Degradation of Methylene Blue by RF Plasma in Water

Plasma Chemistry and Plasma Processing - Tập 28 - Trang 467-482 - 2008
T. Maehara1, I. Miyamoto1, K. Kurokawa1, Y. Hashimoto1, A. Iwamae2,3, M. Kuramoto4, H. Yamashita1, S. Mukasa1, H. Toyota1, S. Nomura1, A. Kawashima5
1Graduate School of Science and Engineering, Ehime University, Matsuyama, Japan
2Graduate School of Engineering, Kyoto University, Kyoto, Japan
3ITER Diagnostics Group, Division of ITER Project, Japan Atomic Energy Agency, Ibaraki, Japan
4Integrated Center for Science, Ehime University, Matsuyama, Japan
5Faculty of Agriculture, Ehime University, Matsuyama, Japan

Tóm tắt

Radio frequency (RF) plasma in water was used for the degradation of methylene blue. The fraction of decomposition of methylene blue and the intensity of the spectral line from OH radical increased with RF power. RF plasma in water also produced hydrogen peroxide. The density of hydrogen peroxide increased with RF power and exposure time. When pure water (300 mL) is exposed to plasma at 310 W for 15 min, density of hydrogen peroxide reaches to 120 mg/L. Methylene blue after exposed to plasma degraded gradually for three weeks. This degradation may be due to chemical processes via hydrogen peroxide and tungsten. The comparison between the experimental and calculated spectral lines of OH radical (A–X) shows that the temperature of the radical is around 3,500 K. Electron density is evaluated to be ≃3.5 × 1020 m−3 from the stark broadening of the Hβ line.

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