Discharge Plasma Oxidation Research Articles

Degradation of methyl orange using hydrodynamic cavitation coupled with plasma oxidation and ultraviolet C

Combining multiple advanced oxidation processes (AOPs) is essential for the efficient treatment of dye wastewater. In this study, the degradation efficiencies of various oxidation methods, including hydrodynamic cavitation (HC), dielectric barrier discharge (DBD) plasma oxidation, ultraviolet C (UVC), and their combination HC + DBD + UVC, were investigated for Methyl Orange (MO). The photolysis of ozone (O3) and the degradation mechanism associated with HC + DBD + UVC were analyzed to elucidate the pathway of MO degradation. The results demonstrated that the combination of HC + DBD + UVC exhibited a significantly enhanced degradation efficiency compared to other process combinations, achieving a removal efficiency exceeding 91% within a 5-min timeframe. Optimal parameters for achieving a 99.5% degradation rate of 10 mg/L MO were determined as follows: pH 4, inlet pressure of 1.5 MPa, utilization of eight UV lamps with a power input of 46.11 W. During the degradation process, hydroxyl radicals (·OH) and ozone (O3) played crucial roles, while the incorporation of UV lamps effectively mitigated ozone (O3) emissions and enhanced the oxidation of ozone (O3). In conjunction with the analysis of degradation products using liquid chromatography-mass spectrometry, it is highly probable that the MO degradation pathway involves reductive cleavage of the azo bond through ·OH attack. Compared to other experimental methods in literature, HC + DBD + UVC exhibits significant advantages such as enhanced efficiency and absence of additives. This innovative approach offers a rapid and practical on-site solution for efficient MO dye wastewater treatment.

Distribution and dynamics of antibiotic resistance genes in sludge under discharge plasma oxidation

Antibiotic resistance genes (ARGs), emerging environmental contaminants, have been largely accumulated in sludge during wastewater treatment. Discharge plasma oxidation, an advanced oxidation technology, has been demonstrated as an effective strategy in sludge pretreatment. However, the effect of plasma oxidation on the distribution and dynamics of ARGs in sludge is unknown. Herein, the variations of four typical ARGs (tetC, tetW, blaTEM-1, aac(3)-Ⅱ) and one integron (intI-1) in sludge during discharge plasma treatment were investigated. The results showed that under low discharge voltage or short treatment time, weak plasma oxidation enriched the contents of ARGs and intI-1 in sludge (with 1.14 log unit maximum increment) via proliferating biomass or promoting horizontal gene transfer. Further increasing discharge voltage or prolonging treatment time, strong plasma oxidation eliminated target genes due to the destroyed bacteria or inhibited horizontal transfer of ARGs. Especially, the homogeneous condition greatly promoted the reduction of ARGs in liquid phase (up to 1.52 log unit reduction). Furthermore, the correlation analysis between intI-1 and ARGs implied that tetC and tetW abundances might be significantly affected by intI-1 through horizontal transfer. At the same time, the microbial communities in sludge were investigated to help understand the effect of plasma oxidation on ARGs variation. Notably, the most predominant phylum Proteobacteria and genus Acinetobacter resisted the oxidative infringement from plasma to maintain high relative abundances (52.05 % in solid phase and 84.10 % in liquid phase for Proteobacteria, 13.82 % in solid phase and 78.00 % in liquid phase for Acinetobacter at 20 kV). Meanwhile, the co-occurrence analysis between genes and dominant genera further showed that Romboutsia sp. might be a potential host bacteria of ARGs and intI-1 in solid phase, and Acidovorax sp., Parachlamydia sp., and Armatimonadetes_gp5 sp. might be the potential hosts of tetW, tetC, and intI-1 in liquid phase.

Excess Sludge Disintegration by Discharge Plasma Coupled with Thiosulfate

Surplus sludge disposal and treatment are major issues in wastewater treatment plants. Discharge plasma oxidation is an effective approach for sludge dewatering and digestion. In this study, excess sludge disintegration by non-thermal discharge plasma coupled with thiosulfate (TSA) was investigated. After 20 min of the single discharge plasma treatment, the soluble chemical oxygen demand (SCOD) increased to 404.93 mg L−1, and it climbed even more to 549.08 mg L−1 after adding 15 mmol L−1 of TSA. The water content of the filter cake also reduced even more in the presence of TSA. There was an appropriate dosage of TSA available. In the discharge plasma coupled with TSA system, reactive oxygen species (·OH and O2−) were generated and had significant involvement in the disintegration of the sludge. The addition of TSA enhanced the production of OH. These reactive oxygen species decomposed the floc structures and facilitated the transformation of organic compounds, resulting in a decrease in the average size of the sludge aggregates. The ratio of soluble extracellular polymer substances (S-EPS) was enhanced, while the ratio of the tightly bound fraction was reduced after the treatment. Thus, discharge plasma coupled with TSA promoted microbial cell lysis and facilitated the release of intracellular organic matter and bound water, ultimately enhancing the sludge’s dewaterability.

Cascade N2 Reduction Process with DBD Plasma Oxidation and Electrocatalytic Reduction for Continuous Ammonia Synthesis.

Due to the extremely high bond energy of N≡N (∼941 kJ/mol), the traditional Haber-Bosch process of ammonia synthesis is known as an energy-intensive and high CO2-emission industry. In this paper, a cascade N2 reduction process with dielectric barrier discharge (DBD) plasma oxidation and electrocatalytic reduction as an alternative route is first proposed. N2 is oxidized to be reactive nitrogen species (RNS) by nonthermal plasma, which would then be absorbed by KOH solution and electroreduced to NH4+. It is found that the production of NOx is a function of discharge length, discharge power, and gas flow rate. Afterward, the cobalt catalyst is used in the process of electrocatalytic reduction of ammonia, which shows high selectivity (Faradic efficiency (FE) above 90%) and high yield of ammonia (45.45 mg/h). Finally, the cascade plasma oxidation and electrocatalytic reduction for ammonia synthesis is performed. Also, the performance of the reaction system is evaluated. It is worth mentioning that a stable and sustainable ammonia production efficiency of 16.21 mg/h is achieved, and 22.16% of NOx obtained by air activation is converted into NH4+. This work provides a demonstration for further industrial application of ammonia production with DBD plasma oxidation and electrocatalytic reduction techniques.

Degradation of atrazine in river sediment by dielectric barrier discharge plasma (DBDP) combined with a persulfate (PS) oxidation system: response surface methodology, degradation mechanisms, and pathways.

Single degradation systems based on dielectric barrier discharge plasma (DBDP) or persulfate (PS) oxidation cannot achieve the desired goals (high degradation efficiency, high mineralization rate, and low product toxicity) of degrading atrazine (ATZ) in river sediment. In this study, DBDP was combined with a PS oxidation system (DBDP/PS synergistic system) to degrade ATZ in river sediment. A Box-Behnken design (BBD) including five factors (discharge voltage, air flow, initial concentration, oxidizer dose, and activator dose) and three levels (- 1, 0, and 1) was established to test a mathematical model by response surface methodology (RSM). The results confirmed that the degradation efficiency of ATZ in river sediment was 96.5% in the DBDP/PS synergistic system after 10min of degradation. The experimental total organic carbon (TOC) removal efficiency results indicated that 85.3% of ATZ is mineralized into CO2, H2O, and NH4+, which effectively reduces the possible biological toxicity of the intermediate products. Active species (sulfate (SO4•-), hydroxy (•OH), and superoxide (•O2-) radicals) were found to exert positive effects in the DBDP/PS synergistic system and illustrated the degradation mechanism of ATZ. The ATZ degradation pathway, composed of 7 main intermediates, was clarified by Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS). This study indicates that the DBDP/PS synergistic system is a highly efficient, environmentally friendly, novel method for the remediation of river sediment containing ATZ pollution.

Microstructure, Micro-Mechanical and Tribocorrosion Behavior of Oxygen Hardened Ti-13Nb-13Zr Alloy.

In the present work, an oxygen hardening of near-β phase Ti–13Nb–13Zr alloy in plasma glow discharge at 700–1000 °C was studied. The influence of the surface treatment on the alloy microstructure, tribological and micromechanical properties, and corrosion resistance is presented. A strong influence of the treatment on the hardened zone thickness, refinement of the α’ laths and grain size of the bulk alloy were found. The outer hardened zone contained mainly an oxygen-rich Ti α’ (O) solid solution. The microhardness and elastic modulus of the hardened zone decreased with increasing hardening temperature. The hardened zone thickness, size of the α’ laths, and grain size of the bulk alloy increased with increasing treatment temperature. The wear resistance of the alloy oxygen-hardened at 1000 °C was about two hundred times, and at 700 °C, even five hundred times greater than that of the base alloy. Oxygen hardening also slightly improved the corrosion resistance. Tribocorrosion tests revealed that the alloy hardened at 700 °C was wear-resistant in a corrosive environment, and when the friction process was completed, the passive film was quickly restored. The results show that glow discharge plasma oxidation is a simple and effective method to enhance the micromechanical and tribological performance of the Ti–13Nb–13Zr alloy.

Formation of Nitrogen Doped Titanium Dioxide Surface Layer on NiTi Shape Memory Alloy.

NiTi shape memory alloys are increasingly being used as bone and cardiac implants. The oxide layer of nanometric thickness spontaneously formed on their surface does not sufficiently protect from nickel transition into surrounding tissues, and its presence, even in a small amount, can be harmful to the human organism. In order to limit this disadvantageous phenomenon, there are several surface engineering techniques used, including oxidation methods. Due to the usually complex shapes of implants, one of the most prospective methods is low-temperature plasma oxidation. This article presents the role of cathode sputtering in the formation of a titanium dioxide surface layer, specifically rutile. The surface of the NiTi shape memory alloy was modified using low-temperature glow discharge plasma oxidation processes, which were carried out in two variants: oxidation using an argon + oxygen (80% vol.) reactive atmosphere and the less chemically active argon + air (80% vol.), but with a preliminary cathode sputtering process in the Ar + N2 (1:1) plasma. This paper presents the structure (STEM), chemical composition (EDS, SIMS), surface topography (optical profilometer, Atomic Force Microscopy—AFM) and antibacterial properties of nanocrystalline TiO2 diffusive surface layers. It is shown that prior cathodic sputtering in argon-nitrogen plasma almost doubled the thickness of the produced nitrogen-doped titanium dioxide layers despite using air instead of oxygen. The (TiOxNy)2 diffusive surface layer showed a high level of resistance to E. coli colonization in comparison with NiTi, which indicates the possibility of using this surface layer in the modification of NiTi implants’ properties.

Excess sludge disintegration by discharge plasma oxidation: Efficiency and underlying mechanisms

A huge amount of excess sludge is inevitably produced in wastewater treatment, and it is becoming more and more urgent to realize efficient sludge reduction. Discharge plasma oxidation was used to efficiently disintegrate excess sludge for sludge reduction in this study. Approximately 18.22% sludge disintegration and 27.8% reduction of total suspended solids (TSS) were achieved by discharge plasma treatment. The water content of the filter cake decreased from 81.9% to 76.0% and the bound water content decreased from 2.66 g/g dry solid to 0.73 g/g dry solid after treatment. The large quantities of reactive oxygen species (ROS) generated by discharge plasma played important roles in sludge disintegration by destroying flocs and promoting the transformation of organic substances. Concurrent cell lysis induced by ROS oxidation released intracellular organics and water into the liquid phase. The fraction of soluble extracellular polymer substances (S-EPS) was enhanced from 16.10% to 58.51%, whereas the tightly bound fraction was reduced from 70.62% to 28.91%. Migration and decomposition of EPS were the main processes for EPS changing at a low oxidation capacity, whereas cell lysis became important at a high oxidation capacity. In summary, the plasma treatment effectively improved sludge disintegration.

Insights into the highly efficient detoxification of the biotoxin patulin in water by discharge plasma oxidation

Patulin is a neurotoxic secondary metabolite and is widely present in fruit-based products and even in drinking water. The low-temperature discharge plasma approach was developed to detoxify patulin in water. Patulin decomposition and mineralization efficiencies reached 93% and 74% at an applied voltage of 16 kV in a 30 min treatment period, respectively. 1O2, OH, O2−, and hydrated electrons generated in the discharge plasma process contributed to patulin decomposition. The lactone and hemiacetal groups that are responsible for the toxicity of patulin were significantly destroyed by discharge plasma oxidation, and some ring-opening intermediates, such as ethers, organic acids, and alcohols, were generated. Patulin decomposition pathways in this low-temperature discharge plasma process were then proposed. Model prediction indicated that acute oral toxicity in rats and developmental toxicity decreased after discharge plasma treatment, which was verified by actual cytotoxicity tests using yeast cells and HepG2 human hepatocellular carcinoma cells.

Decontamination of heavy metal complexes by advanced oxidation processes: A review

Heavy metal complexes with high mobility are widely distributed in wastewater from modern industries, which are more stable and refractory than free heavy metal ions. Their removals from wastewater draw increasing attentions and various technologies have been developed, among which advanced oxidation processes (AOPs) are more effectively and promising. Progresses on five representative types of AOPs, including Fenton (like) oxidation, electrochemical oxidation, photocatalytic oxidation, ozonation and discharge plasma oxidation for heavy metal complexes degradation are summarized in this review. Their rationales, advantages, applications, challenges and prospects are introduced independently. Combinations among these AOPs, such as electrochemical Fenton oxidation and photoelectrocatalytic oxidation, are also comprehensively highlighted. Future efforts should be made to reduce acid requirement and scale up for practical applications of AOPs for heavy metal complex degradation efficiently and cost-effectively.

Investigation of friction and wear performance on oxidized Ti6Al4V alloy at different temperatures by plasma oxidation method under ambient air and vacuum conditions

The Ti6Al4V alloy has a series of advantages such as low density, corrosion resistance and high strength. Along with these advantages, the low wear resistance of the Ti6Al4V alloy prevents its wide application in the industry. Ti6Al4V alloy is also frequently used in the aerospace industry. Thus, the wear resistance under vacuum condition is as important as the wear resistance under ambient air. In this study, it is investigated that the wear resistance of the Ti6Al4V alloy improved by glow discharge plasma oxidation at 3 different temperatures. The characterization of the formed oxide layers is determined by the Vickers micro-hardness tester, scanning electric microscope, 3D profilometer, energy distributor X-ray spectrometer, atomic force microscope and X-ray diffractometer. The wear resistance of the untreated and plasma oxidized samples are tested under 1 and 2 N constant normal load under ambient air and vacuum conditions. It has been determined that in the both wear conditions, oxidized samples have lower wear rates than untreated samples. The best wear resistance in both wear conditions is obtained in the sample with the highest hardness value. In addition, it has been determined that the wear resistance under vacuum condition is higher than the ambient air.

Probing the aging processes and mechanisms of microplastic under simulated multiple actions generated by discharge plasma

Microplastics (MPs) are becoming one class of pollutants with high global concerns. Information regarding aging behaviors of MPs in complicated natural conditions is still lacking due to the very slow aging processes. In this study, discharge plasma oxidation was applied to simulate the various radical oxidation and physical effects naturally occurring in the environment to shed light on the aging behaviors and mechanisms of MPs, with polyvinyl chloride microplastic (PVC-MP) as a model. The surface morphology, particle size, specific surface area, crystallinity, and chemical compositions of PVC-MP were comprehensively characterized as a result of aging. The aging degree indicated by carbonyl index and oxygen-to-carbon ratio increased with the plasma oxidation intensity and duration. The aged PVC-MP was characterized as more O-containing functional groups, smaller particle size, larger specific surface area, higher hydrophilicity, and higher crystallinity. Consequently, the aged PVC-MP provided more sites for adsorption of tetrabromobisphenol (TBBPA) in solutions by forming hydrogen-bonds, and electrostatic force. The changes in the properties of the aged PVC-MP, and the strong adsorption with TBBPA led to unexpected synergistic toxic effects to Scenedesmus obliquus. The results provide direct evidences of aging processes of MPs and the potential environmental risks due to aging in the environment.

Efficient degradation of antibiotics by non-thermal discharge plasma: Highlight the impacts of molecular structures and degradation pathways

Pollution of antibiotics in water has aroused global concerns. In this study, non-thermal discharge plasma oxidation was applied to eliminate three antibiotics with different substituent groups and chemical properties, tetracycline (TC), sulfadiazine (SD), and ciprofloxacin (CIP). All the three antibiotics could be effectively degraded but with different reaction kinetics, and the reaction rate of TC was always the highest, followed by SD and CIP. Reactive oxygen species (ROS) including O2−, 1O2, and OH all contributed to the removal of the three antibiotics. The theoretically calculation using Gaussian with DFT indicated that the ionization potential (IP) of the three antibiotics was in the order of TC < SD < CIP. Since the compounds with lower IP values were more vulnerable to ROS attack, the lowest IP of TC suggested that it was the easiest to be degraded among the three target compounds. In addition, the Gaussian calculations predicted that the chemical bonds with low energies were susceptible for oxidation. Integrating the results of theoretical calculation and those of UV–vis spectra, three-dimensional fluorescence spectroscopy, gas chromatography-mass spectrometry and ion chromatography, the degradation pathways of the three antibiotics were figured out, mainly including hydroxylation, decarboxylation, dealkylation, and ring-opening reactions. The results provide clues to predict the potentials and pathways of oxidative degradation of antibiotics in water.

The Effect of Anodization and Glow Discharge Plasma Oxidation Surface Treatments on the Wear Resistance of Ti6Al4V Alloy

Günümüzde titanyum ve alaşımları yüksek biyouyumluluk ve düşük elastisite modülüne sahip olmaları nedeniyle çeşitli implantların üretiminde kullanılmaktadır. Titanyum ve alaşımlarının dezavantajlarından biri, yüksek sürtünme katsayısı ve düşük aşınma dayanımına sahip olmalarıdır. Bu dezavantajı gidermek için titanyum ve alaşımlarının yüzeylerine bir takım işlemler uygulanarak başta aşınma direnci olmak üzere yüzey özelliklerinin iyileşmesi sağlanabilmektedir. Bu çalışmada, yük taşıyan implant üretiminde kullanılan Ti6Al4V (Grade 5) taban malzemesi plazma oksitleme ve anodik oksitleme (anodizasyon) işlemlerine tabi tutulmuştur. İki farklı oksitleme işleminden elde edilen yüzeyler sertlik, yüzey pürüzlülüğü, ıslanabilirlik ve aşınma direnci açısından işlemsiz malzeme ile karşılaştırılmıştır. Bu testlerin gerçekleştirilmesi için XRD, SEM, AFM, Mikro sertlik cihazı, Temas açısı ölçüm cihazı ve Doğrusal aşınma cihazı kullanılmıştır. Çalışma sonucunda sertlik değeri işlemsiz malzemeye göre plazma oksitleme için %116 ve anodik oksitleme için %36 artış göstermiştir. Yüzey pürüzlülüğü incelendiğinde, plazma oksitleme işleminin yüzey pürüzlülüğünde %11 artış ve anodik oksitleme işleminin %33 düşüşe sebep olduğu görülmüştür. Temas açısı değerleri işlemsiz malzeme için 48,31° iken plazma oksitleme işlemi sonrası 73,34° ve anodik oksitleme işlemi sonrası 85,36° olmuştur. Ayrıca her iki oksitleme işlemi sonrası işlemsiz malzemeye nazaran tribolojik özelliklerin iyileştiği gözlemlenmiştir.

Novel Cu(II)-EDTA Decomplexation by Discharge Plasma Oxidation and Coupled Cu Removal by Alkaline Precipitation: Underneath Mechanisms.

Strong complexation between heavy metals and organic complexing agents makes the heavy metals difficult to be removed by classical chemical precipitation. In this study, a novel decomplexation method was developed using discharge plasma oxidation, which was followed by alkaline precipitation to treat water containing heavy metal-organic complex, that is, Cu-ethylenediaminetetraacetic acid (Cu-EDTA). The decomplexation efficiency of Cu complex reached up to nearly 100% after 60 min's oxidation by discharge plasma, which was accompanied by 82.1% of total organic carbon removal and energy efficiency of 0.62 g kWh-1. Presence of free Cu2+ favored Cu-EDTA decomplexation, whereas the presence of excessive EDTA depressed this process. Cu-EDTA decomplexation was mainly driven by the produced 1O2, O2•-, O3, and •OH by discharge plasma. Cu-EDTA decomplexation process was characterized by UV-vis, ATR-FTIR, total organic carbon, and three-dimensional fluorescence diagnosis. The main intermediates including Cu-EDDA, Cu-IDA, Cu-NTA, small organic acids, NH4+, and NO3- were identified, accompanied by Cu2+ releasing. The followed precipitation process removed 78.1% of Cu2+, and Cu-associated precipitates included CuCO3, Cu2CO3(OH)2, CuO, and Cu(OH)2. A possible pathway of Cu complex decomplexation and Cu2+ removal in such a system was proposed.

Photosensitive MIS structures with ultrathin dielectric based on CdXHg1‐XTe (x ∼ 0.4)

AbstractThe work is aimed to studying a possibility of CdHgTe surface passivation and stabilization by tunnel‐thin (∼ 2 nm) native oxide formed by glow discharge plasma oxidation. Kinetics of MCT plasma treatment in two regimes has been obtained. Investigation of the stabilization effect during vacuum annealing and platinum deposition has been performed. It has been established that presence of a native oxide layer on MCT surface results in elimination of mercury out diffusion during the processes. MIS structures with platinum contacts and thin native oxide have been made. They have rectifying behaviour in contrast with structures without the native oxide layer. The barrier height and the detectivity have been determined from the capacitance‐voltage and current‐voltage dependences. The detectivity value of 4×1011cm.Hz1/2W‐1 (at 78 K) determined by dark current shot noise has been reached. (© 2016 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Distinguish the Role of DBD-Accompanying UV-Radiation in the Degradation of Bisphenol A

Discharge plasma oxidation has been widely applied in treatment of organic pollutants including bisphenol A (BPA). However, the conventionally accepted mechanism of BPA degradation is mainly ascribed to oxidation by the active species produced from discharge plasma. Ultraviolet (UV) radiation as one source of plasma discharge energy release is intrinsically accompanied with plasma discharge, yet its role in degradation of BPA has not been explicitly identified. In present study, the light emission from the dielectric barrier discharge (DBD) at spectral region 190–620 nm for different working discharge gases was determined and the role of the UV radiation in the degradation of BPA was carefully scrutinized. It was confirmed for the first time that in the DBD treatment of BPA, the UV radiation accompanied with the plasma discharge could work together with hydrogen peroxide generated from the plasma discharge so that the efficiency of BPA degradation could be improved remarkably.

Comparative analysis of insulating properties of plasma and thermally grown alumina films on electrospark aluminide coated 9Cr steels

Iron aluminides with a protective alumina layer are considered candidate coating for test blanket modules of fusion reactor. In order to study the properties of plasma grown alumina in comparison with thermally grown alumina, oxidation studies on electro spark deposited (ESD) FeAl coating have been conducted. Glow discharge plasma oxidation has been adopted as plasma oxidation technique. Reduced activation 9Cr steel samples were coated with a coating of iron aluminide (FeAl) layer containing 45at% Al. The ESD coated 9Cr steels were oxidized in air and plasma environments at 750°C for 48h. Resultant surfaces were studied using X-ray diffraction, electron probe microanalysis, SEM and electrochemical impedance spectroscopy (EIS) techniques. Although the presence of Al2O3 was found on both thermally oxidized and plasma oxidized samples, the EIS studies clearly revealed improved dielectric properties of plasma grown Al2O3. The plasma grown oxide thin films seems a promising approach to apply alumina coatings with improved dielectric properties onto fusion reactor materials.

Deep oxidative desulfurization of model fuel via dielectric barrier discharge plasma oxidation using MnO2 catalysts and combination of ionic liquid extraction

This paper developed a novel oxidative desulfurization (ODS) technique via dielectric barrier discharge plasma oxidation using MnO2 catalysts and a combination of ionic liquid [BMIM]CH3COO extraction. MnO2 catalysts were synthesized using hydrothermal synthesis and characterized using various analytical techniques. Their ODS performances were investigated. The results indicated that MnO2 catalysts could effectively improve the performance of the desulfurization system. Under optimized technical conditions, the sulfur removal of thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in n-octane reached 99.9%, 99.9%, 97.9%, and 90.7%, respectively. The oxidation activities of the four sulfur compounds decreased in the order of TS>BT>DBT>4,6-DMDBT.

Degradation of microcystin-LR in water by glow discharge plasma oxidation at the gas–solution interface and its safety evaluation

Microcystin-LR (MC-LR) is one of the most commonly found microcystins (MCs) in fresh water and it poses danger to human health due to its potential hepatotoxicity. In the present study, we employed a novel method by using discharge plasma taking place at the gas–solution interface in gas atmosphere to degrade MC-LR in aqueous solution. The initial degradation rate of MC-LR was fastest under acidic conditions (5.41 ± 0.17 × 10−3 mM min−1 at pH 3.04) and decreased to 2.22 ± 0.11 × 10−3 mM min−1 and 0.912 ± 0.02 × 10−3 mM min−1 at pH 4.99 and 7.02, respectively. The effects of total soluble nitrogen (TN), total soluble phosphorus (TP) and natural organic matter (NOM) on the degradation efficiency were studied. The degradation rate was remarkably affected by TP and TN. Mass spectrometry was applied to identify the products of the reactions. Major degradation pathways are proposed according to the results of liquid chromatography/mass spectrometry (LC/MS) results. It suggests that the degradation of MC-LR is initiated via the attack of hydroxyl radicals on the conjugated carbon double bonds of Adda and on the benzene ring of Adda. Finally, the toxicity of intermediates or end-products from MC-LR degraded by this method was assessed using Caenorhabditis elegans. Our findings demonstrates that discharge plasma oxidation is a promising technology for degradation and removal of MC-LR and it may lead us to a new route to efficient treatment of other cyanotoxins from aqueous solutions.