Spectral Diagnosis of Hydroxyl Radical in Multiphase Pulsed Discharge System
WANG Hui-juan1,3,LI Jie2*,QUAN Xie1,WU Yan2,LI Guo-feng2
1. School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, China 2. Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024, China 3. College of Life Science and Technology, Xiaogan University, Xiaogan 432000, China
Abstract：A gas-liquid hybrid pulsed discharge system with a multi-needle-to-plate electrode geometry was used in the present study. A multiphase (gas-liquid-solid) pulsed discharge system was then formed by adding glasses beads immobilized with TiO2 photocatalyst into the discharge system. In the present paper, ultraviolet light produced during the pulsed discharge process was used as the lamp-house to induce the photocatalytic activity of the TiO2 photocatalyst. The synergistic effect of pulsed discharge and TiO2 photocatalysis was reviewed by the spectral diagnosis of hydroxyl radical (·OH) in the pulsed discharge system. The obtained results showed that the emission spectrum of ·OH could be observed at 306 nm (A2Σ+→X2Π), 309 nm (A2Σ+ (ν′=0)→X2Π(ν″=0)) and 313 nm (A2Σ+(ν′=1)→X2Π(ν″=1) transition). The relative emission intensity of ·OH at 313 nm in the discharge system was the strongest among the three characteristic spectra. The relative emission intensity of ·OH at 313 nm was stronger by adding TiO2 photocatalyst into the pulsed discharge system than that in the sole pulsed discharge system. In the case of experiments that changing the gas bubbling varieties and initial solution pH values, the results revealed that the relative emission intensity of ·OH at 313 nm in the synergistic system was stronger when Ar was used as bubbling gas compared with that when air and oxygen were bubbled into the reaction system. Furthermore, the acidic solution system was favorable for producing more ·OH, and therefore the corresponding emission intensity of ·OH at 313 nm was stronger than that in the neutral and basic solution.
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