The Application Of The Low-Temperature Plasma Technology In Aqueous Chemistry

Plasma, which is composed of positive and negative ions, electrons, and neutral species, is commonly called as the fourth state of matter. It exists widely in the universe. There are two kinds of plasmas that are mainly used in laboratory. They are called the high-temperature and low-temperature plasmas.The glow discharge plasma is a kind of novel electrochemical method which can be used in treating the organic contamination and dye in water. During the process of electrolysis, the solvent can be boiled away swiftly and decomposed to the steady steam sheath, when the voltage between the two electrodes is high enough, and all kinds of active intermediates can be produced and the plasma can also be produced continually. Some of the high active component, such as H·,·OH and H₂O₂, can diffuse to the solution near the electrode easily and offer the active intermediate sources for all kinds of solution chemistry reaction. On one hand, it can treat some kinds of waste water as the advanced oxidation technology, on the other hand, it can be as the initiator of some kinds of reactions to finish the preparation reaction. The design and improvement of the instruments and set-up can influence the reaction efficiency obviously. In this dissertation, a brief review has been made firstly, then, we put our focus on the application in chemistry fields, such as the methods to produce the low-temperature plasma and the application of inducing chemistry reaction. The whole paper includes five parts.Part I ReviewThis part gives a mini-review of the main methods to produce the gas discharge plasma and their working mechanism, expatiates their mainly application fields, and introduces the concept of contact glow discharge plasma, the chemistry reaction mechanism, and the actuality and prospect in its application fields.Part II Modification of glow discharge electrolysis reactor The glow discharge plasma ( GDP ) was regarded as the promising technology and was widely investigated in waste water treatment. After the conventional reactor of contact glow discharge inducing the chemical reaction was modified by us, the experimental operation was predigested, the reaction efficiency was increased, the ability of the instrument to treat waste water was enlarged, the lifetime of the electrodes was prolonged, and the process of glow discharge was steady. This attained our anticipative purpose. Accord to the basic principle, the contact glow discharge electrolysis reactor was modified and a new reactor was re-designed. The new designed setups and the application technique, which was named the device of purification of drinking water by plasma and a polymerization of acrylamide with acrylic acid by plasma, have been submitted to Chinese Patent Bureau.Part III The application of the multi-electrode in the treatment of dye-contained waste waterThe application of multi-anode in degrading the waste water containing Alizarin Red was studied, and the effects of all kinds of factors on the degradation efficiency were investigated. The process of degradation was traced by UV spectrum etc. The degradation products were determined by atom force microscopy (AFM) and FTIR. The change of COD, absorbance, and the pH value were also determined.The results showed that this instrument could improve the ability of glow discharge plasma to treat the waste water, and made an elementary exploration of the application of this technology in treating a mass of waste water.Part IV The application of polymerization in aqueous solution induced by glow discharge plasmaGlow discharge plasma as an initiation technique has been utilized in polymerization reaction in aqueous solution. Poly (acrylamide-co-acrylic acid) hydrogels, was synthesized by aqueous solution polymerization using free radicals produced by glow discharge plasma as an initiator and N , N-methylene-bis-acrylamide as a cross-linking agent. Acrylic acid content in the monomer was varied from 20% to 50%. In comparison with the FTIR spectra of two copolymers (between the proposed and conventional methods), it indicated that the proposed method can be used in polymerization reaction without any chemical initiator.Part V The application of glow discharge in treating the complex solutionAs an example, the ferric thiocyanate was used to explore elementarily another application of glow discharge plasma in aqueous reaction. The reaction process was determined by UV spectrum. The changing factors were investigated in the reaction process. The results showed that the glow discharge plasma could be used efficiently in treating complex-contained waste water.