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) low-temperature plasma with large volume was explored. High concentration of hydroxyl radical (centerdotOH) (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, centerdotOH 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 kV 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.