| Advanced Oxidation Processes, which have also been called profound oxidation process, are the processes based on the generation of highly potential chemical oxidants such aments the hydroxyl radical (·OH) to degrade organic contaminants in polluted water and air. These processes have some prominent virtues in wastewater treatment, such as high treatment efficiency, complete mineralization of undesirable organic contaminants, organic pollutants degraded non-selectively, and no secondary pollution, etc. As one of Advanced Oxidation Processes, the photocatalysis oxidation technologies has attracted much more attention. And among the photocatalysis oxidation technologies, UV/Fenton reagent system is a typical case. Using ultraviolet irradiations as light sources, and catalyzed by ferrous ions, UV/Fenton reagent system not only demonstrates much higher efficiency of catalysis and better ability of oxidation, but also show some advantages of degrading wastewater of high concentration, non-easily degradation in shorter time. However, UV/Fenton reagent system also has some shortcomings, such as the light source of ultraviolet irradiations having shorter life, the change rate between electricity and photo being lower, etc. Therefore, to expand the scope of spectrum and make use of sun light in photo degradation has become the hot topic in present research.Phenol is a simple, but important phenolic compounds in modern ago-industrial activity. With the rapid development of chemical industry, it has been used in many areas, such as in manufacturing phenolic resin, diacetic acid, diethylamine, chemical herbicides, synthetic dye, medicine, wood preservatives and dynamite, etc.To use routine physical, chemical, and biological methods to treat phenolic wastewater will not achieve hoped results. In this research, using phenol as stimulated contaminants, the author studies the feasibility of photo-Fenton process in the treatment of wastewater containing phenolic compounds. Using the light from Xenon lamp as stimulated natural sun light, and adding hydrogen peroxide (photo-Fenton reagent system) and ferrous ion into the solution containing phenol to study the process and the conditions of degradation of phenol is one of the purposes of this article. The experimental results show: The light intensity impacts the reaction speed greatly. As the electric current intensity increases, the rate of removal of phenol increases, too. When the reaction time reaches 160minutes, and the electric current intensity of the Xenon lamp is 15A, the degradation rate of phenol is 63.39%; while the electric current intensity is 10A, the degradation rate of phenol is 53.49%. The hydrogen peroxide concentration directly influences the generative rate and the output of hydroxyl radicals, and further influences the rate of phenol. When the amount of H2O2 is 20mg/L, the degradation rate of phenol increases slowly. So 25mg/L is selected as the standard amount of H2O2 in these experiments.Ferrous ion is also an important factor which impacts the degradation speed. When compared with Fe(Ⅱ), the result of degradation by Fe(Ⅲ) is better. So Fe(Ⅲ)is selected as degradation reagent in this experiment. In the meantime , the concentration of Fe(Ⅲ) also influences the degradation speed. The degradation speed of phenol by photo-Fenton increases as the Fe(Ⅲ) concentration is raised. When Fe(Ⅲ) concentration is 2mg/L , to reach the ceiling of degradation rate of phenol needs 60minutes, while Fe(Ⅲ) concentration is 4mg/L , to reach the ceiling of degradation rate of phenol needs only 20minutes. However, higher Fe(Ⅲ) concentration impacts the quality of water degraded, so 2mg/L is choose as the Fe(Ⅲ) concentration.Another important factors which impact the reaction is pH value. When pH value is below 4, the degradation decreases as the pH value decreases. When the pH value is above 5, the degradation speed decreases as the pH value increases ,because when the pH value is raised, it would not only inhibit the generation of hydroxyl radica...
|
PDF Full Text Request