The invention relates to a filtering material permeable to air and impermeable to oral, nasal and/or ocular human liquid aqueous excretions, comprising at least one bundle, referred to as a hydrophobic bundle, of at least two hydrophobic sheets which are superimposed and each formed by porous paper, having a gsm substance less than 30 g/m.sup.2, each hydrophobic sheet being formed by cellulose fibres, referred to as cross-linked cellulose fibres, which are connected to each other by hydrogen bonds and by covalent bonds which are formed with at least one group of cross-linking atoms, characterised in that at least some of the hydroxyls of the cross-linked cellulose fibres which are not engaged in hydrogen bonds and which are accessible to the gases form a covalent bond with an acyl group with a hydrophobic chain.

Articles and methods involving filter media are generally provided. In certain embodiments, the filter media includes at least a first layer, a second layer, and an adhesive resin positioned between the first layer and the second layer. In some embodiments, the first layer may be a pre-filter layer or a support layer. The second layer may, for example, comprise fibers formed by a solution spinning process and/or may comprise fine fibers. In some embodiments, the adhesive resin may be present in a relatively low amount and/or may have a low glass transition temperature. The filter media as a whole may have one or more advantageous properties, including one or more of a high stiffness, a high bond strength between the first layer and the second layer, a high gamma, and/or a low increase in air resistance after being subjected to an IPA vapor discharge. The filter media may be, for example, a HEPA filter and/or an ULPA filter.

A filtering unit (1) for aquariums of the hang on back type comprising: a housing (6); a suction pipe (2) provided with a lower inlet (3); and a pump (5) integral with said housing (6) and configured to determine a water circulation through a recirculation path extended inside the filtering unit (1) between said inlet (3) and said outlet mouth (4), wherein a non-return valve (10) is advantageously provided upstream of the pump (5) to maintain a water volume necessary for priming the pump (5) itself.

In order to address the sustainability and environmental issues associated with conventional HVAC filters, inventive HVAC filters have been developed that are completely biodegradable and compostable and exhibit Minimum Efficiency Reporting Value (MERV) ratings that are superior to conventional HVAC filters. More particularly, it has been discovered that biodegradable electrospun nanofibers can be used to produce biodegradable HVAC filters that exhibit superior filtration performance relative to conventional HVAC filters produced from polypropylene electrostatic media or triboelectric nonwoven media.

A face mask includes a filter body including a composite film. The composite film includes a first layer of a stretched sintered polymeric material, and a second layer of an expanded polymer film secured to the first layer. The face mask includes one or more straps for securing the filter body over the mouth and nose of a wearer. A process for making a face mask includes providing a composite film including a sintered polymeric material adjacent an expanded polymer film, thermoforming the composite film to produce a filter body of the face mask, and attaching one or more straps to the filter body.

The present invention provides a filter material comprising an antistatic substrate having a predefined antistatic capacity, and one or more layers of nanofibers applied on the substrate. The one or more layers of nanofibers may be fabricated to have gradient structure in various parameters including thickness of nanofiber layer, nanofiber pore size, nanofiber diameter, nanofiber content and the like to suit different filtration applications. The present invention also provides a face mask comprising the filter material and a method for making the filter material.

A high-adsorption-performance nanofiber filter medium includes a support material and a composite nanofiber filtration layer that includes multiple nanometer composite nanofiber layers deposited and stacked on the support material. The nanometer composite nanofiber layer includes first, second, and third nano-powder composite nanofibers, which are uniformly mixed by means of an airflow or are sequentially laminated to form the nanometer composite nanofiber layer. The nanometer composite nanofiber layer formed through sequential lamination includes first, second, and third nanofiber layers. The first nanofiber layer includes multiple first nano-powder composite nanofibers. The second nanofiber layer is stacked on the first nanofiber layer and includes multiple second nano-powder composite nanofibers. The third nanofiber layer is stacked on the second nanofiber layer and includes multiple third nano-powder composite nanofibers. The composite nanofiber filtration layer is formed of multiple nanometer composite nanofiber layers, so that the high-adsorption-performance nanofiber air filter medium shows improved performance.

An embodiment is an article configured to inhibit or prevent pathogen growth. The article includes an inner layer configured to face a wearer's skin when the face covering article is applied to the face of the wearer; a middle layer adjacent to the inner layer; and an outer protection layer adjacent to the middle layer and opposite the inner layer and comprising a substrate and metal particles in the substrate, wherein the metal particles are configured to inhibit or prevent pathogen growth.

A list of highly suitable textiles and a method to combine them into a durable reusable filtration medium with high particles filtration efficiency (PFE) and breathability that lasts over 50-75 laundering cycles. Filtration medium achieves PFE only through mechanical means, without fragile and harmful physicochemical pre-treatments. Different textiles are assembled considering their individual breathability and their complementary in terms of PFE on different particles' sizes to achieve good breathability and high PFE on a large range (20 nm-4 μm) after many laundering cycles, or several layers of the same textile are paired, while varying the fibers' orientation and dimensions in each layer to increase efficiency. This assembling method highly improves PFE, service life and performances' stability of the filtration medium by addressing structural weaknesses linked to anisotropy in each layer, and by protecting their fine fibers from mechanical wear and clogging through a face-to-face closed filtration cell-type pairing.

The present disclosure provides for filters, filter systems, methods of using filter systems, and methods of detecting targeting airborne particles, and the like. The present disclosure provides for filters that can capture one or more types of targeted airborne particulates, where the presence of each of the targeted airborne particulates can then be detected. The filters can be used in industrial gas systems, laboratory gas systems, HVAC systems, portable filter systems, respirator systems, and other residential, commercial, or industrial air circulation or air control systems.