Technical field

The present invention relates to a method and device for purification of gas, which may find industrial and domestic applications, particularly for purifying of air in interior spaces.

Background art

Since the industrial revolution humanity has been destroying its natural ecosystem through irresponsible innovation. A serious footprint of this uncontrolled problem is the gradual deterioration of the quality of air that we breathe both indoors and in urban environments. Various types of gas purification methods are known, including liquid to gas contact methods used in scrubbing systems based on the effect of adsorption and/or dissolution of pollutants by liquid drops. These known methods require large volumes of water or other chemicals, and they create the active surface by droplet formation.

The most common method of purifying gases from pollutants and gas-borne microbes is by using permeable natural or synthetic fiber and solid porous media based high-efficiency particulate absorption filters and high-efficiency particulate air (HEPA) filters. The main mechanism used in these filtration systems is to provide a highly active surface area that can also be statically charged, resulting in the capture of particles and microbes due to coulombic attraction. HEPA filters must be changed or washed after a certain period of time, depending on the level of environmental contamination. If HEPA filters are not washed or replaced, they become incubators for airborne pathogens that can then be released into the air we breathe. Therefore, this technology becomes unreliable in the event of a pandemic like COVID-19. There are other types of air purifiers such as water spray-based microdroplet purification that require a supply of fresh water. Another example is pathogenic oxidation, which primarily uses TiO2 nanoparticles that oxidize and thereby destroy airborne volatile organic compounds (VOCs) and microbes without removing them from the air. And finally, there are ionizing purifiers that ionize and settle airborne microbes and particles, but they form toxic ozone and new NOx emissions as well as other oxide pollutants.

Disclosure of invention

The object of the present invention is to create a method and a device for capturing and separating, deactivating, or disintegrating unwanted pollutants, pathogens, and allergens present in a gas and delivering a purified gas with a desired degree of purity.

The problem has been solved by a method for purification of gas, according to the present invention, which includes the following sequence of operations: - a polluted gas is sucked and directed as a gas stream through a surfactant based aqueous solution;

- a surfactant foam is generated by passing the polluted gas through surfactant based aqueous solution, wherein the surfactant foam is a plurality of foam cells, each of which has an active cell surface in the form of a surfactant film with a water core located between two layers of surfactant molecules, the water core being made up of water with an alkaline pH and dissolved hydroxides;

- the volume of the surfactant foam is increased to create a greater amount of active cell surfaces;

- the polluted gas is encapsulated in the surfactant foam, surrounded by the active cell surface of each foam cell, with all volatile organic pollutants, oxide gaseous pollutants and airborne unwanted particles from the polluted gas are adsorbed and dissolved by the water core of the surfactant film, while all microbes, pathogens and allergens from the polluted gas bind to the surfactant molecules of the two layers of the surfactant film, after which they are deactivated and removed from the polluted gas;

- the surfactant foam bursts, wherein a purified gas is released from the surfactant foam.

In a preferred embodiment of the gas purification method according to the present invention, the surfactant foam is subjected to external stimuli to facilitate the gas purification. The external stimulus is one or a combination of the following: visible, ultraviolet and/or infrared light and/or microwave or radio waves, ionizing radiation such as preferably gamma or X-ray radiation, and/or an acoustic stimulus such as sound or ultrasonic vibrations.

In another preferred embodiment of the gas purification method according to the present invention, the surfactant based aqueous solution is placed in a solid porous medium. The solid porous medium is preferably a polymer, metal or ceramic rigid foam, a porous material or a fibrous mesh.

In a further embodiment of the gas purification method according to the present invention, the surfactant foam is burst by radio frequency field, a mechanical vibration, a hot or cold surface, a chemically treated surface, an infrared light source or with antifoam entities such as drops of lipophilic material, hydrophobic solid particles or mixture of both.

In another embodiment of the gas purification method according to the present invention, the surfactant is selected from the following substances: a photoactive or photocatalytic surfactant that forms free radicals and charges upon photoexcitation and/or a protein denaturing surfactants, that are binding to proteins and destroying their folds and/or a pathogen-inactivating surfactant, which attaches to the pathogen, encapsulates it and deactivates its active sites, and/or a lipid dissolving surfactants that dissolve the cell walls of pathogens and destroys them and/or a 2-Dimensional surfactant that can keep the water vapor content low in the regenerative surfactant foam and assist in pathogen deactivation. In yet another embodiment of the gas purification method according to the present invention, silver ions are added with the surfactants in the surfactant based aqueous solution to facilitate the disintegration of the pathogens in the polluted gas.

In another embodiment of the gas purification method of the present invention the temperature, pressure and moisture of the purified gas are controlled before its final releasing. Furthermore, the pH, pressure and temperature of the designed surfactant based aqueous solution and the regenerative surfactant foam and the quality, type and quantity of the purified gas and/or the level of removed unwanted pollutants from the purified gas are monitored online. in a further embodiment of the gas purification method according to the present invention, the used polluted surfactant based aqueous solution is replaced by pumping in fresh solution or through a replaceable solution cartridge, and the used and contaminated aqueous surfactant solution is periodically or continuously discarded to maintain optimum purification efficiency. In this embodiment, the discarded used and polluted surfactant based aqueous solution may be deactivated to ensure environmental protection and recyclability.

The problem according to the present invention has been solved by creating also a gas purification device applyingthe gas purification method having a chamber, which is divided into four consecutive segments, wherein the first segment is a reservoir for a surfactant based aqueous solution and a solid porous media, the second segment is a regenerative surfactant foam filter, which is a large cavity, filled with up with surfactant foam, the third segment has a foam bursting mechanism and is separated from the second segment with a perforated sieve and the fourth segment has a mechanism for control of temperature, pressure and moisture.

In a preferred embodiment of the gas purification device according to the present invention, that a pump or a fan configured to suck the entering polluted gas and direct it as a gas stream may be mounted at a first end of the chamber and an additional fan for sucking the purified gas may be installed at a second end of the chamber.

In other preferred embodiment of the gas purification device according to the present invention, the porous media may be an open cell polymeric foam, a metallic foam, a ceramic foam or is a collection of particulate matter like a sand or glass balls or is a wire or a fabric mesh.

In further embodiments of the gas purification device according to the present invention, in the second segment is desirable to be mounted an external stimulus. In that embodiment, the external stimulus may be one or combination of the following: means for ultraviolet, an infrared or a visible light, means for ionizing radiation, means for neutrons, means for radio frequency, including microwaves, means for electromagnetic radiation or means for audible or ultrasonic vibrations.

In yet another preferred embodiment of the gas purification device according to the present invention, the foam bursting mechanism may be one or combination of the following: a radio frequency generator, an infrared heat source, a source of mechanical vibrations or a functional surface for disintegration of the surfactant foam by contact or a source of electrical field. In other preferred embodiment of the gas purification device according to the present invention, the mechanism for control of temperature, pressure and moisture may be a temperature controlled perforated sieve heat exchanger.

In yet other embodiment of the gas purification device according to the present invention, in the first, second and fourth segments are installed sensors, configured to provide information for the pH, pressure and temperature of the surfactant solution and the surfactant foam.

In yet another embodiment of the gas purification device according to the present invention, the designed surfactant based aqueous solution is in a replacement cartridge.

The present method and device for purification of gas are specifically aimed at removing airborne viruses such as COVID19 and volatile organic compounds (VOC), and generally can be applied to purify gases from a host of pollutants, pathogens and allergens. The method and device for gas purification remove gas borne microbial pollutants such as pathogens and destroy them providing pathogen free gas. They are especially useful if airborne viruses such as COVID-19 and similar viruses are presented, as they can be captured and broken down using the present method and device for purification of gas. The disclosed gas purification method can also be used to remove toxic gaseous pollutants such as SOx, NOx, CO, H2S and VOC in the form of micelles such as polyfluoroalkyl substances (PFAS). The method and device may also be used to capture airborne allergens and to remove target gases such as CO2 from gas mixtures. They can be used for air purification in hospitals, in commercial and public spaces such as movie theaters, shopping malls, airports, etc., in vehicles such as ships, airplanes, trucks, cars, etc., as well as for indoor air purification such as buildings, houses or others.

Brief description of drawings

The method and device for purification of gas, according to the present invention, is clarified on the accompanying figures, wherein:

Figure l is a schematic block diagram, describing the method for gas purification in form of operations and results associated with the segments within the chamber.

Figure 2 is an illustration, describing the device for purification of gas.

Figure 3 is an illustration, showing the surfactant foam generation in the first segment of the chamber.

Figure 4 is an illustration of the third operation in the second segment 2, which is the forming of designed regenerative surfactant foam filtration system, trapping polluted gas within its many surfactant foam cells.

Figure 5 is an illustration, describing the three classes of functional materials used in gas purification.

Figure 6 illustrates the classical methods for deactivation of microbial pathogens, which are protein denaturing, lipid membrane cell wall solubilization in surfactant micelles and pore formation in the lipid membrane cell wall. Figure 7 is an illustration, describing the third segment, which functions as the surfactant foam bursting cavity.

Figure 8 is an Illustration, describing the fourth segment, that functions as a cavity for moisture control of the purified gas.

Detailed description of the invention

The following is a detailed description of exemplary embodiments to illustrate the principles of the invention. The embodiments are intended to illustrate aspects of the invention but should not limit its embodiments. The invention may include other alternatives, modifications, or equivalents falling within the scope of claims. Certain specific details are disclosed in the following description to provide a thorough understanding of the invention. However, the invention may be made, as claimed, without some of these specific details. For the sake of clarity, technical materials known in the art related to the invention have not been described in detail, so that the detailed description of the invention will not be unnecessarily complicated. A gas purification invention using designed surfactant foam as a regeneration filter solves critical problems associated with existing gas purification techniques.

The method for purification of gas (Figure 1), according to the invention, includes a sequence of operations, wherein in the first operation a polluted gas is sucked and directed as a gas stream through a designed surfactant based aqueous solution 2.1. and a solid porous media.

The method for gas purification (Figure 1), according to the invention, includes a sequence of operations, of which in the first operation a polluted gas is sucked in and directed as a gas stream through an aqueous surfactant solution 2.1. The aqueous surfactant solution 2.1 can be in a solid porous medium 2.1. Porous medium 2.1 is essentially a low density solid having interconnected gas paths and can retain the entire amount of aqueous surfactant solution 2.1.

In the second operation, when the polluted gas passes through designed surfactant based aqueous solution 2.1 and the solid porous medium 2.2, a surfactant foam is generated (part IV. B on Figure 4), which is composed of a plurality of surfactant foam cells (part IV.C in Figure 4 ). In this operation, the solid porous media 2.2 acts as a reservoir for the surfactant based aqueous solution 2.1 and serves as a foam generator and an indicator of the level of pollutants, pathogens and allergens.

Each foam cell has an active cell surface in the form of a surfactant film (part IV.D in Figure 4). A surfactant film is an aqueous core sandwiched between two layers of surface-active molecules with surface-targeted functions (Part IV.E in Figure 4). The aqueous core is made up of water with an alkaline pH and dissolved hydroxides. The aqueous core contains reagents that extract the pollutants through a chemical reaction. Alkaline pH water is used to effectively dissolve SOx, NOx, H2S, CO, and CO2. Sodium hydroxide (NaOH) solutions and ferrous hydroxide solutions are used to form the surfactant foam. The alkaline pH aqueous core in the surfactant foam effectively absorbs oxide gaseous pollutants from the gas stream. The surfactant molecules on the surface of the surfactant film (part V.A in Figure 5) are a broad class of molecules called surfactants that have a hydrophilic head and a hydrophobic tail. In the method for purification of gas, advanced functional surfactant molecules and a mixture thereof are used to achieve purification of the polluted gas from volatile organic compound pollutants and from microbes such as pathogens and others. Surfactants can be (but are not limited to):

• Surfactants that break down the cell wall of pathogens and absorb volatile organic pollutants into micelles;

• Photoactive and photocatalytic surfactant (item V.B on Figure 5) producing free radicals and charges on photoexcitation. These will attach to pollutants and microbes and will photo-catalytically oxidize them. The uniqueness of this system over TiO ₂ based nanoparticle photocatalytic oxidation is that the surfactants within surfactant films will preferably attach to the pollutants and microbes in contrast to TiO ₂ nanoparticles that have no preferential attachment.

• Protein denaturing surfactant (item V.C on Figure 5) that would bind to proteins and destroy their folds. Example will be sodium dodecyl sulfate that can attach to the crown protein of a COVID-19 pathogen and denature it.

• Pathogen deactivating surfactant (item V.D on Figure 5) that will attach to the pathogen and encapsulate them and deactivate their active sites. Example is CHAPS zwitterionic detergent.

• Lipid-dissolving surfactants that dissolve the cell walls of pathogens and destroy them.

• 2-Dimensional surfactant like modified Graphene and Graphene Oxide surfactant that will keep the surfactant foam low in water vapor content and support pathogen deactivation.

Silver ions (Ag+) can be added to the surfactants in the surfactant based aqueous solution 2.1 to help break down the cell walls of bacterial pathogens and viruses such as COVID- 19. Pathogens such as the example virus have their genetic material embedded in the cell, where the wall is made of lipid. The silver ions can be incorporated into the surfactant based aqueous solution 2.1 as counterions of the ionic surfactants or as soluble silver salts such as silver nitrate and silver fluoride. Silver ions are effective in neutralizing pathogens, especially in combination with surfactants.

Next comes the third operation, increasing the volume of the surfactant foam to create millions of micro cells with multiple active surfaces, creating a larger amount of active cell surfaces (Part IV. A in Figure 4).

In the fourth operation, the polluted gas is encapsulated in the surfactant foam, surrounded by the active cell surface of each foam cell of the plurality. The active cell surfaces are in contact with the polluted gas, resulting in the adsorption of pollutants and VOCs from the gas, as well as the capture and separation of gas-borne pathogens and allergens. All volatile organic pollutants, oxide gaseous pollutants and airborne unwanted particles from the pollutant gas are adsorbed and dissolved by the aqueous core of the surfactant film, while all microbes, pathogens and allergens from the pollutant gas bind to the surfactant molecules of the two surface layers of the active film.

In the fifth operation, which is optional, the surfactant foam is subjected to an external stimulus such as electromagnetic and/or acoustic excitation to deactivate and/or disintegrate the pathogens. The external stimulus may be one or a combination of the following: visible, ultraviolet and/or infrared light and/or microwave or radio waves, ionizing radiation such as preferably gamma or X ray radiation, and/or an acoustic stimulus such as sound or ultrasonic vibrations. The process of inactivating, denaturing, and disintegrating microbial pathogens with a particular example virus, COVID-19, is shown in Figure 6. Pathogens, like the example virus, have genetic material embedded in a cell where the wall is made of lipid (part VI. D in Figure 6). The cell wall has crown-shaped folds of functional protein (part VI.A in Figure 6) that attach to target living cells. A way to deactivate these pathogens is to provide surfactant molecules that attach to the proteins and immobilize the pathogens in the surfactant foam, whereby the tail of the surfactant molecule attaches to the pathogen protein or lipid cell wall (part VLB in Figure 6) and the head of the surfactant molecule is designed to be excited by an external stimulus such as radio frequency, infrared light, etc. (part VI. C of Figure 6). These attached surfactant molecules are further functionalized with an active main group that: oxidizes the crown protein when the surfactant molecules are excited by light using photocatalytic oxidation; denatures the corona protein by breaking its folds; inactivates the pathogen by corona encapsulation and then breaks down the corona protein and lipid cell by generating local heating due to thermal motion caused by absorption of for example (but not limited to) an externally applied radio frequency field or infrared light. After the disintegration of the pathogens, the surfactant molecules further encapsulate the protein or cell membrane fragments by forming micelles or by immobilizing the fragments in the surfactant foam. The said silver ions are added to the surfactant to facilitate dissolution (Part VI. E in Figure 6). The surfactant foam can be irradiated to facilitate gas purification after the pollutaed gas is encapsulated. For example, the radiation may be (but is not limited to) ultraviolet or visible light, infrared light, ionizing radiation (gamma, x-rays), neutrons, radio frequency, or electromagnetic radiation.

Within the method, after the purification operations, the sixth operation is bursting of the surfactant foam, in its advancing front (part VILA in Figure 7). The advancing front of the surfactant foam is disintegrated, successively releasing the purified gas. Bursting the surfactant foam (part VII.B in Figure 7) also disintegrates all microbes and allergens along with the surfactant molecules. A surfactant foam can be burst by a radio frequency field, a mechanical vibration, a hot or a cold surface, a chemically treated surface, an infrared light source, or with antifoam entities such as drops of lipophilic material, hydrophobic solids, or a mixture of both. After the advancing surfactant foam front is burst, the temperature, pressure and moisture of the released purified gas stream are controlled (part VIII.A in Figure 8) during the seventh operation of the gas purification method.

According to the method, the eighth operation is online monitoring of the amount and/or type and quality and/or level of the removed unwanted pollutants from the purified gas. Online monitoring provides feedback to control the quality and production rate of purified gas by adjusting operational parameters.

The ninth operation is periodic or continuous replacement of the polluted designed surfactant based aqueous solution 2.1 to maintain optimal purification efficiency of the method. This operation is facilitated by online monitoring in the eighth operation. The replacement can be done with the use of a pump orthrough a replaceable cartridge containing a freshly designed surfactant based aqueous solution 2.1.

Within the method, the tenth operation is deactivation of the discarded polluted solution to ensure environmental protection and recyclability according to regulatory standards. This operation can be facilitated using non toxic and degradable surfactants and standard recycling and disposing protocols for water based degradable solutions. For example, the polluted solution will be collected in standard disposal bottles containing an acid pill for neutralizing the basic pH to acceptable pH limits. The neutralized solution can then be disposed of through standard sanitary practices.

Furthermore, the invention discloses a gas purification device (shown in figure 2) that implements the gas purification method, which has a chamber 1 divided into four consecutive segments 2, 3, 4 and 5. The first segment 2 is a reservoir (figure 3) containing the surfactant based aqueous solution 2.1 and the solid porous medium 2.2.

The polluted gas is directed into the chamber 1 by a pump or fan 7 (part III. A in Figure 3) mounted at the first end of the chamber 1 and passes through the designed surfactant based aqueous solution 2.1 in the first segment 2 of the chamber 1, which successively leads to the formation of the surfactant foam (part III.B in Figure 3) with the desired foam composition, geometry and formation rate by controlling the density and morphology of the solid porous medium 2.2. The polluted gas passes through the soap foam in the second segment 3. The solid porous media 2.2 can be open cell polymeric foam (polyurethane foam, polyacrylamide foam etc.), metallic foam (aluminum foam etc.), ceramic foam (alumina foam), or it can be a collection of particulate matter like sand or glass balls, or a mesh of wire or fabric.

The second segment 3 is a regenerative filter, which is a large cavity filled with the surfactant foam. The surfactant foam in the second segment 3 of the chamber 1 is driven at the desired flow rate to increase the volume of the surfactant foam to create a larger amount of active cell surfaces and an advancing front. An external stimulus 3.1 can be installed in the second segment 3 to facilitate gas purification. The external stimuli 3.1 can be one or combination of the following means for ultraviolet, infrared or visible light, means for ionizing radiation, means for neutrons, means for radio frequency, including microwave, means for electromagnetic radiation or means for audible or ultrasonic vibrations. The third segment 4 (Figure 7) has a foam bursting mechanism 4.1 (item VILA of Figure 7) and is separated from the second segment 3 with a perforated sieve 6 (item VII. B of Figure 7). The regenerative surfactant foam moves through said perforated sieve 6, that separates the third segment 4 from the second segment 3. In that case the advancing front of the regenerative surfactant foam is driven through the perforated sieve 6 and the third segment 4 of the chamber 1 with bursting mechanism 4.1 to break the foam boundary by bursting the foam cells resulting in the releasing of the purified gas from the foam cells. The sieve 6 can be made of plastic fibers or metal wire frame, depending on the used foam bursting mechanism 4.1. The foam bursting mechanisms 4.1 can operate either on a continuous wave mode or on a pulsed mode and can be (but not limited to) one or combination of the following:

• A radio frequency generator like a magnetron (for microwaves) to generate RF that will be strongly absorbed by the advancing front of regenerative surfactant foam leading to local heating and its consequent disintegration. The radio frequency can also be absorbed by the surfactants and lipids leading to faster destruction of pathogens by cell wall disintegration.

• An infrared (IR) heat source like an infrared lamp, LED or laserto locally heat the advancing front of regenerative surfactant foam and disintegrate it.

• A source of mechanical vibrations like sound or ultrasound waves to disintegrate the advancing front of regenerative surfactant foam without the use of significant temperature raise.

• A functional surface that can disintegrate the regenerative surfactant foam by contact, which can be (but not limited to) lipophobic or hydrophobic fibers, or fibers with high static charges.

• A source of electric field to burst the regenerative surfactant foam cells.

The foam bursting mechanism 4.1 releases the purified gas from the surfactant foam and isintegrate any microbes and allergens in contact with the designed surfactant. Upon the surfactant foam bursting, the surfactant solution drains back to the first segment 2 and second segments 3. The purified gas enters the fourth segment 5 (Figure 8), where a temperature, pressure and humidity control mechanism 5.1 is located (Part VIII .A in Figure 8).

The mechanism for control of temperature, pressure, and moisture 5.1 can function by passing the moist purified gas over a temperature controlled perforated sieve heat exchanger (item VIII. B of Figure 8). The heat exchanger temperature is controlled (but not limited to) electrically (thermoelectric effect or electrical resistance heater) or by a standard thermodynamic heating or cooling cycle depending on the gas handling capacity of the device for purification.

An additional fan 8 is mounted at the second end of the chamber 1, which ejects and distributes the purified gas outside the device. According to the method for gas purification, online monitoring of the quality and/or type and amount and/or level of removed unwanted pollutants from the purified gas in the device can be performed with sensors installed in the first segment 2, the second segment 3 and the fourth segment 5 to provide information on the pH, pressure, and temperature of the surfactant based aqueous solution 2.1 and the surfactant foam. According to the method, to facilitate the replacement of the surfactant solution in the device for gas purification, the designed surfactant based aqueous solution 2.1 can be in a replacement cartridge.

The first embodiment of the invention is a method for purification of gas that finds application in removing water-soluble or partially water-soluble gaseous pollutants such as SOx, NO _x , H ₂ S, CO, CO ₂ from water-insoluble gases such as nitrogen or breathing air. The second embodiment of the invention is a gas purification method for removing volatile organic compounds (VOCs) such as alcohols, aldehydes, ethers, esters, chloromethane, PFAS, etc. from air and from other water-insoluble gases such as nitrogen. The third embodiment of the invention is a gas purification method for removing, inactivating or breaking down gas-borne microbes such as pathogens (bacteria, viruses) and allergens such as mites, spores and pollen. When all three embodiments are combined, the result reveals a simple, elegant and scalable solution revealing a method and device for gas purification and in particular for breathing air purification.