An insightful analysis of dimethyl phthalate degradation by the collaborative process of DBD plasma and Graphene-WO3 nanocomposites.

In this paper, the prepared graphene-WO3 nanocomposites (rGO-WO3) were added into a dielectric barrier discharge (DBD) plasma system with spiral discharge electrode to set up a collaborative process to treat the dimethyl phthalate (DMP) in water. Degradation of the DMP under different experimental conditions were studied to illustrate the catalysis of the rGO-WO3 in the DBD plasma system. The obtained results proved that there was the catalysis of the rGO-WO3 for the DMP degradation within the studied DMP concentration, solution initial pH values and conductivities. From the results of the energy utilization efficiency (G50) analysis, the catalysis was more apparent in the case of the oxygen bubbling system than that in the nitrogen or the air bubbling system, which was due to the higher oxygen constitution in the oxygen bubbling system. The reduction of the measured liquid phase ozone concentrations in the DBD/rGO-WO3 system bubbled with air as well as oxygen than those measured in the sole DBD system, which verified the consumption of the ozone by the catalysis of the rGO-WO3. Furthermore, the UV-Vis and the three-dimensional fluorescence spectra analysis were also carried out to state the catalytic effect of the rGO-WO3 for the DMP degradation. Toxicity analysis for the degradation byproducts confirmed the collaborative process could reduce the negative effect of the original DMP on the environment.

Dielectric barrier discharge plasma coupled with WO3 for bisphenol A degradation.

Based on the difficulty of the refractory organic compounds degradation in water by the traditional wastewater treatment methods, the research relies on the technology of the dielectric barrier discharge plasma (DBDP) and the catalysis of the nano WO3, investigating the bisphenol A (BPA) degradation in the synergistic system of DBDP/WO3. The coupled degradation percentage of the BPA under different amounts of WO3 addition, different initial solution pH and carrier gas were investigated to confirm the catalysis of the WO3 in the DBDP system. It was obtained from the experimental results that the optimal additive amount of the WO3 was 175 mg L-1 and change of the solution pH value and the carrier gas variety could not change the catalysis of the WO3. The BPA degradation percentage could reach 100% after treating 30 min in the DBDP/WO3 system with 0.5 L min-1 O2 as the carrier gas. The WO3 still had a better catalysis after four times usage and the discharge had little effect on the microstructure of the WO3. The existence of the WO3 in the DBDP system could result in the reduction of the O3 concentration and the enhancement of the H2O2 concentration, which improve the catalysis of the WO3 in the DBDP system, while the experiments on the scavengers' addition verified the major role of the OH on the BPA degradation. The catalytic mechanism of the WO3 as well as the BPA degradation pathway was also speculated in the research.

Catalysis of rGO-WO3 nanocomposite for aqueous bisphenol A degradation in dielectric barrier discharge plasma oxidation process.

Due to the multi-catalysis of the WO3 and excellent properties of the graphene (GO), a series of rGO-WO3 nanocomposites were prepared through the hydrothermal synthesis procedure by changing the material ratio, the reaction temperature and the reaction time in this paper, and then added it into a dielectric barrier discharge plasma (DBDP) system for investigating the bisphenol A (BPA)'s degradation and corresponding catalytic mechanism of the rGO-WO3 in the DBDP system. The obtained results show that there was an optimum dosage of the rGO-WO3 (40 mg/L) as well as the preparation conditions (5:1000 mass ratio of the GO and the WO3, 18 h reaction time and 120 °C reaction temperature) for achieving the highest catalytic effect, and the highest degradation rate constant of the BPA was 0.03129 min-1. The determined higher TOC removal, higher COD removal as well as UV-Vis analysis also demonstrated the catalysis of the rGO-WO3. The measurement of the change of the O3 and the H2O2 concentrations in the reaction system with or without the rGO-WO3 and with or without the BPA proved the catalysis of the rGO-WO3 on the ·OH formation, while the combination of the GO had the positive effect for enhancing the catalytic effect. A figure on the catalysis and degradation procedure of the BPA in the DBDP/rGO-WO3 system was provided in the paper.