Degradation Of Sodium 3-Nitrobenzene Sulfonic Acid By Catalytic Wet Peroxide Oxidation

Galvanization was widely applied in many industries, such as machine building, light industry, electron and so on, since Galvanization could retrieve huge economic loss causing by metal corrosion. But the plating wastewater could also bring serious environmental problems. Different industries request different coating metals for galvanizing work, and the production craft is also different, so the components of plating wastewater was very different. According to the origin, Wastewater from the plating factories was divided into four types: pre-plating wastewater, the coating stripping wastewater, the post-plating wastewater and the galvanization waste liquid (the waste plating solutions and rinsing solutions and so on). At present, there are many technologies for plating wastewater treatment domestic and abroad. Because of different composition of the plating wastewater in various industry and extremely complex ingredient, technologies of treatment were very different. They generally could be divided into 4 kinds: chemical process, physical process, physical-chemical process and biochemistry process. The chemical process is most important techniques because of the low price and the quite mature technology, which was simultaneously suitably assisted by other treatment methods. The chemical process is widely applied for plating wastewater treatment abroad. Many researches about plating wastewater treatment by chemical method have been made in our country and some has been applied efficiently.In the process of nickel galvanization, the wastewater when the nickel coating was stripped by chemical process contains Sodium 3-Nitrobenzene Sulfonate, Sodium 3-aminobenzene sulfonate, CN^-, Ni²⁺, and so on, the nickel ion can be separated by electrodialysis, ion-exchange and others methods. CN^- also can be removed by many other methods, but Sodium 3-Nitrobenzene Sulfonate is a extremely steady material, so it is hard to be degraded with common bio-chemistry and physical-chemistry methods, Therefore it builds foundation for the nickel plating wastewater treatment if the Sodium 3-Nitrobenzene Sulfonate was successfully decomposed.In this thesis, catalytic wet air oxidation was adopted to treat Sodium 3-Nitrobenzene Sulfonate and catalysts like Co/Bi, Mn/Ce, Cu/Mn/Ce, Cu(NO₃)₂ , active carbon and oxidants like peroxide and oxygen were applied for the treatment process. The result showed that the Catalytic Wet Peroxide Oxidation with catalyst Cu(NO₃)₂ was more effective for the Sodium 3-Nitrobenzene Sulfonate treatment. The Wet Peroxide Oxidation (WPO) can efficiently decompose the Sodium 3-Nitrobenzene Sulfonate because of the strong oxidizability of hydroxyl that Peroxide produced in the high temperature. Catalytic Wet Peroxide Oxidation (CWPO) using Cu(NO₃)₂ as catalyst can more efficiently decompose the Sodium 3-Nitrobenzene Sulfonate because of catalysis of Cupric nitrate; whereas, when Co/Bi catalysis, Mn/Ce catalysis, Cu/Mn/Ce catalysis and active carbon were used as catalyst, they can reacts with peroxide in low temperature, and the peroxide finally turned into oxygen, which makes the peroxide inefficiently decompose.Then effects of reaction temperature, amounts of peroxide and catalyst, oxygen partial pressure, the initial concentration, pH value of the solution and the progress of heating up on the removal efficiency were studied respectively by analyzing the TOC removal percentage. At last, intermediate products was also measured by GC-MS for mechanism analyzing of the reaction.The result suggested that reaction temperature and amounts of peroxide have obvious effects on the reaction. With the reaction temperature and amounts of peroxide rising, the TOC removal percentages of the solution tend to climb. The oxygen and the catalyst can enhance the reaction efficiency, but influence of the initial oxygen partial presses and the catalyst amount is not obvious to the catalytic reaction. The initial of solution could obviously influence the catalytic reaction with other condition fixed. When the initial reaction concentration was increased, the removal quantity of TOC increased, but removal rate of TOC reduced. Influence of initial pH value to the catalytic reaction is greater and complex. With initial pH value increasing, removal rate of TOC increased at first and then decreased.Catalytic Wet Peroxide Oxidation (CWPO) of 24.0g/L Sodium 3-Nitrobenzene Sulfonate (TOC 7800mg/L) with temperature 270℃, amount of the hydrogen peroxide 90mL, the oxygen partial pressure 1.0Mpa, and amount of the catalyst 1.0g, could remove above 99% of TOC. Moreover, under the certain condition, the proper increase of the amount of hydrogen peroxide the reaction temperature could further increase the removal efficiency.In the entire reaction process, the oxidation of the hydroxyl made Sodium 3-Nitrobenzene Sulfonate breaking into nitryl, sulfogroup and phenyl. The partial phenyl was further decomposed into inorganic substances, for example CO₂ , H₂O and so on, and the other phenyl combined with nitryl, sulfogroup and other radicals into other complex matters. Under the oxidation of the hydroxyl, these intermediary products could also be broken into nitryl, sulfogroup and phenyl, and then the phenyl was broke into inorganic substances similarly. At last, when the hydroxyl was consumed, the partial intermediary products have not been degraded. Therefore, if TOC was requested to be completely degraded, enough quantity of the hydroxyl is needed.The successful degradation of the Sodium 3-Nitrobenzene Sulfonate in this experiment is helpful to treat actual nickel plating and rinsing wastewater, which contains Sodium 3-Nitrobenzene Sulfonate. Stability of Sodium 3-Nitrobenzene Sulfonate is strongest in the wastewater, if the Sodium 3-Nitrobenzene Sulfonate is successfully degraded; other organics and inorganic components also can be easily removed. In addition, copper ion, which was introduced in the treating processes, is able to remove in the recycling nickel process by using electro analysis or mediating the pH value. After treatment, wastewater reached the goal of discharging; moreover, nickel in it has been recycled.