The Effect of Discharge Frequency of a Gas–Liquid Plasma Reactor on Bulk Liquid Transport and Removal of Organic Contaminants

Vasilev, M. B.; Conlon, Patrick R.; Bohl, Douglas; Thagard, Selma Mededovic

doi:10.1007/s11090-022-10246-2

Cited by 10 publications

(3 citation statements)

References 54 publications

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“…The slight decrease in defluorination rates over time (Figure c) may be the result of transport limitations or the formation of shorter-chain PFAS, which have lower surface activity, thus lowering the surface concentration. Thagard and co-workers have presented a similar argument, and they have recently mentioned the major role of mass transport in plasma-based water treatment . However, a simple quantitative model that explains interplay of reaction kinetics, mass transport, and surface accumulation during plasma degradation of PFAS in a well-mixed environment is lacking.…”

Section: Resultsmentioning

confidence: 92%

“…Thagard and co-workers have presented a similar argument, 53 and they have recently mentioned the major role of mass transport in plasma-based water treatment. 79 However, a simple quantitative model that explains interplay of reaction kinetics, mass transport, and surface accumulation during plasma degradation of PFAS in a well-mixed environment is The film model that we presented can be modified to include all these mechanisms in a quantitative manner, along with incorporating the direct interaction of PFOA with gaseous electrons at the plasma− water interface.…”

Section: Langmuirmentioning

confidence: 99%

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Rate, Efficiency, and Mechanisms of Electrochemical Perfluorooctanoic Acid Degradation with Boron-Doped Diamond and Plasma Electrodes

et al. 2022

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The removal of per- or polyfluorinated alkyl substances (PFAS) has received increasing attention because of their extreme stability, our increasing awareness of their toxicity at even low levels, and scientific challenges for traditional treatment methods such as separation by activated carbon or destruction by advanced oxidation processes. Here, we performed a direct and systematic comparison of two electrified approaches that have recently shown promise for effective degradation of PFAS: plasma and conventional electrochemical degradation. We tailored a reactor configuration where one of the electrodes could be a plasma or a boron-doped diamond (BDD) electrode and operated both electrodes galvanostatically by continuous direct current. We show that while both methods achieved near-complete degradation of PFAS, the plasma was only effective as the cathode, whereas the BDD was only effective as the anode. Compared to the BDD, plasma required more than an order of magnitude higher voltage but lower current to achieve similar degradation efficiency with more rapid degradation kinetics. All these factors considered, it was noted that plasma or BDD degradation resulted in similar energy efficiencies. The BDD electrode exhibited zero-order kinetics, and thus, PFAS degradation using the conventional electrochemical method was kinetically controlled. On the contrary, analysis using a film model indicated that the plasma degradation kinetics of PFAS using plasma were mass-transfer-controlled because of the fast reaction kinetics. With the help of a simple quantitative model that incorporates mass transport, interfacial reaction, and surface accumulation, we propose that the degradation reaction kinetically follows an Eley–Rideal-type mechanism for the plasma electrode, and an intrinsic rate constant of 2.89 × 108 m4 mol–1 s–1 was obtained accordingly. The investigation shows that to realize the true kinetic potential of plasma degradation for water treatment, mass transfer to the interface must be enhanced.

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Section: Resultsmentioning

confidence: 92%

Section: Langmuirmentioning

confidence: 99%

Rate, Efficiency, and Mechanisms of Electrochemical Perfluorooctanoic Acid Degradation with Boron-Doped Diamond and Plasma Electrodes

et al. 2022

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“…Recently, non-equilibrium atmospheric pressure plasma has been widely investigated for environmental, agricultural, and biomedical applications [1][2][3]. For example, Vasilev et al decomposed organic compounds (solutes), such as phenol, caffeine, perfluorooctanoic acid (PFOA), and so on, in water by using pulsed plasmas generated over the water surface, and a rate-limiting step of the solutes' decomposition was investigated based on a mathematical model [4]. Griseti et al irradiated an atmospheric pressure plasma jet to phosphate-buffered saline (PBS) and sodium chloride (NaCl) solutions, and it was found that the plasma-activated PBS was more suitable for killing cancer cells than the plasmaactivated NaCl solution [5].…”

Section: Introductionmentioning

confidence: 99%

Development and Evaluation of Newly Designed Coaxial Cylindrical Plasma Reactor with Liquid Flow Control and Post-Discharge Reactions for Water Treatment

et al. 2022

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Water purification by non-equilibrium atmospheric pressure plasma has attracted much attention and is expected to be a next-generation method. However, general approaches to improve the energy efficiency of the water purification have not been revealed. Therefore, to investigate important factors for increasing its energy efficiency, we developed coaxial cylindrical plasma reactors where pulsed streamers were generated between a high-voltage electrode and running water film. To evaluate the performance of the plasma reactors, we measured hydroxyl (OH) radicals in solution based on a chemical probe method using disodium terephthalic acid (NaTA) and decolorized indigo carmine solution. Our experimental results showed that the production rate of the OH radicals was approximately 20 nmol/s and that the energy efficiency of the decolorization was on the order of 10 g/kWh. In addition, we found that controlling liquid flow based on the Coandă effect and introducing the intermittent operation of the streamer discharges to use post-discharge reactions increased the energy efficiency by a factor of approximately 3.5, which indicated that these approaches are effective to improve the performance of the water purification by plasma.

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The Chemical Composition of Species Formed in a Water Anode Under the Action of a Direct Current Electric Discharge: Comparison with Liquid Cathode—Experiment and Simulation

Shutov

Smirnova

Ivanov

et al. 2023

Plasma Chem Plasma Process

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The Effect of Discharge Frequency of a Gas–Liquid Plasma Reactor on Bulk Liquid Transport and Removal of Organic Contaminants

Cited by 10 publications

References 54 publications

Rate, Efficiency, and Mechanisms of Electrochemical Perfluorooctanoic Acid Degradation with Boron-Doped Diamond and Plasma Electrodes

Rate, Efficiency, and Mechanisms of Electrochemical Perfluorooctanoic Acid Degradation with Boron-Doped Diamond and Plasma Electrodes

Development and Evaluation of Newly Designed Coaxial Cylindrical Plasma Reactor with Liquid Flow Control and Post-Discharge Reactions for Water Treatment

The Chemical Composition of Species Formed in a Water Anode Under the Action of a Direct Current Electric Discharge: Comparison with Liquid Cathode—Experiment and Simulation

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