The Study On The Treatment Of Nitrobenzene Wastewater By Heterogenious Catalysts And Electrode Oxidation

Nitrobenzene is the high poisonous substance which is difficult to be biodegraded and can inhibit and poison biochemical reaction. Wastewaters contain Nitrobenzene come widely and can cause a large pollution, its popular treatment include biological, physical and chemical methods. These years, Advanced Oxidation Processes which can degrade organic pollutants effectively is becoming a hot field, creating hydroxyl radical which has a wonderful oxidant performance is the primary characteristic of AOP.Electrode Oxidation Methods is useful in the degradation of persistent pollutants, but there are also some shortcomings in the treatment by classical Electrod Oxidation Methods, such as a low reaction rate, a rigorous reaction condition, a large energy consumption. This article put Fe3+ / TiO2 catalyst into electrode oxidation system, to decompose nitrobenzene in wastewater, with a view to enhance the reaction rate and improve the removal rate of nitrobenzene and COD.Electrode was made by thermal decomposition method and electric deposition of lead dioxide electrode, and the catalyst is maded by titanium dioxide as the carrier and Ferric chloride as activating agent, mixed with distilled water and then produced at a high temperature calcination.By changing the electrolysis conditions and catalyst preparation conditions determine the best treatment conditions of electrode oxidation with non-homogeneous catalytic system.By changing the electrolysis time, current intensity, solution pH value, electrolyte concentration, the amount of catalyst, stirring rate compared the removal effect of COD and nitrobenzene in oder to determine the optimal electrolysis conditions, by changing the catalyst calcination time and calcination temperature determine the Optimal catalyst preparation conditions. The experimental results show that the reaction rate of non-homogeneous which adding the catalysts in the electrolysis system is higher than ordinary electrolysis system. Under the conditions of the adequate reaction time,catalysts can make the nitrobenzene degradation products be oxidized further, which can improve the removal of COD significant. In this experiment, we determine the electrolysis time is 4h. In a certain range of current intensity, with the addition of the catalysts, current efficiency can be raised. Accourding to the comprehensive analysis we choose the current intensity is 0.6A. PH value in the traditional electrolysis system has a great influence, in ordinary electrolysis system, the effect of neutral or acidic is better than alkaline. But in the system which contains catalysts, the impact of the pH value is relatively weak. So we chose 5 as the pH value. Whether or not to add the catalysts, the electrolyte concentration could affect the removal of the effect of water samples. Both the degradation rate of nitrobenzene and COD would be changed. So accourding to the result of the experiment we choose the electrolyte concentration is 1500mg/L. In the experiment, the amount of the catalysts is not better to use more, we should according to specific experimental conditions to select the appropriate dosage. And choose a suitable stirring rate to raise the overall efficiency of electrolysis is the key to improve the removal efficiency. Change the catalyst preparation conditions can optimize the catalyst performance, experimental results show that the catalyst could has the best effect if we calcined at 400℃under 2 hours. Taking all these experimental conditions to draw the ultimate removal of nitrobenzene and COD could achieve 98.41% and 87.68%.In order to analyze the effect of the catalysts in the experiment, we analyse the catalytic efficiency, the result show that in the more demanding conditions, the catalytic efficiency is more better. And this may provide the data infrastructure for taking full usage of the catalyst and choosing suitable catalytic conditions.In the experimengt of the comparison of carrier and catalyst for the removal of the water samples we found that the carrier in the electrolysis system also played a catalytic role, but it is mainly physical catalyst, however, the addition of the catalysts which contained the active component includes the physical and chemical catalysis.The re-use of the Fe3+/TiO2 catalyst is good. After repeated use, the trend of wastewater treatment effect is still gently downward. By 5 times after use, the nitrobenzene and COD removal efficiency of wastewater is still considerable.Treatment of organic wastewater contains high poisonous and bio-refractory substance will be a difficulty and a emphasis in environment fathering of our country for a long time. Fe3+/TiO2 is an effective and environment-friendly catalyst because of its good reusing ability and recycling ability.