A system and method for making electret media is presently provided. The method involves placing a piezoelectric material adjacent a media and applying a mechanical stress to the piezoelectric material and thereby transferring an electric charge from the piezoelectric material to the media and making the electret media. The system is configured to place the piezoelectric material adjacent the media and to apply mechanical stress to the piezoelectric material.

Articles such as filter media, which include dendrimers and/or other components, are provided. The filter media may further include a water repellant (e.g., a fluorinated species) to impart desirable properties to the media such as high water repellency. The filter media may also have a high efficiency as a function of pressure drop (i.e., high gamma values). In some embodiments, the filter media includes a fiber web which may be formed of various components such as glass fibers. The fiber web can also include additional components such as synthetic fibers, binder components, as well as other additives. The media may be incorporated into a variety of filter element products.

Charged polymeric webs, such as electret webs, include a thermoplastic resin and a charge-enhancing additive. The additives are substituted heterocyclic thiolate salts. The heterocyclic thiolate salt 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 are a sub-micron fibrous membrane in which sub-micron fibers aligned along one axis and sub-micron fibers in a random pattern form a network, and a method for producing the sub-micron fibrous membrane.

A bacterial cellulose-based air filter mesh and use thereof are disclosed. The bacterial cellulose-based air filter mesh comprises a three-layer structure, in which a layer of a bacterial cellulose-based filter mesh is sandwiched by two layers of polymer fiber filter meshes; wherein the polymer fiber filter mesh is a mesh having a uniform grid size formed from polymer fibers by blended-yarn weaving; and the bacterial cellulose-based filter mesh is formed by in-situ synthesis of bacterial cellulose on a non-woven fabric through fermentation by bacteria. The bacterial cellulose-based air filter mesh has better particle filtering effect, better formaldehyde adsorption capacity, better antibacterial performance and good electrostatic capacity; and it can be used for producing gauze windows, air conditioning filters, air purification filters and the like, and has a wide range of applications.

A filter media construct includes a plurality of flexible laminas joined in a stack, each lamina including an array of nanofibers extending from a surface thereof. Each lamina is configured to be permeable to a fluid such that the fluid can flow through each lamina normal to the surface thereof and in any direction along at least a portion of said surface when the fluid is flowed through the construct. The laminas can include a plurality of perforations extending therethrough such that the fluid flows through at least some of the perforations of the laminas when the fluid is flowed through the construct. A contaminant contained in the fluid is at least partially filtered from the fluid by the nanofibers when the fluid is flowed along the surface of any lamina or into or through the perforations.

Provided is a filter medium. A filter medium according to an embodiment of the present invention comprises: a first porous support body which has been electrostatically treated; and a nanofiber web which is disposed on one surface of the first support body and formed by accumulating nanofibers. Accordingly, excellent air filtering efficiency is obtained even for fine dust of PM 2.5 or below, and furthermore, deterioration in air filtering efficiency may be prevented or minimized even when usage is extended for a long period of time. Therefore, the filter medium and the composite filter according to an embodiment of the present invention can be widely utilized as media of filters for various air filtering devices.

A combination of nanoparticles applied onto a mask filtration system, exemplarily including 1%-10% graphene; 1%-10% titanium dioxide; 1%-10% zinc oxide; 1%-10% copper oxide; 1%-10% silicon dioxide; and balance solvent is provided.

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.

A filter assembly is provided. The filter assembly includes a plurality of filter modules each filled with activated carbon and continuously connected; and a frame to which the plurality of filter modules are fixed, wherein the plurality of filter modules are disposed at predetermined angles relative to each other.