Purifier containing a photocatalytic filter

The present invention is a filtration medium having a fibrous structure, wherein the fibers have a photocatalytic action for purifying the ambient air, more specifically for removing volatile organic compounds present in the ambient air. With respect to the filtration medium coated with.

Volatile organic compounds (VOCs) can be oxidized by the "advanced oxidation" method. The most effective accelerated oxidation method (AOT) is hydroxyl radical OH.^・This radical has a stronger oxidizing power than ordinary oxidizing agents. This is a heterogeneous photocatalytic reaction. The basic principle of this phenomenon is that photons are absorbed by a solid semiconductor and electrons are promoted from the valence band to the conduction band by releasing holes, giving the solid the properties of an oxidizing agent and a reducing agent. Is. Many volatile organic compounds as well as many pesticides, herbicides, surfactants and colorants are also completely oxidized in this way to produce less toxic products.

PCO (photocatalytic oxidation) reactors that purify ambient air generally include prefilters, UV sources and PCO filters that trap dust and particles. The UV source is generally placed between the pre-filter and the PCO filter. The air to be purified is generally pulsated or aspirated through a PCO filter using a turbine or fan.

In order to operate, the PCO filter has the following points: -Intensity of UV received Processing amount of purifier -The speed at which pollutants pass through the medium -Insensitivity of media and PCO coating to the action of UV and hydroxyl radicals -Pressure drop due to PCO medium -Inhibition of the production of potentially toxic intermediate compounds known as by-products Must be optimized for.

In air treatment applications, the design of various components, fans, exteriors and engine power is directly related to the pressure drop caused by the various filtration components of the device, including PCO media. This point is fundamental in terms of air treatment equipment costs and energy recurring costs. The inventors of the present invention have found that the problem of pressure drop caused by the filtration medium is important.

Filters already provided for this type of application often cause excessive pressure drop, so it is necessary to use a stronger and more energy consuming fan. To overcome this drawback, the filter density was reduced by inserting members such as honeycombs, highly porous cloths, mosquito screens or ceramic foams, but pure priority channels were produced, resulting in airflow. The amount of "effective" material that comes into contact with the filter is reduced and the efficiency of oxidizing the volatile organic compounds of the filter is reduced.

International Publication No. 03/010106 has a specific surface area of at least 10 m.²Equal to / g, especially at least 30m²It teaches to deposit a photocatalytic coating on the surface of a silica veil or felt equal to / g. This document does not suggest the idea of combining low pressure reduction with satisfactory efficiency for the intended application.

US Pat. No. 4,732,879 can be cited as a prior art document. This document teaches the deposition of a porous catalytic coating on a flexible fiber substrate composed of glass or ceramic fibers. This document suggests the use of such substrates for filter bag applications.

European Patent No. 1132133 provides TiO on pure sintered silica.₂Teaches the photocatalytic reactor manufactured in. Such a sintering method imparts high rigidity to the structure and is not desirable when it is desired to fold it. Further, in FIG. 3 of this document, it is clearly recognized that a high pressure drop occurs. This is 1 m / sec (ie about 3600 m)³This is because at / h), the pressure drop is 200 Pa in the best case. Such products, when thin, are very brittle and fragile. Since this product is brittle, its thickness cannot be reduced to reduce the pressure drop it causes.

WO 00/25919 and 00/76660 teach the use of needled cut yarn mats as carriers for photocatalytic coatings. Choosing such fibers requires the use of organic binders and therefore a high density (150-600 g / m).²) You can make a mat. It is not possible to achieve low density and low pressure drop at the same time with such fibers.

WO 99/64364 (or European Patent No. 1084086) teaches fixing agents for photocatalytic coatings. This fixing agent is an organic substance.

U.S. Pat. No. 6,241,856 teaches an analyzer of volatile organic compounds and a pump that circulates a gas but is not controlled by the analyzer at all. Therefore, this pump does not serve to regulate the gas passing through the purifier according to the analytical results provided by the analyzer.

Other references relating to the current state of the art include US Pat. Nos. 6,358,374 and WO 03/03738.

The present invention relates to a stable filtration medium of minerals, especially minerals, which is insensitive to UV and PCO oxidation reactions, where the medium is pressure-reduced, compatible with the requirements of air treatment equipment, and PCO through its active surface and its volume. Due to its action, it has high effectiveness against air pollutants as well as the surface effect normally encountered in the prior art. This filtration medium is preferably particularly mineral (ie inorganic), which means that its ignition loss is less than 0.1 wt% and even less than 0.01 wt%, which can actually be zero. Means that. Such filtration media can be obtained, in particular, using felt produced by stretch blow molding the fibers, thus eliminating the use of binders and mechanical binding operations (stitching, suturing). be able to.

The filtration medium of the present invention is obtained by depositing a coating having a photocatalytic action on a known felt-type fabric.

The present invention is, firstly, a photocatalytic, at least 2 mm thick, homogeneous, macroscopic, perforated filtration medium in which the fibers are coated with a coating containing a photocatalytic catalyst. The felt of the mineral fiber is contained, and the mass of the felt per unit area is 30 to 80 g / m.²The present invention relates to a filtration medium, wherein the coating is 5 to 80 wt% of the filtration medium, and the filtration medium exhibits a pressure drop of less than 150 Pa at 1 m / s in the absence of folds.

The present invention relates to specifications for various uses of the medium of the present invention, a molding method for increasing the effective surface area of the "front surface" as much as possible, and a molding method for reducing the problem of pressure drop as much as possible.

Furthermore, the present invention relates to methods and devices of varying the intensity of UV light and the rate at the substrate at the start of the purifier and / or at the peak of contamination in order to reduce the production of intermediate reaction compounds that may be toxic.

Finally, another subject of the invention is an industrial alcohol or solvent that is the primary user of gaseous ozone effluent or alcohol or solvent in the indoor atmosphere of the home or industry (composite materials, perfume production, etc.). It is an application of the PCO medium and the PCO purifier in the treatment of steam.

The medium of the present invention can be used to clean the air of a facility (house) or service department (building containing an office) used at home. Generally, the mass per unit area is 300 g / m.²You can use felt in the range up to. However, the felt used in connection with the present invention has a mass of 30 g / m per unit area.²And 80g / m²Since it is within the range between, the pressure drop of the gas passing through it is very low. The felts and media of the present invention are more suitable for cleaning the home environment. For service sector or industry, for example 200-300 g / m²It should be noted that there may be cases where a substrate with a higher mass per unit area is required, such as. In such a service sector and industry, several media of the present invention can be sequentially arranged and used behind each other. In these departments, felt is 80g / m²Larger, for example 80-300 g / m²A single filtration medium containing a catalyst coated felt as described in this patent application can also be used, except when indicating mass per unit area of. Some of these media can be placed side by side in sequence.

The felt used as the base material has a density of 30 kg / m.³Can be less than. Felt used as a base material generally has a density of 0.5 to 60 kg / m.³It is within the range of 1 to 30 kg / m more generally.³Is within the range of.

The photocatalytic coating formed by the present invention on the surface of felt fibers used as a substrate is 5 to 80 wt%, generally 10 to 50 wt% of the filtration medium.

The catalyst having a photocatalytic action is generally the following oxide, that is, TiO.₂, ZnO and CeO₂Contains at least one oxide selected from the group of. The catalyst preferably contains at least partially crystalline titanium oxide.

The felt has a fiber structure containing mineral fibers. These fibers are glass (generally containing at least 30 wt% silica, which glass may be of E, C, R, S, D or AR type), washed glass (chemically leached). And then in some cases heat-stabilized, generally glass fibers containing more than 90 wt% silica and, as standard, 96-99 wt% silica), ceramics (UniFlux and Thermal Ceramics are well-known suppliers. Certain mulite-based fibers, 3M-derived Nextel fibers, or pure alumina fibers commercially available under the trade name Saffil can be mentioned) or pure silica (also known as quartz, at least 99% amorphous SiO.₂Is often based on silica such as).

Some glass compositions suitable for the present invention are shown in Table 1 below.

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Metallic fibers (generally based on 316 or 316 L stainless steel, the main suppliers are Bekaert and Ugitech) can also be used. The material used is preferably glass, more preferably silica, so that it is as transparent as possible to UV light during use and allows the UV light to penetrate sufficiently to the core of the filter medium to make the filter medium more active. is there.

Felts are preferably unsintered and contain no organic matter, which is possible in particular by utilizing the following stretch blow molding processes applied to mineral materials.

By stretching a rod of material of interest (such as silica or glass, as the case may be), generally less than 7 mm in diameter, in a burner (particularly an oxypropane burner) into filaments less than 0.5 mm in diameter. In particular, felt made of mineral fiber containing silica (glass or pure silica) can be produced. The filament is then restretched in a second burner by flame stretch blow molding and thrown onto a moving surface such as a moving belt or the surface of a rotating receiving drum. The filaments thus obtained are generally less than 50 μm in diameter and are best concentrated at 9 μm, for example between 7 and 15 μm. The larger the filament, the more generally the felt loses its flexibility. In this way, dozens of filaments can be drawn at the same time. The stretched material may be of the quartz, silica or glass type, more generally of the type of mineral material that can be melted by heat, including alumina and mullite. Very low mass per unit area due to flame stretch blow molding followed by a method of making this non-woven fabric (or mat) by throwing it onto an advancing surface (advancing belt or rotating receiving drum). Even in the case, a particularly homogeneous structure with no visible holes is obtained. This method produces substantially curled fibers, which are naturally intertwined to form a non-woven mat that assembles and adheres to each other, using binders or machines such as needling or suturing. It means that there is no need to make a target connection. This curling can be more easily achieved by adjusting the flame that stretches under turbulent conditions.

Needling mineral fibers creates holes that are visible to the naked eye, and the needled mat weighs 150 g / m per unit area.²If less than, it is clearly known to those skilled in the art that it is not homogeneous. In the conventional web manufacturing method, the mass per unit area is 200 g / m.²Less than, it is not possible to produce a well-bonded homogeneous mat. The fibers obtained by the technique of spinning with a bush require the use of an organic binder in order to tight-junction them into a non-woven fabric. In fact, such organic binders can decompose under the action of ultraviolet light, damaging their mats and generating VOCs.

Pure silica fiber (SiO₂At least 99%) is particularly transparent to UV light, and is therefore particularly preferred as it allows the UV light to be delivered throughout the medium and the amount of absorption to be minimized in the optical fiber manner.

The felt obtained by this method (flame stretch blow molding followed by throwing it onto a moving surface) is a non-woven fabric whose mass per unit area is the rotational speed of the receiving device (eg, a rotating drum). Can be adjusted with. The receiving device is 30 to 80 g / m.²Adjusted to achieve mass per unit area between. These felts have a density of 60 kg / m in the range of 1 to 200 mm in thickness.³Is less than. The fibers of this non-woven fabric are generally in the range of 3 cm to 100 cm in length. By this stretch blow molding process, pure silica or glass (in the case of glass, SiO₂At least 60%) can be manufactured. These mats are excellent and preferred because they are flexible (if not sintered) and free of organic matter.

The medium of the final product is generally thinner than the felt used and is generally in the range of 1-50 mm and more generally in the range of 2-30 mm.

Instead of this stretching method, existing fibers with a diameter of 7-14 μm cut to a length of less than 150 mm and generally longer than 45 mm can be started. The cut fibers are made into a web form by an air web forming method or a carding web forming method. The web thus formed is then pre-needed, followed by about 100 strokes / m.²Do need ringing at. By this method, the mass per unit area is 60 g / m.²And 2000g / m²Web can be manufactured. For PCO applications to which the present invention is relevant, 80 g / m²Basis weight less than is preferable. These products are generally less than 30 mm thick and generally 70 kg / m in density.³Less than 60 kg / m³It may be less than. Those skilled in the art will appreciate the substrate 1 / m performed in needling²The density and thickness can be adjusted according to the number of strokes per hit to increase or decrease the density of the felt.

This medium is converted to a ceramic precursor, preferably a sol-gel type, particularly for example TEOS (tetraethyl orthosilicate) or MTES (methyltriethoxysilane) type after calcination, because it retains the structure of the mineral material. It can also be produced by a papermaking method (a method in which fibers are dispersed in a pulper and then wet paper is produced) using a binder. The binder can be deposited locally in dots or in a predetermined pattern to protect the flexibility of the felt.

By the above method, felt having no visible holes can be produced.

A preferred fiber as a support felt for a catalyst having a photocatalytic action is quartz fiber (at least 99% silica). This fiber is well tolerated by the conversion of silica sol-gel to ceramics (temperatures between 400 and 600 ° C.), is very pure and contains no alkalis. This is because it is particularly inert to the catalyst and transmits very well without absorbing ultraviolet light.

The finished felt is followed by an organic precursor of silica (eg TEOS, MTES, in fact the chemical formula R'._xSi (OR)_4-xA solution containing (in the formula, R and R'are organic radicals and x is an integer in the range 0-3) and a photocatalyst containing a mixture of several precursors of the alkoxysilane type represented by. Working TiO₂Alternatively, it is impregnated with a dispersion of a photocatalytic compound such as zinc oxide (ZnO) (although titanium oxide is still the preferred catalyst due to its high efficiency in PCO applications). The present invention also includes tetraethyl orthosilicate (TEOS) and formula R'._xSi (OR)_4-x(In the formula, R and R'are organic radicals, x is an integer of 0 to 3), and the amount of the alkoxysilane is 10 to 40 wt%, preferably 15 of the TOES. The present invention relates to a method for producing a medium, which comprises a step of impregnating a felt of an inorganic fiber with a composition of ~ 25 wt%.

The impregnated solution can be prepared according to the description described in International Publication No. 97/10186 and No. 03/087002. For example, the impregnated solution can be prepared by premixing solution A (silica precursor) and solution B (surfactant), and then adding a dispersion of titanium oxide to the premix. For example, the impregnating liquid can be prepared based on the components shown in Table 2 below.

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Adjust the amount of water to obtain a final solution with a volume of 100 liters. The two solutions A and B were prepared as described above, then mixed and then the catalyst TiO.₂Suspension in water is added to this A + B mixture. 33.33 kg of C is the mass of the 19.3% suspension of catalyst (not pure catalyst).

A second example of the impregnating solution is shown in Table 3 below.

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Compositions that are particularly suitable for depositing coatings contain a mixture of MTES and TEOS as a precursor of silica. This is because the sol-gel obtained from this mixture is more flexible and produces less dust compared to the precursor of 100% TEOS or 100% MTES. Preferably, a mixture of 15-30% MTES and 85-70% TEOS is used.

The felt is impregnated with an impregnating solution in a full bath, the impregnated solution is aspirated through the felt and then squeezed (meaning squeezing to remove the impregnating solution) and then dried.

The resulting felt is then fired at a temperature from the outside temperature to 550 ° C, especially about 450 ° C. At this temperature the silica precursor can be converted to silica. It is preferable to raise the temperature to the above maximum temperature at a moderate rate, preferably less than 6 ° C. per minute. As an example, this heat treatment is shown in Table 4 below.

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The cooling may be natural cooling in the ambient air.

When Si and Ti precursors are used to produce a catalytic coating, the ratio of Si and Ti precursors is determined by the ratio of Si / Ti molars in the catalytic coating to 0.25 and 1.35. It is preferable to change the value between 0.5 and 1.3, more preferably.

The filtration medium having a photocatalytic action of the present invention is thus obtained. The medium can be aspirated by a suction table to remove the micron and submicron particles of the coating, which exhibit low adhesion. This method avoids the generation of significant dust by the PCO medium and the generation of particles during the initial start-up of the PCO purifier.

The filtration medium of the present invention can be attached to a cartridge and a photocatalytic reactor device.

Catalyst (TIO₂Etc.) is generally 40 wt% or less, and in some cases less than 30 wt%, with respect to the final product (medium) obtained, with an optimum mass of about 15 wt%. The mass of the catalyst is preferably 1 wt% or more and more preferably 5 wt% or more with respect to the medium of the final product.

TiO₂In the case of a catalyst, it is preferable to contain as much anatase type as possible.

Several types of applications (sterilization applications, ozone and H)₂S or DMDS (formula: CH₃-S-S-CH₃In the application of destroying a sulfur compound of the type of dimethyl disulfide represented by (), MnO, Mn is added to the composition.₂O₃, Dicyanoanthracene (DCA) and at least one compound or element: V, Cr, Mn, Mo, In, Sn, Fe, Ce, Co, Cu, Nd, Zn, W, Nb, Ta, Bi, Ni, Compounds containing at least one element selected from the Ru and Ag groups may be doped at a concentration of less than 0.5 wt% of the mass of the catalyst to increase the efficiency of the medium.

The felt produced as described above exhibits the following characteristics. -This felt is mineral in nature. -This felt has a pressure drop of less than 150 Pa at 1 m / s, more generally less than 50 Pa at 1 m / s, and even less than 20 Pa at 1 m / s of gas. -This felt is homogeneous and therefore has no potential gas pathway through it. -This felt does not show visible holes.

During the manufacture of photocatalytic coatings, for example, when mechanical stresses are applied to the fibers during handling, even weak mechanical stresses can cause adhesion problems to the fibers. Delamination of the coating is indicated by the formation of unwanted dust. This exfoliation is also known as "dust formation".

The thickness of the coating can be reduced to reduce the generation of this dust. Polymers can also be used to bond the coatings. However, the polymer must be able to withstand oxidation under the combined action of UV light and the catalytic PCO action, and the intensity received is 2-40 mW / of UV-A, UV-B or UV-C. cm²Very often the strength between.

Polymers containing fluorine, such as polytetrafluoroethylene (PTFE) or fluorosilanes (eg, fluorosilanes commercially available by Degussa under reference numbers F8820, F8810 and F8263) and less so polysiloxane polymers (eg, fluorosilanes). Silicone, for example) has been found to be sufficiently stable to UV and PCO reactions in this type of application. The polymer can then be deposited on the fibers of the medium in the form of a dispersion in a liquid, especially using an aqueous dispersion. It is preferable to use an aqueous dispersion that does not contain a surfactant or contains as little surfactant as possible. This is because, for example, when some of the surfactants used in these dispersions to disperse PTFE began to use the filtration medium for that application, the surfactants decomposed by the action of PCO. This is because it may give off a strong odor. Suitable polymer dispersions are, for example, DuPont de with reference numbers Teflon 30 B, Teflon 304 A, Teflon B and Teflon-3823. It is a PTFE dispersion liquid commercially available from Nemours. Silicone polymers available from Rhodia Silicone such as 83% Rhodiasil Resin 20B or Rhodiasil Resin 6405, or siloxane polymers available from Wacker such as SiLres H62C can also be mentioned. PTFE is the preferred polymer.

This polymer dispersion is applied to a medium and then heat treated to make it ceramic to form a photocatalytic coating. Generally, 0.1 to 5 wt% polymer is deposited on the medium with respect to the mass of the final product medium. The polymer can be deposited by spraying the suspension on one or both sides or by immersion-immersing in the suspension and then squeezing. These impregnations are generally carried out at ambient temperatures, especially between 10 and 40 ° C. When the polymer dispersion contains a surfactant, the heat treatment is preferably carried out after the polymer dispersion is applied or before actual use, generally at a temperature between 45 ° C and 250 ° C (fluoropolymer). In the case of (not a polysiloxane type polymer), is it carried out at a temperature between 150 and 250 ° C., for example, at 230 ° C. for several minutes, and especially in the case of fluorinated polysilane, at a temperature between 100 and 180 ° C.)? , Or UV treatment (in this case, especially at high UV intensity 15-100 mW / cm²The surfactant used to disperse the polymer in the dispersion, especially the fluoropolymer used to disperse in the aqueous dispersion, is removed as much as possible.

It was further accidentally discovered that PCO substrates whose coatings contain hydrophobic polymers, especially fluoropolymers or polysiloxane-type polymers, can float on the surface of the water. Such a medium is very advantageous when purifying the air discharged from a sedimentation tank, a water purification plant, a (factory) reservoir, or the like. This is a few millimeters where this medium floats on the surface of the water to be treated.²From a few centimeters²This is because it can be cut into flat fragments in the range of. This medium is easily dispersed on the surface of the water due to its floating nature (without a large additional cost, eg a floating container attached to the float). The medium then adsorbs pollutants generated from contaminated water and oxidizes them by the action of solar ultraviolet light. This principle is extremely economical in reducing very significantly the emissions from this type of device that emit an unpleasant odor and are sometimes dangerous because they are chemical compounds. Therefore, the present invention generates volatile organic compounds in the air above the water by arranging a photocatalytic filtration medium (according to the present invention) that self-suspends by an appropriate coating suspended on the water surface. It relates to a method of purifying the air on water containing impurities. The coating preferably contains a hydrophobic polymer that is applied to the fibers of the medium.

The medium of the present invention has an active and homogeneous surface (without an obvious potential path of air) over the entire surface of the medium, especially its basis weight (ie, mass per unit area) is very small and its surface. Due to the low medullary bulk density, the pressure drop is very low. Moreover, since the medium is so thick, it can have a photocatalytic oxidation action (PCO action) over the entire thickness.

A simple method of determining the photocatalytic properties of a medium is to test the decomposition rate of certain contaminants, such as methanol, in a laboratory reactor in traversing mode. To this end, reactors developed by Professor Pichat's team at L'Ecol Center de Lyon are commonly used in universities and laboratories. The reactor is generally composed of a stainless steel body in which, for example, a disk of medium having a diameter of 47 mm is placed. Ultraviolet light from the HPK 125 w lamp is emitted through a silica slit at the top of the reactor. The irradiation intensity is adjusted by adjusting the lamp / medium distance. 1 mm of medium measured on medium at 365 nm²The UV-A intensity of 5 mW per hit is generally used. A continuous stream of filtered air containing 300 ppm of contaminants (particularly methanol) is guided upstream of the reactor at a rate of 350 ml / min. After PCO treatment, the concentration of contaminants is then generally measured by chromatography downstream of the reactor. By checking the chemical balance, pollutants are converted to minerals (CO), not just the pure adsorption phenomenon seen in activated carbon type equipment.₂And H₂It is important to confirm that it has been converted to O). This test method applied to methanol is hereinafter referred to as "methanol test method".

The filtration medium of the present invention causes a pressure drop of less than 150 Pa in a 1 m / s gas, and generally less than 50 Pa in a 1 m / s gas, and even less than 20 Pa in a 1 m / s gas, in the absence of folds. Because of this, it is extremely low and provides excellent purification.

When the concentration of pollutants in the air to be treated is high (for example, when the pollution is at its peak, or when the decontamination treatment with the filtration medium of the present invention is started, this can be easily detected by the sensor of volatile organic compounds). The formation of intermediates, such as formaldehyde, acetaldehyde or acetone, becomes more pronounced as the flow rate and / or UV intensity increases. Some of these derivatives are particularly toxic, so to overcome their production, in a nutshell, -Greatly reduces UV intensity and / or -Significantly reduce the flow rate of the purifier, that is, the rate at which the gas to be processed passes through the filtration medium. It is recommended (when such a particular situation occurs).

By combining these two operations, the photocatalytic purifier effectively purifies the air at the start of the device or in the first few minutes of the peak stream of contaminants, without increasing the concentration of harmful intermediates. it can. The UV intensity and device flow rate can then be returned to their nominal values to provide maximum PCO action.

This lowering operation should be performed indoors or at the beginning of the operation when the atmosphere is filled with a large amount of VOCs. This is because, in this case, the high concentration VOCs at the start are brought into contact with the filtration medium and decomposed to generate other VOCs, and the other VOCs themselves become relatively high concentration and high concentration. Due to the combination of VOCs and high gas velocities, the filtration medium is probably not able to "convert" all VOCs in the purifier into minerals. In other words, since there are a large amount of VOCs in the purifier, there is a risk that a high proportion of these VOCs will pass through the purifier. The lower the initial concentration of VOCs, the less the risk, as the surface area of the filtration medium will be sufficient to convert all intermediate VOCs to minerals. Therefore, the chemical decomposition reaction of VOCs that occurs in the purifier is actually the same, but when the concentration of VOCs in the air to be cleaned is high, the purifier is saturated and the process of conversion to minerals (a series of chemistry). There is a risk that the reaction) cannot proceed completely.

As an example of a series of chemical decomposition reactions in a purifier, the decomposition process of methanol: methanol formaldehyde formic acid CO₂There is. As an example of a series of chemical reactions, the decomposition process of ethanol: ethanol acetaldehyde acetic acid formaldehyde formic acid + CO₂ 2CO₂There is. Depending on the characteristic values of the photocatalytic purifier (medium type, air velocity, UV irradiation level) and the concentration of VOCs (pollutants) at the inlet of the purifier, the intermediate reaction product will be the first molecule of the starting pollutant to be a photocatalyst. While passing over the medium, it may or may not be completely convertible to minerals.

In order to further increase the efficiency of the photocatalytic reactor of the present invention, the surface area of the active medium can be increased and the pressure drop can be reduced. Even if several filtration media can be placed side by side in sequence to increase the active surface area, the resulting pressure drop will increase correspondingly. In order to achieve the above object, an increase in the surface area of the active photocatalytic medium and an increase in the front surface area can be combined, and the pressure drop becomes smaller as the front surface area in contact with the air flow increases. For this purpose, the medium of the invention may be placed in a filtration cartridge to provide a longer surface for the gas to be treated. Therefore, instead of arranging the medium in a direction opposite to the direction of the gas with a simple straight line thickness, the medium is given a form having at least one angle such as a V-shape, a W-shape, etc. (a true "accordion" is The pleated structure can be imparted to the medium (until it is formed). Further, the medium of the present invention can be placed in the attachment cartridge according to the above design, and the cartridge can be placed in the reactor with minimal lost space. This is particularly advantageous for home air conditioners. This is because the suction pipe is very often bent very quickly at an angle behind the dust filter component. The bulkiness of the PCO reactor must be limited as long as the PCO purifier is located in the dust filtration area. Such an attachment cartridge device, when mounted, avoids the bulkiness of the angled device, and once in the working position, benefits from the angled form to reduce the pressure of the device. Can be lowered. Therefore, this cartridge can be inserted straight (without an angle) into a slit that can be introduced into the PCO reactor, and the angled form will be inserted into the reactor at the time of the insertion. Enter automatically. FIGS. 3a and 3b show PCO filters in which the PCO medium is V-shaped or W-shaped. Accordingly, the present invention includes a filter cartridge that includes at least one angle and contains a PCO medium that, where appropriate, is articulating.

The PCO purifier of the present invention is particularly intended for home air purifying applications. One of the main uses is to reduce ozone in the home environment. According to the present invention, an ozone reduction efficiency of 90% can be achieved.

The PCO purifier of the present invention can also be used to purify air in the service sector, commercial or industrial sector. In this type of application, the mass per unit area is higher than that of a medium suitable for the home environment, so it is recommended to use the media of the present invention in sequence behind them. For example, when using in an environment of a cooking service providing industry where a device for removing grease (starting with ozone) is installed, 50 g / m²In general, the medium of ozone cannot reduce the concentration of ozone having a sufficiently high concentration of 300 ppb at 1 m / s in a single passage. Therefore, it is necessary to sequentially arrange the media of the present invention behind (contact, if appropriate) and use 2 to 10 in general, particularly 3 to 6, and thus the UV intensity received by the filter is 50 mW. / Cm²UV-C irradiation can, for example, oxidize 150 ppb of 300 ppb of ozone present in the inlet gas in a single pass. This type of method is particularly conceivable for kitchen utensils in the cooking industry that generate ozone to remove grease deposited on kitchen sampling hoods. As a result, the PCO apparatus of the present invention can remove the strong odor and high concentration of ozone.

The PCO apparatus of the present invention can also be used in industrial applications such as warehouses or refrigerators used to store perishable plant products (eg fruits, vegetables, flowers). In this case, it is important to reduce the concentration of ethylene in the warehouse in order to delay the ripening of fruits or the wilting of flowers. Accordingly, the present invention relates to the use of the medium or purifier or device of the present invention to purify the air in a warehouse or refrigerator containing plants, in particular fruits or vegetables or flowers.

The PCO apparatus of the present invention is also very effective in decomposing alcohols (methanol, ethanol, propanol) and solvents used in, for example, the resin or composite industry or the fragrance manufacturing industry. In this type of application, it is necessary to operate under EXAT regulated conditions to avoid the risk of explosion (the term EXAT originates from the explosive atmosphere). One of the problems is the nature of the PCO filtration medium, which is actually a mineral in nature to avoid the risk of ignition. Particularly preferably, for EXAT applications, the polymer is not applied to the medium after impregnation to suppress dust formation. The medium of the present invention is composed of a mineral base material (felt) containing a mineral coating coated with titanium oxide, and is sufficiently compatible with specifications for using PCO in an EXAT environment.

The PCO apparatus of the present invention includes a light source necessary for catalytically activating the titanium oxide coating. The light source may be a UV-A, UV-B or UV-C mercury lamp.

Furthermore, the present invention also relates to specific irradiation devices for PCO media suitable for the PCO medium of the present invention or other PCO media. These devices are particularly advantageous in terms of energy savings, reduced maintenance costs or compatibility with EXAT.

The device for irradiating the fiber medium is at least 1 mW / cm.²It can be manufactured with UV-A, UV-B or UV-C LEDs having the same irradiation intensity. Such a device can combine minimal energy consumption with outstanding efficiency. Moreover, this type of irradiation device can be designed very specifically to optimize the irradiation of the medium. Therefore, the present invention also includes a filtration medium having photocatalytic activity (either that of the present invention or not according to the present invention), and at least 1 cm of medium.²The present invention relates to a gas purifier provided with a device for irradiating a medium with UV, including an LED preferably containing UV, which emits an intensity equal to 1 mW per medium.

A device for irradiating a fiber medium can be manufactured with a light guide, eg, an optical fiber, i.e., the device can move the light source from the irradiation area, thus creating an EXAT region in a PCO reactor relatively easily. To do. Accordingly, the present invention also comprises a filtration medium having photocatalytic activity (one of the present invention or not according to the present invention) and at least one optical guide (eg, an optical fiber) for carrying light to the medium. The present invention relates to a gas purifier having a device for irradiating ultraviolet rays. In industrial applications, it is not uncommon to find EXAT areas (outlets, uptakes). Currently, conventional UV bulbs are not approved as EXAT. Because the light bulb is not strong enough. A device that irradiates light with a light guide can remove the UV lamp from the EXAT region and match the device with the requirements of EXAT. The following devices can be considered. Starting from a UV source, several strands of optical guides (eg, fiber optic type) can be introduced into the reactor. These strands act as guides that introduce light energy into the reactor. 1 cm substrate to distribute UV energy as evenly as possible in the reactor²One strand is considered for each. The principle of such a device is shown in FIG. Starting from a UV source, a single strand light guide (eg, an optical fiber) can be introduced into the reactor. These strands then irradiate a reflector or mirror with the appropriate curvature, and then the UV light is reflected by this mirror or this reflector as uniformly as possible within the reactor. The principle of this device is shown in FIG. Other dispersers can also be used to achieve this goal.

The device irradiating the fiber medium can also be concentrated on several PCO reactors. As a result, it is possible to have a single region that emits ultraviolet light that is relayed to different PCO media via a device that irradiates with a light guide (eg, fiber optic type). This device saves considerable energy by avoiding the need to include multiple light sources and reducing ballast consumption and unavoidable loss due to the multiple light source device. The principle of this device is shown in FIG. Thus, the invention also provides air with several air purifiers, each with a catalytically active filtration medium (either of the present invention or not according to the invention) and a single light source illuminating the purifier medium. Regarding the device for cleaning.

Therefore, the present invention also irradiates a filter medium having catalytic activity (one of the present invention or one not according to the present invention) and said filter medium having an optical guide (for example, an optical fiber type) and / or cold light with ultraviolet rays. Regarding gas purifiers equipped with equipment.

The device for irradiating the fiber medium can be manufactured with a flat lamp. Since this device can irradiate the entire surface of the PCO medium extremely uniformly, the yield of the oxidation reaction can be increased and the efficiency of the device can be improved. Therefore, the present invention also relates to a filtration medium having catalytic activity (those of the present invention or not according to the present invention) and a gas purifier having a flat lamp and equipped with a device for irradiating the filtration medium with ultraviolet rays.

When operating PCO equipment in VOC-contaminated air, the concentrations of these VOCs can be quite high at the start of operation. Such high concentrations of VOCs may be indicated by the undesired production of intermediate compounds (formaldehyde, acetaldehyde, acetone) that are also toxic, following the operation of the PCO apparatus of the present invention. This means that if the concentration of VOCs is considered to be high, the PCO apparatus of the present invention is started to operate in attenuation mode by reducing the UV intensity, the gas flow rate, or both. Is the reason why it is recommended. When the concentration of VOC decreases after a predetermined time has elapsed, the operating power can be increased. UV irradiation to reduce (when the operation is started) is, for example, 8 mW / cm.²Less than 7.5 mW / cm²It may be less than. The reduced gas flow rate is, for example, less than 60% of the nominal gas flow rate and may even less than 50%. Table 5 below shows the concentrations of several VOCs measured under standard conditions in residential rooms. These values are the values obtained as a result of measuring several hundred times. The "critical concentration" in the right column of Table 5 is reduced by reducing the operating capacity of the PCO purifier of the present invention by reducing the flow rate of gas passing through it and / or by reducing the intensity of UV irradiating the PCO medium. The concentration recommended to be used is shown as an index. Therefore, the present invention uses a purifier equipped with a filter medium having a photocatalytic action (one of the present invention or one not of the present invention) and an irradiation device for irradiating the filter medium with UV radiation. When the concentration of the compound in the gas is larger than the V1 value, the operating capacity of the purifier is smaller than V2 in which the concentration of the compound in the gas is V1 or less. It relates to a method of making it smaller than the working capacity of. In the case of formaldehyde (a very common impurity), the concentration of formaldehyde is 30 μg / m.³When it exceeds, it is recommended to reduce the operating capacity of the purifier. Formaldehyde concentration is 30 μg / m³When less than, the working capacity of the purifier can be increased. More generally, purifiers have a formaldehyde concentration of 0.3 μg / m.³And 80 μg / m³If it is larger than the V1 value between, the working capacity can be reduced and the formaldehyde concentration is 0.3 μg / m.³And 80 μg / m³If it is less than the V2 value between, and V2 is V1 or less, the operating capacitance can be increased.

<tables num="5"><img id="000006" he="183" wi="158" file="0005551592.tif" img-format="tif" img-content="drawing" /></tables>

The purifier of the present invention comprises an analyzer of volatile organic compounds so that it can detect whether the value of the gas to be cleaned (generally air) exceeds the value recommended to reduce the output of the purifier. It is advantageous to have it. The purifier of the present invention can operate completely automatically according to the content of volatile organic compounds sent by the analyzer, and when the content is lower than a specific value, it operates at a higher capacity, said. When the content is higher than a certain value, it operates at a lower capacity.

Accordingly, the present invention also comprises a photocatalytic filtration medium (with or without the present invention) and varying or (meaning "and / or") the flow rate of gas passing through it. ) The present invention relates to a gas (generally air) purifier provided with means for changing the intensity of UV irradiation. The purifier of the present invention is an analyzer for volatile organic compounds, and UV irradiation according to the content of the volatile organic compounds analyzed by the analyzer, which automatically adjusts the rate of gas passing through the purifier. A means for adjusting the strength may be provided. The purifier of the present invention can analyze the inflowing gas or the outflowing gas, but generally analyzes the inflowing gas. An example that can be shown as a mode given to a suitable device operating according to this principle is an operating mode in which the device operates in a reduced mode when the VOC content exceeds C1. When the VOC content exceeds C1, the analyzer provides a signal 1 that enters a regulator, which regulator is programmed to convert the signal 1 to an outlet instruction 1 according to a mathematical formula, and then the instruction is Drive the fan of the purifier A variable speed drive that controls the speed of the engine is operated (low), and the fan drives the flow rate D1 of gas passing through the purifier (medium).

When the concentration of the VOC in the gas drops below C2 (C2 is lower than C1) after lowering this capacitance and operating for a specific time, the analyzer sends signal 2 to the regulator, which The signal 2 is programmed to be converted to an outlet command 2 according to a mathematical formula, which then activates a variable speed drive that controls (higher) the speed of the drive motor of the fan of the purifier, which fan. Drives (higher) the flow rate D2 of gas passing through the purifier.

The velocity of the gas and / or the intensity of the light can also be adjusted very easily as a function of time. For example, when a purifier begins to operate in a room containing contaminants, it is recommended to operate at a low gas velocity and / or low UV irradiation, for example for 2 hours, during which time the room should be thoroughly cleaned and nominal. It is time to change to the capacity of. Such a device prevents the production of by-products, for example when the purifier is started. Therefore, the purifier may be provided with a time delaying means (ie, a means of measuring or determining the time to trigger the device after a specified time), which means the purifier is moderate or higher. Capacity can be controlled. Therefore, the purifier automatically adjusts the velocity of the gas passing through the purifier and / or the intensity of the UV irradiation according to the time delay means and the time determined by the time delay means. The means may be provided. This time-based device is utilized to predetermine the device while detecting peaks of contamination, such as information communicated wirelessly, by a device that is independent or non-independent of the purifier of the present invention. It can be put into a reduced volume mode (low gas velocity and / or low UV irradiation) for a given period of time, followed by an automatic larger cleaning volume after the predetermined time has elapsed. Can be executed. In such a device, as an example, after starting the purifier, the control sequence, including the time delay relay, sends command 1 to the variable speed drive to perform reduced operation during period 1. This drive device transmits a velocity command 1 to the drive motor of the turbine of the fan to execute a flow rate D1 (decreased) of gas passing through the purifier. After a predetermined period of time with this reduced capacitance, the control sequence, including the time delay relay, tells the variable speed drive to operate at a larger capacitance, which drives the speed. Command 2 is transmitted to the drive motor of the turbine of the fan to execute the flow rate D2 (greater than) of the gas passing through the purifier.

<figref num="1">It is a figure which shows the structure of the PCO purifier of this invention which has two layers 2 of a PCO medium very graphically. The gas flow is represented by thick arrows, the arrow on the left represents the inflow gas and the arrow on the right represents the outflow gas. The UV lamp 3 is arranged between the two layers 2 of the PCO medium. Juan 5 circulates air. All of these parts are located in the stainless steel chamber 1. The distance 4 between the UV lamp and the medium may be 20 mm. Further, in such a purifier, the particle purifier may be arranged at the place where the air starts to arrive, that is, on the left side of the first PCO medium.</figref><figref num="2">It is a figure which shows the structure of the PCO purifier of this invention which has only one layer 2 of a PCO medium. The air flow is represented by a thick arrow. The UV lamp 3 irradiates the medium 2. The fan 5 circulates the air. All of these parts are located in the stainless steel chamber 1. The distance 4 between the UV lamp and the medium may be 20 mm. Further, in such a purifier, the particle purifier may be arranged at the place where the air arrives, that is, on the left side of the first PCO medium.</figref><figref num="3">It is a figure which shows the PCO filter module in which the PCO medium contained is V-shaped or W-shaped. This module typically includes a generally metal (stainless steel, galvanized or aluminum) housing 6 with an attached or unattached cartridge 9 having a particle purifier 7, a UV lamp 8 and a photocatalytic medium. I have. The cartridge enters the housing through the opening 10. The location available for the opening in the housing determines whether the cartridge should or should not be attached. For example, the attached cartridge travels straight into the module through the opening 10 (FIG. 3c) and is then folded into a V shape by the joints 11 (see FIG. 3a). The cartridge can be W-shaped with three joints 12, as shown in FIG. 3b.</figref><figref num="4">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 24.</figref><figref num="5">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 25.</figref><figref num="6">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 26.</figref><figref num="7">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 27.</figref><figref num="8">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 28.</figref><figref num="9">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 29.</figref><figref num="10">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 30.</figref><figref num="11">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 31.</figref><figref num="12">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 33.</figref><figref num="13">It is a figure which shows the result of having cleaned the air contaminated with various molecules by the medium of this invention, and shows the result of Example 34.</figref><figref num="14">It is a figure which shows the principle of irradiation to the filtration medium carried to the PCO reactor 15 by some optical guide (for example, an optical fiber). In FIG. 14a), it can be seen that some strands of the light guide 14 carry the light to the reactor 15 starting from the UV light source 13 to irradiate the PCO medium. In FIG. 14b), it can be seen that eight optical guides 14 reach and are distributed in the cross section of the reactor 15 in order to distribute the UV energy in the reactor 15 as uniformly as possible.</figref><figref num="15">It is a figure which shows the principle of irradiation to the filtration medium carried to PCO reactor 21 by a single light guide (for example, an optical fiber). Starting from the UV light source 16, a single strand 17 of the light guide carries the UV light to the reactor 21. In this case, the optical guide passes through the medium 18 and reaches the irradiation point 19 at the end of the optical guide. The strands then illuminate a mirror 20 with the appropriate curvature, and the UV light is then reflected by the mirror towards the medium 18 as uniformly as possible in the reactor (arrows).</figref><figref num="16">FIG. 5 shows the principle of irradiation of some PCO media present in some PCO reactors 22 by an optical guide (eg, an optical fiber) 23 connected to a single UV generator 24. In this way, several PCO reactors are connected in a concentrated manner in this irradiation device. In this way, a single generation region of ultraviolet light can be relayed to various PCO media by an irradiation device having an optical guide. This device does not need to include multiple light sources.</figref>

[Examples 1 to 13 (evaluation of dust generation)] The felt is manufactured as follows. A rod of fused silica having a diameter of 4.4 mm is stretched in an oxypropane burner to form a filament having a diameter of 0.2 mm. The filament is then re-stretched in a second burner by flame stretch blow molding to an average diameter of 9 μm and thrown onto a receiving belt or receiving drum. The speed of the drum is adjusted to obtain the felt of mass per unit area shown in the table below (Table 2). Then, the obtained felt is impregnated with the preparation obtained by the formulation shown in Table 6 below.

<tables num="6"><img id="000007" he="131" wi="158" file="0005551592.tif" img-format="tif" img-content="drawing" /></tables>

Different amounts of TEOS, MTES and catalytic TiO as reported in Table 7 below₂Various tests were carried out using.

<tables num="7"><img id="000008" he="158" wi="158" file="0005551592.tif" img-format="tif" img-content="drawing" /></tables>

The impregnated felt is then heat treated under the conditions shown in Table 4 above. After impregnation, the obtained final product medium has a mass of about 120 g / m per unit area.²The apparent thickness is 20 mm, and the titanium oxide content thereof is about 20 wt% (excluding the catalyst of Example 1: without catalyst and Example 2: less than 4% of catalyst).

Next, a measurement to assess the tendency of the coating to produce dust is taken on a PCO medium 100 x 100 mm.²It was carried out starting from the sample of. The sample is placed in a Frithsh / Labogerdebau type sieve at Amplitude 4 (value specific to the sieve) for 30 minutes. After 30 minutes, the mass of the residue is measured and the weight loss is measured by 1 m of the base material.²Convert to hit. 5 Average the values of the samples. The results obtained are reported in Table 7 for comparison. The test result is "dust formation", that is, the amount of dust produced per unit surface area of the medium (mg / m).²) And PCO efficiency based on the above-mentioned "methanol test method". This efficiency is described as the amount of oxidized methanol (ppm). In particular, Example 13 is excellent because it has very good PCO activity and very little dust generation.

[Examples 14 to 23 (oxidation of methanol)] A reactor made of stainless steel and containing a medium disc having a diameter of 47 mm is used. A UV irradiation of HPK 125 W is generated at the top of the reactor through a slit of silica. The intensity of the irradiation is controlled by adjusting the lamp / medium distance. 5 mW / cm at 365 nm measured in medium²Use the UV intensity (of the medium). A continuous stream of filtered air containing 300 ppm methanol is introduced upstream of the reactor at a rate of 350 ml / min. The concentration of methanol is measured by gas chromatography downstream of the reactor after the PCO treatment. Conversion of pollutants to minerals (CO)₂And H₂Conversion to O) is confirmed by confirming that its chemical equilibrium is not merely a pure adsorption phenomenon that activated carbon type devices may encounter. The more specific operating conditions for producing the medium and the efficiencies observed for the different media in the "methanol test" described above are shown in Table 8. For Millennium S5 300, TiO₂Was 100% anatase. This does not necessarily mean TIO₂Not applicable to all catalysts based on. For example, TIO of catalyst P25 available from Degussa₂About 1/3 is rutile and 2/3 is anatase.

<tables num="8"><img id="000009" he="138" wi="158" file="0005551592.tif" img-format="tif" img-content="drawing" /></tables>

[Examples 24-31 (oxidation of organic molecules at various flow rates and irradiation intensities)] A rod of fused silica having a diameter of 4.4 mm is stretched in an oxypropane burner to form a filament having a diameter of 0.2 mm. The filament is then re-stretched in a second burner by flame stretch blow molding to an average diameter of 9 μm and thrown onto a receiving drum. Adjusting the speed of the drum, the mass per unit area is 80 g / m²Get the felt. The resulting felt is then impregnated according to the formulation shown in Table 9 below.

<tables num="9"><img id="000010" he="118" wi="158" file="0005551592.tif" img-format="tif" img-content="drawing" /></tables>

The impregnated felt is then heat treated under the conditions shown in Table 4 above.

The obtained filtration medium has an apparent thickness of 20 mm. After impregnation, the felt has a total mass of 120 g / m.²And the level of titanium oxide is 20% of the total mass of the medium.

The efficiency of the photocatalytic medium is that the flow rate is 130 m.³/ H, front velocity is 1 m / s, and the intensity of irradiation received is 1 cm of the medium.²The medium was placed in a PCO purifier with UV-C per 15 mW and measured (these values were measured with a Bioblock VLX-3W radiometer equipped with a 254 nm probe). The chamber is made of stainless steel and has a volume of 1 m.³Is. The purifier is made of stainless steel. The purifier is equipped with three Philips 36 W TUV lamps at a distance of 20 mm from one or more PCO media. The surface area of the medium is 270 x 420 mm²Is. The PCO purifier comprises one or two media as shown in FIGS. 1 and 2. Fans are located behind a single or multiple PCO filters.

A mixture of contaminants is introduced into the chamber using a permeator at a flow rate of 1.95 l / min. This mixture is composed of benzene, toluene, o-xylene, decane, limonene and formaldehyde.

Fresh filtered air is introduced at a flow rate of 21 l / min and the outlet device pumps the air at 23 l / min to simulate the degree of substitution of fresh air present in the building. In order to reduce the production of toxic reaction intermediates, such as formaldehyde, acetaldehyde or acetone, when the concentration of VOCs is high, the substrate is operated at moderate UV irradiation levels and moderate flow rates. It is important to increase the reaction time of the formaldehyde so that the organic compounds (including these undesired intermediate compounds that may be formed) can be more completely oxidized in the substrate.

The meanings of the various abbreviations are as follows. 1F: 1 PCO medium 2F: Two PCO media placed on both sides of the UV lamp Dmax: Maximum flow rate (130m)³/ H) D1 / 2: 1/2 of the maximum flow rate UVmax: Maximum UV irradiation UV / 2: UV irradiation that is 1/2 of the maximum UV irradiation UVmin: Received UV irradiation 2mW / cm²

The test results are shown in FIGS. 4-11. The operating time of the purifier is indicated in the figure by the double-headed arrow "Purifier in operation".

Oxidation of various compounds, benzene, toluene, decane, xylene and limonene by the PCO filter of the present invention is very remarkable in view of various curves. Correspondingly, it is clear that the production of intermediates such as formaldehyde, acetaldehyde or acetone becomes more pronounced as the flow rate and UV intensity increase.

[Example 32 (ozone)] A rod of fused silica having a diameter of 4.4 mm is stretched in an oxypropane burner to form a filament having a diameter of 0.2 mm. The filament is then re-stretched in a second burner by flame stretch blow molding to an average diameter of 9 μm and thrown onto a receiving drum. Adjusting the speed of the drum, the mass per unit area is 65 g / m²Get the felt. The obtained felt is then impregnated with the obtained formulation according to the formulation shown in Table 10 below.

<tables num="10"><img id="000011" he="117" wi="158" file="0005551592.tif" img-format="tif" img-content="drawing" /></tables>

The impregnated felt is then heat treated under the conditions shown in Table 4 above.

The obtained filtration medium has an apparent thickness of 20 mm. After impregnation, the felt has a total mass of 100 g / m.²The level of titanium oxide is 20 wt% of the total mass of the medium.

The test was conducted in the laboratory. The purifier was provided with the two media described in Examples 24-31.

The test conditions were as follows. -Office: 30m³ -Air degree of substitution (DRA): 0.6 to 1 volume / h -Trademark Quartzel (Saint-Gobain Quartz SAS registered trademark) felt made of fused silica fiber with a mass of 65 g / m per unit area.²(The mass of the medium is 100 g / m²) -Nominal flow rate in the purifier: 130m³/ H -UV irradiation received: 15 mW / cm²

The measurements were performed one week before the purifier was installed, one week when the purifier was in operation, and one week after the purifier was stopped. The test results are shown as the ratio of internal ozone concentration / external ozone concentration. This is because under real conditions, air replacement always occurs, fresh air containing pollutants enters the room and fresh air containing pollutants exits the room. Therefore, in order to compare efficiencies, it is useful to be able to operate in relation to the pollutant concentration in the internal air / the pollutant concentration in the external air. In the absence of a PCO purifier, the ratio is 0.14. If equipped with a PCO purifier, this ratio is 0.01.

[Examples 33 to 34] A rod of molten silica having a diameter of 5.5 mm is stretched in an oxypropane burner to form a filament having a diameter of 0.2 mm. The filament is then re-stretched in a second burner by flame stretch blow molding to an average diameter of 9 μm and thrown onto a receiving drum. Adjusting the speed of the drum, the mass per unit area is 50 g / m²Get the felt. Then, the obtained felt is impregnated with the preparation prepared according to the formulation shown in Table 11 below.

<tables num="11"><img id="000012" he="113" wi="158" file="0005551592.tif" img-format="tif" img-content="drawing" /></tables>

The impregnated felt is then heat treated under the conditions shown in Table 4 above. The obtained filtration medium has an apparent thickness of 20 mm. After impregnation, the felt has a total mass of 85 g / m.²And the level of titanium oxide is 20% of the total mass of the medium.

Next, the medium is placed in the same purifier (single PCO medium) as described in Examples 24 to 31 with the following parameters. -Nominal flow rate in the purifier: 130m³/ H -UV irradiation received: 15 mW / cm²

The purifier to be tested has a volume of 1 m.³Place in the Plexiglas chamber.

Prior to testing, the chamber is purged with ultra-pure moist air to remove contaminants present prior to the introduction of the mixture of model molecules. A liquid mixture of various pollutants is introduced into a glass weighing boat through a diaphragm by syringe. The two mixtures were tested. One mixture contains propionaldehyde, heptane, acetone, toluene, acetaldehyde, ethylene, styrene and o-xylene (Example 33) and the other mixture contains toluene, heptane, butyraldehyde, acetone and ethoxyethanol. (Example 34). The concentrations of the various compounds after evaporation are on the order of ppmv. CO₂Is monitored by a gas microchromatography equipped with a thermal conductivity detector (μGC-TCD), and contaminants outside it are analyzed by a gas chromatograph equipped with a photoionization detector (PID). This PID can analyze volatile organic compounds (VOCs) that can be ionized in the range of ppbv. The presence of degradation by-products in the gas phase was detected by adsorption to the adsorbent cartridge (flow rate: 100 ml / min, time: 20 min) and then by thermal desorption analysis and mass spectrometry linked to a gas chromatograph. To. The test results are shown in FIGS. 12 and 13. The PCO apparatus of the present invention has been found to be particularly effective in triggering UV irradiation and immediately removing various solvents (the time of irradiation is indicated by the arrow "UV in operation"). In the case of Example 34 (FIG. 13), as soon as UV irradiation begins, acetaldehyde is produced and then itself is oxidized. The peak of methoxyethanol between 40 and 70 minutes corresponds to a second injection of this product into the chamber. The affinity of methoxyethanol for the medium is such that it is immediately adsorbed.