Spectral Properties And Application Of The Glow Discharge System Using Liquid Cathode

With the development of the industry and human civilization, people’s life is greatly improved, along with the arising problems of soil pollution, air pollution and water pollution. The detection of metallic element types and content in water is crucial for solving the problem of water pollution. Currently, detection methods for metallic element in water can be roughly divided into two categories: electrochemical method, spectroscopic and mass spectrometric techniques. Spectroscopic and mass spectrometric techniques can be further divided into following kinds: spectrophotometry, atomic emission spectrometry, atomic absorption spectrometry and so on. Atomic emission spectrometry is the research highlights at present, and liquid cathode glow discharge method is extensively researched due to such advantages as the small instrument’s size, good stability, simple operation, high sensitivity, and so on.Liquid cathode glow discharge system refers to the sample solution as the discharge cathode, and generates plasma under external electrical excitation. The atomic emission lines of metal element in test sample liquid can be obtained by analyzing the plasma spectra. But it needs more researches in the spectral characteristics analysis of different metal elements, the suitable detective condition, and the stability of the concentration standard curve. This system can be applied in other fields such as plasma surface modification of photo-catalysis materials, but this application is seldom studied so far.In order to solve above-mentioned matters, we designed a liquid cathode glow discharge system in the paper, and applied the system to detect metal elements in water. The detecting mechanism is studied. Besides we used the system to process photocatalytic material for the first time, and degradation rate of the organic compounds in water is improved by employing as-processed photocatalytic material. The specific contents are organized as follows:(1) We described the improvement of the liquid cathode glow discharge sy stem at home and abroad, and generalized the research status for detection of the metallic elements.(2) We designed a liquid cathode glow discharge system, studied the spectral properties of the system, assessed the stability of the device, and diagnosed the plasma in physical terms.(3) We designed experiments to explore the mechanism for detecting metal elements in water, and put forward own view. Besides we applied the system to detecting trace metal elements in water such as Ca、Mg、Cu、Mn、Al、Zn、Fe、Hg、Cd and Ni at the optimum conditions, plotted standard concentration analytical curve using the internal standard method, and calculated the detection limit of the elements.(4) We prepared titanium dioxide photocatalytic thin film materials on carbon film, applied the device to processing the photocatalytic materials for the first time, obtained improved photocatalytic properties by plasma surface modification, and analyzed the reason.