Air purification device using a chemical scrubber and electrochemically generated ferrate(VI) solution

Abstract

This invention relates to an air purification device designed to remove a wide range of volatile and semi-volatile organic compounds from contaminated air The system integrates a chemical scrubber with an electrochemical reactor that generates ferrate(VI) solution in situ. The reactor uses two iron electrodes immersed in a 14 molar sodium hydroxide solution, powered by a direct current converter operating at 24 volts. Upon activation, ferrate(VI) ions are formed, indicated by a purple coloration in the solution. The ferrate(VI) solution is immediately circulated through a packed- bed scrubber, where it contacts the polluted air. Organic compounds are absorbed into the liquid phase and oxidized by ferrate(VI), resulting in cleaner air. The system is equipped with drainage for spent solution and can be integrated into industrial, laboratory, or indoor ventilation setups.

Description

[0001] Air Purification Device Using a Chemical Scrubber and Electrochemically Generated Ferrate (VI) Solution

[0002] Field of the Invention

[0003] The present invention belongs to the field of environmental engineering, specifically to advanced technologies for air purification and the control of airborne organic pollutants. It relates to the design and development of an air treatment device that utilizes a chemical scrubber in combination with an electrochemically generated ferrate(VI) solution. Ferrate(VI), a powerful oxidizing agent, is capable of removing a wide range of volatile and semi-volatile organic compounds (VOCs and SVOCs) from air, including but not limited to formaldehyde, acetaldehyde, toluene, xylene, benzene, phenolic compounds, and other oxygenated or aromatic organics commonly found in industrial, urban, and indoor environments.

[0004] This technology falls under the category of Advanced Oxidation Processes (AOPs) and employs a packed-bed chemical scrubber to ensure effective contact between the contaminated air stream and the ferrate(VI) solution. In this process, organic pollutants are first absorbed into the liquid phase and subsequently degraded through strong oxidation reactions.

[0005] The ferrate(VI) solution is generated in situ within an electrochemical reactor, enhancing operational efficiency, reducing chemical handling risks, and minimizing costs associated with reagent storage and transport. Applications of this invention include the treatment of exhaust air from chemical plants, pharmaceutical facilities, petrochemical industries, laboratories, healthcare centers, and enclosed spaces with elevated levels of organic contamination. The system can also be integrated into HVAC and centralized purification units, offering a sustainable and safe solution for reducing airborne organic pollution.

[0006] Background of the Invention

[0007] Air pollution caused by VOCs and SVOCs remains one of the most critical environmental and health challenges worldwide [1 , 2], These organic pollutants include substances such as formaldehyde, acetaldehyde, benzene, toluene, xylene, phenol, and various ketones, which are commonly released from industrial operations, petrochemical processes, solvents, paints, adhesives, cleaning agents, and laboratory exhausts [3, 4], In both outdoor and indoor environments, these pollutants contribute to smog formation, unpleasant odors, and respiratory irritation [5], Prolonged exposure has been associated with neurological disorders, liver and kidney damage, and carcinogenic effects, as documented by the World Health Organization [6], The concentration of these compounds is often higher indoors due to limited ventilation, accumulation from building materials, and continuous emissions from chemical usage. Indoor air quality degradation has thus become a major public health issue, especially in industrial buildings, hospitals, laboratories, and urban residences [7], A wide range of air purification technologies has been developed to mitigate these pollutants. Common methods include activated carbon adsorption, catalytic oxidation, thermal combustion, photocatalytic oxidation using titanium dioxide (TiO2), and mechanical filtration [8], Although each method can be effective in specific situations, they all exhibit significant limitations.

[0008] Activated carbon filters and chemical adsorbents require frequent regeneration or replacement and can release captured pollutants once saturated [9], Thermal oxidation systems demand high temperatures (typically 300-800 °C), leading to excessive energy consumption and the possible formation of harmful byproducts such as NOx and CO2

[0010] , Photocatalytic systems often suffer from limited quantum efficiency and incomplete oxidation of complex VOCs, resulting in secondary pollutants such as formaldehyde [11 , 12]. Meanwhile, conventional electrostatic precipitators remove particulates efficiently but cannot oxidize gaseous organic pollutants. In recent years, AOPs have gained attention for their ability to destroy VOCs through strong oxidizing radicals such as hydroxyl ( OH) and superoxide (O2“)

[0013] , Among these oxidants, ferrate(VI) (Fe042“) has emerged as a powerful, eco- friendly, and multifunctional reagent [14, 15], It possesses a high oxidation potential (E° = +2.2 V) in acidic media and decomposes into non-toxic iron(lll) hydroxide after reaction

[0016] , Ferrate(VI) can degrade a wide range of organic pollutants, including phenolic compounds, pharmaceuticals, and dyes, while simultaneously providing disinfection capability against bacteria and viruses

[0017] , Its application in water and wastewater treatment is well documented; however, its use in air purification systems remains largely unexplored. The challenge with ferrate(VI) lies in its instability — especially in aqueous form — requiring on-site or in-situ generation

[0018] , This has motivated research into electrochemical ferrate generation systems, where ferrate(VI) ions are continuously produced via anodic oxidation of iron electrodes in an alkaline electrolyte. Such systems eliminate the need for external chemical storage and transportation, thereby improving safety and sustainability.

[0009] The present invention builds upon these principles to introduce an innovative air purification device that integrates electrochemical ferrate(VI) generation with a chemical scrubber or electrostatic air mover. In this system, polluted air is passed through an electrochemical reactor that produces ferrate(VI) in situ. The ferrate(VI) reacts immediately with absorbed VOCs and other organic pollutants, oxidizing them into harmless byproducts such as CO2and H2O. Alternatively, in hybrid designs using an ion thruster-type air mover, ozone generated by corona discharge or electrostatic propulsion provides an additional oxidative pathway. This dual oxidation mechanism — through ferrate(VI) and ozone — ensures deep degradation of pollutants at room temperature without the need for thermal input or chemical dosing.

[0010] Compared to existing air treatment systems, this approach is compact, energyefficient, and environmentally safe. It does not require high heat, external oxidant storage, or periodic filter replacement. The system can be implemented in industrial facilities, laboratories, pharmaceutical cleanrooms, hospital wards, and confined indoor spaces where chemical and microbial air contaminants pose health and safety risks. The technology represents a sustainable and adaptable solution for modern air purification challenges by combining electrochemical oxidation, advanced materials, and intelligent design to minimize environmental impact while maximizing air quality improvement.

[0011] Summary of the Invention

[0012] This invention presents a complete air purification system that uses a chemical scrubber and a ferrate(VI) solution to remove a wide range of organic pollutants from air. The ferrate(VI) solution is produced inside the system using an electrochemical reactor, which makes the process safer, more efficient, and environmentally friendly. The system is designed to treat air that contains volatile and semi-volatile organic compounds (VOCs and SVOCs), such as formaldehyde, acetaldehyde, benzene, toluene, xylene, phenols, ketones, and other harmful chemicals. These pollutants are common in industrial plants, laboratories, hospitals, and enclosed spaces with poor ventilation. The invention aims to reduce health risks and improve air quality in such environments. The device includes the following main components:

[0013] • Electrochemical Reactor: This unit generates ferrate(VI) solution on-site by applying electrical current to a solution containing iron and sodium hydroxide. This method avoids the need to store or transport dangerous chemicals and allows for real-time control of concentration and flow rate.

[0014] • Ferrate(VI) Solution Tank: The freshly produced solution is stored temporarily in a tank before being circulated through the scrubber.

[0015] • Packed-Bed Chemical Scrubber: This column contains supporting media that help mix the polluted air with the ferrate(VI) solution. As the air flows through the scrubber, organic pollutants are absorbed into the liquid phase and then oxidized by ferrate(VI), breaking down their chemical structure and neutralizing their harmful effects.

[0016] • Air Inlet and Outlet System: Contaminated air enters the scrubber through an inlet, and clean air exits through an outlet after treatment. The system can be connected to existing ventilation or exhaust systems.

[0017] • Effluent Handling: After the reaction, the used ferrate(VI) solution (now containing oxidized byproducts) is collected and can be treated or disposed of safely.

[0018] Description

[0019] Ferrate solution has been used not only for wastewater purification but also for air treatment. According to an unpublished study by

[0019] , air contaminated by formaldehyde can be removed by ferrate (VI) solution in a chemical-packed bed scrubber (jError! No se encuentra el origen de la referenda.1). In this study, ferrate (VI) was produced in an electrochemical reactor and circulated through a packed bed, which was used to scrub formaldehyde from an air stream. In the packed bed, formaldehyde is absorbed from the gas phase into the liquid phase, and then it is oxidized by reacting with ferrate (VI). In this invention, the ferrate(VI) solution is produced in situ using an electrochemical reactor. This reactor consists of two iron electrodes immersed in an alkaline electrolyte solution.

[0020] To supply the required electrical current, a power converter is used to transform alternating current (AC) at 220 volts into direct current (DC) with an adjustable voltage range between 1 and 24 volts and a current capacity of up to 6 amperes. This converter allows precise control over the electrolysis conditions. Although several studies have reported that increasing the voltage can enhance ferrate(VI) production, voltages above 40 volts may pose a risk of electric shock. Therefore, to ensure operational safety, a voltage of 24 volts is used in this invention.

[0021] According to Talaiekhozani et al. (2017b), the highest efficiency for ferrate(VI) generation occurs in a solution containing distilled water and sodium hydroxide at a concentration of 14 molar. Once the 24-volt current is applied to the electrodes, the electrolysis reaction begins. Immediately upon connection, a distinct purple color appears in the solution and gradually intensifies — this color indicates the formation of ferrate(VI) ions. Since ferrate(VI) is unstable and gradually converts to ferric iron (Fe3+), which lacks oxidizing power, the freshly prepared solution is used immediately in the air purification process.

[0022] To maintain production efficiency, the electrode surfaces are polished with sandpaper after several uses to remove passive layers formed during previous electrolysis cycles (Eskandari, 2016). This ferrate(VI) generation process plays a key role in the operation of the air purification device. When combined with the chemical scrubber, it enables effective removal of volatile and semi-volatile organic compounds from gas streams. Figure 1 illustrates the schematic layout of the system, showing the main components: the electrochemical reactor, electrolyte solution, electrodes, power converter, ferrate(VI) solution tank, scrubber column, air inlet and outlet, and the discharge path for the spent solution.

[0023] The main goal of this invention is to create an air purification device that can remove many types of organic pollutants from the air. It uses a chemical scrubber filled with ferrate(VI) solution, which is made inside the system using an electrochemical method. This device is designed to improve air quality in industrial areas, cities, and indoor spaces, and to offer a safer and more efficient alternative to traditional air cleaning methods. Specific objectives of the invention include:

[0024] • Providing a system that produces ferrate(VI) solution on-site, without needing to store or transport dangerous chemicals

[0025] • Increasing the efficiency of removing organic pollutants from the air using advanced oxidation processes

[0026] • Reducing energy use and operating costs compared to thermal or physical adsorption methods

[0027] • Making the system suitable for use in factories, hospitals, laboratories, and enclosed spaces with high pollution

[0028] • Offering an environmentally friendly solution that does not create harmful byproducts

[0029] The invention offers several key advantages, including high efficiency, safety, sustainability, low energy consumption, scalability, flexibility, and environmental compatibility. Ferrate(VI) is a strong oxidant that can destroy complex organic molecules quickly and thoroughly. On-site electrochemical generation reduces chemical hazards and supports green technology goals. Compared to thermal oxidation or UV-based systems, this method requires less energy and operates at ambient temperature. The system can be scaled for small laboratories or large industrial facilities. It can also be adapted for mobile units or emergency response applications. Ferrate(VI) decomposes into non-toxic iron(lll) after use, making it safer for the environment than many other oxidants. Brief Description of Drawings

[0030] [Fig 1]: Schematic of using ferrate (VI) in a chemical scrubber for removing pollutants from air

[0031] References:

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[0035] 4. Sarigiannis, D.A., et al., Exposure to major volatile organic compounds and carbonyls in European indoor environments and associated health risk. Environment international, 2011. 37(4): p. 743-765.

[0036] 5. Soni, V., et al., Effects of VOCs on human health, in Air pollution and control. 2017, Springer, p. 119-142.

[0037] 6. Khan, A., et al., Volatile organic compounds and neurological disorders: from exposure to preventive interventions, in Environmental contaminants and neurological disorders. 2021 , Springer, p. 201-230.

[0038] 7. Tham, K.W. and buildings, Indoor air quality and its effects on humans — A review of challenges and developments in the last 30 years. Energy, 2016. 130: p. 637-650.

[0039] 8. Shah, K.W. and W. Li, A review on catalytic nanomaterials for volatile organic compounds VOC removal and their applications for healthy buildings. Nanomaterials, 2019. 9(6): p. 910.

[0040] 9. Pui, W.K., R. Yusoff, and M.K.J.R.i.C.E. Aroua, A review on activated carbon adsorption for volatile organic compounds (VOCs). 2019. 35(5): p. 649-668. 10. Bhaskaran, A., et al., Technological solutions for NOx, SOx, and VOC abatement: recent breakthroughs and future directions. Environmental Science Pollution Research, 2023. 30(40): p. 91501-91533.

[0041] 11. Zhang, Y., et al., Photocatalytic Oxidation for Volatile Organic Compounds Elimination: From Fundamental Research to Practical Applications. Environmental Science & Technology, 2022. 56(23): p. 16582-16601.

[0042] 12. Huang, Y., et al., Removal of indoor volatile organic compounds via photocatalytic oxidation: a short review and prospect. Molecules, 2016. 21(1): p. 56.

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[0046] 16. Tiwari, D., Ferrate (VI) a greener solution: Synthesis, characterization, and multifunctional use in treating metal-complexed species in aqueous solution, in Ferrites and Ferrates: Chemistry and Applications in Sustainable Energy and Environmental Remediation. 2016, ACS Publications, p. 161-220.

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Claims

Claims1.- An air purification device for removing volatile and semi-volatile organic compounds from gas streams, comprising:(a) an electrochemical reactor configured to generate ferrate(VI) solution in situ using two iron electrodes immersed in an alkaline electrolyte;(b) a power converter adapted to supply direct current with adjustable voltage up to 24 volts and current up to 6 amperes;(c) a ferrate (VI) solution tank connected to the reactor for temporary storage and circulation;(d) a packed-bed chemical scrubber comprising a column filled with supporting media, wherein the ferrate(VI) solution is distributed over the media and contacts the incoming polluted air;(e) an air inlet and outlet system for introducing contaminated air and discharging treated air;(f) a drainage system for collecting the spent ferrate(VI) solution after oxidation reactions.2.- The device of claim 1 , wherein the alkaline electrolyte comprises distilled water and sodium hydroxide at a concentration of approximately 14 molar.3.- The device of claim 1 , wherein the electrochemical reactor operates at a voltage of 24 volts for safety purposes, avoiding risks associated with higher voltages.4.- The device of claim 1 , wherein the ferrate(VI) solution is used immediately after generation to prevent degradation into ferric iron.5.- The device of claim 1 , wherein the iron electrodes are polished periodically to remove passive layers and maintain electrochemical efficiency.6.- The device of claim 1 , wherein the packed-bed scrubber is constructed from corrosion-resistant materials such as PVC, FRP, or stainless steel.7.- The device of claim 1, wherein the system is integrated with a control unit for monitoring voltage, current, flow rates, pH, and ferrate(VI) concentration.

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