The Application Of Contact Glow Discharge Electrolysis In The Treatment Of Organic Dyes Wastewater And The Selection Of The Optimum Reaction Conditions

The widespread presence of organic dyes in industrial wastewater results in a potentially serious environmental problem, and most of them couldn't be degraded efficiently. Dye wastewaters differ from commonly industrial wastewater because of their complex components, high colority, varying properties and so on. In recent years, lots of methods have been used to treat the wastewater, such as physically-absorbed method, chemical oxidation method and biological degradation. The chemical oxidation methods include wet air oxidation, super critic catalytic wet air oxidation, photocatalytic and electrochemistry. Some of the methods have reached the practical application stage. However, the significant energy consumption is still a common problem.Contact glow-discharge electrolysis (CGDE) is a special electrochemical process, including both conventional electrolysis and non-Faradic electrolysis. That is, with increasing the applied voltage the normal Faradic electrolysis would be converted into the glow-discharge electrolysis, in which there are a lot of highly energetic species called plasma. Thus, the glow-discharge electrolysis, in general, could be considered as a plasma process. From the point of view of chemistry, the plasma in aqueous solution can attack the water molecule to produce hydroxyl radical, while the hydroxyl radical reacts with other organic molecule. This is the basic reason for the application of CGDE to treat organic wastewater.Using methyl violet as a model organic substrate in wastewater to study the effect of Fe²⁺ on the contact glow discharge electrolysis (CGDE). The production of H₂O₂ and the better condition for the reaction of Fe²⁺ with CGDE have been examined. It is found that the production of H₂O₂ increases with increasing the applied voltage; the presence of ferrous ins can accelerate obviously the degradation of methyl violet, because the Fe²⁺ ion reacts with H₂O₂ in the CGDE process to yield hydroxyl radical, just acting as a Fenton-like reagent. Moreover, the optimal conditions for degrading methyl violet were studied by means of an orthogonal experiment, and methyl violet could be degraded quickly under the condition of high voltage, alkali solution and little time, so the combined method will be a better method to treat the wastewater. In treating organic dyes wastewater, the contact glow discharge electrolysis is a potential technique in future, it can be considered as a green chemistry technology. As a novel technique, the contact glow discharge electrolysis used in the wastewater treatment would be investigated extremely in future.