FILTER MEDIUM FOR AIR AND WATER PURIFICATION AND DISINFECTION

Abstract

The present invention relates to a filter medium (10) for air and/or water cleaning, comprising a semiconductor photocatalytic material (14) and a light energy source (15) for radiating light provided to activate photocatalytic reactions of the semiconductor photocatalytic material (14). The light energy source (15) is configured as a support (16) for the semiconductor photocatalytic material (14). The filter medium (10) can be incorporated into a filter unit (100).

Claims

1. Filter medium for air and/or water purification and disinfection, comprising: a semiconductor photocatalytic material, a light energy source for radiating light adapted to activate photocatalytic reactions of the semiconductor photocatalytic material, wherein: the light energy source is configured as a support for the semiconductor photocatalytic material.

2. Filter medium according to claim 1, wherein photocatalytic nanofibers are provided by photocatalytic nanoparticles in or on nanofibers or by a photocatalytic film coated at least partially on nanofibers, wherein a plurality of the photocatalytic nanofibers forms a structure.

3. Filter medium according to claim 2, wherein the photocatalytic nanofibers are made of an optical material.

4. Filter medium according to claim 2, wherein the semiconductor photocatalytic material comprises a non-woven mesh of the photocatalytic nanofibers supported on a substrate of the light energy source made of an optical material.

5. Filter medium according to claim 3, wherein the optical material is poly(methylmethacrylate).

6. Filter medium according to claim 1, wherein the light energy source comprises side glow fibers or fibrous optical waveguides, receiving photons from at least one light source.

7. Filter medium according to claim 6, wherein the at least one light source is a UV light source comprising a UV lamp, a laser or a light emitting diode (LED).

8. Filter medium according to claim 1, wherein the light energy source is configured as a structure of electroluminescent material.

9. Filter medium according to claim 8, wherein the electroluminescent material and the semiconductor photocatalytic material are arranged as layers between a first electrode and a second electrode, which are provided in a form of a mesh, respectively.

10. Filter medium according to claim 2, wherein a diameter of the nanofibers in the range between 70 nm and 700 nm.

11. Filter medium according to claim 1 wherein the semiconductor photocatalytic material includes TiO.sub.2.

12. Filter medium according to claim 1 wherein the semiconductor photocatalytic material includes nanoparticle compounds comprising TiO.sub.2, or TiO.sub.2 decorated Ag or decorated W or decorated WO.sub.3.

13. Filter unit comprising the filter medium according to claim 1, a housing, and at least one light source arranged inside or outside the housing and adapted to pump photons in the light energy source.

14. Filter unit according to claim 13, combined as part of an air circulation system, a personal breath device and/or a stand-alone filtering device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Embodiments of the filter medium according to the invention will be explained more closely in the following, by way of example, with reference to the attached drawings:

[0033] FIG. 1 schematically illustrates a filter medium according to a first embodiment of the invention; and

[0034] FIG. 2 schematically illustrates a filter medium according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0035] FIG. 1 illustrates a filter medium 10 according to a first embodiment of the invention. The photocatalytic filter medium 10 includes a plurality of photocatalytic nanofibers 12 (shown schematically) doped with or including photocatalytic nanoparticles or coated at least partially with a photocatalytic film. The filter medium 10 can be formed as a non-woven mesh providing a 3D lattice structure. The nanofibers 12 can be provided as polymeric nanofibers on which photocatalytic nanoparticles, for example TiO.sub.2, are decorated. A plurality of the photocatalytic nanoparticles creates photocatalytic surfaces to which water molecules absorbed from a gas or fluid phase can adhere. Due to the hydrophilicity of the TiO.sub.2 water forms an adsorption layer close to the photocatalytic surfaces, which defines a fundamental process occurring at the heterogeneous photocatalytic reaction. Nano-sized TiO.sub.2 has shown enhanced photocatalytic performance due to a large surface to volume ratio or surface to weight ratio. TiO.sub.2 is preferably used in the form of immobilized coating, for example prepared from depositing TiO.sub.2 nanoparticles onto nanofibers 12 or from depositing TiO.sub.2 nanofibers onto a substrate or support.

[0036] One possible technique of fabricating network-like three-dimensional nanofibers in a cost-efficient manner is electrospinning. The fabricated nanofibers 12 have a mean diameter of up to 100 nm and the network-like 3D structure functions as carriers for photocatalytic nanoparticles or photocatalytic film.

[0037] Furthermore, the purification performance of the filter medium 10 depends on the humidity, the light energy source, the inlet concentration of the pollutants, the type of the photocatalyst and the design of the filter medium.

[0038] As shown in FIG. 1, a plurality of nanofibers 12 doped with a photocatalytic compound used as semiconductor material 14 can be configured in form of a structure 17 such as a non-woven mesh or a 3D structure of a predetermined thickness. This structure 17 of semiconductor photocatalytic material 14 can be deposited on a substrate or support 16 made of an optical material. The support can be seen as the light energy source 15 of the filter medium 10. The support 16 can be made of a plurality of fibers made of optical material or optical waveguides such as PMMA fibers. These PMMA fibers can be of side glow type emitting UV photons pumped in by a light source 18 such as a UV light source along the length of the optical waveguides.

[0039] FIG. 2 shows another embodiment of the filter medium 10 in a schematic way. As in the first embodiment, the filter medium 10 comprises the structure 17 of a plurality of nanofibers 12 doped with or including photocatalytic nanoparticles. The structure 17 of the semiconductor photocatalytic material 14 is in the form of a non-woven mesh and is deposited on the support 16. According to the second embodiment, the support 16 is made of electroluminescent material 20, in particular in the form of a lattice structure. Both the semiconductor photocatalytic material 14 and the electroluminescent material 20 form layers, which are arranged between a first electrode 22 and a second electrode 24, forming capacitor plates of a condenser device.

[0040] In this embodiment, the light energy source is configured as a structure of electroluminescent material 20 and is adapted to support the semiconductor photocatalytic material 14. The electroluminescent material 20 emits light in response to the application of electrical current or a strong electric field, in particular light of high luminance. The embodiment of the filter medium 10 shown in FIG. 2 comprises the first electrode 22 and the second electrode 24 in form of a mesh and in between layers of the electroluminescent material 20 and the semiconductor photocatalytic material 14.