Name: Implementation of a Hyperbolic Vortex Plasma Reactor for the Removal of Micropollutants in Water (Video) | JoVE Journal
Uploaded: 2025-07-25T14:55:00.000+00:00
Duration: 6 min 35 s
Description: Learn plasma discharge optimization for micropollutant degradation in water using a hyperbolic vortex reactor. This method achieves nearly 100% PFAS removal with surfactant enhancement and moderate energy input.

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5 minutes

This work was performed in the cooperation framework of Wetsus European Center of Excellence for Sustainable Water Technology (www.wetsus.eu) within the Applied Water Physics theme in the Gilbert-Armstrong high voltage laboratory. Wetsus is cofounded by the Dutch Ministry of Economic Affairs and Ministry of Infrastructure and Environment, The Province of Friesland and the Northern Netherlands Provinces. This research has received funding from the European Union&#8217;s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 665874.&#160;

1. General recommendations
<ol>
	<li>Prior to handling the experimental setup, discharge any accumulated static charge by touching conductive parts with a grounding stick.</li>
	<li>Inspect all hydraulic and electrical connections of the setup for integrity and proper functionality.</li>
	<li>Initiate the pumps at a low flow rate (80 L&#183;h-1) using clean water and verify the absence of leakages.</li>
	<li>Ensure that the reactor is free from gas leaks by purging it with compressed air at 1 atm and applying a soap-water solution to all connections. 
	NOTE: If bubbles appear after performing step 1.4, this indicates a gas leak that must be identified and sealed before treatment.</li>
</ol>
2. Experimental setup
<ol>
	<li>Hyperbolic vortex plasma setup (Figure 2)
	<ol>
		<li>Discharge all metallic components by touching them with a grounding stick. 
		NOTE: If a residual charge is present after working with high voltage, a visible and audible spark will occur between the grounding stick and the charged component.</li>
		<li>Activate the Dr&#228;ger sensor (12 in Figure 2), by pressing and holding the OK button for three seconds to enable detection of ozone, nitrite, and oxygen generated by the plasma. Place the sensor inside the right cabinet to check for potential gas leaks.</li>
		<li>Connect the water reservoir (14 in Figure 2) containing deionized water to the setup via the designated hose line.</li>
		<li>Start the primary pump by pressing the play button, to introduce water into the hyperbolic funnel, ensuring a flow rate of 85 L&#183;h-1, that slightly exceeds the threshold required for formation of desirable vortex6. 
		NOTE: At higher flow rates, the water level in the reactor may rise slightly above the optimal level required for stable operation.</li>
		<li>Start the secondary pump by pressing the play button, ensuring a flow rate of 10 L&#183;h-1 to extract water from the upper section of the hyperbolic funnel, thereby stabilizing the water level and maintaining a constant distance between the electrodes and the water surface. 
		NOTE: Using both the primary and secondary pumps ensures a stable water level in the reactor. Operating only the primary pump may lead to fluctuations in the water level.</li>
		<li>Once a stable vortex is achieved and no leaks are detected, replace the clean water with the experimental sample and repeat steps 2.1.3 and 2.1.4.</li>
		<li>If necessary, fine-tune the electrode-to-water distance to optimize plasma formation.</li>
		<li>Purge the reactor with a low flow of compressed air (0.1 atm) to stabilize the internal atmosphere and ensure optimal plasma discharge conditions31.</li>
		<li>If using a cationic surfactant, connect an auxiliary reservoir containing the surfactant solution and introduce it via a dosing pump at the desired concentration before the reactor inlet.</li>
	</ol>
	</li>
</ol>
3. Different types of plasma discharges
<ol>
	<li>DC arc discharge
	<ol>
		<li>Utilize the electrical circuit depicted in Figure 3A.</li>
		<li>Connect the positive and negative high-voltage outputs from the bridge rectifier to the electrodes positioned above the water vortex surface. 
		NOTE: If working with a single polarity (either positive or negative), ground the respective terminal and operate exclusively with the preferred polarity.</li>
		<li>Connect the variac to the 230 V AC power outlet and disengage the red safety switch to enable high voltage.</li>
		<li>Ignite the plasma discharge by gradually increasing the voltage (0 V to 250 V) using the variac.</li>
	</ol>
	</li>
	<li>AC arc discharge
	<ol>
		<li>Utilize the electrical circuit depicted in Figure 3B.</li>
		<li>Connect both high-voltage outputs to the electrodes positioned above the water vortex surface. 
		NOTE: If operating with a single output, ground the respective terminal.</li>
		<li>Connect variac to the 230 V AC power outlet and disengage the red safety switch to enable high voltage.</li>
		<li>Ignite the plasma discharge by gradually increasing the voltage (0 V to 250 V) using the variac.</li>
	</ol>
	</li>
	<li>Glow discharge in helium atmosphere
	<ol>
		<li>Utilize the electrical circuit depicted in Figure 4. 
		NOTE: Different electrical circuits can be employed depending on the specific glow discharge requirements (Figure 3, Figure 4, Figure 5, and Figure 6).</li>
		<li>Connect the high-voltage outputs to the electrodes positioned above the water vortex surface. 
		NOTE: The glow discharge forms between electrodes of opposite polarity. Adjusting the number and placement of electrodes modifies the discharge topology.</li>
		<li>Connect variac to the 230 V AC power outlet and disengage the red safety switch to enable high voltage.</li>
		<li>Introduce helium at the preferred flow rate by opening a gas valve. 
		NOTE: Allow sufficient time for helium to replace the ambient air. The glow discharge color transitions from purple to white as helium concentration increases. Higher flow rates of helium gas enhance discharge brightness.</li>
		<li>Ignite the plasma discharge by gradually increasing the voltage from 0&#8239;V using the variac until electrical breakdown occurs between the electrodes and the plasma transitions from glow discharge to arc discharge. 
		NOTE: Excessive voltage may transform the glow discharge into a pulsed arc discharge due to capacitor effects in the circuit.</li>
	</ol>
	</li>
	<li>Bipolar &#34;flashover&#34; pulsed discharge
	<ol>
		<li>Utilize the electrical circuit depicted in Figure 4.</li>
		<li>Connect the high-voltage outputs to the electrodes positioned above the water vortex surface. 
		NOTE: The circuit in Figure 4 allows for flexible electrode configuration. In this study, 16 electrodes were utilized.</li>
		<li>Connect variac to the 230 V AC power outlet and disengage the red safety switch to enable high voltage.</li>
		<li>Ignite the plasma discharge by gradually increasing the voltage (0 V to 250 V) using the variac.</li>
	</ol>
	</li>
	<li>Monopolar positive and negative pulsed streamer discharges
	<ol>
		<li>Utilize the electrical circuit depicted in Figure 5 or Figure 6 for positive or negative discharge, respectively.</li>
		<li>Connect the respective high-voltage output (positive or negative) to the electrodes positioned above the water vortex surface.</li>
		<li>Connect the opposite terminal to a spark gap and ground the other end. 
		NOTE: Alternatively, the spark gap can be grounded via an electrode submerged in the grounded water of the reactor.</li>
		<li>Purge the spark gap with compressed air (0.5-1 atm) by opening the gas valve and adjusting the flow to ensure a stable internal atmosphere and maintain consistent temperature. 
		NOTE: Variations in gas composition, temperature, pressure and electrode spacing within the spark gap influence plasma characteristics.</li>
		<li>Connect variac to the 230 V AC power outlet and disengage the red safety switch to enable high voltage.</li>
		<li>Ignite the plasma discharge by gradually increasing the voltage (0 V to 250 V) using the variac.</li>
	</ol>
	</li>
	<li>Experiment termination
	<ol>
		<li>Cease high voltage operation by reducing the variac voltage, switching off the power supply, and engaging the safety switch.</li>
		<li>If applicable, stop the dosing pump for the cationic surfactant.</li>
		<li>Close all gas valves for helium and compressed air if they were used.</li>
		<li>Verify the grounding of all metallic components by touching them with a grounding stick.</li>
		<li>Reverse pump flow direction to transfer treated samples back to the water reservoir.</li>
		<li>Rinse the setup by circulating clean water and/or an organic solvent through the system.</li>
		<li>Properly collect and dispose of waste, ensuring compliance with safety regulations for hazardous substances.</li>
		<li>Conduct a final inspection to confirm that all components are powered off, no leaks are present, and the setup is secure for subsequent use.</li>
	</ol>
	</li>
</ol>

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<li>Chen, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Degradation+of+perfluoroalkyl+and+polyfluoroalkyl+substances+%28PFAS%29+in+water+by+use+of+a+nonthermal+plasma-ozonation+cascade+reactor%3A+Role+of+different+processes+and+reactive+species%5BTitle%5D)+AND+%22Chem+Eng+J%22%5BJournal%5D)">Degradation of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in water by use of a nonthermal plasma-ozonation cascade reactor: Role of different processes and reactive species.</a> Chem Eng J. 486, 150218(2024).</li>
<li>Lewis, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Rapid+degradation+of+PFAS+in+aqueous+solutions+by+reverse+vortex+flow+gliding+arc+plasma%5BTitle%5D)+AND+%22Environ+Sci+Water+Res.+Technol%22%5BJournal%5D)">Rapid degradation of PFAS in aqueous solutions by reverse vortex flow gliding arc plasma.</a> Environ Sci Water Res. Technol. 6 (4), 1044-1057 (2020).</li>
<li>McIntosh, G. J., Agbenyegah, G. E. K., Hyland, M. M., Metson, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+pivotal+role+of+alumina+pore+structure+in+HF+capture+and+fluoride+return+in+aluminum+reduction%5BTitle%5D)+AND+%22JOM%22%5BJournal%5D)">The pivotal role of alumina pore structure in HF capture and fluoride return in aluminum reduction.</a> JOM. 68, 2463-2471 (2016).</li>
<li>Mukherjee, S., Siddiqi, H., Maiti, P., Parmar, P., Meikap, B. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+comprehensive+analysis+of+removal+of+hazardous+dust+particulates+from+chemical+and+process+industries+off+gases+by+advanced+wet+scrubbing+techniques+-+A+review%5BTitle%5D)+AND+%22J+Loss+Prev+Process+Ind%22%5BJournal%5D)">A comprehensive analysis of removal of hazardous dust particulates from chemical and process industries off gases by advanced wet scrubbing techniques - A review.</a> J Loss Prev Process Ind. 91, 105406(2024).</li>
<li>Comparison of sodium and calcium based sorbents for the dry treatment of flue gas from waste-to-energy plants. Zach, B., et al. 2nd International Conference on Energy Production and Management (EQ 2016), , Ancona. (2016).</li>
</ol>

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. During the preparation of this work the authors used OpenAI (2023) ChatGPT (version March 2025) [Large language model] in order to structure text. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Before initiating experiments, all electrical connections must be thoroughly inspected. Prior to interacting with high-voltage components, a grounding stick should be used to discharge any residual charge in the circuit. These comprehensive safety measures must be implemented to mitigate the risk of accidental electric shocks, even in cases of procedural oversight (door switches, bleeder resistor connected to the capacitors, etc.), because high voltage capacitors can recharge due to memory effect, atmospheric static electricity or cosmic radiation. Their order of magnitude stored energy for these experiments typically is 10-1-101 J, being hazardous to even lethal. Therefore steps 1.1 and 2.1.1 are critical for ensuring safe operation of the system. Before powering the system, the setup should be checked for reactor gaseous and liquid phase leakages. Plasma-generated gases contain reactive species that may pose inhalation hazards, making steps 1.4 and 2.1.2 especially important. All inlets and outlets of the operational chamber must be grounded. The reactor enclosure should be constructed from metal and properly grounded to ensure safe operation. Additionally, verifying the absence of water leaks is essential, as PFAS compounds are classified as CMR substances and must not be allowed to contaminate the laboratory environment. Therefore, particular attention should be paid to step 1.3 prior to initiating the experiment.
In this study, the highest performance was achieved with flashover discharges. This discharge mode resulted in greater RONS production (Figure 10) and higher PFOS degradation (Figure 11) while requiring less power than the other tested discharge types (Figure 9). Although flashover discharges demonstrated superior performance, their implementation presents challenges due to the requirement of two oppositely charged channels connected to the same capacitor. Scaling up this approach necessitates a more powerful power supply. In our current setup, a transformer converts main-voltage AC (up to 220 V) to high-voltage AC (up to 10 kV), which is then rectified into DC using diodes. While the resulting DC signal closely approximates an ideal DC waveform, minor fluctuations remain34. Our circuit design provides operational flexibility across multiple regimes. However, large-scale applications will require high-voltage DC power supplies, which typically operate with a single polarity and a single high-voltage output, restricting the ability to work with multiple polarities simultaneously.
AC and DC arc discharges were not tested for micropollutant degradation due to their significantly higher energy consumption, which would render their industrial application economically unfeasible, particularly in the case of DC plasma. In a previous study8 it was demonstrated that increasing the plasma-liquid interfacial area enhances RONS generation for the same energy input, thereby improving micropollutant degradation efficiency. In our electrical circuits (Figure 3A, Figure 4, Figure 5, and Figure 6), diodes convert AC power into DC for charging the capacitors, their stored energy then is distributed over the electrode geometries to generate multiple pulsed power plasma discharges.
At atmospheric pressure and standard conditions, a stable glow discharge can only be sustained using noble gases with high ionization energies, such as helium (first ionization energy 24.6 eV) or neon (first ionization energy 21.6 eV)35. Argon, with a first ionization energy of 15.8 eV35, does not support stable glow discharge under these conditions. However, glow discharge can still be generated in air through the application of an external magnetic field for plasma stabilization36. The high cost of noble gas usage made glow discharge unsuitable for micropollutant degradation in this study.
As discussed in the introduction, conventional treatment methods such as adsorption, membrane filtration, and advanced oxidation processes face significant limitations in effectively addressing PFAS contamination. Plasma discharge presents a promising alternative for PFAS degradation, with reported energy consumption ranging from several kWh&#183;m-3&#160;to over 1000 kWh&#183;m-3, depending on factors such as micropollutant concentration, sample composition, and plasma parameters29,37,38,39,40,41. However, short-chain PFAS remain particularly resistant to degradation, and shorter-chain byproducts, such as PFBA, have been identified as intermediates in the breakdown of longer-chain PFAS.
The novelty of our work lies in combining a Hyperbolic Vortex Plasma Reactor with cationic surfactant Hyamine 1622 dosing, significantly improving degradation rates, including for short-chain PFAS (Figure 13). This reactor design increases the plasma-liquid interfacial area and facilitates enhanced mixing through the water vortex. In 75 min of treatment at a moderate energy input of 1.2 kWh&#183;m-3, our system achieves 95-100% degradation of most PFAS (except PFBA, which still shows 53% removal). These results outperform many plasma-only studies and demonstrate that our approach can achieve deep PFAS mineralization under relatively low energy input. However, this study was conducted at the laboratory scale. To enhance its practical application, scaling up is required, including modifications to reactor geometry-specifically, expanding the top cylindrical section-to increase treated water volume and accommodate additional electrodes. These modifications would enhance plasma-water interaction and improve treatment efficiency. While the reactor&#39;s electrical design allows for straightforward scaling, increasing operational power demands more robust power supplies and improved safety measures to ensure stable and efficient performance on a larger scale. Scaling up the system will necessitate an increase in power supply and capacitor bank size, which introduces significant safety concerns. All electrical components must be carefully arranged and positioned in close proximity to the reactor while remaining inaccessible during operation. To ensure safe discharge, each capacitor must be individually grounded after use, requiring dedicated grounding switches, as they cannot be interconnected and must be isolated from one another with diodes for direct current separation. Additionally, higher power levels will generate stronger electromagnetic fields that could interfere with nearby instrumentation. Therefore, both the reactor and surrounding equipment should be properly shielded, preferably within a Faraday cage. Precise control of the water vortex is essential, as plasma discharge performance is highly sensitive to flow conditions and funnel geometry. This necessitates a well-programmed hydraulic control system. Furthermore, the reactor must be adequately insulated, connected to a ventilation system, and equipped with a gas inlet for purging. If high concentrations of volatile fluorinated byproducts, such as hydrogen fluoride, are expected, supplementary gas treatment steps should be implemented. These may include dry or wet scrubbing systems42,43, or the application of calcium-based sorbents44.
The energy consumption of the pilot-scale reactor could potentially be reduced through the addition of surfactants, which concentrate PFAS at the air-water interface. By decreasing the surface-to-volume ratio, PFAS compounds become more localized at the interface, allowing the plasma to interact with a higher concentration of target compounds per unit area, thereby increasing degradation efficiency per discharge. However, increasing the overall water volume may extend the required treatment duration, potentially offsetting the energy savings. Utilizing a high-voltage, high-power DC power supply for capacitor charging enables precise control of energy input, allowing systematic evaluation of different energy regimes for optimization.
Future research will focus on scaling up the technology based on the described operational principles to achieve a treatment capacity of 1 m3&#183;h-1&#160;for pilot-scale applications. Additionally, a detailed investigation of degradation products is essential, with particular interest in the formation and breakdown of the shortest-chain PFAS, trifluoroacetic acid, as well as other potential transformation products. Further studies will also aim to identify an effective, biodegradable, and cost-efficient cationic surfactant capable of enhancing PFAS degradation through improved formation of surfactant-PFAS complexes.

Spiral structures are fundamental to nature, influencing phenomena ranging from the microscopic arrangement of DNA to the vast formations of galaxies1,2. In fluid dynamics, helical flows exhibit unique properties of mixing, energy transfer, and stability, which can be harnessed for innovative engineering applications3. Inspired by these natural flow patterns, hyperbolic water vortices have been investigated for their potential in enhancing aeration and enabling advanced water treatment technologies4,5,6,7. This study explores the integration of hyperbolic vortex dynamics with plasma discharge for the degradation of persistent micropollutants, in particular per- and polyfluoroalkyl substances (PFAS).
The initial research into hyperbolic funnels was motivated by their efficiency in aeration, a crucial process in water treatment. These geometrically confined vortices significantly enhance gas-liquid interactions, thereby increasing oxygen transfer rates while minimizing energy consumption7. A detailed explanation of the formation and operation of hyperbolic water vortices is provided elsewhere6. It soon became clear that the high degree of mixing and surface area increase that resulted in such high aeration capacity could be further utilized for pollutant degradation. Building upon this idea, plasma discharge was introduced into the vortex system, creating a novel hybrid approach for micropollutant removal8.
Micropollutants, including pharmaceuticals, pesticides, and PFAS, pose significant environmental and public health challenges due to their persistence and resistance to conventional water treatment methods9. Among these, PFAS-commonly referred to as &#34;forever chemicals&#34;-are particularly problematic due to their strong carbon-fluorine bonds, which confer extreme stability and bioaccumulative potential10,11.
A wide range of technologies has been developed to address PFAS contamination, including adsorption using activated carbon12,13 and membrane separation14. While effective at capturing PFAS, these methods are non-destructive and generate secondary waste streams. Activated carbon becomes costly due to frequent regeneration needs-especially at high PFAS loads-and competes with co-contaminants, while membrane systems concentrate PFAS into waste brines requiring further treatment.
Advanced oxidation processes (AOPs) such as electrochemical oxidation, ozonation, UV-based systems, and supercritical water oxidation aim to degrade PFAS rather than separate them15,16.&#160;However, they often suffer from high energy demands, poor selectivity (especially for short-chain PFAS), and the generation of harmful byproducts or incomplete degradation.
Plasma-based technologies have recently gained attention as a promising destructive method, offering rapid PFAS degradation across chain lengths17,18,19,20. However, most studies report reduced performance on short-chain PFAS, which are frequently generated as intermediate byproducts during the treatment process. Additionally, plasma treatment alone can be energy-intensive and difficult to scale.
Various types of plasma discharge have been explored for water treatment applications. These include direct current (DC) glow and arc discharges, alternating current (AC) discharges, pulsed corona discharge, dielectric barrier discharge (DBD), and gliding arc discharge8,21,22,23,24. Each type of plasma discharge exhibits distinct characteristics in reactive species generation, energy distribution, and pollutant degradation pathways. While glow discharge operates at lower temperatures and provides uniform ionization, arc discharge delivers intense localized heating, making it effective for breaking down persistent organic pollutants25,26,27. Pulsed discharges, such as monopolar and bipolar pulsed plasma, are characterized by their high-energy density and the generation of transient reactive species, which contribute to enhanced efficiency of micropollutant degradation at moderate energy requirements8.
This study demonstrates a method for generating and operating six different types of plasma discharges within a Hyperbolic Vortex Plasma Reactor: (i) pulsed monopolar negative, (ii) pulsed monopolar positive, (iii) pulsed bipolar &#34;flashover&#34; , (iv) AC arc, (v) DC arc, and (vi) glow discharge. Each of these discharge modes has unique interactions with the hyperbolic vortex, influencing the generation of reactive oxygen and nitrogen species (RONS), ultraviolet radiation, shockwaves, energetic electrons, and solvated electrons, all of which contribute to pollutant degradation. The electrode configurations for each plasma discharge type utilized in the experiments are depicted in Figure 1. The integration of such plasma discharge modes with vortex-induced mixing enables enhanced mass transfer and improved contact between contaminants and reactive species, resulting in more effective degradation of micropollutants.
As demonstrated in28,29, the addition of a cationic surfactant further enhances degradation efficiency by promoting the transport of PFAS molecules to the plasma-water interface, where the most intense reactive processes take place. The results indicate that this system achieves near-complete degradation of PFAS while maintaining operational feasibility.
In addition, as demonstrated elsewhere30, PFAS-contaminated samples treated in a Hyperbolic Vortex Plasma Reactor under an air atmosphere exhibited no increase cytotoxicity or genotoxicity. These findings further support the potential of this technology as a promising approach to PFAS removal.
The implications of this research extend beyond PFAS degradation. The combination of Hyperbolic Vortex Induced Mixing and plasma treatment offers a scalable and adaptable solution for various water treatment challenges, from organic contaminant removal to enhanced oxygenation. Future studies will focus on optimizing reactor configurations, investigating the fate of degradation byproducts, and evaluating long-term system performance in real-world applications.
By combining nature-inspired fluid dynamics with advanced plasma chemistry, this study paves the way for more sustainable and effective water treatment technologies that address critical environmental issues while reducing energy and resource consumption.

<table><tbody><tr><td>Bleeder resistors</td><td>Tedss</td><td>RCR42G206JS</td><td>20 MOhm</td></tr><tr><td>BNC connectors</td><td>AliExpress</td><td>N/A</td><td>BNC ADAPTER</td></tr><tr><td>Capacitor</td><td>AnXon</td><td>AXCT8GD202K40DB</td><td>40 kV 2000 pF</td></tr><tr><td>Cationic surfactant</td><td>Sigma-Aldrich</td><td>51126-1L-F</td><td>Hyamine 1622 solution</td></tr><tr><td>Column</td><td>Agilent&amp;nbsp;</td><td>&amp;nbsp;Zorbax Eclipse Plus C18 RRHD</td><td>1.8 &amp;mu;m, 50 &amp;times; 2.1 mm</td></tr><tr><td>Current transformer</td><td>Magnelab</td><td>CT-F0.25-S</td><td></td></tr><tr><td>Data Logger</td><td>Endress+Hauser</td><td>CM442</td><td>Liquiline</td></tr><tr><td>Door switches</td><td>QWORK</td><td>ME-8104</td><td>10A 250VAC</td></tr><tr><td>Dosing pump&amp;nbsp;</td><td>KNF</td><td>1.10 TT.18RC2</td><td>FEM</td></tr><tr><td>Dr&amp;auml;ger sensor&amp;nbsp;</td><td>Dr&amp;auml;ger</td><td>X-am 5000</td><td>O2, O3, NO2</td></tr><tr><td>EC sensor</td><td>Endress and Hauser</td><td>CLS15E</td><td>Memosens</td></tr><tr><td>Electrodes</td><td>AliExpress</td><td>N/A</td><td>Ceramic Ignition Rod</td></tr><tr><td>Fluoride electrode</td><td>Mettler Toledo</td><td>perfectION</td><td></td></tr><tr><td>Funnel lid&amp;nbsp;</td><td>Custom made</td><td>N/A</td><td>PVC matetial</td></tr><tr><td>Grounding stick</td><td>Custom made</td><td>N/A</td><td></td></tr><tr><td>Helium gas</td><td>Westfalen</td><td>UN 1046</td><td>99.999 Vol. % He</td></tr><tr><td>High voltage diode</td><td>Ebay</td><td>FHVP5446</td><td>1p 5A 40kV</td></tr><tr><td>Highvoltage probe</td><td>North Star High Voltage</td><td>PVM-5</td><td></td></tr><tr><td>Hyperbolic funnel</td><td>Custom made</td><td>N/A</td><td>Glass material</td></tr><tr><td>LC/MS</td><td>Agilent Technologies</td><td>6420 Triple Quad LC/MS</td><td>Santa Clara, CA, USA</td></tr><tr><td>Noen-transformer</td><td>F/ART</td><td>SBD63HT2X</td><td>10000V 18mA&amp;nbsp;</td></tr><tr><td>ORP sensor</td><td>Endress and Hauser</td><td>CPS12D</td><td>Memosint</td></tr><tr><td>Peristaltic pump</td><td>Masterflex L/S</td><td>13-200-007</td><td>MFLX7771236</td></tr><tr><td>PFBA</td><td>Sigma-Aldrich</td><td>375-22-4</td><td>PFAS for experiments</td></tr><tr><td>PFBS</td><td>Sigma-Aldrich</td><td>375-73-5</td><td>PFAS for experiments</td></tr><tr><td>PFDA</td><td>Sigma-Aldrich</td><td>335-76-2</td><td>PFAS for experiments</td></tr><tr><td>PFHpA</td><td>Sigma-Aldrich</td><td>375-85-9</td><td>PFAS for experiments</td></tr><tr><td>PFNA</td><td>Sigma-Aldrich</td><td>375-95-1</td><td>PFAS for experiments</td></tr><tr><td>PFOA</td><td>Sigma-Aldrich</td><td>335-67-1</td><td>PFAS for experiments</td></tr><tr><td>PFOS</td><td>Sigma-Aldrich</td><td>1763-23-1</td><td>PFAS for experiments</td></tr><tr><td>pH sensor</td><td>Endress and Hauser</td><td>CPS11D</td><td>Memosens Orbisint</td></tr><tr><td>Safety interlock control panel</td><td>Custom made</td><td>N/A</td><td></td></tr><tr><td>Spark Gap</td><td>Custom made</td><td>N/A</td><td></td></tr><tr><td>Variac</td><td>Weltechniek</td><td>TDGC2-1K</td><td>4a</td></tr><tr><td>Water reservoir&amp;nbsp;</td><td>Custom made</td><td>N/A</td><td>Glass material</td></tr></tbody></table>

implementation of a hyperbolic vortex plasma reactor for the removal of micropollutants in water

Implementation of a Hyperbolic Vortex Plasma Reactor for the Removal of Micropollutants in Water

The presence of micropollutants in water is an increasingly pressing environmental concern. While some micropollutants are readily biodegradable, others, such as per- and polyfluoroalkyl substances (PFAS), are extremely persistent and resistant to conventional water treatment technologies. Plasma-based treatment has been investigated for water and wastewater decontamination for decades, with recent studies demonstrating its high efficacy in degrading both short- and long-chain PFAS. Here, plasma-based waste treatment is combined with a free surface hyperbolic water vortex, which has an oxygen volumetric mass transfer coefficient exceeding that of similar systems. Various types of plasma discharges can be employed for such applications, each requiring specific power supply configurations and operational strategies. The use of pulsed signals, in particular, presents unique engineering challenges. This study explores the generation and characterization of six different plasma discharge types within a Hyperbolic Vortex Plasma Reactor: pulsed monopolar (negative and positive), pulsed bipolar "flashover," AC and DC arc, and glow discharge. The pulse characteristics of monopolar and bipolar pulsed discharges were analyzed, and their efficiency in PFAS degradation was evaluated. Among the tested configurations, the bipolar flashover discharge exhibited the highest degradation efficiency in a Hyperbolic Vortex Plasma Reactor. However, its practical implementation poses significant engineering challenges, making its utilization challenging on a larger scale.

This study presents the methodology for the generation of six different types of plasma discharges within a Hyperbolic Vortex Plasma Reactor for the degradation of micropollutants in water, including pharmaceuticals and per- and polyfluoroalkyl substances (PFAS).

The presence of micropollutants in water is an increasingly pressing environmental concern. While some micropollutants are readily biodegradable, others, ...

The focus of our research is to optimize plasma discharge for the degradation of micropollutants in water, which is a growing environmental concern nowadays. We discovered that by optimizing plasma discharge and carefully dosing cationic surfactants, we can reach nearly 100%PFAS degradation using only moderate energy input. Plasma treatment is typically an energy-intensive process.However, by applying plasma pulses, energy consumption can be significantly reduced while improving performance. And in this study, we demonstrate how to achieve this optimization. After setting up the hyperbolic vortex plasma, use the electrical circuit designed for the direct current arc discharge setup.Connect the positive and negative high voltage outputs from the bridge rectifier to the electrodes positioned above the surface of the water vortex. Plug the variac into a 230 volt alternating current power outlet and switch off the red safety switch to enable high voltage. Using the variac, gradually increase the voltage from zero to 250 volts to ignite the plasma discharge.Next, use the electrical circuit configured for alternating current arc discharge. Then connect both high voltage outputs to the electrodes located above the surface of the water vortex. After connecting the variac and disengaging the safety switches shown earlier, gradually increase the voltage from zero volts to 250 volts to ignite the plasma discharge.Next, to perform a glow discharge in a helium atmosphere, use the electrical circuit shown here. Connect the high voltage outputs of the electrical circuit to the electrodes positioned above the surface of the water vortex. Once the variac is connected and the safety switch is disengaged, open the gas valve to introduce helium at the desired flow rate.Then using the variac, slowly increase the voltage to ignite the plasma discharge until electrical breakdown occurs between the electrodes and the plasma shifts from glow discharge to arc discharge. Next, to initiate the bipolar flashover pulse discharge, use the electrical circuit as shown in the schematic, connect the high voltage outputs to the electrodes, variac to a 230 volt alternating current power outlet and disengage the safety switch. Then gradually increase the voltage from zero to 250 volts to ignite the plasma discharge.For monopolar pulsed streamer discharges, use the circuit shown in the schematic for positive or negative discharge as needed. Connect the opposite terminal to a visible spark gap and ground electrode. Attach the rest of the high voltage outputs to the electrodes situated above the water vortex surface.Then open the gas valve and adjust the compressed airflow to 0.5 to one atmosphere to purge the spark gap. After connecting the variac and engaging the safety switch, ignite the plasma discharge as shown earlier. To terminate the experiment, reduce the variac voltage, switch off the power supply, and engage the safety switch.Then close all gas valves for helium and compressed air if they were used during the experiment. Using a grounding stick, touch all metallic components to verify that they're properly grounded. Among the three discharges, flashover generated the highest concentrations of hydrogen peroxide at approximately 450 milligrams per liter, nitrite at around 90 milligrams per liter, and nitrate at about 340 milligrams per liter.The flashover discharge caused the most pronounced drop in pH, reducing it from approximately 5.5 to 2.3. Electrical conductivity was highest in the flashover treated samples, reaching about 2, 300 microsiemens per centimeter. Oxidation-reduction potential increased most significantly in the flashover discharge, reaching approximately 600 millivolts.Flashover discharge achieved the fastest and most complete PFOS degradation for both initial concentrations, reaching nearly 100%conversion by 60 minutes, outperforming the positive and negative discharges. In the PFAS matrix, without surfactant, long-chain compounds like PFDA, PFNA, PFOS, and PFOA exhibited degradation above 90%after 75 minutes. In contrast, short chain species, such as PFBS and PFBA, remained largely ungraded or increased in concentration due to byproduct formation.With surfactant addition, all long-chain PFAS compounds were degraded above 95%and degradation of short-chain compounds, like PFBA, improved from minus 19%to approximately 53%and PFBS from 22%to about 95%The concentration of PFHxA started decreasing after 20 minutes and PFPeA dropped after 30 minutes of treatment with surfactant dosing, indicating progressive breakdown of PFAS byproducts.

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Learn plasma discharge optimization for micropollutant degradation in water using a hyperbolic vortex reactor. This method achieves nearly 100% PFAS removal with surfactant enhancement and moderate energy input.

Implementation of a Hyperbolic Vortex Plasma Reactor for the Removal of Micropollutants in Water

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