FR3128887A1 - Filter material and its application - Google Patents

Abstract

The invention is abbreviated to the title of the patent: Filtering material and its application

Description

Filter material and its application

Technical field of the invention

In some cases, the air – whether outdoor or indoor – is polluted with chemicals, bio-contaminants or particles and fibers that can harm health. These pollutants can be of natural origin (pollen, emissions from volcanoes, etc.) or linked to human activity (particles from industrial activities, agriculture or road transport, volatile organic compounds emitted by building materials , etc.) In the case of indoor air, the nature of the pollutants depends in particular on the characteristics of the building, the activities carried out and behavior (smoking, DIY, painting, etc.). For outdoor air, activities emitting pollutants, such as industrial activities, transport, heating of buildings and agriculture also influence the chemical composition of the emissions. For years, air quality has caused us serious concern and today represents a serious public health issue.

Air pollution represents a major environmental problem because it affects the entire population, it is an unlimited type of pollution, made of multi-pollutants, of multiple origins and it causes acute and chronic effects on health. It is also linked to direct emissions into the atmosphere and to the complex phenomena of atmospheric chemistry and photochemistry allowing the formation of harmful secondary substances.

Outdoor air quality

The results of the Erpurs program, set up by the ORS Ile-de-France in 1994, demonstrate in particular that there is a link between the level of pollution and the health of the population.

In 1996, the law of December 30 relating to air transposed into French law Community Directive 96/62/EC introducing a framework for the development of EU regulations on air quality control. . It requires the Commission to submit proposals aimed at determining regulatory limit values (annual average values, even maximum values) for SO ₂ , NO ₂ , volatile dust, O ₃ , benzene, CO, PAHs, arsenic, cadmium, mercury and nickel. This directive is at the origin of four other directives relating to the determination of regulatory limit values for various pollutants (directives 99/30/EC, 2000/69/EC and 2002/3/EC on dangerous gases and directive 2004/107 /EC introducing measures concerning limit values for PM2.5, PAHs, Hg and Ni).

Even today, these guidelines are mostly still relevant. The reference values (standards) linked to these European regulations, required of the Member States are the result of the work carried out by the WHO, a solid health basis is therefore necessary.

In addition, the question of the management of alerts and maximum values must, on a daily basis, be subject to the fight against chronic pollution.

Indoor air quality

Unlike the more publicized outdoor air pollution, indoor air pollution remained relatively unknown until the early 2000s. However, we spend the vast majority of our time, on average 85%, in enclosed environments, and much of that time – in our homes or places of work, in utility rooms or on means of transport – we are likely to be exposed to many pollutants.

The main indoor air pollutants are:

• Chemical pollutants: volatile organic compounds (VOC), nitrogen oxides (NOx), carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAH), phthalates, etc.
• Bio-pollutants: molds, allergens from house dust mites, pets and cockroaches, pollen, etc.
• Physical pollutants: radon, particles (artificial mineral fibers), etc.

The presence of these pollutants is due to different emission sources: building components, furniture, combustion devices (boilers, stoves, water heaters, etc.), transmission of external pollution (ambient air, contaminated soils), but also depends on the way of life (smoking or the presence of pets, for example).

Air quality can have effects on health and well-being, ranging from simple discomfort (unpleasant odors, drowsiness, eye and skin irritation) to the formation or aggravation of acute or chronic (respiratory diseases, respiratory allergies, reduced respiratory capacity, asthma, cancer, poisoning, etc.), it is therefore a major health issue.

The World Health Organization (WHO) document titled Air Quality Guidelines (updated 2005) begins with the following claims: "Clean air is a fundamental condition of health and human well-being. However, air pollution continues to pose a major threat to health around the world. [...] Each year, more than 2 million early deaths can be attributed to the effects of outdoor and indoor air pollution. Faced with this situation, the WHO publishes recommendations aimed at reducing the effects of pollution on health. In 2013, the WHO's International Agency for Research on Cancer (IARC) classified outdoor air pollution and airborne particulate pollution as carcinogenic.

Taking these effects into account, many pollutants are regulated both in France and in Europe. The majority of regulations for this purpose are based on WHO recommendations.

The state of the prior art of the invention

In line with the ambitions mentioned above, by filtering or lowering the concentration of combustion products, great efforts have long been made to eliminate or significantly reduce the health effects of combustion gases.

The solutions most frequently used to eliminate harmful combustion gases are HEPA filters or activated carbon. A HEPA filter (high efficiency particulate absorbing), as its name suggests, removes particles from the air. However, it is not able to filter gases, volatile organic compounds (VOCs), cigarette smoke or unpleasant odors. In these cases, instead of or in addition to the HEPA filter, the use of an activated carbon filter is necessary.

Activated carbon is carbon with a large surface area and a porous structure. Due to its high microporosity, the surface of one gram of activated carbon is greater than 500 m ² . The level of activation required to achieve the gas adsorption property can be achieved by simply increasing the surface area. Chemical treatments can further improve adsorption properties. Its production is dangerous and requires large amounts of energy with high costs, as well as its regeneration, otherwise impossible in practice. According to data from the scientific literature, its gas adsorption capacity is insufficient for certain molecules.

The article J. Phys. Chem. C , 2013, 117(26): 13452-13461 (hereinafter NPL1) describes that by chemisorption at low temperature, sodium silicate is capable of capturing CO ₂ gas. Indeed, by way of a reaction in solid phase and a method of combustion, one manufactured Na ₂ SiO ₃ and one examined its capacity of adsorption of gases. During the latter process, the raw materials were mixed in the aqueous phase and the heat treatment step was carried out at a temperature lower than that of the solid phase process. Na ₂ SiO ₃ produced by a combustion process has a greater adsorption capacity for CO ₂ gas, however it is important to note that chemisorption requires the presence of water.

1. Filter material containing Na ₂ SiO ₃ , characterized in that the water content of the filter material is 8 to 14% by mass, preferably 10 to 14% by mass, better still 12 to 13% by mass relative to the total mass of filter material.

2. Filtering material according to the previous point, characterized in that it can be manufactured by the following process:

Water is extracted from the aqueous solution of Na ₂ SiO ₃ , the water extraction is carried out by microwaves in the frequency range from 2.0 to 3.0 GHz, at a temperature below 200 °C.

3. Filtering material according to the previous point, characterized in that it can be manufactured by the following process:

The water is extracted from the aqueous solution of Na ₂ SiO ₃ , the water extraction is carried out by microwaves at a frequency of 2.45 GHz, at a temperature below 200°C.

4. Filter material according to point 2 or 3, characterized in that, during the manufacturing process, the water extraction is carried out continuously or in stages and/or the material is stirred during the extraction of water.

5. Filtering material according to any of the previous points, characterized in that it is in the form of powder, granules or pellets.

6. Filter material according to any one of the preceding points, characterized in that it has characteristic peaks in its Raman spectrum, at the following wavenumbers (± 5 cm ^-1 ): 281 cm ^-1 and 712 cm ^{- 1} , preferably at the following wavenumbers (± 5 cm ^-1 ): 155 cm ^-1 , 281 cm ^-1 and 712 cm ^-1 ; to be measured using a laser with a wavelength of 532 nm.

6. Filter material according to any one of the preceding points, characterized in that, preferably, in the range below the wave number 120 cm ^-1 , its Raman spectrum does not include a peak whose integral reaches half of the integral of the peak located at wavenumber 540 cm ^-1 (± 5 cm ^-1 ), preferably, in the range below wavenumber 120 cm ^-1 , it does not include any peak at all.

7. Filter material according to any one of the preceding points, characterized in that it has at least 3 decomposition stages on its thermogravimetric curve (TG), preferably at the following temperatures (± 2°C): 195° C, 276°C and 293°C; to be measured according to standard (MSZ) EN ISO 11358-1:2014.

8. Filtering material according to any one of the preceding points, characterized in that, in the range of 100 to 110°C, it has at most one peak representing a mass loss of less than 2% with respect to the initial mass of the filter material.

9. Use of filter material containing Na ₂ SiO ₃ to reduce the concentration of the following substances in gaseous media, preferably in air, in the vapor space and/or in waste gases: volatile organic compounds ( VOCs), semi-volatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs);

or to reduce the concentration of the following substances: formaldehyde, benzene, toluene, xylenes, ethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, 1,3,5 -trimethylbenzene, 2-ethyltoluene, 3-ethyltoluene , 4-ethyltoluene, n-propylbenzene, i-propylbenzene, styrene, cyclohexane, cyclopentane, n-propanol, i-propanol, n-butanol, i-butanol, diacetone alcohol, methyl acetate, ethyl acetate, n-acetate -propyl, i-propyl acetate, n-butyl acetate, i-butyl acetate, acetone, methyl ethyl ketone, methyl-i-butyl ketone, 2-heptanone, cyclohexanone, methyl tert-butyl ether, tetrahydrofuran, n-pentane , n-hexane, 2-hexane, n-heptane, n-octane, n-nonane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, trichloroethylene, dichloromethane, tetrachloroethylene , trichloromethane, ethyl glycol, 1-methoxy-2-propanol, butyl glycol, butyl glycol acetate, ethylene glycol, propylene glycol, methanol, hydrochloric acid, sulfuric acid and sulfur trioxide, sulfur trioxide, ammonia, dioxins and dioxin-like PCBs ( polycyclic chlorobenzenes).

10. Application according to point 9, in which the filter material is the filter material according to any one of points 1 to 8.

11. Application according to point 9 or 10, which serves to reduce the concentration of PAHs.

12. Filter for filtering particles harmful to health in a gaseous medium, comprising a filter material (9) arranged in a filter housing (1), characterized in that the filter material (9) consists of sodium silicate having a grain size of 0.2 to 0.4 mm.

13. Filter according to point 12, characterized in that the filter housing (1) accommodates powdered sodium silicate as filter material (9).

14. Filter according to point 12, characterized in that the filter housing (1) accommodates sodium silicate granules as filter material (9).

15. Filter according to any one of points 12 to 14, characterized in that the filter housing (1) is designed as a housing made of metal, preferably steel, provided with orifices (6) ensuring the flow gaseous media to be filtered, purified.

16. Filter according to point 15, characterized in that the orifices (6) are made with a metal net (5).

17. Filter according to any one of points 12 to 16, characterized in that the filter material (9) is arranged in an envelope permeable to the flow of gaseous medium, constituting the filter insert (8).

18. Filter according to point 17, characterized in that the casing of the filter insert (8) constitutes a pre-filtration layer and a post-filtration layer (11, 12), depending on the direction of the flow of the gaseous medium.

19. Filter according to point 17 or 18, characterized in that the filter insert (8) comprises a rigid frame (7) forming a filter cartridge (2).

20. Filter according to any one of points 12 to 18, characterized in that it is the filter housing (1) itself which is shaped as the filter frame (2) in which the filter insert (8) can be inserted, stored and removed.

21. Filter according to any one of points 12 to 20, characterized in that in the filter insert (8) a support structure (10) is installed ensuring the homogeneous distribution of the previously filled filter material (9).

22. Filter according to point 21, characterized in that the support structure (10) is designed in a honeycomb and, the support structure (10) including the previously filled filter material (9) is enclosed by the envelope constituting the filter insert (8) so as to prevent the filter material from escaping or dispersing.

23. Filter according to point 21 or 22, characterized in that in case of application in the automotive industry, the support structure (10) is made of stainless steel.

24. Filter according to any one of points 12 to 23, characterized in that one or more sensors (14) are installed in the filter cartridge (2).

25. Filter according to point 24, characterized in that the outputs of the sensor (14) are electrically connected to the connection surfaces (15) formed on the filter cartridge (2).

26. Filter according to item 24 or 25, characterized in that a closable door (13) for inserting the sensor(s) (14) is provided on the filter cartridge (2).

Detailed disclosure of the invention

The invention relates to a filtering material capable, by the combination of physico-chemical processes, of reducing the concentration of reactive molecules and harmful free radicals present in a gaseous medium, preferably in the air. The filtering material that is the subject of the invention works both mechanically and by adsorption and chemisorption, it is therefore capable of capturing gases and vapors of substances harmful to health. The harmful molecules in question are mainly produced during combustion processes thus, the invention presents a filter material which, within the scope of one of the embodiments, is able to reduce, preferably in the combustion gases or in the waste gases, the concentration of reactive molecules and harmful free radicals produced during combustion. Another aspect consists in making it enter into a chemical reaction with the free radicals of a more or less long life, present in the waste gases, so that it neutralizes them. The filtering material can be regenerated by blowing hot air or by washing with an apolar liquid. Its reactivation can be effected by repeating the manufacturing process.

The manufacture of these filtering materials as well as the filtration system comprising the filtering material are also the subject of the invention.

Our analyzes aimed at solving the above problems, surprisingly led us to conclude that solid sodium silicate, namely Na ₂ SiO ₃ , containing a small amount of water, was an excellent adsorbent, this property not not being known until now. The areas of application of water glass were up to now quite different, such as, for example, metal repair, adhesives, drilling fluids, passive fire protection or concrete and wall processing. .

Consequently, the object of the invention is a filtering material containing Na ₂ SiO ₃ , characterized in that the water content of the filtering material is from 8 to 14% by mass, preferably from 10 to 14% by mass, better from 12 to 13% by mass relative to the total mass of the filtering material. The water content was determined using a Benetech GM620 type moisture meter, in SPC1 (M1) mode.

According to one of the embodiments, the filtering material containing Na ₂ SiO ₃ , which is the subject of the invention, is the material obtained by the following manufacturing process: the water is gradually extracted from the aqueous solution of Na ₂ SiO ₃ until the formation of a hard foam which is then ground into a fine powder.

To prepare the aqueous solution, any solid Na ₂ SiO ₃ can be used without restriction and there are no restrictions regarding the concentration of the prepared solution either. Preferably, the dry matter content of the prepared solution is 30 to 40%. According to one of the embodiments, the starting material is Na ₂ SiO ₃ dissolved in water and, moreover, commercially available. The water extraction is preferably carried out by microwave, preferably at a frequency of 2.0 to 3.0 GHz. The duration of water extraction depends on the mass of the substance contained in the solution. During the extraction of water, the temperature of the solution containing the Na ₂ SiO ₃ , then that of the suspension obtained by the concentration, and finally that of the solid substance must be maintained at a value lower than 200°C . If necessary, the extraction of water by microwave irradiation can be carried out continuously or in several stages with alternating pauses. Indeed, the pauses allow the substance to cool down so that its temperature never exceeds 200°C during the process to reach the appropriate water content. Water extraction is carried out until reaching the value mentioned above. During microwave irradiation, samples of the irradiated substance are regularly taken and the water content is determined by procedures known to any expert. If necessary, the material is agitated during the pause(s). The last step is to give the final shape to the filter material, preferably it can be in the form of powder, granules or pellets, depending on the application.

The powder is produced by grinding, preferably down to a grain size of 0.2 to 0.4 mm. The grain size is a number-average size to be determined using a scanning electron microscope (SEM). The substance thus obtained is a snow-white powder. The granule is an asymmetrical aggregate, partly cylindrical and partly spherical in shape. Its surface is uneven and its texture is more or less porous. Its size determined using a sieve is preferably 0.8-2.0 mm. It can be produced by methods known to any expert, eg by dry granulation. The pellet is a round-shaped symmetrical aggregate. It has a smooth, uniform surface and a less porous texture than that of the granule. Its size determined using a sieve is preferably 0.5-2.0 mm, better 0.5-1.0 mm. It can be produced by methods known to any expert, eg by dry granulation or by oscillating granulation.

The filtering material containing Na ₂ SiO ₃ which is the subject of the invention, comprises in its main mass Na ₂ SiO ₃ . In addition to water, the filter material can comprise one or more additional components in an amount of 0 to 1% by mass, preferably 0 to 0.2% by mass relative to the total mass of the filter material. These other components are generally the residues of additives and other synthesis auxiliaries of said adsorbent. The filter material containing Na ₂ SiO ₃ which is the subject of the invention, preferably consists essentially of Na ₂ SiO ₃ (and comprises adsorbed water) as well as it comprises traces of contaminants introduced into the material. filtering during the manufacturing process, eg the following metals or their ions: magnesium, calcium, potassium, aluminium, iron and manganese.

According to one of the embodiments, the filtering material comprising Na ₂ SiO ₃ which is the subject of the invention has characteristic peaks in its Raman spectrum at the following wavenumbers (± 5 cm ^-1 ): 281 cm ^{- 1} and 712 cm ^-1 , preferably at the following wavenumbers (± 5 cm ^-1 ): 155 cm ^-1 , 281 cm ^-1 and 712 cm ^-1 . The Raman spectrum of the filtering material that is the subject of the invention, preferably, in the range below the wave number 120 cm ^-1 , does not include a peak whose integral reaches half of the integral of the peak located at wavenumber 540 cm ^-1 (± 5 cm ^-1 ), the better it does not include a peak at all in this range. Better still, the Raman spectrum of the filtering material which is the subject of the invention is substantially identical to the spectrum represented on the . The wavelength of the laser used to record the Raman spectra is 532 nm, the instrument used is a Raman imaging microscope DXR3xi (ThermoFisher).

According to one of the embodiments, the filtering material comprising Na ₂ SiO ₃ which is the subject of the invention has at least 3 decomposition stages on its thermogravimetric (TG) curve, preferably at the following temperatures (± 2° C): 195°C, 276°C and 293°C. In the range of 100 to 110° C. (water loss peak), the TG curve of the filtering material that is the subject of the invention preferably has at most one peak representing a mass loss of less than 2 % compared to the initial mass of the filtering material. Better still, the TG curve of the filtering material which is the subject of the invention is substantially identical to that illustrated by the . Thermogravimetric analysis was performed in accordance with MSZ EN ISO 11358-1:2014.

The adsorbent of the present invention may be in various forms, such as those well known to any expert specialized in adsorption processes, and for example and in a non-exhaustive manner, the adsorbent of the invention may be in form of balls, strands, extrudates, but also membranes, films or others.

According to one of the embodiments, the filter material is preferably placed in an envelope permeable to the flow of the gaseous medium, such as a fine-mesh metal net, and forms a filter insert. In addition, in this case, always preferably, the casing of the filter insert constitutes a pre-filter layer and a post-filter layer depending on the direction of the flow of the gaseous medium. The pre-filtration and post-filtration layers to be used can be, for example, a fine-mesh metal net, a biopsy sponge, textile (e.g. a G3 or G4 textile filter layer) or, for example, when are used as a cigarette filter, a filter layer made of cellulose acetate fibers.

The filtering material or the filtering insert comprising Na2SiO3 which is the subject of the invention may comprise other adsorbent materials, for example activated carbon, zeolites, silicates and/or plastic polymers.

According to another aspect of the invention, the object of the invention is a filter, that is to say a filtering material arranged in a filter housing, the filtering material being the above filtering material.

According to one of the embodiments, the filter housing preferably contains powdered filter material.

According to one embodiment, the filter housing preferably contains granules of filter material.

According to one of the embodiments, the filter housing is preferably designed in the form of a housing made of metal, preferably of steel, provided with orifices (6) ensuring the flow of the gaseous media to be filtered, to be purified. Preferably, in this case, the walls of the filter housing are made of a fine mesh metal net.

According to one of the embodiments, in order to prevent the filtering material of small grain size from dispersing from the filter housing, the filtering material is preferably placed in an envelope permeable to the flow of the gaseous medium and forms an insert of filter. In addition, in this case, always preferably, the casing of the filter insert constitutes a pre-filter layer and a post-filter layer depending on the direction of the flow of the gaseous medium.

According to another embodiment, preferably the filter insert has a rigid frame forming a filter cartridge.

In another embodiment, preferably, the filter housing itself is shaped as the filter frame into which the filter insert can be inserted, stored and removed.

According to another embodiment, preferably in the filter insert a support structure is installed ensuring the homogeneous distribution of the previously filled filter material. According to one of the embodiments, preferably, the support structure is designed as a honeycomb and it - including the previously filled filter material - is enclosed by the envelope constituting the filter insert so as to prevent the filter material from escaping or dispersing.

The support structure material may vary depending on the actual application, for uses in the automotive industry for example it may be stainless steel.

According to one of the embodiments, preferably, one or more sensors are installed in the filter cartridge, which preferably is provided with a door which can be closed, allowing the sensors to be introduced. According to another embodiment, the outputs of the sensor are preferably electrically connected to the connection surfaces made on the filter cartridge.

The filter according to the sample can be considered universal, since its indicated construction and its unrestricted geometric design allow the filter with specific manufacturing parameters to be cut to dimensions suitable for the current application and integrated into a target system.

It is with the help of an example of realization that I present the filter in more detail, by referring to the attached drawings of which

there illustrates a perspective view of a possible embodiment of the filter which is the subject of the invention

there illustrates the filter cartridge – partially cut out – to be placed in the filter housing of one of the possible embodiments of the filter which is the subject of the invention,

there shows an extract of the sectional view of the filter cartridge intended to be used in a possible filter forming the subject of the invention.

The embodiment of the proposed filter, illustrated by the figures, comprises a filter cartridge 2 placed in a filter casing 1. In the example illustrated, the filter casing 1 has been made of stainless steel but it can also be made of other suitable materials, such as plastic, but also wood or even cardboard. The filter housing 1 has an opening 3 through which the filter cartridge 2 can be inserted into the filter housing 1. In the present example, the opening 3 can be closed by a door 4 when the filter is in operation, but door 4 is not essential if filter cartridge 2 sufficiently fills the interior of filter housing 1 so that the gaseous medium to be filtered – in this example air – cannot bypass the filter cartridge 2, which could render filtration ineffective. The side walls of the filter housing 1, which during operation are perpendicular to the air flow, are made in the present example of a fine-mesh metal net 5, but in the side walls it is possible to make one or more orifices 6 of any type allowing the air flow to be filtered to pass through the filter without significant pressure drop.

The cutting of the illustrates an example of the construction of the filter cartridge 2. The filter cartridge 2 comprises a frame 7 framing the filter insert 8. The function of the frame 7 is to hold together the layers of materials used for filtration and, although safe, the filter material 9, as well as ensuring the necessary mechanical strength. According to the example, in the filter insert 8, a honeycomb support structure 10 is placed ensuring the homogeneous distribution of the filter material 9 – in the present example, granules – previously filled. Such a support structure 10 is mainly required for the filter material 9 in the state of powder or fine-grained granules, whereas for larger-grained granules and in sufficient quantity, it can be considered that the homogeneous distribution of the material filter 9 is ensured.

The two outer boundary surfaces of the filter insert 8 consist of pre-filtration and post-filtration layers 11, 12 respectively, in this example stainless steel, but HEPA filters can also be used. In the filter of the present example, the thickness of the filter material 9 present in the filter insert 8 is 20 mm, the thickness of the layers 11, 12 is 5 mm. According to the results of the experiments, these thicknesses make it possible to ensure the efficiency of the desired filtration, without however constituting an obstacle for the gaseous medium, in this case the air circulating through the filter, no untimely pressure drop occurs. Of course, the application, number and arrangement of the layers 11, 12 can also be implemented in other ways in order to adapt them to the current task at hand.

In the case of the example shown, the filter insert 8 with moderate mechanical resistance is inserted into a filter cartridge 2 guaranteeing the required mechanical resistance and great ease of handling. This solution makes it quick and easy to insert into a filter cartridge 2, a filter insert 8 with the parameters adapted to the use. It is of course possible to design the filter according to the model so that the filter insert 8 itself takes on the role of the filter cartridge 2 and the filter insert 8 itself can be inserted into the housing of filter 1.

For a professional, it is obvious that structural elements not shown in the drawing can be fixed or formed on the filter housing 1 to allow, in accordance with the current application of the filter, the connection of the latter to other structural units. , for example, to the air ducts of ventilation systems, vehicle cleaning systems, etc.

In order to monitor, during use, the efficiency of the filtration or the value of other parameters related to the filtration, it is possible to insert one or more sensors, for example a detection module of the air quality of type ZP07-MP503, in filter cartridge 2, either during assembly or later during use. On the , a door 13 is provided for this purpose, through which a selected sensor 14, shown only symbolically in the figure, can be inserted and fixed. In the present example, the sensor 14 comprises two outputs which are connected to the connection surfaces 15 formed on the wall of the filter cartridge 2. They should be placed close to the sensor 14, on the , they are shown on top of filter cartridge 2 for illustration purposes only. In this case, in the filter housing 1, contacts corresponding to the connection surfaces 15, not shown in the drawing, are formed in the usual way in the field, for example so as to make a spring connection, and an electronic circuit processing the monitored parameter is in communication with the sensor 14 via these contacts. The number of connection surfaces 15 and the contacts functionally connected thereto depends, depending on the case, on the current sensor 14 as well as on the number of sensors 14. Of course, it is also possible to install in the filter cartridge 2 a or more sensors 14 with their own power source and their own wireless communication unit, where the life of the power source is consistent with the usability and life of the filter insert 8 In this case, there is no need for a connection surface 15 or a spring contact.

Legend

1 filter box

2 filter cartridge

3 opening

4 door

5 metal netting

6 hole

7 frame

8 filter insert

9 filter material

10 support structure

11, 12 layer

13 door

14 sensor

15 connection area

According to another aspect of the invention, the invention relates to the use of the above filter material to reduce the concentration of the following substances in gaseous media, preferably in air, in the vapor space and/or in waste gases: for example volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), or, for example, to reduce the concentration of the following substances in media gaseous, in the air, in the vapor space and/or in the waste gases: formaldehyde, benzene, toluene, xylenes, ethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, 1,3, 5-trimethylbenzene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, n-propylbenzene, i-propylbenzene, styrene, cyclohexane, cyclopentane, n-propanol, i-propanol, n-butanol, i-butanol, diacetone alcohol, acetate methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, acetone, methyl ethyl ketone, methyl-i-butyl ketone, 2-heptanone, cyclohexanone, methyl tert-butyl ether, tetrahydrofuran, n-pentane, n-hexane, 2-hexane, n-heptane, n-octane, n-nonane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n- pentadecane, n-hexadecane, trichlorethylene, dichloromethane, tetrachlorethylene, trichloromethane, ethyl glycol, 1-methoxy-2-propanol, butyl glycol, butyl glycol acetate, ethylene glycol, propylene glycol, methanol, hydrochloric acid, sulfuric acid and sulfur trioxide, sulfur trioxide, sulphur, ammonia, dioxins and dioxin-like PCBs (polycyclic chlorobenzenes).

By reducing the concentration is preferably meant filtration, i.e. during application, the gaseous medium containing the substance in question is directed through the space containing the filtering material.

Examples

Example 1 - Production process

The water is continuously extracted from the water glass (Product name: DIY Onyx sodium silicate, product code: C29050106, solids: approx. 35.8%, pH in aqueous solution: approx. 12.5, specific gravity: 1.372 + /- 0.015, viscosity: 625 mPa.s at 20° C.) until the formation of a hard foam which is then ground into a fine powder. Water extraction is carried out in a microwave generator at a frequency of 2.45 GHz. It is observed that the thermal effect is not the only one that plays a role when using microwaves, but physical and chemical changes also occur in the material. It modifies the properties of the material, as shown by our measurements. During our measurements, we found that the material produced by microwave had a different quality and a higher adsorption capacity than the material produced in an electric oven with the same parameters (examples 5 to 8). The irradiation time for 200 g of liquid starting material is 12 minutes in total, consisting of three equally distributed phases. The first 4 minutes are followed by a 1 minute pause, during which the material temperature is 108.2°C. The next 4-minute irradiation is followed again by a 1-minute break, the temperature is 133°C. The material is then vigorously agitated. Then comes the last phase of 4 minutes closing the process. It is important that the temperature of the material is not higher than 200°C during the last irradiation either. Water content was determined using a Benetech GM620 moisture meter in spc 1 (M1) mode. The water content of the material obtained by this process is 12% by weight. The grinding process allows to obtain a particle size of 0.2 to 0.4 mm. The material obtained is a snow-white powder having an amorphous structure (Example 9).

Example 2 - Efficiency

From the filter material of example 1, using a G3 filter material (its properties: polypropylene material, thickness: 16mm, gravimetric separation efficiency: 82%, filtration class: G3, pressure drop at 1.5m/ s: 22Pa, maximum pressure drop: 250Pa), a filter insert was formed as an envelope. The source of PAHs was a furnace connected to the filter insert in a closed system. It was connected to a gas wash bottle filled with hexane (200ml). The entire system was connected to a water jet pump providing the necessary suction power. During the test, when using the filter, we did not observe any visible smoke in the gas washing bottle and no odor could be perceived. In the case without a filter, the waste gas present in the gas washing cylinder took on an opaline and non-transparent brownish color, whereas when using the filter we obtained a colorless waste gas, perfectly translucent and clear.

The gas scrubber contained 15 ml of n-hexane which we transferred after the measurement into a test tube and evaporated to 1.5 ml in a stream of nitrogen. The hexane sample obtained was analyzed by gas chromatography, the method used having a detection limit (nd) set at 0.0005 µg per component.

MS000: Blank sample (white hexane, without passing gas);

MS001: Atmospheric air (air conducted through hexane, without filter);

MS002: Active PAH source (waste gas conducted through hexane, no filter);

MS003: Source of PAH MS002 with 0.3 g of filter material;

MS004: Active intensive source of PAHs;

MS005: source of PAHs according to MS004 with 30.0 g of filter material.

Components MS 000
WHITE / µg MS 001 /
µg MS 002 /
µg MS 003 /
µg MS 004 /
µg MS 005 /
µg naphthalene n/a n/a 0.304 0.305 42.9 2.91 2-methyl-naphthalene n/a n/a 0.067 n/a 1.29 n/a 1-methyl-naphthalene n/a n/a 0.097 0.012 1.07 0.003 acenaphthylene n/a n/a 0.039 0.002 2.79 0.052 acenaphthene n/a n/a 0.014 n/a 0.026 n/a fluorene n/a n/a n/a n/a 0.233 n/a phenanthrene n/a n/a n/a n/a 0.753 n/a anthracene n/a n/a 0.009 n/a 0.224 n/a fluoranthene n/a n/a n/a n/a 0.631 n/a pyrene n/a n/a n/a n/a 0.574 n/a benzo(a)anthracene naphthalene ne n/a 0.001 0.004 0.001 0.229 n/a chrysene n/a n/a 0.002 n/a 0.158 n/a benzo(b)fluoranthene+
n/a
0.019
0.015
0.037
0.393
0.023 benzo(k)fluoranthene benzo(e)pyrene n/a 0.002 0.001 0.001 0.147 n/a benzo(a)pyrene n/a 0.002 0.002 n/a 0.25 n/a indeno(1,2,3-cd)pyrene n/a n/a 0.001 n/a 0.222 n/a dibenzo(a,h)anthracene n/a 0.002 n/a n/a 0.028 n/a benzo(g,h,i)perylene n/a 0.004 n/a n/a 0.211 n/a Total naphthalene n/a n/a 0.468 0.317 45.3 2.91 Total PAH without naphthalene n/a 0.03 0.087 0.041 6.87 0.075 Total PAHs n/a 0.03 0.555 0.358 52.2 2.99

As can be seen by comparing data series MS002 - MS003, as little as 0.3 g of filter material is able to filter 35.5% of PAHs. A comparison of the MS004 - MS005 data series clearly shows that 30g of filter material filters 94% of the PAHs from the waste gas.

Example 4 - Process for manufacturing the product NPL1

The NPL1 product was made by the combustion process described in this article. The sample was prepared by the combustion method using sodium hydroxide (NaOH, Aldrich), SiO ₂ and urea (CO(NH ₂ ) ₂ , Aldrich). The NaOH and the urea were dissolved in a minimum quantity of water, then the SiO ₂ was dispersed in this solution to thus obtain a viscous material which was heated at 70°C until it dried. Finally, the powder was heat treated at 500°C for 5 min, then at 700°C for 4 h so that the material crystallized.

Example 5 - Raman Comparison

The silicates produced according to examples 1 and 4 were analyzed using the Raman microscope available to us, which is one of the most modern techniques with a possible resolution of up to 1 to 5 μm. The instrument is a DXR3xi Raman imaging microscope (ThermoFisher). The wavelength of the laser used is 532 nm.

Figures 1 and 2 illustrate each Raman spectrum separately recorded from the samples over the entire range (50 to 3400 cm ^-1 ). Tables 2 and 3 include the intensities corresponding to the peaks. There shows a comparison of the sample spectra. There is a significant difference in the Raman spectra of the samples: the Raman spectrum of the sample subject of the invention has peaks at 281.5 and 712.7 cm ^-1 , whereas the NPL1 sample does not shows no peak at these wavenumbers. The peak with the highest intensity is observed at wave number 1086.3 for the sample which is the subject of the invention; and at 1069.2 cm ^-1 for the NPL1 sample. This clearly indicates that considering also the quality of the two samples, the materials are partially different.

Position of the peaks in the sample subject of the invention / cm-1 Relative peak intensity 155.37 1373.121 281.52 3069.677 545.52 2452.104 712.67 510,722 1086.3 11045.308

Peak positions in NPL1/cm-1 sample Relative peak intensity 60.46 1113,154 72.65 978.019 94.09 761,232 108.73 1098.92 165.94 574,484 540.38 1162.581 1069.22 7275.068

Example 6 - Thermogravimetric (TG) comparison

The TG test was carried out in accordance with MSZ EN ISO 11358-1:2014.

The measurements were carried out with a TGA Setaram, Labsys Evo measuring instrument. A nitrogen atmosphere was used as the inert medium, the temperature range being 50-800°C and the heating rate 20°C/min. In the instrument, the sample is placed on a high-sensitivity analytical balance located in an electrically heated and programmed oven. The device thus records the curve Δm as a function of the temperature. In this way, the device is able to describe many physical changes and phase transitions. For a more precise and detailed analysis, the derivative of the curves (DTG) is also indicated in the figures.

Table 4 summarizes the results of the TGA analysis of the samples. For the sample that is the subject of the invention, 4 decomposition stages can be distinguished and 2 for the NPL1 sample. Early stages may indicate water loss. The total mass loss at 800° C. is 9.7% for the sample that is the subject of the invention and 14% for the NPL1 sample. Figures 4 and 5 show the mass losses (TG) of the two samples and their derivative (DTG) as a function of temperature, while the compares the relative TG curves of the two samples.

Decomposition stages Tinf [°C] A loss of mass [%] Product subject of the invention NPL1 Product subject of the invention NPL1 1 105.2 111.1 0.26 2.6 2 194.9 226.7 3.8 11.4 3 276.1 - 1.4 - 4 292.7 - 4.5 -

Mass losses can be attributed to drying and the presence of physically bound volatiles. No phase transition has occurred in this range. It can be clearly seen that the two different samples are able to adsorb different amounts of other molecules, furthermore they release them in different ranges. This suggests that these related components have different qualities.

Also, it is important to note the shape of the two TGA curves presented in the . This clearly shows that not only are they offset from each other, but their bumps also form different curves. This suggests that there is not only a difference in the shape of the crystal, but also in the quality and composition of the material, and clearly shows that the molecules released differ in volume and bond strength, and therefore probably also in their capacity.

Example 7 - ICP-OES

The mobile metal ions present in the lattice can have a significant effect on the interactions created by the crystals thus, their analysis was also carried out. The instrument we used was the PlasmaQuant PQ9000 ICP-OES, TOPwave from Analytik Jena, suitable for trace analysis.

Our results are shown in Table 5.

Samples Product subject of the invention NPL1 Elements DM mg/kg DM mg/kg mg 3.98 6.32 That 233 301 N / A 29086 29557 K 480 635 Al 10.6 12 Fe 4.34 3.06 min 0 0.13

The table clearly shows that the content of magnesium among the listed metals is significantly different, furthermore, that of potassium is also significant, but the two samples show differences in their content for all metals. This is the reason for the difference in their ability to establish certain interactions.

Example 8 - Microscope

Figures 7 and 8 illustrate photographs of the crystals. They demonstrate the different crystal structure, which is evident at a resolution of 50 micrometers. The different crystal structures and morphologies depend on the different production techniques and fundamentally determine the properties of silicates, their ability to adsorb and retain certain molecules.

Example 9 - XRPD

We carried out the phase identification by X-ray diffraction of the sample which is the subject of the invention. The analyzes were carried out with a Bruker D8 Davinci Advance device. The measurements of the parts analyzed were carried out in Bragg-Brentano geometry using Cu K-alpha1-alpha2 radiation with an acceleration voltage of 40 kV and a current of 40 mA.

As can be clearly seen in the , the sample exhibits an amorphous structure.

Example 10 - Efficiency Comparison

From the subject sample and the NPL1 sample, 3-3 individual samples of known exact mass were taken. The samples were placed in sealed containers, in which a volume of approximately 20 to 30 ml of the following solutions was previously poured and then sealed:

• Ammonia: nominal concentration: 25%;
• Formaldehyde: 36% formaldehyde (39 w/v%) stabilized with 10% methanol.

Each sample was exposed to the different vapor spaces for at least 72 hours, and each sample was exposed in a vapor space containing a single component to prevent competitive binding of the different compounds.

They were then packaged in packaging that reduces exposure to outside air as much as possible, and transported to a partner laboratory.

It is necessary to mention that the samples lost their porous structure, they fell like puffs, and their original white color became light blue. These materials mix with water, so it can be assumed that water retention has also occurred on the surfaces.

The results are summarized in Table 6.

Component analyzed Bound quantity [μg/g] Product subject of the invention NPL1 1. Ammonia 22 16 2. Formaldehyde 231 215

The results in the table show that the samples contained ammonia and formaldehyde. In addition, it can be observed that per unit mass, the sample object of the invention is polluted by more ammonia and formaldehyde.

Claims (10)

Use of filter material containing Na ₂ SiO ₃ ,
the filtering material containing Na ₂ SiO ₃ characterized in that the water content of the filtering material is from 8 to 14% by mass, preferably from 10 to 14% by mass, better still from 12 to 13% by mass relative to the total mass of the filter material, and in that it has characteristic peaks in its Raman spectrum, at the following wave numbers (± 5 cm-1): 281 cm-1 and 712 cm-1, preferably at the numbers of following waves (± 5 cm-1): 155 cm-1, 281 cm-1 and 712 cm-1; to be measured using a laser with a wavelength of 532 nm and that it has at least 3 decomposition stages on its thermogravimetric (TG) curve, preferably at the following temperatures ( ± 2°C): 195°C, 276°C and 293°C; to be measured according to (MSZ) EN ISO 11358-1:2014;
to reduce the concentration of the following substances in gaseous media,
preferably in air, vapor space and/or waste gases: compounds
volatile organic compounds (VOC), semi-volatile organic compounds (SVOC), hydrocarbons
polycyclic aromatics (PAHs), polychlorinated biphenyls (PCBs)
Or
to reduce the concentration of the following substances: formaldehyde, benzene, toluene, xylenes, ethylbenzene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, 1,3,5 -trimethylbenzene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, n-propylbenzene, i-propylbenzene, styrene, cyclohexane, cyclopentane, n-propanol, i-propanol, n-butanol, i-butanol, diacetone alcohol, methyl acetate, ethyl acetate, n-acetate propyl, i-propyl acetate, n-butyl acetate, i-butyl acetate, acetone, methyl ethyl ketone, methyl-i-butyl ketone, 2-heptanone, cyclohexanone, methyl tert-butyl ether, tetrahydrofuran, n-pentane, n-hexane, 2-hexane, n-heptane, n-octane, n-nonane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, trichloroethylene, dichloromethane, tetrachloroethylene, trichloromethane, ethyl glycol, 1-methoxy-2-propanol, butyl glycol, butyl glycol acetate, ethylene glycol, propylene glycol, methanol, hydrochloric acid, sulfuric acid and sulfur trioxide, sulfur trioxide, ammonia, dioxins and dioxin-like PCBs (chlorobenzenes polycyclic). Use of a filter material according to claim 1 to reduce the concentration of PAHs. Use of a filter material according to one of Claims 1 or 2, in which the filter material consists essentially of Na₂SiO₃ and adsorbed water. Filtering material containing Na ₂ SiO ₃ , characterized in that the water content of the filtering material is from 8 to 14% by mass, preferably from 10 to 14% by mass, better still from 12 to 13% by mass relative to the total mass of the filter material, and in that it has characteristic peaks in its Raman spectrum, at the following wave numbers (± 5 cm-1): 281 cm-1 and 712 cm-1, preferably at the numbers of following waves (± 5 cm-1): 155 cm-1, 281 cm-1 and 712 cm-1; to be measured using a laser with a wavelength of 532 nm, and that it has at least 3 decomposition stages on its thermogravimetric (TG) curve, preferably at the following temperatures ( ± 2°C): 195°C, 276°C and 293°C; to be measured according to standard (MSZ) EN ISO 11358-1:2014. Filter material according to Claim 4, characterized in that
that in the range below the wavenumber 120 cm-1, its Raman spectrum does not include
no peak whose integral reaches half the integral of the peak located at wavenumber 540 cm-1 (± 5 cm-1), preferably in the range below wavenumber 120 cm-1 , it doesn't include a pic at all. Filter material according to one of Claims 4 or 5, characterized in that, in the range from 100 to 110°C, it has at most one peak representing a mass loss of less than 2% with respect to the mass initial filter material. Process for the manufacture of a filtering material from an aqueous solution of Na2SiO3 in water according to one of Claims 4 to 6, characterized in that it comprises a step of extracting water until reaching a water content value of 8 to 14%, preferably 10 to 14% by mass, better still 12 to 13% by mass relative to the total mass of the filtering material and in that the extraction is carried out by micro- waves in a frequency range between 2.0 and 3.0 GHz, at a temperature below 200°C. Process for the manufacture of a filtering material from an aqueous solution of Na2SiO3 in water according to Claim 7, characterized in that the water is extracted from the aqueous solution of Na2SiO3 by microwaves at a frequency of 2 .45 GHz and at a temperature below 200°C. Process for the manufacture of a filtering material from an aqueous solution of Na2SiO3 in water according to one of Claims 7 or 8, characterized in that the extraction of water is carried out continuously or in stages. . Process for the manufacture of a filtering material from an aqueous solution of Na2SiO3 in water according to one of Claims 7 to 9, characterized in that the material is agitated during the extraction of water.