| The hazard of organic pollutants in water environment, especially the difficult degradable organic pollutants, is always paid attention. Most phenol belongs to this class, including octylphenol, nonylphenol and bisphenol A. They are divided into the main persistent toxic substances list by United Nations Environment Program. These phenols are a representative kind of environmental endocrine disrupting chemicals. They have strong biological accumulation, three induced effects and endocrine interference. The accumulation of these phenols in the environment will cause serious damage to various biological. A variety of alkyl phenols endocrine disruptors were demonstrated can be degraded in the natural light. But, the degradation period was long. So, it is a feasible path of photocatalytic degradation of organic pollutants. TiO2is the most commonly used optical catalyst. Researchers often adopted other miscellaneous elements in TiO2to broaden the light absorption capacity, thereby improving the optical catalyst performance. The elements doping, single or multiple, was better to the degradation rate. Some single elements can broaden the absorption of light, some multiple elements also can effectively reduce the imbalance resulting lattice defects because of the single element doping.In this paper, TiO2, Fe-TiO2and Fe/C-TiO2were prepared, with octylphenol, nonylphenol and bisphenol A, three representative environmental hormones, as the test molecules. The Fe/C-TiO2was screened from the three kinds of catalyst because of its high catalytic performance. In this paper, the kinds of catalyst were made by sol gel method and solvent thermal synthesis. And with octylphnol, nonylphenol and bisphenol A degrading, their degradation performance were studied. Because the photocatalytic degradation of octylphnol had been rarely studied, it was comparatively detailed researched. The effects of iron doping amount, catalyst dosage, pH and light were studied, as well as the interfering ions. Finally, the degradation intermediates of octylphenol were analyzed by GC-MS. The main results are as follows.1、The comparison of degradation performanceWhen pH was9and concentration was lOmg/L, the degradation rates of octylphnol and nonylphenol were72%and79%by TiO2roasting in450℃under the300W mercury lamp irradiation, while, when pH was5, the rate of bisphenol A was65%. The degradation rates were82%、87%and79%in the same reaction condition by Fe-TiO2 roasted at450°C and iron doping at0.6%. And, the degradation rates were93%>95%and98.7%in the same reaction condition by Fe/C-TiO2, which iron doping was0.6%.2、Fitting reaction kinetics curve of OP degradationTaking octylphenol as example, TiC2: reaction rate constant for0.0.131min-1and half-life of43.54min;0.6Fe-TiO2: reaction rate constant for0.0167mm"1and half-life of29.15min;0.6Fe/C-TiO2: reaction rate constant for0.0266mm"1and half-life of19.89min.3、The effect of iron doping content on Fe/C-TiO2catalytic performanceThis paper prepared a series of Fe/C-TiO2with different iron doping amount. The best ratio for Fe/C modified TiO2catalyst was0.6%Fe/C-TiO2.When the amount increased from0.3%to0.6%, the degradation rate decreased gradually at the same time. While, when the amount increased from0.6%to0.9%, the rate decreased gradually. When the doping content was lower than0.6%, the composite sites caused by iron atoms and carbon atoms increased, leading to the enhancement of catalyst activity. While more than0.6%, too much iron atoms and carbon atoms could not effectively increase more composite sites.4、Characterization of0.6%Fe/C-TiO2Form the diffraction peaks of the XRD map, its main characteristic peaks appeared in the25.42,37.88,48.16,54.2,55.04,62.80,68.78,70.32and75.37. It was anatase titanium dioxide. The relative strength decreased slightly in37.88and62.80and this may be caused by the diffraction effect of iron doping. On the other hand, the characteristic peak of iron atom was not observed in the XRD pattern. When the iron doping amount was less, iron atoms may be dispersed in the catalyst, forming photocatalytic activity with anatase TiO2, and could not form microcrystalline in the TiO2crystal. Therefore, the characteristic peak could not be observed. Surface of the catalyst particle size is about1nm and the appearances were basically the same from the analysis of the SEM diagram. And, the small amount of iron did not form a unique polycrystalline on the surface and the observational depth.5、The effect of the reaction conditions such as pH, amount of catalyst and light intensity on the0.6%Fe/C-TiO2degradation rateWith octylphenol as an example, the degradation capacity increased by the alkaline of the solution. The more amount of catalyst could improve the ultimate degradation rate. But, when the amount reaching enough more, the excess catalyst could not be effectively utilized. And it would reduce the system’s transmission which may hinder the absorption of a photon of light degradation, thereby adversely effect. Improving the light intensity could improve octylphenol degradation effect to a certain extent. Strong light intensity could improve the degradation rate more in the short reaction time. And, when the reactant consumption exceeded50%, the improved efficiency was relatively reduced. From the efficient use of energy, remaining relatively moderate light intensity was more appropriate. In addition, the effects of these factors on nonylphenol were similar. While, the degradation rate of bisphenol A were good in acidic water, and other similar.6> The effect of interfering ions in water environment on degradationWith octylphenol as example, keeping the reaction conditiongs and catalyst dosage unchanged, the effects of the existence of Na+, K+and Ca2+on degradation were studied. The results showed that, the existence of Na+, K+and Ca2+had no effect on the degradation activity of the catalyst of0.6%Fe/C-TiO2.7、Degradation intermediates of OPFrom the GC-MS atlas, the intermediate products were analyzed, which were4-Hexadecyloxy-2-pentadecyl-1,3-dioxane and5-Hexadecyloxy-2-pentadecyl-1,3-dioxane. |
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