Production Of OH Radicals Research Articles

Efficient production and transport of OH radicals in spatial afterglow of atmospheric-pressure DC glow discharge using intersecting helium flows

An efficient method for generating OH radicals in the spatial afterglow of atmospheric-pressure plasma was investigated. The method employed a DC glow discharge along two intersecting helium flows in air. Tiny helium flows were ejected from two metal nozzles with inner diameters of 0.5 mm, and they intersected at a distance of 3–5 mm from the nozzles. A stable glow discharge was formed along the intersecting helium flows by applying a DC high voltage between the two nozzles. It was shown by laser-induced fluorescence spectroscopy that an origin of OH radicals was water vapor admixed into the intersection point of the two helium flows from ambient air. OH radicals were transported from the intersection toward the spatial afterglow along the coalesced helium flow. This is a distinctive feature of the present plasma source, by which we can obtain the stream of OH radicals in the outside of the active plasma zone even though we employ the DC discharge. In addition, we observed the production of OH radicals in the spatial afterglow. We presume that the production process of OH radicals in the spatial afterglow is dissociative electron attachment to H2O2.

Photo-generated hydroxyl radicals contribute to the formation of halogen radicals leading to ozone depletion on and within polar stratospheric clouds surface

Polar stratospheric clouds (PSCs), of which the surface is a dynamic liquid water layer and might consist of aqueous HNO3 and H2O2, is a well-known key meteorological condition contributing to the ozone hole in the polar stratosphere. PSCs has been considered to provide abundant surface for the heterogeneous reactions causing the formation of the Cl2 and HOCl, which are further photolyzed into Cl and ClO radicals leading to the ozone destruction. Here we demonstrated that the sunlight drives the massive and stable production of OH radicals in aqueous HNO3 and its main photo-induced byproduct HNO2. We also found that the photo-generated OH radicals in aqueous HNO3, HNO2 and H2O2 have the remarkable capability to react with the dissolved HCl, Cl− and Br− to form halogen radicals. In addition, we observed that the H2O2 can react with dissolved HCl and Br− in darkness to form and release Cl2 and Br2 gases, which could further be photolyzed into reactive halogen radicals whenever sunlight is available. All these findings suggest that, except for the well-known heterogeneous reactions, photochemical reactions involving the aqueous HNO3 and H2O2 on and within PSCs surface might constitute another important halogen activation pathway for ozone destruction. This study may shed deeper insights into the mechanism of halogen radicals resulting in ozone depletion in polar stratosphere.

Disclosing the Origin of Transition Metal Oxides as Peroxidase (and Catalase) Mimetics.

Since Fe3O4 was reported to mimic horseradish peroxidase (HRP) with comparable activity (2007), countless peroxidase nanozymes have been developed for a wide range of applications from biological detection assays to disease diagnosis and biomedicine development. However, researchers have recently argued that Fe3O4 has no peroxidase activity because surface Fe(III) cannot oxidize tetramethylbenzidine (TMB) in the absence of H2O2 (cf. HRP). This motivated us to investigate the origin of transition metal oxides as peroxidase mimetics. The redox between their surface Mn+ (oxidation) and H2O2 (reduction) was found to be the key step generating OH radicals, which oxidize not only TMB for color change but other H2O2 to produce HO2 radicals for Mn+ regeneration. This mechanism involving free OH and HO2 radicals is distinct from that of HRP with a radical retained on the Fe-porphyrin ring. Most importantly, it also explains the origin of their catalase-like activity (i.e., the decomposition of H2O2 into H2O and O2). Because the production of OH radicals is the rate-limiting step, the poor activity of Fe3O4 can be attributed to the slow redox of Fe(II) with H2O2, which is two orders of magnitude slower than the most active Cu(I) among common transition metal oxides. We further tested glutathione (GSH) detection on the basis of its peroxidase-like activity to highlight the importance of understanding the mechanism when selecting materials with high performance.

Degradation of Rhodamine B and Methylene Blue by Underwater Dielectric Barrier Discharge

Numerous reports have elucidated different methods for treating dyeing wastewater using UV irradiation, ozonation, and chlorination. However, the high operational costs of these methods have necessitated the use of plasma. In this study, dielectric barrier discharge (DBD) was used to purify dyeing wastewater, generating ozone as a byproduct. An underwater DBD plasma system was designed to directly interact with water, thereby producing reactive oxygen species (ROS) and functioning as a powerful oxidizer. Additionally, UV, O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> are generated by the developed plasma system without using any other additives to produce OH radicals for purifying organic pollutants; therefore, this system circumvents the use of complex and advanced oxidation processes. A simulation test was performed, which revealed that methylene blue and rhodamine B were completely removed within 7 and 3 min, respectively. Therefore, the developed plasma system can be successfully applied for the purification of dyeing wastewater.

Exploring the low-temperature oxidation chemistry with ozone addition in an RCM: A case study on ethanol

The low reactivity of some fuels restricts their oxidation experiments at temperatures lower than a specific threshold value. The oxidation of fuel exhibiting low reactivity can be initiated in practical combustors by other highly reactive components at lower temperatures beyond this threshold. To meet the lack of corresponding experimental study, ozone (O3) was utilized as the active species to extend experimental conditions towards lower temperatures. A new experimental facility combining an O3 system and a rapid compression machine (RCM) was developed, with which the generation and qualification of O3 in the RCM was achieved. The RCM-O3 facility can be used to directly investigate the ignition behavior and provide time-resolved species information in the presence of O3 under high-pressure conditions. As a case study, the oxidation and ignition behavior of ethanol were investigated under low-temperature conditions (<820 K) where the auto-ignition of pure ethanol cannot be initiated. Ignition delay times for stoichiometric ethanol/O2 mixtures containing varying concentrations of O3 (0 ppm, 1000 ppm, and 2000 ppm) were determined in the temperature region of 769–1036 K under the pressures of 15 and 25 bar. Time-resolved species profiles were obtained during the ignition process. A combination of a fast sampling system and gas chromatography (GC) technique was used to record the species profiles at 840 K and 802 K in the presence of O3. Model analysis revealed that the addition of O3 promoted the production of OH radicals. The reactivity of the system was not restricted by the decomposition of H2O2 in the presence of O3. The hydrogen-abstraction reactions of ethanol by OH radicals were highlighted to a great extent. The reaction network was not significantly affected when O3 was used as the additive, which makes the experimental results can well characterize ethanol-based chemistry. The H-abstractions at α- and β-site of ethanol by OH radicals showed opposite effects on ignition, and the branching ratio of the reaction pair was constrained according to experimental results in this work.

Comparison of the anticancer effects between helium plasma jets and electrochemical treatment (EChT)

AbstractCold atmospheric plasma, a promising technology for cancer therapy, can simultaneously induce electrochemistry, which has been widely demonstrated to be effective against cancer. Herein, the anticancer effects of direct current plasma jets and electrochemical circuit are comparatively studied with similar topological structures and average currents. The cell inactivation patterns formed by plasma and electrochemical treatment (EChT) are disparate, and the inactivation is mainly caused by the emission of charged species, helium flow, in situ OH radical production, or local alkalization. The culture medium treated by EChT exerted no sustained anticancer effect, whereas the medium treated by plasma could maintain a strong effect due to the production of more reactive species, suggesting that the electrochemistry does not dominate the plasma inactivation of cancer cells.

Scalable production of hydroxyl radicals (.OH) via homogeneous photolysis of hydrogen peroxide using a continuous-flow photoreactor

We establish the fact that in a continuous-flow scalable photoreactor system employed for the homogeneous photolysis of H2O2 into .OH radicals, the quantum yield of photolytic conversion in aqueous solution cannot be regarded as a linear function of H2O2 initial concentration. We were successful in repeatedly producing high concentrations of .OH radical (between 40 and 90 mM) from relatively low concentrations of hydrogen peroxide (between 0.1 M − 5 M) in aqueous solution in a scalable manner using our serially connected photoreactor system. Our investigation demonstrates that merely selecting a very high initial concentration of H2O2 will not necessarily result in the highest conversion into .OH radical. We also developed a simple and in-situ acid-base titrimetric method for quantitation of .OH radicals and demonstrated an accuracy of our method within ~±6.6% of a 31P NMR method. Hence, our proposed scalable .OH radical production method via continuous-flow photoreactors can be regarded as a safe, simple, accurate and cost-effective technique for various industrial processes, particularly in aquaculture and swimming pool disinfection, as a replacement of high concentrations of hazardous oxidisers.

Measuring Photodissociation Product Quantum Yields Using Chemical Ionization Mass Spectrometry: A Case Study with Ketones.

Measurements of photolysis quantum yields are challenging because of the difficulties in measuring the first-generation photodissociation products, interference from other products or contaminants, sufficient photon fluxes and/or low absorption cross sections of the photolyte to make detectable amounts of products, and quantification of the photon flux. In the case of acetone (and other atmospherically relevant ketones) the uncertainty in the photolysis quantum yield creates uncertainty in the calculated OH radical and acyl peroxy nitrate production in the atmosphere. We present a new method for determining photodissociation product quantum yields by measuring acyl peroxy radicals (RC(O)O2) produced in the photolysis of ketones in air using chemical ionization mass spectrometry (CIMS). We show good agreement of our CIMS method with previously published quantum yields of the acyl radical from photolysis of biacetyl and methyl ethyl ketone (MEK) at 254 nm. Additionally, we highlight the capabilities of this CIMS method through the measurement of photolysis branching ratios for MEK. We suggest future applications of CIMS (in the laboratory and field) to measure RC(O)O2 and associated photolysis processes.

Tight electrostatic regulation of the OH production rate from the photolysis of hydrogen peroxide adsorbed on surfaces

Recently, experimental and theoretical works have reported evidence indicating that photochemical processes may significantly be accelerated at heterogeneous interfaces, although a complete understanding of the phenomenon is still lacking. We have carried out a theoretical study of interface and surface effects on the photochemistry of hydrogen peroxide (H2O2) using high-level ab initio methods and a variety of models. Hydrogen peroxide is an important oxidant that decomposes in the presence of light, forming two OH radicals. This elementary photochemical process has broad interest and is used in many practical applications. Our calculations show that it can drastically be affected by heterogeneous interfaces. Thus, compared to gas phase, the photochemistry of H2O2 appears to be slowed on the surface of apolar or low-polar surfaces and, in contrast, hugely accelerated on ionic surfaces or the surface of aqueous electrolytes. We give particular attention to the case of the neat air-water interface. The calculated photolysis rate is similar to the gas phase, which stems from the compensation of two opposite effects, the blue shift of the n→σ* absorption band and the increase of the absorption intensity. Nevertheless, due to the high affinity of H2O2 for the air-water interface, the predicted OH production rate is up to five to six orders of magnitude larger. Overall, our results show that the photochemistry of H2O2 in heterogeneous environments is greatly modulated by the nature of the surface, and this finding opens interesting new perspectives for technological and biomedical applications, and possibly in various atmospheres.

Photocatalyst production from wasted sediment and quality improvement with titanium dioxide to remove cephalexin in the presence of hydrogen peroxide and ultrasonic waves: A cost-effective technique

In this study, wasted sediment (sludge waste from shipping docks) was coupled with titanium isopropoxide by the thermal and sol-gel method as a new photocatalyst. The sediment-titanate catalyst alongside ultrasonic and UV was activated hydrogen peroxide to produce OH radicals and decompose cephalexin (CEP). The photocatalyst was crystalline with 52.29 m2/g BET area. The best destruction rate of 87.01% based on COD test was achieved at optimal conditions (pH: 8, cephalexin concentration: 100 mg/L, H2O2: 1.63 mg/L, UV: 15 W/m2, ultrasonication time: 100 min at 40 kHz, photocatalyst quantity: 1.5 g/L). The trend of anions effect was NO3− ≤ SO42− ≤ Cl−. Decomposition of cephalexin in water solution followed the first-order kinetics (k > 0.01 min−1, R2 > 0.9). The percentage of cephalexin removal from urban water (76%) and hospital wastewater (63%) has decreased compared to the distilled water solution (87%), which is probably due to the presence of radical inhibitors. The consumed electrical energy of the studied system was calculated by 0.031 kW/h. The developed system is a promising and economical method to remove cephalexin.

Sonodegradation of amitriptyline and ibuprofen in the presence of Ti3C2Tx MXene

This study, which investigated the sonodegradation of selected pharmaceutical active compounds (PhACs) (amitriptyline (AMT) and ibuprofen (IBP)) with MXene, was carried out in an aqueous solution. To investigate the practicality of the degradation process, the experiments were conducted in various water quality conditions, including pH, temperature, natural organic matter, and ionic strength. Based on the experimental results, the produced hydrogen peroxide, which could be a representative of the produced OH radicals, was a vital factor that affected the degradation performance of both PhACs. To confirm the importance of OH radicals, the effect of a OH radical promoter (H2O2) and scavenger (t-BuOH) was also studied. In addition, the synergism between ultrasonication (US) and MXene was evaluated with the rate constants of US only, MXene only, and a US/MXene combined system. Mineralization of the PhACs was also investigated, and removal of AMT was higher than that of IBP, which could be attributed to the physicochemical properties of the compounds and enhanced adsorption by the well-dispersed MXene. Overall, utilization of MXene by means of ultrasonication could enhance the removal performance of PhACs in water.

Secondary Production of Gaseous Nitrated Phenols in Polluted Urban Environments.

Nitrated phenols (NPs) are important atmospheric pollutants that affect air quality, radiation, and health. The recent development of the time-of-flight chemical ionization mass spectrometer (ToF-CIMS) allows quantitative online measurements of NPs for a better understanding of their sources and environmental impacts. Herein, we deployed nitrate ions as reagent ions in the ToF-CIMS and quantified six classes of gaseous NPs in Beijing. The concentrations of NPs are in the range of 1 to 520 ng m-3. Nitrophenol (NPh) has the greatest mean concentration. Dinitrophenol (DNP) shows the greatest haze-to-clean concentration ratio, which may be associated with aqueous production. The high concentrations and distinct diurnal profiles of NPs indicate a strong secondary formation to overweigh losses, driven by high emissions of precursors, strong oxidative capacity, and high NOx levels. The budget analysis on the basis of our measurements and box-model calculations suggest a minor role of the photolysis of NPs (<1 ppb h-1) in producing OH radicals. NPs therefore cannot explain the underestimated OH production in urban environments. Discrepancies between these results and the laboratory measurements of the NP photolysis rates indicate the need for further studies aimed at understanding the production and losses of NPs in polluted urban environments.

Aerosol Promotes Peroxyacetyl Nitrate Formation During Winter in the North China Plain.

Peroxyacetyl nitrate (PAN) is an important indicator for photochemical pollution, formed similar to ozone in the photochemistry of certain volatile organic compounds (VOCs) in the presence of nitrogen oxides, and has displayed surprisingly high concentrations during wintertime that were better correlated to particulate rather than ozone concentrations, for which the reasons remained unknown. In this study, wintertime observations of PAN, VOCs, PM2.5, HONO, and various trace gases were investigated to find the relationship between aerosols and wintertime PAN formation. Wintertime photochemical pollution was affirmed by the high PAN concentrations (average: 1.2 ± 1.1 ppb, maximum: 7.1 ppb), despite low ozone concentrations. PAN concentrations were determined by its oxygenated VOC (OVOC) precursor concentrations and the NO/NO2 ratios and can be well parameterized based on the understanding of their chemical relationship. Data analysis and box modeling results suggest that PAN formation was mostly contributed by VOC aging processes involving OH oxidation or photolysis rather than ozonolysis pathways. Heterogeneous reactions on aerosols have supplied key photochemical oxidants such as HONO, which produced OH radicals upon photolysis, promoting OVOC formation and thereby enhancing PAN production, explaining the observed PM2.5-OVOC-PAN intercorrelation. In turn, parts of these OVOCs might participate in the formation of secondary organic aerosol, further aggravating haze pollution as a feedback. Low wintertime temperatures enable the long-range transport of PAN to downwind regions, and how that will impact their oxidation capacity and photochemical pollution requires further assessment in future studies.

Enhanced photocatalytic degradation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) by the addition of H2O2

Photocatalytic remediation technology has been shown to be a favorable approach for the removal of a range of environmental pollutants in water treatment. While this approach can often achieve complete degradation, often overlooked are reaction intermediates that are potentially as harmful as the original parent compound. In the case of photocatalytic oxidation of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA), we have recently shown that 4-chloro-2-methylphenol (CMP) is formed as the primary intermediate. To ensure the continued development of the technology, it is crucial to ensure the removal of both MCPA and CMP can be achieved by photocatalysis. Reported here is the enhanced photocatalytic removal and subsequent suppression of MCPA and CMP respectively, by the addition of small quantities of H2O2. While the addition of H2O2 often accelerates degradation rates (via increased OH radical production), it was found to restrict the formation of CMP in this study through competitive adsorption at the surface of TiO2. Based on the combination of MCPA removal coupled with supressed CMP formation, 0.5% H2O2 was determined to be an optimal loading for the process. Under these conditions 100% MCPA removal was achieved (to the limit of HPLC detection) after 45 min irradiation at a degradation rate of ∼1 mg L−1 min−1 (ƞphoton = 4.4), which also resulted in a ∼83% reduction in CMP formation when compared to a system with no H2O2 present.

An experimental and kinetic modeling study on the laminar burning velocity of NH3+N2O+air flames

In the present work, the laminar burning velocities of the NH3+N2O+air flames were measured using the heat flux method at 1 atm and 298 K, with varied equivalence ratios and N2O mixing ratios. For the mixing ratio N2O/(N2O+air) = 0.5, a full range of equivalence ratios was covered. Moreover, at three equivalence ratios an extended range of mixing ratios was investigated. The laminar burning velocity has an approximately linear relationship against the fraction of nitrous oxide in the oxidizer mixture, regardless of the tested equivalence ratios. Several recently published NH3 mechanisms were compared with these new experimental data; among them the models of Nakamura et al. and Stagni et al. show the best performance for NH3+N2O+air flames over the entire range of the mixing ratios. The H/N/O kinetic mechanism of the authors was analyzed and updated focusing on the rate constants of reactions most sensitive in ammonia flame propagation and self-ignition of NH3+O2 and H2+N2O mixtures. The choice of the new rate constants is outlined, however, no modification (adjustment or tuning) of the rate parameters to accommodate experimental results was attempted. The updated mechanism demonstrates significantly improved agreement with all measurements used for the model development and with other experimental data from the literature for ammonia flames and self-ignition. A comparative reaction path analysis for NH3+N2O+air and NH3+air flames revealed that an almost linear increase of the laminar burning velocity with an increased fraction of N2O in the oxidizer originates from the rate controlling reaction N2O+H = N2+OH, which produces OH radicals dominating ammonia oxidation.

Vertical distributions of wintertime atmospheric nitrogenous compounds and the corresponding OH radicals production in Leshan, southwest China

Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations were operated from 02 to 21 December 2018 in Leshan, southwest China, to measure HONO, NO2 and aerosol extinction vertical distributions, and these were the first MAX-DOAS measurement results in Sichuan Basin. During the measurement period, characteristic ranges for surface concentration were found to be 0.26–4.58 km−1 and averaged at 0.93 km−1 for aerosol extinction, 0.49 to 35.2 ppb and averaged at 4.57 ppb for NO2 and 0.03 to 7.38 ppb and averaged at 1.05 ppb for HONO. Moreover, vertical profiles of aerosol, NO2 and HONO were retrieved from MAX-DOAS measurements using the Heidelberg Profile (HEIPRO) algorithm. By analysing the vertical gradients of pollutants and meteorological information, we found that aerosol and HONO are strongly localised, while NO2 is mainly transmitted from the north direction (city center direction). Nitrogen oxides such as HONO and NO2 are important for the production of hydroxyl radical (OH) and oxidative capacity in the troposphere. In this study, the averaged value of OH production rate from HONO is about 0.63 ppb/hr and maximum value of ratio between OH production from HONO and from (HONO+O3) is > 93% before12:00 in Leshan. In addition, combustion emission contributes to 26% for the source of HONO in Leshan, and we found that more NO2 being converted to HONO under the conditions with high aerosol extinction coefficient and high relative humidity is also a dominant factor for the secondary produce of HONO.

The analysis of several types of catalysts for ozone decomposition

There has been rapid technological development in the aspect of water and wastewater treatment, including the application of ozone technology, commonly known as Advanced Oxidation Processes (AOPs). This involves the use of ozone gas converted to oxygen and OH● radicals, which possess the capacity to degrade the unwanted compounds present, although there is need for performance optimization to enhance the ease of formation and decomposition. This process is faced with serious problems that require immediate attention, particularly the presence of excess ozone, which is harmful to the health of living things, especially humans. Ozone decomposition uses an MnOx active core catalyst with a nominal loading of 0–2%. As a comparison used catalyst supports such as Zeolite Alam Lampung (ZAL), Granular Activated Carbon (GAC) and Green Sand (GS) with diameter 18–100 mesh. However, the challenge is comprehensively attenuated by using catalysts possessing the capacity to degrade the excesses, and promote procedure optimization, subsequently enhancing conversion and decomposition. Furthermore, previous studies have demonstrated the potential to elevate the production of OH radicals, and it was also established that catalysts from natural origin are less expensive, easy to operate, highly selective and difficult to damage under various conditions. The result of this study is GAC is more effective and efficient compared to others for decomposition.

From the accelerated production of •OH radicals to the crosslinking of polyvinyl alcohol: The role of free radicals initiated by persulfates

Persulfates are the concerned oxidants in the advanced oxidation processes recently. Besides, persulfates with higher concentrations can initiate the free radical crosslinking of the polymeric chain, which is considered as one of the solutions for the pollution control of soluble polymers. In this study, the combination of free radical crosslinking and oxidation initiated by a thermally activated persulfate system was used to simultaneously remove polyvinyl alcohol (PVA) and the coexisting organic pollutants, i.e. dyes. Especially, the catalyst-like function of PVA could accelerate the production of OH radicals via the elimination of −OH groups. It can promote the crosslinking itself and facilitate the degradation of coexisting pollutants. Given initial COD and PVA concentrations of 14406.0 mg/L and 8063.2 mg/L, respectively, a maximum of 93.6 % COD and 98.4 % PVA was removed under the optimal conditions. Meanwhile, the PVA with high concentration did not have negative effects on the degradation of coexisting pollutants.

Photocatalytic and antifouling properties of electrospun TiO2 polyacrylonitrile composite nanofibers under visible light

Polyacrylonitrile and its TiO2 composites were electrospun into nanofibers in N, N’-dimethylformamide for photocatalysis and antifouling experiments. The resultants nanofibers were characterized using field emission scanning microscope, Fourier transform infrared spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy and contact angle analyses. Fourier transform infrared spectroscopy confirmed the formation of polyacrylonitrile-TiO2 composite nanofibers with their diameter ranging from 10 to 340 nm. The x-ray photoelectron spectroscopy results indicate the formation of O–Ti–C bonds on polyacrylonitrile-TiO2 matrix. polyacrylonitrile-TiO2 and polyacrylonitrile nanofiber surfaces showed superhydrophobicity with water contact angle of 155 ± 1 and 154 ± 1, respectively at 120 s. The photocatalytic properties of polyacrylonitrile nanofibers and polyacrylonitrile-TiO2 nanofibers were investigated under a simulated visible light source of 1000 W/m2 using methylene blue. About 90% of methylene blue was degraded within 3 h of exposure using polyacrylonitrile-TiO2 nanofibers while 55% methylene blue degradation was achieved for polyacrylonitrile nanofibers. Photoluminescence experiment conducted on both materials showed that polyacrylonitrile-TiO2 could produce OH radicals 10-fold compared to polyacrylonitrile nanofibers. Antimicrobial tests were conducted using E. coli and Bacillus sp. The results showed that only polyacrylonitrile-TiO2 under visible light hindered the growth of these bacteria with a greater effect on the Gram-positive bacterium, Bacillus sp. The photo-degradation and microbial growth inhibition properties of polyacrylonitrile-TiO2 showed that the material could be used as an antifouling material under visible light.

Anchoring of premixed jet flames in vitiated crossflow with pulsed nanosecond spark discharge

This paper deals with the effect of non-equilibrium plasma on the anchoring of a premixed jet flame in hot vitiated crossflow at atmospheric pressure. The turbulent vitiated crossflow was generated by an array of 4×4 premixed turbulent jet flames burning a lean mixture of air and natural gas at an equivalence ratio of 0.7 and a thermal power of 50 kW. The rich jet, with equivalence ratio ϕjet varied between 1 and 3, was injected perpendicularly to the vitiated crossflow in a rectangular duct, with jet-to-crossflow momentum flux ratios J ranging from 1 to 26. A nanosecond repetitively pulsed discharge was initiated in the vicinity of the windward side of the jet root. The effect of discharge power and repetition rate on the lift-off height of the flame is systematically analyzed for different combinations of ϕjet and J. High speed chemiluminescence imaging of the flame and of the discharge shows that the initiation of the discharge on the windward side of the jet enhances the combustion chemistry, reducing the ignition time and the lift-off height of the flame. It is shown that the nanosecond repetitively pulsed discharges are able to maintain a robust anchoring of the flame for a wide range of operating conditions at relatively low electric power cost. Emission spectroscopy and OH-PLIF measurements were carried out to show that the plasma has both thermal and kinetic effects on flame anchoring respectively via intense localized heating of the mixture at temperatures exceeding 3000 K and via an intense production of OH radicals.