Research on the degradation mechanism of dimethyl phthalate in drinking water by strong ionization discharge

The degradation mechanism of dimethyl phthalate（DMP） in the drinking water was investigated using strong ionization discharge technology in this study. Under the optimized condition, the degradation efficiency of DMP in drinking water was up to 93% in 60 min. A series of analytical techniques including high-performance liquid chromatography, liquid chromatography mass spectrometry, total organic carbon analyzer and ultraviolet–visible spectroscopy were used in the study. It was found that a high concentration of ozone（O_3） produced by dielectric barrier discharge reactor was up to 74.4 mg l^（-1） within 60 min. Tert-butanol, isopropyl alcohol,carbonate ions（CO_3^（2-）） and bicarbonate ions （HCO_3^-） was added to the sample solution to indirectly prove the presence and effect of hydroxyl radicals（·OH）. These analytical findings indicate that mono-methyl phthalate, phthalic acid（PA） and methyl ester PA were detected as the major intermediates in the process of DMP degradation. Finally, DMP and all products were mineralized into carbon dioxide（CO_2） and water（H_2O） ultimately. Based on these analysis results, the degradation pathway of DMP by strong ionization discharge technology were proposed.

Research on quinoline degradation in drinking water by a large volume strong ionization dielectric barrier discharge reaction system

Quinoline is widely used in the production of drugs as a highly effective insecticide,and its derivatives can also be used to produce dyes.It has a teratogenic carcinogen to wildlife and humans once entering into the aquatic environment.In this study,the degradation mechanism of quinoline in drinking water by a strong ionization dielectric barrier discharge(DBD)lowtemperature plasma with large volume was explored.High concentration of hydroxyl radical(·OH)(0.74 mmol l^(-1))and ozone(O3)(58.2 mg l^(-1))produced by strongly ionized discharge DBD system were quantitatively analyzed based on the results of electron spin resonance and O3 measurements.The influencing reaction conditions of input voltages,initial pH value,·OH inhibitors,initial concentration and inorganic ions on the removal efficiency of quinoline were systematically studied.The obtained results showed that the removal efficiency and TOC removal of quinoline achieved 94.8%and 32.2%,degradation kinetic constant was 0.050 min^(-1) at 3.8 k V and in a neutral pH(7.2).The proposed pathways of quinoline were suggested based on identified intermediates as hydroxy pyridine,fumaric acid,oxalic acid,and other small molecular acids by high-performance liquid chromatography/tandem mass spectrometry analysis.Moreover,the toxicity analysis on the intermediates demonstrated that its acute toxicity,bioaccumulation factor and mutagenicity were reduced.The overall findings provided theoretical and experimental basis for the application of a high capacity strong ionization DBD water treatment system in the removal of quinoline from drinking water.

Study on the Removal of SO_2 from Simulated Flue Gas Using Dry Calcium-Spray with DBD Plasma

In this study, lime-hydrate （Ca（OH）2） desulfurizer was treated by plasma with strong ionization discharge of a dielectric barrier. The removal of SO2 from simulated flue gas was investigated. The principles of SO2 removal are discussed. Several factors affecting the efficiency of SO2 removal were studied. They included the ratio of calcium to sulfur （Ca/S）, desulfurizer granularity, residence time of the flue gas, voltage applied to the discharge electrode in the plasma generator, and energy consumption. Experimental results indicate that the increase in Ca/S ratio, the applied voltage and discharge power, the residence time, and the reduction in the desulfurizer granularity all can raise the SO2 removal efficiency. The SO2 removal efficiency was up to 91.3% under the following conditions, namely a primary concentration of SO2 of 2262×10^-6 （v/v） in the emission gas, 21%（v/v） of oxygen, 1.8% （v/v） of water, a Ca/S ratio of 1.48, a residence time of 2.8 s, a 3.4 kV voltage and a 10kHz frequency power applied to the discharge electrodes in the plasma generator, and a flow rate of 100 m^3/h for emission gas.