Portable plant-based plasma air purification system with porous anodized metal cathode

Abstract

The present invention relates to a portable, plant-based plasma air purification system based on non-thermal electrical discharge to improve discharge stability and increase ion production uniformity, which includes a high voltage power source, at least one surface-engineered metal cathode, and a biological collector surface as a counter electrode; the cathode of this system consists of a conductive metal substrate on which a plasma electrolytic oxidation process has created a porous oxide dielectric layer with micro- and nanoscale microstructured holes and channels, which The porous structure, as a dielectric barrier, distributes the electric field across the surface openings and, while preventing arcing and erosion, provides multiple, controlled points for initiating localized discharge and producing active species without the need for sharp electrodes. This oxide layer, due to its surface hydroxyl groups, passively absorbs air moisture in the discharge area. In this arrangement, by connecting the positive pole of the power source to the humid cultivation environment, the entire living structure of the plant acts as an equipotential anode and a biological collector with a high effective area, so that airborne suspended particles, after being charged by the cathode, are attracted to the leaves under the influence of electrostatic force and settle, so that the system, without dependence on consumable filters or active cooling systems, has high efficiency in reducing suspended particles and charge. Microbes of indoor environments provide

Description

Description of the invention Note: Items must be written only inside [ ], otherwise they will not be reviewed. Title of the invention (as stated in the declaration) Portable plant-based plasma air purification system with porous anodized metal cathode Technical background of the relevant invention Air purification Technical problem and stating the objectives of the invention Indoor air can contain fine particulate matter, volatile organic compounds, unpleasant odors, and airborne microorganisms due to limited ventilation and accumulation of pollutant sources. Particles such as PM2.5 and PM10, fumes from household chemicals, smoke, dust, bacteria, and fungi can reduce indoor air quality and negatively impact people's respiratory health, comfort, concentration, and quality of life in the long term. Common air purification technologies each have limitations. Mechanical filters, such as HEPA and carbon filters, rely primarily on physical separation of particles and adsorption of some chemical compounds, and require periodic replacement. Ultraviolet-based systems are used more for inactivating microorganisms and usually do not play a direct role in collecting particulate matter. In contrast, ionizing and plasma systems can affect particles and some biological or chemical contaminants, but many existing examples use needle electrodes, thin wires, carbon fibers, or sharp-tipped electrodes to create a corona discharge. The technical problem with these types of electrodes is that the electrical discharge is usually concentrated in a few limited and very localized points. This localized concentration can cause discharge instability, increase the probability of sparking or arcing, electrode erosion, reduce the uniformity of ion production, and limit the effective surface area for the production of charged species. On the other hand, if the electrode surface is completely smooth and without structure, it is difficult to concentrate the electric field and initiate the discharge at lower voltages, and the efficiency of ion or plasma production is reduced. In plant-based systems, plants alone usually play a limited role in absorbing carbon dioxide, producing oxygen, and absorbing some pollutants, and cannot alone meet the need for active air purification in closed spaces. Also, in many previous methods, the role of plants has been considered more as a natural source or ion enhancer, while the possibility of using the extensive surface area of ​​leaves as a biological collector for charged particles has received less attention. The present invention is intended to overcome these limitations. The main objective of the invention is to provide a plant-based plasma air purification system in which, instead of using conventional needle electrodes or carbon fibers, one or more porous anodized metal cathodes are used. The cathode comprises a conductive metal substrate, such as titanium, and a porous anodized oxide layer formed on its surface. The pores, channels, surface openings and microstructured regions of this layer can provide preferential locations for electric field concentration, charge extraction and non-thermal discharge initiation. In this structure, the porous oxide layer acts as a dielectric or semi-insulating barrier, reducing direct and localized discharge from the metal surface. At the same time, the presence of microscale holes and channels causes charge escape and ion generation or localized discharges to be distributed at multiple surface points. Therefore, a relatively large surface can behave like a collection of tiny ion generating points, without the need for very sharp, brittle, or erosive electrodes. Another object of the invention is to use the plant and the culture medium as part of the electrical path and biological collector of charged particles. In one embodiment, the negative pole of the high voltage source is connected to a porous anodized metal cathode and the positive pole is connected to a metal electrode placed in the humid culture medium. Thus, the culture medium and the plant can act as a counter electrode, a charge return path or a surface for collecting charged particles. The leaves of the plant, due to their large surface area and direct contact with the air, can absorb or collect some of the charged particles and thus play the role of a biological and decorative collector in addition to the plasma function of the device. Another object of the invention is to increase the stability and uniformity of ion production or plasma discharge in air, reduce the possibility of local arcing, reduce electrode erosion, and improve the efficiency of the system in removing or reducing airborne particulates and microbial load. Also, due to the formation of an anodized oxide layer in an aqueous environment, the cathode surface can have hydrophilic groups such as hydroxyl groups. These groups, together with the porous structure and higher specific surface area, can facilitate the absorption of surface moisture and provide the presence of adsorbed water near the discharge area without the need for an active cooling or condensation unit. Therefore, the present invention seeks to provide a portable, low-power, and indoor air purification system in which the porous anodized metal cathode provides ion generation or non-thermal discharge in a more distributed and controlled manner, and the plant participates as a high-effective biological collector in the process of reducing suspended pollutants. This combination can provide a technical solution to improve indoor air quality, without the system relying solely on consumable filters, conventional needle electrodes, or complex active condensation mechanisms. A description of the state of the prior art and the history of developments related to the claimed invention. 1.Patent CN203313745U Subject: A device to increase plant capacity in purifying PM2.5 using electrical pulses In this invention, high-voltage electrical pulses are applied to the soil or surrounding environment of the plant to stimulate the plant and release more negative ions from the surface of the leaves. These ions bind to particulate matter such as PM2.5 and cause them to settle. Limitations: This technology focuses more on stimulating the plant to release negative ions and does not explore the plasma electrode structure as the core component of the innovation. Its focus is mainly on PM2.5 reduction and does not have a specific mechanism for generating a controlled plasma discharge from an engineered cathode. Applying voltage to soil and roots may pose challenges to plant health in long-term use. Differences of the present invention: In the present invention, the plant is not the main source of ions, but can act as a counter electrode or a biological collector of charged particles. Ion generation and non-thermal discharge are mainly carried out by the porous anodized metal cathode. 2. Patent US9736993B2 Subject: Stimulator device to increase the release of negative ions by plants This patent describes a plant pot or system in which the release of negative ions is enhanced by applying a high voltage to parts of the plant or growing medium. Limitations: The main focus is on stimulating the plant and increasing natural negative ions. It does not have a special electrode with an anodized oxide layer, microstructured pores, or preferential charge exit pathways. In this system, the plant's role is more as a source of ions, rather than as a biological collector of charged particles. Differences of the present invention: In the present invention, the cathode electrode is an engineered active component. Its surface is transformed into a porous oxide layer by anodizing or PEO process, and its holes or channels can be the preferred locations for field concentration and discharge initiation. 3.Patent CN115135137B Subject: Air purification system by creating a plant-based ionic hedge or wall In this technology, several plants are connected with cables and electrodes, and by applying a voltage, a wide area of ​​negative ions is created. The goal is more likely to be to create an “ionic wall” to reduce air pollution in large or public spaces. Limitations: Its structure is complex and dependent on several plants. Not suitable for desktop, portable, or home devices. Its focus is on the plant network and ion zone generation, not on the plasma cathode design. Differences of the present invention: The present invention can be implemented with a small and portable device. In it, the anodized porous cathode is the main agent for producing ions or plasma, and the plant plays the role of a collector or biological counter electrode. 4.Patent CN107029882A Subject: Plasma purifier with plate electrodes for industrial environments This invention introduces a plasma system for large-scale air or gas purification. Limitations: Its design is industrial and large-scale. Not suitable for desktop or decorative use. Its electrode is not a porous anodized cathode with microscale channels. Differences of the present invention: In the present invention, the plasma discharge is generated in a small, portable system, and the porous oxide-coated cathode provides multiple charge exit sites. 5.Patent CN102068713B Subject: Device for releasing large amounts of negative ions using indoor plants This patent is a plant-based technology for releasing negative ions. The patent abstract discusses a high-voltage pulsed electric field to stimulate potted plants and increase the release of negative ions from the rhizosphere and around the plant. The patent page includes keywords such as pulse, output voltage, plant, and soil, and the subject matter is related to stimulating plants with an electric field. Limitations: It focuses on plant metabolism and ion release from the plant itself. Plasma electrode with anodized TiO2 layer or no PEO. The mechanism of particle collection by leaves as the main collector has not been explained. Differences of the present invention: In the present invention, the plant does not have to be the main source of ions. Ionization is carried out from the cathode electrode and the plant can act as a collector of charged particles due to its large leaf surface area. 6.Patent CN202363738U Subject: Negative ion generator using cactus plant as ion releasing body This patent uses a cactus plant as the negative ion releasing component. In its abstract, a negative DC voltage source with a range of about 3,000 to 18,000 volts and a current of a few microamperes is mentioned, and the goal is to stimulate the cactus to release negative ions. Limitations: It depends on a specific type of plant, namely cactus. Focus on the plant as an ion releasing body. No porous anodized cathode or engineered dielectric coating to control discharge. Differences of the present invention: In the present invention, the innovation is not limited to the type of plant. The main part is the porous anodized cathode, and the plant can be any suitable plant with sufficient leaf area and growing medium. 7.Patent CN105841265A Subject: Plasma air purification unit with metal foam electrodes The patent describes a plasma unit consisting of a power supply, two metal foam electrode plates, and a porous insulating plate. In this example, the electrodes are made of nickel foam with a porous ceramic plate between them. The patent says that this structure can generate plasma by creating a high field, and the air is purified after passing through this unit. Limitations: Its electrode is a sheet nickel foam, not an anodized metal cathode with a porous oxide layer. Its structure is designed to allow airflow through the plasma unit and is not related to the plant or biological collector. Metal foam pores are different from pores anodized on the surface of a conductive metal substrate. Differences of the present invention: The cathode electrode is a metal electrode with an anodized oxide coating whose surface simultaneously acts as a dielectric barrier and provides preferential charge escape sites. This is different from a simple nickel foam or a separate ceramic plate. 8.Patent CN102548177B Subject: Discharge electrode structure in plasma air purifier This invention provides an electrode structure for a plasma air purifier, which includes a positive electrode group and a negative electrode group. The patent states that at least one of the electrode groups is covered with an insulating material, and a low-temperature plasma is generated at the contact or intersection points. Limitations: Its structure is based on electrode groups and contact or intersection points. It does not have an anodized oxide layer that forms on the metal substrate itself. Its mechanism is not related to the distribution of micro / nano pores on the surface of a single cathode. Differences of the present invention: In the present invention, the preferential discharge points are created on the cathode surface itself and by holes or channels in the oxide layer, rather than simply at the intersection of two electrode groups. 9.Patent CN111569617A Subject: Air purifier with wire electrode array and plate electrode The patent describes an air purification device with at least one module comprising a frame, an array of wire electrodes, and at least one plate electrode. The aim is to improve discharge stability, reduce gas resistance, and combine plasma with a catalyst to purify VOCs. Limitations: Uses wire and plate electrodes. Its focus is on the industrial or semi-industrial plasma and catalyst module. It lacks a porous anodized cathode and lacks the role of the plant as a collector. Differences of the present invention: The present invention uses a porous anodized metal surface instead of a wire or plate. The collection of charged particles can also be done by the surface of plant leaves. 10.Patent US20150290348A1 / US10149916B2 Subject: Ion spray device, related to moisture-containing ion technology such as nanoe This patent belongs to Panasonic and concerns a device for spraying ions onto a target. The background section of the patent notes that in a known technology, a needle discharge electrode and a Peltier device are used to cool the electrode and cause water condensation on the electrode to produce nanoe. Limitations: Depends on electrode cooling and active water condensation. Uses a needle electrode. Its focus is on delivering ions to the target from the appropriate distance, not on designing the porous cathode surface. Differences of the present invention: In the present invention, the aim is that the anodized TiO2 surface, due to the hydroxyl groups and porous structure, passively absorbs moisture. Therefore, the presence of water near the discharge area does not necessarily require a Peltier or active cooling unit. 11. Patent US7368003B2 Subject: Air purification system with odor removal This patent relates to a combination of air purification and odor removal, and the issue of air purification is mostly raised alongside odor removal, filter, and ionizer combinations. Limitations: Its focus is on the combination of filter, odor removal and ionizer. The anodized cathode electrode is not porous. The plant has not been proposed as a counter electrode or biological collector. Differences of the present invention: The present invention takes a different route: generating ions or plasma from a surface-engineered cathode and collecting the charged particles on the plant. Providing a solution to an existing technical problem along with an accurate, sufficient, and integrated description of the invention The present invention is a portable, plant-based plasma air purification system designed to reduce particulate matter and airborne pollutants in indoor environments. The main solution of the invention is based on the use of one or more porous anodized metal cathodes, which are used instead of the needle, wire, or carbon fiber electrodes commonly used in ionizers and corona systems. In this system, the porous anodized metal cathode 123 comprises a conductive metal substrate and a porous oxide layer. In one embodiment, the metal substrate is made of grade 2 titanium and its surface is anodized by a plasma electrolytic oxidation or PEO process. However, the invention is not limited to titanium and can include other metals capable of forming a porous insulating or semi-insulating oxide layer. The anodized oxide layer has pores, surface openings, channels, and microstructured regions. These structures can serve as preferential sites for electric field concentration, charge extraction, and non-thermal discharge initiation. As a result, unlike sharp-pointed electrodes where discharge is concentrated at a few limited points, the present invention allows for the creation of multiple, distributed regions for the generation of ions or charged species on the cathode surface. In a practical example, the diameter of the cathode can be in the range of about 1 to 10 mm, and in the fabricated example, a diameter of about 2 mm is used. The length of the cathode can also vary depending on the design of the device, and in one example it is about 15 mm. The number of cathodes is also not fixed and can be one, two or more, depending on the dimensions of the device, the power of the power supply and the desired space. In the example shown, two porous cathodes are placed near the pot. The system consists of a main body, a plant pot or container, a growing medium, a plant, a high-voltage power supply module, and electrodes connected to the power supply. The negative pole of the high-voltage power supply is connected to a porous anodized metal cathode or cathodes. The positive pole is connected to a metal electrode placed in the growing medium or soil. Due to the presence of moisture and relative ionic conductivity in the growing medium, the growing medium and the plant can act as a counter electrode, a charge return path, or a biological collector of charged particles. During operation, by applying a high voltage between the porous cathode and the culture medium connected to the positive pole, the electric field is concentrated near the surface holes and openings of the cathode. This causes charge to escape, producing ions or creating a non-thermal discharge in the air. The ions and charged species produced can interact with and charge airborne particles and pollutants. Once charged, these particles can be attracted to surfaces of opposite potential or collector surfaces, such as leaves and plant surfaces. In this arrangement, the plant is not merely a decorative element, but can also act as a biological collector with a high effective surface area. The leaves and aerial parts of the plant, due to their direct contact with the air and their large surface area, can absorb or retain some of the charged particles. Therefore, the system uses a combination of an engineered plasma cathode and a biological collector surface. One of the important aspects of the invention is the surface structure of the anodized cathode. The oxide layer formed on the metal, especially in titanium-based samples, can have hydrophilic surface groups such as hydroxyl groups. The presence of these groups, together with the porous structure and increased specific surface area, can facilitate the adsorption of surface moisture. The presence of adsorbed moisture near the discharge zone can affect the formation of active species and the stability of the ionization performance, without necessarily requiring an active cooling or condensation unit. In one method of sample fabrication, the titanium surface is anodized by the PEO process in an aqueous electrolyte. In one example, the process voltage can be selected in the range of about 150 to 250 V DC pulsed, with a frequency of about 30 to 300 Hz. In the fabricated sample, the frequency was about 50 Hz and the anodization time was about 30 seconds. After anodization, the electrode is rinsed with distilled water and dried at ambient temperature. The electrolyte composition can be selected from those commonly used in the PEO titanium process and in some examples includes fluoride species to help create or maintain porous structures. The system power supply can have a DC or high voltage pulsed DC output. In an exemplary embodiment, the output voltage is in the range of about 5 to 30 kV, and in the experiments performed, a voltage of about 15 kV was used. To increase safety, the power supply can be isolated, the output current limited, the body made of an insulating polymer material, and the cathodes protected from direct user contact by a shield or suitable mechanical structure. The present invention can operate without the use of a consumable filter or, if necessary, be combined with conventional filters, air circulation fans or control sensors. These components can be added in some embodiments to improve air flow uniformity, control environmental conditions or increase safety, but the core of the invention does not depend on them. The main feature of the system is the use of a porous anodized metal cathode to create multiple areas of charge removal and non-thermal discharge next to the plant as a biological collector. In a pilot study, the system performance was evaluated in a Plexiglas chamber with a volume of approximately one cubic meter. Particulate pollution was generated with smoke and PM2.5 concentrations were measured in the presence of the control condition, the plant alone, and the plant system with plasma. Also, to qualitatively investigate the reduction in the transmission of airborne microorganisms, a sterile plate containing a suitable culture medium for bacterial growth was placed in the chamber and after exposure to polluted air, the growth rate of the colonies was qualitatively compared. These results indicate that system activation can be effective in reducing suspended particles and qualitatively reducing airborne microbial deposition. The technical advantage of the present invention over conventional systems is that the ion-generating electrode consists of a porous anodized surface, rather than a single sharp tip or a thin wire. This surface can behave like a collection of small, distributed ion-generating points. Also, the plant in this system is not only a natural source of oxygen or a decorative element, but can also participate in the role of a counter electrode or a biological collector of charged particles. Thus, the present invention offers a portable, low-power, and indoor-friendly solution based on the controlled combination of plasma technology, electrode surface engineering, and biological collection of pollutants. Explanation of shapes, maps and diagrams Figure 1: Exploded view of the plant-based plasma air purification system. In this figure, the overall system is indicated by 100, the main body of the device by 110, the retaining plate or separator by 111, the high voltage power supply module by 120, the negative output terminal by 121, the positive output terminal by 122, the porous anodized metal cathodes by 123, the plant holding pot or container by 130, the growing medium or soil by 131, and the plant by 132. Figure 2: A general view of one of the porous anodized metal cathodes 123. In this figure, the emission of ions or negative charges from different areas of the porous surface of the cathode is schematically shown. This figure shows that the charge emission in the present invention is not limited to a single pin tip, but rather occurs from multiple surface areas and micro-openings on the cathode. Figure 3: A schematic cross-sectional view of a porous anodized metal cathode 123. In this figure, the conductive metal substrate is indicated by 124, the microstructured holes or channels by 125, and the porous anodized oxide layer by 126. This figure schematically shows the preferred charge escape paths from the metal substrate to the external surface of the cathode. Figure 4: Scanning electron microscope image of the surface of metal substrate 124 before the anodizing process. This image shows the relatively smooth surface of the metal before the formation of the porous oxide layer. Figure 5: Scanning electron microscope image of the cathode surface after the anodizing process. In this figure, the anodized cathode is marked with number 123, the surface holes or openings are marked with number 125, and the porous oxide layer is marked with number 126. This image shows the formation of the porous structure and microstructure of the surface after anodizing. Figure 6: Schematic view showing the chemical and surface structure of a porous anodized cathode 123. In this figure, the metal substrate 124, the microstructured pores or channels 125, and the anodized oxide layer 126 are shown. The presence of hydrophilic surface groups, including hydroxyl groups, and the adsorption of water molecules on the oxide surface are also schematically shown. Figure 7: FTIR spectrum of the anodized cathode surface. This spectrum was used to investigate the presence of hydrophilic surface groups and hydroxyl species or adsorbed water on the porous oxide layer. Figure 8: A graph showing the variation of PM2.5 concentration in an experimental chamber. In this graph, the performance of three modes including control mode, plant-only mode, and plant-plus-plasma system mode is compared. This figure shows the reduction of PM2.5 concentration in the presence of the active system as an experimental sample. Figure 9: Qualitative result of the sedimentation and growth test of airborne microorganisms on the culture plate. In this figure, the control condition is compared with the condition of the plant system with plasma and the qualitative reduction of colony growth in the active state of the system is shown. A clear and precise statement of the advantages of the claimed invention over prior inventions. The present invention is a portable, plant-based plasma air purification system whose main advantage lies in the use of a porous anodized metal cathode. This cathode is designed to provide an engineered surface with microstructured pores, channels, and openings, unlike conventional needle, wire, plate, or metal foam electrodes. This structure can provide multiple, distributed locations for electric field concentration, charge extraction, and non-thermal discharge initiation. The main advantages of the present invention over the prior art are as follows: 1-Focusing innovation on engineered cathode, not direct plant stimulation In some prior art inventions, such as plant-based negative ion generation systems, an electrical voltage or pulse is applied to the soil, growing medium, or parts of the plant to enhance the release of negative ions from the plant itself. In such systems, the plant is usually considered the ion source, and the operation of the device is largely dependent on the electrical stimulation of the plant. In the present invention, ion generation or non-thermal discharge is mainly carried out by a porous anodized metal cathode. The plant and the culture medium can act as a counter electrode, a charge return path, or a biological collector of charged particles. Thus, the role of the plant changes from an excited ion source to a biological surface with a large effective area for collecting charged particles. 2- Creating multiple charge exit points on a porous cathode surface Ionizers and corona systems typically use metal tips, thin wires, or carbon fibers to focus the electric field at a small radius of curvature. This can help produce ions, but the discharge is concentrated at a few points and may be associated with instability, tip erosion, or increased likelihood of localized sparking. In the present invention, the cathode surface is transformed into a porous oxide layer by anodizing or plasma electrolytic oxidation. The microstructured holes and openings in this layer can act as a collection of tiny, distributed points for charge extraction. In this way, a relatively simple cylindrical electrode can function as an array of micro-scale emitters, without relying on individual sharp tips or fragile fibers. 3-Reducing the possibility of unwanted local discharge and increasing performance stability On smooth or uncoated metal electrodes, discharge may start from unwanted areas, sharp edges, or areas with uncontrolled surface finish. Also, the possibility of localized sparking increases if there are uncoated or inhomogeneous areas. In the present invention, the active part of the cathode is generally covered with an anodized oxide layer. This layer has insulating or semi-insulating behavior and can prevent direct and intense discharge from the metal surface. At the same time, the holes, openings and microstructured areas in the layer provide more preferred and controlled locations for charge to escape and discharge to begin. This feature can help to make the discharge more stable and reduce the possibility of localized arcing. 4- Using a hydrophilic surface to absorb moisture without the need for active condensation Some known technologies for producing water-containing ions use active cooling or condensation units to collect water on the electrode surface. These methods typically require additional components, higher energy consumption, and thermal control. In the present invention, the anodized oxide layer, especially in titanium oxide-based samples, can have hydrophilic surface groups such as hydroxyl groups. The presence of these groups, together with the porous structure and higher specific surface area, can facilitate the adsorption of surface moisture. Therefore, the presence of moisture near the discharge area can be provided without the need for an active cooling or condensation unit. 5-Combining ion production with biological particle collection Many ionizing systems rely solely on charging particles and settling them in the environment. In this case, the particles may settle on surrounding surfaces, walls, or equipment, making it difficult to control where they collect. In the present invention, the plant can act as a biological collector with a high effective surface area. The leaves and aerial parts of the plant are in direct contact with the air and due to their large surface area can absorb or retain some of the charged particles. This feature makes the system not only produce ions, but also have a natural and decorative collection surface. 6- Portable, energy-efficient structure suitable for indoor environments Some previous plasma systems were designed for industrial applications, large enclosures, forced air paths, or complex modules. Such systems are generally not suitable for desktop, home, or decorative use. The present invention is designed as a portable system that can be used in indoor environments. The insulating polymer body, isolated power supply, limited current, and mechanical protection to prevent direct contact with the cathodes can increase user safety. The device can also operate without a consumable filter or, in other examples, be combined with a fan, filter, sensor, or controller, without the core of the invention being dependent on these sub-components. 7- Capability of industrial electrode manufacturing The cathode used in the present invention can be produced on metals such as titanium by industrially reproducible processes, such as anodizing or plasma electrolytic oxidation. This process allows the formation of a cohesive, porous, and stable oxide layer on the metal substrate. As a result, the electrode can be more mechanically stable and suitable for mass production than very fine needle electrodes or carbon fibers. 8- Possibility of reducing airborne particulate matter and microbial load In the experimental samples, the present system was investigated in a chamber with a volume of approximately one cubic meter. The results of the tests related to suspended particles and the qualitative test of microbial sedimentation have shown that the activation of the system can be effective in reducing the concentration of suspended particles and qualitatively reducing the growth of airborne microorganisms. These results are presented as practical examples of system performance and show that combining a porous anodized cathode with a plant as a biocollector can provide a suitable technical path to improving indoor air quality. Description of at least one implementation method for implementing the invention In one embodiment, the plant-based plasma air purification system includes an insulating body, a plant pot or container, a growing medium, a plant, a high voltage power supply, a positive electrode positioned in the growing medium, and at least one porous anodized metal cathode. In the illustrated embodiment, two porous anodized metal cathodes are positioned around the pot and above the surface of the growing medium to be in direct contact with the air. In one embodiment, the cathode is made of a titanium substrate. The substrate can be grade 2 titanium, although other metals capable of forming a porous insulating or semi-insulating oxide layer can also be used. The diameter of the cathode can range from about 1 to 10 mm, and in one embodiment, a diameter of about 2 mm has been used. The length of the cathode can also vary depending on the dimensions of the device, and in one embodiment, it is about 15 mm. To prepare the cathode, the metal surface is converted to a porous oxide layer by an anodizing process, particularly plasma electrolytic oxidation. In one embodiment, the anodizing process is carried out in an aqueous electrolyte suitable for anodizing or plasma electrolytic oxidation of titanium. The electrolyte can include common compounds used in titanium PEO processes and in some embodiments includes fluoride species to help create or maintain microstructure pores and channels. In one example, the anodizing process is performed with a DC pulse voltage in the range of about 150 to 250 V and a frequency of about 30 to 300 Hz. In the fabricated sample, the frequency was about 50 Hz and the operation time was about 30 seconds. After the process is completed, the electrode is washed with distilled water and dried at ambient temperature. In this sample, calcination is not performed. The oxide layer formed on the cathode contains pores, channels, surface openings, and microstructured regions. These regions can be preferential sites for electric field concentration, charge escape, and initiation of non-thermal discharge. The oxide coating on the active surface of the cathode also reduces direct discharge from uncoated metal parts, reducing the likelihood of severe localized discharges or arcing. To assemble the system, the plant pot or container is placed in the main body of the device. A metal electrode is connected to the positive pole of the high-voltage power supply and is placed in contact with the growing medium or moist soil. The negative pole of the power supply is connected to one or more porous anodized metal cathodes. The cathodes are placed in an area that is in contact with the surrounding air and are preferably protected from direct contact by the user's hand by an insulating shield or suitable mechanical structure. The power supply can have a DC or high voltage pulsed DC output. In a practical example, the output voltage is in the range of about 5 to 30 kV, and in the tested example, about 15 kV was used. The input to the module can be 12 V DC and the input current, depending on the operating conditions, can be in the range of about 110 to 300 mA. The power supply is preferably isolated and its output current is limited to increase user safety and operational stability. During operation, a potential difference is created between the porous anodized metal cathodes and the positive electrode placed in the culture medium. Due to the relative humidity of the culture medium and its ionic conductivity, the culture medium and the plant can act as a counter electrode, a charge return path, or a biological collector of charged particles. In this case, the leaves and aerial parts of the plant, due to their high contact surface with the air, can absorb or retain some of the charged particles. By applying a voltage to the cathode, the electric field is concentrated near the surface holes and openings of the anodized layer. This causes charge to escape, producing ions and creating a non-thermal discharge around the cathode. The ions and charged species produced can interact with and charge airborne particles and pollutants. The charged particles can then be attracted to surfaces of opposite potential, such as leaf surfaces, growing media or other collecting surfaces. In some embodiments, the system can be equipped with an air circulation fan, a temperature and humidity sensor, a proximity sensor, an air quality sensor, a control circuit, a light indicator or a control button. These components can be used to improve the uniformity of air distribution, increase safety or better control the operating time of the device. However, the presence of these components is not essential to realize the core of the invention, and the core of the invention is based on the porous anodized metal cathode and its arrangement next to the plant as a biocollector. In a typical operation, the user places the device on a table or in an indoor space and connects the low-voltage power supply to the module. After the device is turned on, the high-voltage power supply is activated and the porous anodized cathodes begin to produce ions or non-thermal discharges in the air. If a fan is present, a gentle flow of air can be created to better distribute the particles and ions around the plant. After the device is turned off, the residual loads in the circuit can be reduced by a discharge resistor or appropriate protection circuit. In one test, the device was placed in a Plexiglas chamber with a volume of approximately one cubic meter. To investigate the reduction of suspended particles, particulate pollution was created with smoke and the PM2.5 concentration was compared in the control condition, the plant-alone condition, and the plant-system condition with plasma. In another test, to qualitatively investigate the reduction of airborne microorganisms, a sterile plate containing a suitable culture medium for bacterial growth was placed in the chamber and after exposure to polluted air, the growth rate of colonies was qualitatively assessed. Therefore, in this implementation method, the system uses a porous anodized metal cathode, a high voltage source, and a plant as a biological collector, allowing for the generation of ions or non-thermal discharge and the collection of a portion of charged particles in a portable structure suitable for indoor environments. Explicit mention of the industrial application of the invention The present invention is a portable, plant-based plasma air purification system designed to improve indoor air quality by utilizing a porous anodized metal cathode, a high voltage source, a growing medium, and live plants. The system can be used to reduce particulate matter, reduce some airborne pollutants, and help reduce airborne microbial load. The main industrial application of this invention is in the field of manufacturing home, office and desktop air purification equipment. Given its small dimensions, portable design, low energy consumption and the possibility of producing anodized electrodes with repeatable industrial processes, this system has the ability to be manufactured, assembled and supplied as a commercial product in the indoor air purification device market. This invention can be used in the following environments: 1. Home environments: Use in bedrooms, living rooms, kitchens, home workspaces, and other enclosed spaces to help reduce particulate matter and improve indoor air quality. 2. Office and commercial environments: Use on desks, small offices, stores, hotels, waiting rooms, and service spaces where air quality and the decorative appearance of the device are important. 3. Small educational and public environments: Use in small classrooms, libraries, study halls, and educational spaces to help reduce airborne pollutants and improve environmental breathing conditions. 4. Non-sensitive healthcare environments: Use in spaces such as offices, waiting rooms and service centers, as an auxiliary system to improve air quality. Use in sensitive healthcare environments may be subject to testing and obtaining the necessary permits. 5. Research and development applications: Use as a hybrid technology example in the field of air purification, non-thermal plasma, porous anodized electrodes, and bio-electrostatic systems. The industrial production capability of this invention is provided because its main components, including the polymer body, high-voltage power supply, anodized metal electrode, plant pot or container, and electrical connections, can be produced by conventional industrial manufacturing and assembly methods. Also, the anodizing or plasma electrolytic oxidation process to create a porous oxide layer on the cathode is a repeatable and controllable process on a production scale. Therefore, the present invention has clear industrial application in the field of designing and producing portable, desktop, decorative, and low-power air purifiers for indoor environments, and can be utilized as a mass-produced product in the air purification equipment and clean technology industries.

Claims

Claims What is claimed: (Items should be written only in [ ] [ , otherwise they will not be considered.) Claim 1: An air purification system based on ion generation or non-thermal discharge, comprising a high voltage power supply with an output in the range of 5 to 30 kV, at least one first electrode as a cathode, and at least one second electrode or collector surface as a counter electrode, wherein the first electrode comprises a conductive metal substrate and a porous anodized oxide dielectric ceramic layer formed on at least a portion of the surface of the metal substrate, and the porous anodized oxide layer has micrometer- and nanometer-scale pores, channels, openings or microstructured regions that provide preferential locations for electric field concentration, charge escape or initiation of non-thermal capillary discharge, such that by applying a potential difference between the first electrode and the second electrode or collector surface, ions or charged species in the vicinity The first electrode is produced and charges at least some of the suspended particles or airborne pollutants.Claim 2: The system according to claim 1, wherein the second electrode or collector surface comprises a conductive surface, a semiconducting surface, an ionic conductive surface, a moist substrate, a culture medium, soil, a plant, a plant leaf, a collector plate, or a combination thereof. Claim 3: The system of claim 1, wherein the conductive metal substrate is selected from a metal capable of forming an insulating, semi-insulating, or porous dielectric oxide layer. Claim 4: The system of claim 3, wherein the conductive metal substrate comprises titanium, aluminum, magnesium, niobium, tantalum, zirconium, zinc, alloys thereof, or a combination thereof. Claim 5: The system of claim 1, wherein the porous anodized oxide layer is formed by a process comprising anodizing, acid anodizing, alkaline anodizing, pulse anodizing, hard anodizing, plasma electrolytic oxidation, microarc oxidation, or a combination thereof. Claim 6: The system of claim 5, wherein the porous anodized oxide layer is formed in an aqueous electrolyte comprising acidic, alkaline, phosphate, silicate, sulfate, fluoride, borate, carbonate, organic, inorganic compounds, or a combination thereof. Claim 7: The system of claim 1, wherein the porous anodized oxide layer acts as an insulating or semi-insulating barrier and reduces direct discharge from the metal surface of the substrate, while the microstructured holes, channels or openings provide preferential areas for charge escape or discharge initiation. Claim 8: The system according to claim 1, wherein the first electrode has a rod, cylindrical, plate, strip, wire, mesh, tubular, curved, multi-branched shape, or a combination thereof. Claim 9: The system of claim 1, wherein the porous anodized oxide layer has hydrophilic surface groups, hydroxyl groups, adsorbed water, or moisture-absorbing regions. Claim 10: The system of claim 1, wherein the high voltage power supply has a DC, pulsed DC, AC output, or a combination thereof. Claim 11: The system of claim 1, wherein the system is configured as a portable, desktop, decorative, plant-based, potted, wall-mounted, modular, or mountable device in an air purifier. Claim 12: The system of claim 11, wherein the collecting surface comprises a plant and a culture medium, the second electrode is in electrical contact with the culture medium, and the plant or plant leaves act as a collecting surface for at least a portion of the charged particles. Claim 13: The system of claim 1, comprising an insulating body, a mechanical shield, a contact limiting structure, a current limiting circuit, a residual current discharge circuit, or a combination thereof to enhance user safety. Claim 14: Claim 15: Claim 16: Claim 17: Claim 18: Claim 19:

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