protect the wearer (e.g., from infection).

A filter is disclosed. The filter of the present disclosure includes: a support layer; and a filter layer coupled to the support layer, wherein the filter layer is formed by a melt blown method with, as a melt, a thermoplastic resin-including first base and a first antibacterial agent, wherein the first antibacterial agent includes an antibacterial metal or antibacterial metal oxide.

Membranes suitable for use in membrane distillation are provided. Such membranes may include nano-fibrous layers with adjustable pore sizes. The membranes may include a hydrophobic nanofibrous scaffold and a thin hydrophilic protecting layer that can significantly reduce fouling and scaling problems.

Air filters, and air filter devices for use in helicopters, and methods of use, are disclosed.

Filtration media packs, filter elements, and media are disclosed, including media packs having a plurality of layers of single facer media wherein the layers of single facer media include a fluted sheet, a facing sheet, and a plurality of flutes extending between the fluted sheet and the facing sheet, with the fluted sheet and facing sheet formed of multi-layer media can include a polytetrafluoroethylene (PTFE) layer supported by a polymeric scrim layer.

Charged polymeric webs, such as electret webs, include a thermoplastic resin and a charge-enhancing additive. The additives are substituted heterocyclic thiols. The heterocyclic thiol has 2 nitrogen groups and a third group that may be an NH, N-NH.sub.2, O, or S group. The substituent group is an aromatic or heterocyclic aromatic group. The electret webs may be a non-woven fibrous web or a film. The electret webs are suitable for use as filter media.

Provided is a porous polytetrafluoroethylene membrane in which an absolute value of a difference in lightness between one principal surface and the other principal surface is 1.0 or more, where the lightness is lightness L* of CIE 1976 (L*, a*, b*) color space specified in JIS Z8781-4: 2013. The porous polytetrafluoroethylene membrane may be colored black or gray. The porous polytetrafluoroethylene membrane provided can have properties with a reduced coloring-induced deterioration.