•A gliding arc plasma reactor driven by high frequency AC power is proposed.•Breakdowns occurred hundreds of times within a gliding period in HFAC GAD.•The electrode thickness showed a strong effect on the discharge stability.•The highest conversion rate of the reactants was achieved at 1.65 mmol/L.In this work, a knife-shaped gliding arc discharge (GAD) reactor driven by high frequency AC (HFAC) power was employed to convert CO2 and CH4. The HFAC GAD exhibited good performance in dry reformation of CO2CH4. The development process with the HFAC GAD at a low gas flow rate was recorded and it is discussed with U-I waveforms and discharge images. The effects of input voltage, total gas flow rate, minimum electrode gap distance, and electrode thickness were investigated in terms of the CO2CH4 conversion rate, selectivity of CO, H2, and C2 hydrocarbons, specific energy density, and energy efficiency. The energy efficiency ranged from 1.58 to 2.21 mmol/kJ under changing operating conditions. The best conversions of CO2 and CH4 were achieved as 52.32% and 58.85%, respectively, with an energy efficiency of 1.65 mmol/kJ.

•WO3@g-C3N4 photocatalysts with core@shell nanostructure were fabricated.•The WO3@g-C3N4 has much higher photocatalytic activity than that of pure ones.•The core@shell nanostructure greatly enlarges the heterojunction interfacial area.•Heterojunction could efficiently reduce the recombination of electron-hole pairs.WO3@g-C3N4 composite photocatalysts with core@shell nanostructure were fabricated via a self-assembly method. A large heterojunction interfacial area of WO3@g-C3N4 can be provided in the nanoscale heterostructure. Furthermore, the electron mobility of the composite photocatalysts was improved with the introduction of WO3. These are favorable for increasing the separation efficiency of photoinduced electron-hole pairs and improving the photocatalytic efficiency of WO3@g-C3N4, which was confirmed by the measurements of photocurrent and electrochemical impedance spectroscopy. The results of the photocatalytic degradation of Rh B showed dramatic photocatalytic performance of this composite photocatalyst. The kinetic constant of Rh B degradation on the WO3@g-C3N4 was 0.95 h−1, which was 7.7-fold and 3.5-fold higher than those on pure WO3 and g-C3N4 nanosheets, respectively. In addition, the stability of the composite photocatalyst was also satisfactory according to the result of the three-cycle experiment.

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic organic pollutants of great environmental and health concern. PAHs are very persisted in soils and sediments which make it very difficult to remove them from soil. Therefore, remediation of PAH-contaminated sites has become an important environmental issue. The objective of this work was to study PAH degradation by pulsed corona discharge plasma system.Phenanthrene (Phe) was used as the model pollutant. The Phe-contaminated soil samples were prepared by adding appropriate amount of Phe dichlormethane solution (200 mg/L) into a given amount of pretreated soil, and Phe distributed uniformly in the soil at about 100 mg/kg. The experimental system mainly consisted of a pulse high-voltage power supply and a reactor vessel. The high-voltage electrode comprised of six stainless-steel needles and the ground electrode was a stainless-steel plate. The concentration of Phe was determined by HPLC system after being extracted out from soil. Effect of run parameters such as pulse voltage, pulse frequency, air flow rate, gas atmosphere, and initial concentration of Phe on Phe degradation was investigated, and the consumption of ozone during discharge process was also studied.The results showed that degradation efficiency of Phe (initial concentration 100 mg/kg) approached approximately 70 % after 40 min of discharge treatment under the conditions of pulse voltage 18 kV, pulse frequency 70 Hz, and air flow rate 0.8 L/min, which increased with the pulse voltage and pulse frequency due to the enhancement of input energy. An optimal air flow rate of 0.8 L/min was observed to obtain a maximum Phe degradation efficiency. Oxygen atmosphere favored Phe degradation due to high concentration of generated O-reagents, and ozone was found to act on Phe degradation. The concentration of Phe had influence on remediation capacity that increased with the amount of Phe in soil.The results confirmed that pulsed corona-discharge plasma was a potential method for remediation of PAH-contaminated soil. This study offered a viable treatment option for remediation of Phe-contaminated soil, which was expected to remove PAHs other than Phe from soil with further development.

•Phe in soil was removed by discharge plasma with γ-Al2O3-supported catalyst.•Energy efficiency increased with catalyst dosage.•Catalysts kept stable activity after five times reuse cycle.•Discharge plasma had less effect on physicochemical properties of catalysts.Removal of polycyclic aromatic hydrocarbon (PAH) in soil by pulsed corona discharge plasma with γ-Al2O3-supported catalysts was studied at normal temperature and atmospheric pressure. Phenanthrene (Phe) was used as the model pollutant. Spontaneous CuO/γ-Al2O3, MnO2/γ-Al2O3, Fe2O3/γ-Al2O3 or TiO2/γ-Al2O3 was added into plasma system. Phe removal, energy efficiency and catalytic property were investigated. The results showed that prepared γ-Al2O3-supported catalysts all exhibited catalytic effects on Phe removal from soil. Removal efficiencies of Phe were improved by 14.1%, 21.4%, 16.5% and 9.1% in 40 min at 5 wt% amount of CuO/γ-Al2O3, MnO2/γ-Al2O3, Fe2O3/γ-Al2O3 and TiO2/γ-Al2O3, respectively. The energy efficiency increased when pulsed corona discharge plasma was combined with catalysts. As each catalyst dosage was increased from 5 wt% to 23 wt%, the energy efficiency of the reactor with discharge alone was further increased by approximately 20%–40%. Furthermore, the catalysts kept stable activity in Phe removal after five times reuse cycle. Effect of pulsed corona discharge plasma on physicochemical properties of catalysts were evaluated through XRD and BET characterization. This study implied a promising combined-application of γ-Al2O3-supported catalysts and pulsed corona discharge plasma for the removal of PAH in soil.

The remediation of dye-contaminated soil using silent discharge plasma in dielectric barrier discharge (DBD) reactor was reported in this study. Acid scarlet GR was selected as the representative of azo dye pollutants. Effects of applied voltage, discharge frequency, and gas flow rate on Acid scarlet GR treatment effect which were characterized by degradation efficiency and the change of chemical oxygen demand (COD) during the degradation were investigated. The decolorization rate of Acid scarlet GR in the soil increased with the applied voltage and discharge frequency, and the optimal gas flow rate was obtained at 1.0 L min−1. The energy efficiency was clearly enhanced by way of increasing the amount of contaminated soil in the DBD reactor finitely. The degradation efficiency of Acid scarlet GR and the removal of COD value were achieved 93 % and 74 % after 25-min discharge treatment, respectively. The results indicated that the DBD remediation system was able to degrade Acid scarlet GR in the soil quickly and efficiently. This study is expected to provide a possible pathway of Acid scarlet GR degradation in soil.