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WO2007026387A2 - Filtres photocatalytiques recouverts de suspensions de dioxyde de titane et d'autres substances et procedes permettant d'obtenir de tels filtres - Google Patents

Filtres photocatalytiques recouverts de suspensions de dioxyde de titane et d'autres substances et procedes permettant d'obtenir de tels filtres Download PDF

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Publication number
WO2007026387A2
WO2007026387A2 PCT/IT2006/000633 IT2006000633W WO2007026387A2 WO 2007026387 A2 WO2007026387 A2 WO 2007026387A2 IT 2006000633 W IT2006000633 W IT 2006000633W WO 2007026387 A2 WO2007026387 A2 WO 2007026387A2
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WO
WIPO (PCT)
Prior art keywords
filters
photocatalytic
weight
titanium dioxide
air
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PCT/IT2006/000633
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English (en)
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WO2007026387A3 (fr
Inventor
Luigino Gravelli
Original Assignee
NM TECH LTD. - Nanomaterials and Microdevices Technology
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Publication of WO2007026387A2 publication Critical patent/WO2007026387A2/fr
Publication of WO2007026387A3 publication Critical patent/WO2007026387A3/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/88—Handling or mounting catalysts
    • B01D53/885—Devices in general for catalytic purification of waste gases
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L9/00—Disinfection, sterilisation or deodorisation of air
    • A61L9/16—Disinfection, sterilisation or deodorisation of air using physical phenomena
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L9/00—Disinfection, sterilisation or deodorisation of air
    • A61L9/16—Disinfection, sterilisation or deodorisation of air using physical phenomena
    • A61L9/18—Radiation
    • A61L9/20—Ultraviolet radiation
    • A61L9/205—Ultraviolet radiation using a photocatalyst or photosensitiser
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/50—Silver
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/72—Copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/39—Photocatalytic properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
    • B01J35/45—Nanoparticles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/58—Fabrics or filaments
    • B01J35/59—Membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20707—Titanium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/80—Type of catalytic reaction
    • B01D2255/802—Photocatalytic

Definitions

  • the invention relates to filters of various nature for use in air conditioning and purification systems, particularly filters treated with photocatalytic materials and nanomaterials allowing decontamination from bacterial and viral species also in the absence of light radiation.
  • air purification means are used, which are differently configured in order to meet particular requirements.
  • the air in these environments requires to be often purified and/or filtered, e.g. in order to abate the smoke that is particularly present in public rooms, or the particulate generated for example from industrial processing, or odours produced in a kitchen, or air pollutants, such as NOx, SOx, CO, organic vapours, C 6 H 6 , etc., in order to make the stay in these environments more pleasant and salubrious .
  • air pollutants such as NOx, SOx, CO, organic vapours, C 6 H 6 , etc.
  • viruses or bacteria found in the air require to be eliminated in order to maintain good hygienic conditions, possibly substantially sterile conditions.
  • filters of various types and materials are used to abate the odours generated from food. Said filters have very short saturation times as compared with those described in the invention, as well as very high pressure losses. Furthermore, after a few days of use, these filters are loaded with bacteria. In the household field, again, in the refrigerators, filters should be desirably used, which are capable of abating the odours, such as to preserve the food and abate the bacteria deriving from the decomposition of food.
  • the above-discussed functions are provided by the known purification means, such as fans, air purifiers, air-treatment stations, air conditioners, kitchen hoods, ventilation or conditioning systems in cars, motor vehicles, lorries, buses, airplanes, trains, ships, fume exhaustion and/or evacuation chimneys, or any other system using said means, which use filters that not only do not eliminate bacteria, but rather allow the same to proliferate, and eliminate urban pollutants such as NOx, SOx, CO, C 6 H 6 , CO 2 , O 3 , etc. only by adsorption (active carbons) and in a temporary manner. In addition, they do not eliminate odours and allow mould proliferation.
  • the purification means such as fans, air purifiers, air-treatment stations, air conditioners, kitchen hoods, ventilation or conditioning systems in cars, motor vehicles, lorries, buses, airplanes, trains, ships, fume exhaustion and/or evacuation chimneys, or any other system using said means, which use filters that not only do not eliminate bacteria, but rather allow
  • An object of the invention is to provide improved air-purification filters, which - together with the systems listed below - allow for the actual elimination or reduction of pollutants, bacteria, viruses, or odours found in the air.
  • a non-exhaustive list of systems to which the present invention can be applied comprises: ventilation, purification, conditioning systems, air- treatment stations, air outlets and/or exhaustion and/or inlet channels, kitchen hoods, refrigerators, ventilation or conditioning systems in cars, motor vehicles, lorries, buses, trains, ships, airplanes, fume exhaustion and/or evacuation chimneys, household appliances using an air stream to be moved, conveyed, heated, cooled, ventilated, such as vacuum cleaners, electric brooms, hair driers, computers, etc..
  • Another object of the invention is to provide improved air purification filters, which - together with the above-listed systems - eliminate urban pollutants such as NOx, SOx, CO, C 6 H 6 , CO 2 , O 3 , etc., by turning the compounds into safe substances .
  • Another object is to provide improved air- purification filters, which - together with the above- listed systems - avoid the proliferation of microorganisms and allow eliminating bacteria and viruses found in the environments in which they are provided.
  • Another object is providing improved air- purification filters, which - together with the above- listed systems - allow avoiding unpleasant odours to develop in the environments in which they are installed, and/or allow the same to be abated.
  • Still another object is to provide improved air- purification filters, which - together with the above- listed systems - have photocatalytic and/or anti-mould features .
  • Another object is to provide improved air- purification filters, which - together with the above- listed systems - have durable self-cleaning features as relates to organic compound.
  • Another object is providing improved air- purification filters which - together with the above- listed systems - can be cleaned using water alone, without detergents, are long-lasting, can be easily adapted to any system and with a validated functional efficiency.
  • Another object is to provide improved air- purification filters which - together with the above- listed systems - particularly kitchen hoods or refrigerators are capable of, at the same time, eliminating the odours and abating the bacterial load, as well as preserving food and extending the storage time thereof in the refrigerators.
  • the present invention relates to providing photocatalytic air-purification filters 2 having titanium dioxide of Anatase, Rutile or Brookite types as the active element, which may be in association with silver and/or copper or derivatives thereof.
  • Titanium dioxide is a semiconductor material with a crystalline structure, having a valence band that is separated from a conduction band by a determined energy gap. As most materials, when titanium dioxide is hit by an electromagnetic radiation, it absorbs energy from the radiation. When the absorbed energy is greater than the energy gap between the valence band and the conduction band, an electron is promoted from the valence band to the conduction band, thereby an excess electron charge
  • UV radiation Ultra Violet
  • the electron holes can oxidize most organic contaminants. These electron holes may, for example, react with a water molecule (H 2 O) thereby generating a hydroxyl radical (*0H) that is highly reactive.
  • the excess electrons have very high reducing power and can react with the oxygen molecule to form the superoxide anion (O 2 *-) •
  • the reaction of water molecule oxidation is shown in the scheme (I) and the reaction of oxygen reduction is shown in the scheme (II) : TiO 2 (h+) + H 2 O -> TiO 2 + *0H + H+; TiO 2 (e-) + O 2 -> Ti02 + O 2 *-
  • the hydroxyl radical (*0H) is particularly active both for the oxidation of organic and inorganic substances, such as those found in the air, and for the inactivation of micro-organisms that, for example, can be noxious to crops and human beings.
  • the organic compounds are oxidized to carbon dioxide and water (H 2 O)
  • the nitrogen compounds are oxidized to nitrate ions (NO 3 -)
  • the sulphur compounds to sulphate ions (SO 4 2" )
  • Titanium dioxide also performs, after irradiation with light of a suitable wavelength, a very effective anti-microbial, antibacterial, and anti-mould action. Titanium dioxide is further capable of decomposing many gases or noxious substances, such as thiols or mercaptans, formaldehyde, having an unpleasant odour. The decomposition of these gases or substances eliminates the bad odours associated therewith.
  • said photocatalytic filters 2 are made by means of ceramic filters, preferably dichroite, which are made up as follows :
  • Dichroite ceramic filters having a squared or other reticular shape, having chemical composition
  • Mullite Al 6 Si 2 Oi 3 Aluminium Oxide Al 2 O 3 , Spinel MgAl 2 O 4 , as the remaining 10% material having a porosity ranging between 32% and 36%, and 3 ⁇ l,5 ⁇ m pore diameter, that can be usable up to 1,380 0 C, having 16CSI, 25CSI, 50CSI, 64CSI 1 lOOCSI, 200CSI, 300CSI, 400CSI, 600CSI cells per square inch, with 0.3 mm to 3.000 mm depth, or mixed.
  • said photocatalytic filters 2 are made by means of polymer fiber filters, preferably expanded polyester synthetic fiber impregnated with activated carbons, and consisting of: a filter with material thickness ranging from about 0.2 mm to about 1.000 mm, entirely consisting of (also expanded) polyester synthetic fiber impregnated with activated carbon, mass per unit area ranging from about 10 g/m 2 to about 900 g/m 2 , flow rate of the filtering material ranging from about 0.05 m/s to about 2.0 m/s, made of polymer fiber.
  • the filter has a nominal flow discharge of about 0.100 m 3 /s to about 900 m 3 /s and a pressure loss at 100% nominal flow discharge of about 1
  • said filters are made by means of other polymer fiber, of the polyester, heat-set polyester, (also expanded) polyurethane, cloth-like, also rotary and/or cup-like and/or paper-like, preferably also impregnated with activated carbons, or entirely impregnated with activated carbon, or mixed or filled with zeolite in pellets or other forms .
  • said photocatalytic filters 2 are made by means of high efficiency and ultra high efficiency glass fiber HEPA and ULPA absolute filters, respectively, which are HEPA- classified HlO a H14 according to EN 1822 standard, corresponding to EUlO to EU14 in the Eurovent standard, and classified as ULPA U15 to U17 according to EN 1822 standard, corresponding to EU15 to EU17 in the Eurovent standard, which - both HEPAs and ULPAs, can have the filter media made of glass microfiber paper, either mini-pleated or deep-pleated, also with corrugated aluminium separators, with efficiency particle efficiency ranging from 1.0 ⁇ m to 0.01 ⁇ m, or mixed.
  • HEPA and ULPA absolute filters respectively, which are HEPA- classified HlO a H14 according to EN 1822 standard, corresponding to EUlO to EU14 in the Eurovent standard, and classified as ULPA U15 to U17 according to EN 1822 standard, corresponding to EU15 to EU17 in the Eurovent standard, which - both HEPAs and
  • said photocatalytic filters 2 are made by means of plastic filters, also made of polypropylene (PP) , modified polyphenyl oxide (PPO) , polycarbonate (PC) or polystyrene (PS) , or sintered expanded polystyrene (EPS) consisting of a closed-cell, low-weight, rigid expanded material, or mixed.
  • PP polypropylene
  • PPO modified polyphenyl oxide
  • PC polycarbonate
  • PS polystyrene
  • EPS sintered expanded polystyrene
  • the EPS generally has a specific mass ranging between 10 and 40 kg/me and thus on average consists of 98% volume air and only 2% pure hydrocarbon as the structural material.
  • said photocatalytic filters 2 are used on metal supports made of metal material, also aluminium (both meshed and sheet) , (also stainless) steel (both meshed and sheet) , or mixed.
  • said photocatalytic filters 2 are coated with photocatalytic solutions capable of achieving the objects described above, and can thus be applied to air moving systems for generating a mechanical circulation of air V in said purification means, and for use in purifying the air of a confined, or indoor, household, industrial, hospital environment, offices, shops, public and private rooms in general, or the interior of a car, lorry, bus, train, ship, airplane, or chimneys' fumes, or electrical appliances in which said purification means are provided.
  • plastic filters, metal filters, ceramic filters, polymer fiber filters, paper filters, HEPA filters, and ULPA filters, and sub-groups are provided, which are arranged to filter the air of said environments by means of treatments (coating or covering) with solutions of photocatalytic titanium dioxide energizable by a light source (also UVA) .
  • said purification means comprise further light sources to emit a radiation in the 280 to 450 nm ultraviolet A (UVA) wavelength range. This allows the photocatalytic features of said filters to be enhanced.
  • UVA ultraviolet A
  • plastic filters, metal filters, ceramic filters, polymer fiber filters, paper filters, HEPA filters, and ULPA filters, and sub-groups are provided, which are arranged in order to filter the air of said environments by means of treatments (coating or covering) with solutions of light-photocatalytic titanium dioxide and other active substances, which operate without using any light source.
  • photocatalytic filters can operate with or without lighting, ranging between the visible spectrum and the invisible spectrum of light radiation.
  • said photocatalytic filters 2 comprise a first titanium dioxide layer, preferably in the form of Anatase and/or modified peroxytitanic acid.
  • said photocatalytic filters 2 are coated with further titanium dioxide layers or other compounds, as will be detailed below.
  • said photocatalytic filters 2 comprise, in addition to said first photocatalytic titanium dioxide layer, one or more further photocatalytic titanium dioxide layers, preferably in the form of Rutile, which are interposed between the filter surface and said first layer of photocatalytic titanium dioxide.
  • said photocatalytic filters 2 further comprise one or more photocatalytic layers of titanium dioxide in the form of peroxytitanic acid or other compounds with a strong adhesion power, and not oxidisable, which are interposed between the filter surface and said first layer of photocatalytic titanium dioxide .
  • said photocatalytic filters 2 further comprise titanium dioxide in the form of Brookite or other compounds with a strong adhesion power and non oxidisable, and/or surfactant stabilizers.
  • said photocatalytic filters 2 further comprise silver (Ag) and/or a derivative thereof, preferably a salt such as silver acetate (CH 3 COOAg) .
  • said photocatalytic filters 2 further comprise copper (Cu) and/or a derivative thereof, preferably cupric oxide (CuO) or a copper (II) salt, such as CuSO 4 .
  • inventive filters are capable of providing said filters with surprising antibacterial and antiviral properties, in the absence of light radiation, as will be detailed below in the present description.
  • said photocatalytic filters 2 further comprise at least one component selected from sodium hydroxide (NaOH) , lithium oxide (Li 2 O) , heptahydrate sodium sulphite
  • the photocatalytic filters 2 can be protected from any chemical attack, the isolating features of the photocatalytic filters can be increased, and the titanium dioxide adhesion to the filters can be promoted.
  • a further object of the present invention is the industrial manufacture of said photocatalytic filters 2, using products that are already known and sold on the market, as well as methods for obtaining these products.
  • titanium dioxide is used in a colloidal (also amorphous) solution, that may contain silver and/or copper or derivatives thereof as defined above, either powdered or in microspheres, either in laminar or any other form, such as a solution in suitable solvents .
  • colloidal (also amorphous) solution that may contain silver and/or copper or derivatives thereof as defined above, either powdered or in microspheres, either in laminar or any other form, such as a solution in suitable solvents .
  • These components can be used either individually or aggregated to silica, colloidal silica or other suitable materials for gripping.
  • titanium dioxide an aqueous colloidal solution, also in the amorphous state, containing Anatase and/or solution of modified peroxytitanic acid and/or Rutile and/or Brookite.
  • the compositions listed below can be used either individually or in association with each other. On several substrates, when of an organic nature, the use of a silica-based or peroxytitanic acid-based primer is recommended.
  • the compositions used will generally have a titanium titer (provided in the form of 100% Anatase , or 70-90% Anatase or Anatase peroxide and the remainder being Rutile or peroxytitanic acid or Brookite) ranging between 0.001 and 15% by weight.
  • the Ag derivative when provided, will generally have a concentration ranging between 0.001 and 1.0% by- weight.
  • the silver derivative will be CH 3 COOAg.
  • the copper derivative (II) when provided, will generally have a concentration ranging between 0.001 and 0.5% by weight, preferably 0.005 and 0.1% by weight.
  • the surfactant will generally range between 0.001 and 5% by weight.
  • SiO 2 when provided, will be preferably in colloidal form and will range between 0.001 and 10% by weight .
  • Sodium hydroxide when provided, will preferably range between 0.001 and 1% by weight.
  • Li 2 ⁇ when provided, will preferably range between 0.001 and 2.0% by weight.
  • Na 2 SO 3 -TH 2 O when provided, will preferably range between 0.001 and 2% by weight, while Na 2 S 2 O 3 -SH 2 O, when provided, will generally range between 0.001 and 2% by weight .
  • Sodium sulfate when provided, will preferably range between 0.001 and 2% by weight.
  • the products used are sold and/or manufactured under the name of Titanium from Jokero Invention s.r.l. Via Formichelli 2 - 86170 Isernia (IS) Italy, which are based on titanium dioxide at different concentrations and listed below:
  • Fig. 1 is a schematic side view of an embodiment of an apparatus for treating photocatalytic filters
  • Fig. 2 is a front view of delivery means of the apparatus from Fig. 1;
  • Fig. 3 is a front view of heating means of the apparatus from Fig. 1;
  • Fig. 4 is a further front view of the delivery means of the apparatus from Fig. l which shows means for supplying a photocatalytic solution to the delivery means;
  • Fig. 5 is a front view of a further version of the delivery means of the apparatus from Fig. 1;
  • Fig. 6 is a schematic view of another embodiment of an apparatus for treating photocatalytic filters
  • Fig. 7 shows an image of a control plate in the absence of UVA radiation
  • Fig . 8 shows an image of a control plate in the presence of UVA radiation
  • Fig. 9 shows an image of a plate treated in accordance with the invention, in the presence of UVA radiation
  • Fig. 10 shows the image of a plate treated in accordance with a different embodiment of the invention, in the presence of UVA radiation
  • Fig. 11 shows the image of a plate treated in accordance with the invention, in the absence of UVA radiation
  • Fig. 12 is an exploded view of an experimental filtering device according to the invention.
  • Fig. 13 shows a functional block diagram of the device from Fig . 12 ;
  • Fig. 14, 15 and 16 show the %removed pollutant vs t diagrams for the removal of nitrogen oxides using the photocatalytic filters according to the invention
  • Fig. 17 shows the ln(NO t /N0 0 ) vs t diagram for the removal of nitrogen oxides using the photocatalytic filters according to the invention.
  • a particular object of the present invention is thus providing air filters that are capable of removing or substantially abating the bacterial load found in the treated air.
  • These antibacterial features are given by silver or derivatives thereof and/or copper or a copper (II) salt being provided on the filters.
  • the antibacterial activity is also performed in the absence of UV radiation or other light source.
  • procedures have been developed which allow evaluating the growth of Escherichia CoIi in the presence/absence of light in thermostatic chambers, with temperature control in different ranges, optimum for growing specific strains. The experiments, both in the presence and in the absence of UVA radiation, have been carried out as follows:
  • Escherichia CoIi and using 10% and 20% diluted titanium dioxide in nutrient medium.
  • the activity of the various products has been assessed by use in the liquid form and in the solid form.
  • the plates have been prepared by diluting various aliquots of the products to be analyzed in the nutrient medium, thereby various final concentrations have been obtained.
  • the plates After the plates have been seeded, they have been placed in a thermostatic chamber at 37°C for 14 hours and irradiated in the various stirring, or stationary, conditions with UVA light sources, filtered from the infrared component with water filters to avoid local over-heating.
  • control plates developed in the absence of titanium dioxide containing colonies of Escherichia CoIi in agar are represented in Fig . 7 with bacterial growth in the absence of UVA and in Fig. 8 with bacterial growth in the presence of UVA.
  • Fig. 9 there is illustrated the plate coated with suspended 10% diluted titanium dioxide after contact with Escherichia CoIi
  • Fig. 10 there is illustrated the plate coated with titanium dioxide that has been deposited as a film after contact with Escherichia CoIi
  • Fig. 11 there is illustrated the plate coated with suspended 10% diluted titanium dioxide after contact with Escherichia CoIi provided by holding the plates in the dark under stationary conditions . Results: 100% elimination of bacterial culture both under UVA radiation conditions, and without irradiation in the dark.
  • the microbial contamination of the air enclosed in a building can be also supported by ubiquitous microorganisms, associated with droplets, or corpuscles. These are Gram-negative bacteria belonging to the Pseudomonas, Klebsiella kind or also Gram-positive germs such as Staphylococcus aureus, which are involved in pathologies of the respiratory system. As relates to the mycotic presence in the air, the risks related to the inhalation of fungal spores result to be often associated with allergic disorders (asthmatic symptoms, allergic alveolitis, rhinoconjunctivitis) , but they are capable of causing even aspecific inflammatory states, asthma and secondary pneumonia.
  • allergic disorders asthmatic symptoms, allergic alveolitis, rhinoconjunctivitis
  • a filtering unit which consisted of a mechanical pre-filter and of a combination of a HEPA filter activated with a titanium dioxide and silver salt solution, according to the invention, capable of holding all the submicroscopic particles and an activated carbon filter for retaining unpleasant odours.
  • the absorption capacity of the filtering unit was 5 mq, the suction rate was 395 mc/hr.
  • the equipment In order to ensure suitable air suction and release, the equipment has been placed at 10 cm minimum distance from any wall, and the upper part has been cleared of any obstruction.
  • the equipment has been placed away from possible entry/exit ways, windows and any outlet of conditioned air provided in the rooms and placed at about 1.5 m from the ground.
  • the sampled volume of air has been of 1000 L per each determined parameter.
  • Culture medium Plate Count Agar Standard (CM463B - Oxoid) distributed in rodac contact plates (diameter: 6 cm) .
  • Incubation mode 32 0 C for 24 hours.
  • Colony counting at the end of the incubation time, counting all the colonies grown on the agarized medium surface .
  • C number CFU/mc
  • A number of colonies grown on the agar surface
  • V volume of sucked air.
  • Culture medium MacConkey agar n. 3 (CM 115B - Oxoid) distributed in rodac contact plates (diameter: 6 cm) .
  • CFU Colony forming units
  • Escherichia coli Culture medium: MacConkey agar n. 3 (CM 115B - Oxoid) distributed in rodac contact plates (diameter: 6 cm) .
  • Incubation mode 32 0 C for 18-24 hours.
  • Colony identification all the colonies developed on the agarized surface in red-violed colour have been considered as possible Escherichia Coli . These colonies have been subjected to the indole test. The presence of colonies capable of degrading the tryptophan aminoacid with indole formation after 18-24 hours at an incubation temperature of 44 0 C confirms that they belong to the species in question.
  • C number CFU/mc
  • A number of colonies belonging to the Escherichia coli species
  • V ⁇ volume of sucked air.
  • Pseudomonas spp Culture medium Pseudomonas Agar Base (CM 559B - Oxoid) added with CFC supplement (SRl03 - Oxoid) distributed in rodac contact plates (diameter: 6 cm) . Incubation mode: 32°C for 24-48 hours. Colony identification: all the colonies developed on the surface of the agarized medium have been considered as possible bacteria belonging to the Pseudomonas spp. species. The colonies showing a blue- green or brown pigmentation or a fluorescence could be considered as possible Pseudomonas aeruginosa. All the colonies have been isolated on nutritive agar, and then investigated for more accurate identification by means of Api 20NE miniaturized system (Biomerieux) .
  • C number CFU/mc
  • A number of germs belonging to the Pseudomonas spp. species
  • V volume of sucked air.
  • Culture medium Baird-Parker Agar Base (CM 275B - Oxoid) added with Egg Yolk Tellurite Emulsion (SR054C - Oxoid) distributed in rodac contact plates (diameter: 6 cm) .
  • Incubation mode 32 0 C for 24-48 hours.
  • Colony identification all the colonies developed in black colour (reduction of tellurite to tellurium metal) on the surface of the agarized medium have been identified as possible bacteria belonging to the
  • C number CFU/mc
  • A number of germs belonging to the Staphylococcus spp. species
  • V volume of sucked air.
  • Microfungi Culture medium Sabouraud Dextrose Agar (CM 041B - Oxoid) distributed in rodac contact plates (diameter: 6 cm) .
  • Incubation mode 22 0 C for 3-5 days.
  • Colony counting all colonies have been counted, which can be identified as microfungi grown on the agarized medium surface.
  • C number TFU/mc
  • A number of colonies identified as microfungi
  • V volume of sucked air.
  • Culture medium Legionella CYE Agar Base (CM 655B - Oxoid) added with LegionellaBCYE supplement (SRIlOA - Oxoid) distributed in rodac contact plates (diameter: 6 cm) .
  • Incubation mode 37°C in humid atmosphere enriched with 5% CO 2 for 7-10 days.
  • the inventive filters result to be particularly effective against the aerodispersed microfungal load.
  • TML total mesophilic load
  • staphylococcus staphylococcus
  • a light source L such as UVA PL-S 9W/10/2P lamp
  • a motor M sucks the air by forcing the latter to pass through said photocatalytic filters with 180 m 3 /h nominal flow discharge.
  • the motor M has the function of recycling the air R within a reaction chamber B, which is indicated below as the Smog Chamber (Fig. 13 B) .
  • Said device represented in Fig. 12 for the components and in Fig. 13 in the diagram, has support walls D for enclosing said device, and has been placed within the Smog Chamber B, and tested in UVA radiation conditions (lamp L) .
  • a main line 1 connects the blending chamber A to the reaction chamber B and the latter with the recirculation pump P.
  • valves J On the main line 1, upstream and downstream of the reaction chamber B, valves J are provided which allow drawing air from the main line 1 to be conveyed to the analyzer C through respective ducts 2 and 3, such as to be able to measure the concentration of nitrogen oxides both before and after the treatment of the air in the reaction chamber B.
  • a further duct 4 connects the recirculation pump P to the blending chamber A.
  • the main line 1, ducts 2 and 3 and further duct 4 are made of a material that does not alter the concentration of nitrogen oxides, particularly polytetrafluoroethylene.
  • the concentration of nitrogen oxides is monitored in the NOx / air mixture as a function of time, under conditions of the mixture being recycled through the reaction chamber B containing the sample and with the device indicated in Fig. 12 being turned on.
  • the measurement of the initial NOx concentration and the measurement of the NOx in different irradiation times have been carried out by following an analytic methodology based on chemiluminescence, as illustrated in the UNI 10878 standard.
  • An initial sampling of air through the duct 2 allows detecting an initial concentration of NOx, which results to be in the order of 0.6 parts per million (PPM).
  • the air flows again along the main line 1 and passes through the reaction chamber B at 5 ⁇ 10% 1/min. flow rate.
  • an air stream is taken from the duct 3 in Fig. 13.
  • the filters K indicated in Fig. 12 are lightened with the UVA lamp (L) , the temperature is kept at about 27 0 C ⁇ 2 0 C.
  • the lightened surface of the examined sample is 225 cm 2 x 1 filter.
  • the results of the photocatalytic action of the filters K in abating the nitrogen oxides are reported in Fig. 14, 15, and 16, which illustrate the removal of nitrogen oxides in the presence of light. The removal of the nitrogen oxides
  • NOx in the presence of light occurs in a very short time. Three tests on NO and three tests on NO 2 have been carried out to better understand the validity of the testing.
  • This hypothesis seems to be consistent with the linearity that is generally observed when In [NO] t / [NO] o is plotted as a function of time. The diagrams are reported in Fig.
  • the NO decontamination from ambient air may be carried out in times in the order of a few minutes, regardless of the value of the initial concentration of nitrogen oxide.
  • photocatalytic filters of the invention are also provided with an unexpected antiviral activity.
  • viruses are obligate parasites, which are capable of growing and replicating only within cells .
  • the viruses do not possess enzymes capable of producing energy, they have no ribosomes for protein synthesis, and in addition they must use the cell's enzymes to perform vital processes .
  • the photocatalytic filters 2 according to the invention are capable of carrying out a very high antiviral activity also at very low concentrations.
  • This antiviral activity, as well as the antibacterial one, is conferred to the inventive filters by the provision of silver or a derivative thereof and/or copper or a copper (II) salt and is also performed in the absence of a light source.
  • variable amounts of viral suspension in a Dulbecco's modified medium (D-MEM) with 1% fetal bovine serum (FBS) have been prepared. Different viral concentrations have been used (viral titer) equal to IxIO 6 and IxIO 8 units capable of forming cytolysis plaques (Pfu, Plaque Forming Units) .
  • Variable amounts of photocatalytic products (ATLS-OlG having the following composition: TiO 2 1.49%, SiO 2 0.91%, NaOH 0.05%, Li 2 O 0.13%, Na 2 SO 3 .7H 2 O 0.015%, Na 2 S 2 O 3 .5H 2 O 0.03%, CH 3 CCOAg 0.005%, H 2 O 97.37%) have been added to the various samples.
  • the control was untreated viral solutions . After 5 hours incubation at room temperature, all samples have been diluted to known volumes to titrate the virus .
  • the viral titer of the controls and samples treated with the photocatalytic product has been determined by the following procedure.
  • Determining a viral titer means calculating the number of infectious virions found in 1 mL solution.
  • One of the method used consists in determining the number of cytolysis plaques produced by a sufficiently diluted viral suspension contacted with a cell monolayer.
  • African monkey kidney (Vero) cells have been used. The cells grow at 37 0 C, in the presence of 5% CO 2 in D-MEM, added with 10% FBS, 1% L-glutamine and 1% penicillin- streptomycin. The titration has been carried out in 12- well plates. When the cultures were subconfluent, the viral stock has been diluted to known concentrations in a medium containing 2% FBS.
  • MEM medium The addition of this product has been carried out in various times: i) upon re-suspending the cells after trypsinization; ii) on the day after the re-suspension of the cells.
  • the cytotoxic effects have been observed to increase as the added photocatalytic product increased.
  • the presence of 10 ⁇ l product induces cytotoxicity that is exhibited by a suffering aspect of the cells, which is enhanced at 15 V and 25 V, where a considerable amount has been clearly observed of dead cells suspended in the medium.
  • the 5 ⁇ l dose has not produced appreciable cytotoxic effects: the cells have survived and have proved to grow almost normally, with a slight suffering, when compared with the control samples.
  • the virucidal activity of the photocatalytic product has been then measured in two different experiments.
  • the titer of HSV-I virus has been then traced back both in the controls and treated cells, which was calculated based on what had been obtained with IxIO 3 Pfu virus dilution, by multiplying the mean of the cyt ⁇ lysis plaques both of controls and treated cells by the dilution factor (10 3 ) .
  • the treated cells there is more than one order of magnitude reduction in the viral titer as compared with the non-pretreated controls (1.5xlO 5 Pfu in the controls vs 1.4X10 4 in the treated cells) .
  • the virus having IxIO 8 Pfu viral titer, has been incubated with different amounts of ATLS-OlG (1, 2.5 and 5 ⁇ L, respectively) . After 5 hour-incubation, the virus has been diluted at 1x10 2 , 1x10 3 , 1x10 4 and 1x10 5 Pfu, and it has been titrated according to the above-described method. Increasing amounts of photocatalytic product have produced a progressive increase in the inhibition of the formation of cytolysis plaques, as shown in Table I.
  • the reduction of the HSV-I viral titer is particularly relevant in those samples that have been treated with 5 ⁇ L/mL photocatalytic product .
  • the treatment with 5 ⁇ L ATLS-OlG produces an almost total mortality of the viral particles, by inactivating 47 million viruses out of 50 millions found in the control.
  • the photocatalytic product exhibits an antiviral activity also under extreme dilution conditions.
  • the photocatalytic filters 2 according to the invention are capable of carrying out a substantial antiviral activity on the air of the treated environment, where the viruses are normally found in amounts as much as 1000 times lower than those found in the experimental conditions as discussed above.
  • a particular object of the present invention is a method for eliminating or reducing the bacterial, microfungal or viral load in an environment, said method comprising the stage of causing the air from said environment to pass through photocatalytic filters comprising, on the surface of said filters, one or more surface layers of compounds having a photocatalytic activity comprising photocatalytic titanium dioxide, silver or a derivative thereof and/or copper or a copper (II) salt.
  • the titanium dioxide-based colloidal suspensions used are suitable to be distributed in the form of a film on the surfaces of said filters.
  • the titanium- dioxide colloidal suspension described below is suitable to be distributed by means of spray techniques, or by means of techniques providing said filters to be immersed in a bath, the so-called dip-coating method. Said procedure can be also carried out without using any industrial method.
  • an embodiment is shown of an apparatus 1 for treating photocatalytic filters 2, which are fed on a conveyor belt 3 moved between a pair of moving rollers 4 that rotate in the direction of rotation indicated by the rotation arrow F2 in Fig. 1, which carries the photocatalytic filters 2, in the direction indicated by the arrow F, to the several regions of the apparatus 1 in which said photocatalytic filters 2 will be subjected to the action of the several treating means 5 being provided in the apparatus 1.
  • the treating means 5 of the apparatus 1 comprise a plurality of delivery means 8 that are arranged to deliver a solution of photocatalytic material to said photocatalytic filters 2 and a plurality of heating means 9 that are positioned along the conveyor belt 3 in an alternating manner relative to the delivery means 8 and arranged to release a stream of heating fluid, preferably hot air, to heat the solution of photocatalytic material provided on said photocatalytic filters 2 and facilitate the evaporation of the same.
  • the plurality of the delivery means 8 comprises, in the embodiment as shown in Fig. 1, first delivery means 10, second delivery means 11, third delivery means 12 and fourth delivery means 13, all of which having the same shape and of which different details are shown in Fig.
  • the first delivery means 10, and similarly the second, third, and fourth delivery means 11, 12, 13 may comprise, as shown in Fig. 2 and 4, a plurality of delivery elements, 10', 10'' and, 12', 12'', respectively, which are arranged in the direction of the width L' ' of apparatus 1, i.e. in the crosswise direction relative to the feeding direction F, such as to ensure that all the surface of said photocatalytic filters 2 is suitably reached by the photocatalytic solution, and sufficiently covered by the latter in order to ensure the effectiveness thereof.
  • Each of the delivery means 10, 11, 12, 13 of the plurality of delivery means 8 can further comprise, in the version in Fig. 5, which will be better detailed below, an individual delivery element 10' ' ' movable along the width L'', i.e. in the crosswise direction relative to the feeding direction F to deliver the photocatalytic solution on the whole surface of said photocatalytic filters 2.
  • Each delivery element of the plurality of delivery means 8 is provided with a delivery nozzle 30 having a diameter D that can be adjusted according to the distance H of the nozzle 30 of said photocatalytic filters 2, the extension and composition characteristics of said photocatalytic filters 2, the diameter D being variable between about 0.2 and about 1.5 mm.
  • feeding means 20 for the photocatalytic solution are provided, which comprise reservoirs 20' in which the several components of the photocatalytic solution that must be sprayed on said photocatalytic filters 2 are built-up and are communicated with the delivery means 10, 11, 12, 13, by means of respective valves 21 that are shaped for suitably dosing the amount of each component of the photocatalytic solution to be supplied to each of the delivery means 10, 11, 12, 13, in order to obtain a solution of the composition at the desired concentrations.
  • the delivery means 10, 11, 12, 13 are fixed to a bar 22 that can slide on a pair of support rods 23 fixed to a base portion 24 of apparatus 1 and that can be locked at a desired height along said rods 23 by means of locking elements 25, such as to change the delivery height H of the delivery means 10, 11, 12, 13 to adjust it according to the size and characteristics of the photocatalytic filters 2 to be treated.
  • the position of the delivery elements 10', 10'' of each of the delivery means 10, 11, 12, 13 on the bar 22 can be set and suitably changed, in order to adjust the same according to the characteristics of said photocatalytic filters 2 to be treated, and particularly in order to ensure that the latter are homogeneously coated with the photocatalytic solution.
  • control elements 26 are further provided to control the position of the delivery elements 10' , 10' , and the presence and characteristics of the jet delivered thereby.
  • the control elements 26 comprise optical sensors 27 being provided with first optical sensors 28, preferably placed on the bar 22 adjacent to each delivery element 10', 10' ', and arranged to detect the range of the jet of sterilizing solution being delivered by each delivery element 10', 10'', and then obtaining the extension of the surface of said photocatalytic filters 2 which is reached by the solution, and second optical sensors 29 being preferably placed on the rods 23, which are movable along the latter and arranged to check the actual delivery of the jet of photocatalytic solution by each of the delivery elements 10', 10''.
  • the number of the optical sensors provided per each of the delivery means 10, 11, 12, 13, can be selected based on the characteristics and size of said photocatalytic filters and/or characteristics of the layer of photocatalytic material which one desires to provide, and/or based on the number of delivery elements 10', 10'', 12', 12'' that are actually provided.
  • Any excess photocatalytic solution, which is delivered externally of the surface occupied by said photocatalytic filters 2 on the conveyor belt 3, and/or which drips from said photocatalytic filters 2, as shown in Fig. 1, is collected on a conveying surface 3' of the conveyor belt 3 and, as this is suitably drilled, is collected on a collection tank 31 provided below the conveyor belt 3.
  • the collection tank 31 can be provided with a recycle system for the collected photocatalytic solution, which provides to draw the built-up solution 32 from the collection tank 31 and supply the same back to the delivery means 8 of the apparatus 1.
  • the plurality of the heating means 9 comprise, in the embodiment shown in Fig. 1, first heating means 14, second heating means 15, third heating means 16, fourth heating means 17, that may have either the same or a different shape relative to each other; particularly, fan means such as shown in Fig. 1, or heat-exchanging means or heating ovens can be used as the heating means 9.
  • the first heating means 14, and similarly the second, third, and fourth heating means 15, 16, 17 can comprise, as shown in Fig.
  • the heating means 14, 15, 16, 17 are connected to a further bar 35 that can slide on a further pair of support rods 36 fixed to the base portion 24 of the apparatus 1 and that can be locked at a desired height of said rods 36 by means of further locking elements 37, such as to change the height Hl of the heating means 14, 15, 16, 17 relative to the surface of said photocatalytic filters 2 to be treated, in order to adapt it to the size and characteristics of the photocatalytic filters 2 to be treated.
  • the further bar 35 supporting the heating means 14, 15, 16, 17 can be fastened, by means of a bar 35', provided with locking elements 37' , to the supporting rods 23 of the delivery means 10, 11, 12, 13.
  • each one of the heating means 14, 15, 16, 17, there are provided further control elements 33 to control the position of the heating elements 14', 14" and 15', 15", 16', 16", and 17', 17' ' and the presence and range of the fluid stream delivered thereby, and thus the extension of the surface of said photocatalytic filters 2 that is effectively reached by said stream.
  • the further control elements 33 comprise further optical sensors 34, preferably positioned on the bar 35, which are adjacent to each heating element 14 ',14", 15', 15", 16', 16", and 17', 17" to detect the range of the heating fluid stream as well as further optical sensors, not shown, which are preferably placed on the rods 36 and movable along the latter and arranged to check the actual delivery of the heating fluid by each of the heating elements 14', 14", 15', 15'', 16', 16'', 17', 17"
  • directing means for the stream can be provided at each of the heating means 14, 15, 16, 17 to guide and concentrate the heating fluid to the surface of said photocatalytic filters, in order to increase the effectiveness of the heating means 14, 15, 16, 17.
  • the heating means 9 can further comprise, in a version not shown, an individual delivery element movable in the direction L' ' crosswise relative to the feeding direction F to deliver the photocatalytic solution on the whole surface of said photocatalytic filters 2.
  • an alternative embodiment is shown of the delivery means 10, 11, 12, 13, in which there is provided an individual delivery element 10" ' for each of the delivery means 10, 11, 12, 13, being provided with a body 38 that is slidingly fixed to the bar 22 from which an appendix 39 branches off, which is anchored to a further conveyor belt 40 that is movable between further moving rollers 40' and driven by an electric motor 41, in both ways of the direction indicated by the shifting arrow Fl.
  • Position sensors 42 are further placed on the bar 22 and arranged to define the beginning/end of run of the delivery element 10'''; the position of the position sensors 42 and, thus, the position of beginning/end of run of the delivery element 10''', can be suitably selected and changed based on the size of the photocatalytic filters 2 to be treated.
  • the control elements 26 of the delivery element 10' ' Operation are provided, which comprise first optical sensors 28, which may be either incorporated or connected to the position sensors 42, connected to the bar 22 and arranged to establish the presence of the delivery jet, and second optical elements 29 which are fixed to the rods 23 and arranged to calculate the range of the delivery jet.
  • said photocatalytic filters 2 are manually or mechanically rested on the conveyor belt 3; at the inlet of apparatus 1, said photocatalytic filters 2, which are made of plastic, ceramic, metallic material, during transportation, are rested on the feeding surface 3' of the conveyor belt 3 which faces the treating means 5.
  • the conveyor belt 3 sequentially carries said photocatalytic filters 2 first to a first spraying region in which there are provided the first delivery means 10 that provide delivering the selected solution of photocatalytic material, subsequently to a first heating region in which the first heating means 14 provide to heat the solution being on the surface of said photocatalytic filters 2 to cause the evaporation of the excess solvent or water.
  • This sequence of operations can be repeated for a desired number of times, depending on the size and characteristics of said photocatalytic filters 2. Thereafter, they are carried, again, by the conveyor belt 3, in a further heating region 45, in which further heating means 46, such as an oven 47, provide to further heat said photocatalytic filters that are already provided with the layer of photocatalytic material, in order to consolidate the structure thereof and enhance the adhesion of the photocatalytic material to the surface of said photocatalytic filters 2.
  • further heating means 46 such as an oven 47
  • the photocatalytic filters 2 may be provided applying on said photocatalytic filters 2 the photocatalytic layer and a further intermediate layer to be interposed between said photocatalytic filters 2 and the photocatalytic layer, having the function of protecting the material of said photocatalytic filters 2 from any chemical attack and promoting the adhesion of the layer of photocatalytic material to the latter.
  • This intermediate layer being provided by spraying a primer on said photocatalytic filters, by means of suitable delivery means, such as a solution based on titanium dioxide in the form of Rutile, or silica, or colloidal silica, and drying this primer with relative heating means to facilitate the evaporation of the excess solvent .
  • the apparatus comprises a conveyor belt 3, which is moved between a plurality of moving rollers 4' that are arranged relative to each other such as to hold the conveyor belt 3 tensioned and to cause
  • the moving rollers 4' are provided with cleaning means, such as comprising scrapers 61 being arranged to scrape an outer surface 63 of the moving rollers 4', in
  • the ceramic material grit scraped by the scrapers 61 is collected in suitable containers 62 provided in the vicinity of the scrapers 61.
  • the treating means comprise pre-heating means 48 that can be shaped like a preheating oven 49, such as shown in Fig. 6, or like heat- 0 exchangers, or like fans that pre-heat said photocatalytic filters 2 to prepare the latter to the application of the photocatalytic material solution in the tank 50 where said photocatalytic filters are dipped to receive the photocatalytic solution.
  • the tank 50 is 5 filled with the solution of photocatalytic material to the level designated with Z and is supplied by means of suitable delivery valves 21 from the build-up tanks 20' for the components of this solution, said valves 21 being shaped such as to hold the level Z and the 0 concentration of the photocatalytic solution constant within the tank 50.
  • a dip roll 51 that is shaped such as to deflect the path of said photocatalytic filters 2 to dip them into the photocatalytic material solution.
  • a perforated belt 57 5 is provided within the tank, which is driven by a respective electric drive motor 58, the perforated belt filtering the photocatalytic solution, and holds any material that detaches from said photocatalytic filters while they are dipped, and which falls to the bottom of the tank 50.
  • the tank 50 is further provided with a circulation system for the solution, comprising a pump 53 that draws the solution from the bottom of the tank 50 and the pump by admitting it in the vicinity of the free surface of the tank 50, and a first filtering system 55 positioned upstream of the suction section of the pump 53 and a second filtering system 56 positioned downstream of the delivery section of the pump 53, which are arranged to filter the solution and eliminate any foreign bodies, and the particles of ceramic or plastic or metallic material that have detached from said photocatalytic filters 2 when they were dipped in the tank 50.
  • the tank 50 is further provided with an inspection door 54 for routine and/or extraordinary cleaning and maintenance operations on the tank 50.
  • said photocatalytic filters 2, provided with the layer of photocatalytic solution are carried to heating means 59 to cause the evaporation of the excess photocatalytic solution, and to further heating means 60 to complete said operation and increase the adhesion of the layer of photocatalytic material to said photocatalytic filters 2 and the cementing of this layer.
  • the application of the photocatalytic solution on said photocatalytic filters is carried out by means of immersion, in one individual operation.
  • a primer layer can be applied, in order to promote the adhesion of the layer of photocatalytic material to said photocatalytic filters and protect said photocatalytic filters from damage, these operations being provided upstream of those described above.
  • the operation of heating the primer layer to evaporate the excess solvent therefrom can be the preheating operation of said photocatalytic filters 2 prior to the first application of the photocatalytic solution in Fig. 1, or the application of the photocatalytic solution by immersion, Fig. 6.
  • the layer of photocatalytic material is provided with one or more titanium dioxide-based liquid solutions, which may contain the components described above, such as Ag and/or Cu or derivatives thereof (particularly, oxides or salts) .

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Abstract

Cette invention concerne des filtres de diverses natures destinés à être utilisés dans des systèmes de conditionnement d'air et d'épuration de l'air, en particulier des filtres traités avec des matériaux photocatalytiques et des matériaux nanométriques visant à éliminer la contamination par des espèces bactériennes et virales, même en l'absence de rayonnement lumineux. Cette invention concerne en particulier des filtres photocatalytiques (2) qui comprennent, sur la surface de ces filtres (2), une ou plusieurs couches superficielles de composés présentant une activité photocatalytique comprenant du dioxyde de titane photocatalytique.
PCT/IT2006/000633 2005-09-01 2006-08-31 Filtres photocatalytiques recouverts de suspensions de dioxyde de titane et d'autres substances et procedes permettant d'obtenir de tels filtres WO2007026387A2 (fr)

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ITIS2005A000002 2005-09-01
IT000002A ITIS20050002A1 (it) 2005-09-01 2005-09-01 Filtri fotocatalitici ricoperti con sospensioni di biossido di titanio ed altri composti e metodi per otteneri detti filtri.

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