【作者】 雷雪飞；

【导师】 薛向欣；

【作者基本信息】 东北大学 ， 冶金资源与生态环境， 2009， 博士

【摘要】 本文系统地研究了掺杂硫酸盐的含钛高炉渣催化剂的结构与光催化活性之间的构效关系,并探索了含钛高炉渣光催化处理溶液中Cr6+及Cr6+/有机物复合体系的机理,这对于含钛高炉渣作为光催化材料的开发和应用及处理既含有有机物物种又含有重金属的实际废水有着重要的指导意义。首先,以含钛高炉渣为原料,利用XRF、XRD、SEM、UV-Vis-DR、TG、FTIR等分析方法对含钛高炉渣、掺杂硫酸的含钛高炉渣、掺杂硫酸盐的含钛高炉渣光催化剂的化学成分和矿物组成进行分析,确定了三类光催化材料作为光催化剂的可行性。研究了不同光催化剂中晶相结构、表面形貌、粉体粒度、煅烧温度、掺杂不同硫酸盐以及硫酸盐掺杂比例等对含钛高炉渣光催化活性的影响。通过对比合成的35种催化剂的光催化活性,选出光催化活性最高的掺杂硫酸盐的含钛高炉渣(sulfate-modified titanium-bearing blast furnace slag, STBBFS)催化剂作为实验中的光催化剂。系统地研究了STBBFS催化剂的吸附性能,探讨了初始浓度、催化剂加入量、吸附温度、溶液pH等方面对STBBFS催化剂吸附Cr6+的影响；探讨了吸附等温线模型、表观吸附动力学模型、热力学参数以及吸附机理。结果表明,酸性条件下易于Cr6+去除；增加吸附剂投加量、吸附温度,都有益于Cr6+去除；Cr6+在STBBFS吸附剂表面上的吸附遵循Langmuir吸附等温线模型；不同吸附温度和初始浓度下,Cr6+吸附过程都遵循二级表观吸附动力学模型；通过计算Cr6+吸附过程中的热力学参数：得出Cr6+吸附至STBBFS吸附剂表面具有自发性,且升高温度易于Cr6+的吸附。系统地研究了STBBFS催化剂光催化还原Cr6+单一体系的可行性。研究了紫外光波长和强度、溶液pH、酸介质、初始浓度、催化剂的使用寿命和分离效果等方面对STBBFS催化剂光催化还原Cr6+单一体系的影响；探讨了STBBFS光催化还原Cr6+的机理,进行了表观动力学分析。结果表明,光源的波长越短、光强越强、酸性越强,Cr6+光催化还原效率就越高；不同酸介质对STBBFS催化剂光催化还原Cr6+的促进作用按P043-<NO3-<Cl-<SO422-.逐渐增强；溶液的初始浓度对Cr6+光催化还原效率影响很大；根据正交试验结果分析,不同因素对Cr6+光催化还原效率的影响程度按：pH>初始浓度>酸介质>催化剂投加量；Cr6+单一体系中Cr6+的光催化还原过程遵循Langmuir-Hinshelwood(L-H)动力学规律。研究了STBBFS催化剂光催化处理Cr6+-乙酸(acetic acid, AA)复合体系的可行性。研究复合体系中AA/Cr6+的体积比、初始浓度、溶液pH、协同效应因子等方面对STBBFS催化剂光催化处理Cr6+-AA复合体系的影响；探讨了STBBFS催化剂光催化处Cr6+-AA复合体系的机理,并进行了表观动力学分析。结果表明,最佳AA/Cr6+体积比=0.2%；溶液的初始浓度对Cr6+光催化还原效率仍有较大影响；随着溶液初始pH增大(pH=1.5-3.5),Cr6+的还原率和吸附率都明显降低；根据正交试验结果分析,不同因素对Cr6+-AA复合体系中Cr6+光催化还原效率的影响程度按：pH>初始浓度>AA/Cr6+体积比>催化剂投加量；Cr6+离子在Cr6+-AA复合体系中的光催化还原遵循L-H动力学规律；Cr6+-AA复合体系的SEF始终大于0,证明Cr6+-AA复合体系中存在着较强的协同效应,利于Cr6+离子的去除。研究了STBBFS催化剂光催化处理Cr6+-柠檬酸(citric acid, CA)复合体系的可行性。研究了复合体系中CA/Cr6+的摩尔比、初始浓度、溶液pH、协同效应因子等方面对STBBFS催化剂光催化处理Cr6+-CA复合体系的影响；探讨了STBBFS催化剂光催化处理Cr6+-CA复合体系的机理,并与Cr6+-AA复合体系进行了比较。结果表明,最佳CA/Cr6+摩尔比=3.75;溶液的初始浓度对Cr6+光催化还原效率影响程度降低；改变体系的初始pH,对Cr6+平衡吸附效率有显著影响；酸性条件下,对Cr6+还原效率的影响不大；Cr6+离子在Cr6+-CA复合体系中的光催化还原也遵循L-H表观动力学规律；Cr6+-CA复合体系的SEF始终大于6,证明Cr6+-CA复合体系中存在着较强的协同效应,利于Cr6+离子的去除。研究了STBBFS催化剂光催化处理Cr6+-CA-硝酸铁(ferric nitrate, FN)复合体系的可行性。研究复合体系中Fe3+与CA/Cr6+的摩尔比、初始浓度、溶液pH、协同效应因子等方面对含钛高炉渣光催化处理Cr6+-CA-FN复合体系的影响；探讨了STBBFS催化剂光催化处理Cr6+-CA-FN复合体系的机理,并进行了表观动力学分析。结果表明,Fe3+与CA/Cr6+的最佳摩尔比=0.019；溶液的初始浓度对Cr6+光催化还原效率影响程度高于Cr6+-CA复合体系；改变体系的初始pH,对Cr6+平衡吸附效率和还原效率都有显著影响；Cr6+离子在Cr6+-CA-FN复合体系中的光催化还原也遵循L-H动力学规律；Cr6+-CA-FN复合体系的SEF始终大于1,证明Cr6+-CA-FN复合体系中存在着较强的协同效应,利于Cr6+离子的去除。研究了STBBFS催化剂可见光催化处理Cr6+-甲基橙(methyl orange, MO)复合体系的可行性。研究Cr6+-MO复合体系中Cr6+初始浓度、MO初始浓度、光催化反应时间、溶液初始pH、协同效应因子(SEF)等方面对可见光下STBBFS催化剂光催化处Cr6+-MO复合体系的影响；初步探讨了STBBFS光催化处Cr6+-MO复合体系的机理。此外,也进行了表观动力学分析。结果表明,可见光下,MO和Cr6+在Cr6+-MO复合体系中都存在着较强的协同效应,且MO的协同效应因子(SEFMO=39.8)明显高于Cr6+的协同效应因子(SEFCr6+=18.3),利于两种污染物的去除。更多还原

【Abstract】 The structure-activity relationships between the structure and photocatalytic activity of sulfate-modified titanium-bearing blast furnace slag were studied, and providing a solid theoretical foundation for the development and application of titanium-bearing blast furnace slag. In this paper, the photocatalysis mechanism of Cr6+ single system and Cr6+/organic compound combined pollution system in the presence of titanium-bearing blast furnace slag was first explored, which is profound significance for the real wastewater containing organic species and heavy metals.Firstly, the components and microstructures of TBBFS, SATBBFS and STBBFS photocatalysts were examined by XRF, XRD, SEM, UV-Vis-DRS, TG and FTIR. Then the feasibility of three kinds of photocatalytic materials as photocatalysts is determined. The effects of crystalline phase, surface morphology, powder particle size, calcinations temperature, doped different sulfate and the ratio of sulfate-doped on the photocatalytic activity for Cr6+ by the three kinds of photocatalysts were investigated. By comparing the photocatalytic activities of the 35 kinds of photocatalysts, it can be concluded that the photocatalytic activity of (sulfate-modified titanium-bearing blast furnace slag, STBBFS) photocatalyst is the highest.The effects of the initial concentration, catalyst amount, adsorption temperature and solution pH on the adsorption efficiency for Cr6+ by the STBBFS adsorbents were systematically studied; and the adsorption isotherm model, adsorption kinetics model, thermodynamic parameters and adsorption mechanism were also explored. The results showed that the adsorption data followed the Langmuir model rather than the Freundlich model, and the adsorption equilibrium was described by the Langmuir isotherm model with a maximum adsorption capacity of 8.25 mg/g of Cr6+ ions onto the STBBFS adsorbents at pH= 1.5. A pseudo-second-order kinetic model shows a good fitting to the experimental results at different initial concentrations and adsorption temperatures. The thermodynamic parameters, such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°) have been analyzed. The thermodynamics of Cr6+ ions onto the STBBFS adsorbents indicates the spontaneous and endothermic nature of the adsorption process. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis show that in the process the reduction of Cr6+ could be followed after the adsorption of Cr6+.The feasibility of photocatalytic reduction of Cr6+ by STBBFS photocatalyst in Cr6+ single system was systematically studied. The UV wavelength and intensity, solution pH, acid medium, the initial concentration, catalyst life and separation efficiency were also studied. The photocatalytic reduction mechanism and L-H kinetic mechanism of Cr6+ in Cr6+ single system were also explored. The results showed that, with the increase of light intensity, the photocatalytic reduction efficiency of Cr6+ increased; the photocatalytic reduction efficiency of Cr6+ reached maximum at pH=1.5; the order of the inhibitory effect of four acidic ions (SO42-, Cl-, NO3-, PO43-) on the photocatalytic reduction efficiency of Cr6+ was PO43->NO3>Cr>SCO42-; the initial concentration had a great influence on the photocatalytic reduction efficiency of Cr6+; in accordance with the results of orthogonal test, influencing ratio of the different factors was:pH> initial concentration> acidic medium> catalyst dosage; the photocatalytic reduction of Cr6+ in Cr6+ single system followed L-H kinetics.The feasibility of photocatalytic reduction of Cr6+ by STBBFS photocatalyst in Cr6+-AA system was systematically studied. The effects of the volume ratio of AA/Cr6+, the initial concentration, solution pH and synergistic effect factor on the photocatalytic reduction efficiency of Cr6+ in Cr6+-AA system were studied; The photocatalytic reduction mechanism and L-H kinetic mechanism of Cr6+ in Cr6+-AA system were also explored. The results showed that, the maximum rate of Cr6+ reduction was obtained for an initial AA/Cr6+ volume ratio, R=0.2%, a further increment in R being disadvantageous; the initial concentration still had a great influence on the photocatalytic reduction efficiency of Cr6+; with the increase of initial solution pH(pH=1.5-3.5), photocatalytic reduction efficiency and adsorption efficiency of Cr6+ decreased significantly; according to the results of orthogonal test, influencing ratio of the different factors was:pH> initial concentration> AA/Cr6+ volume ratio> catalyst dosage; the photocatalytic reduction of Cr6+ in Cr6+-AA system also followed L-H kinetics. The synergistic effect factor is always greater than 0 in the compound system, indicating that a marked synergistic effect between the photocatalytic reduction of Cr6+ and acetic acid.The feasibility of photocatalytic reduction of Cr6+ by STBBFS photocatalyst in Cr6+-CA system was systematically studied. The effects of the molar ratio of CA/Cr6+, the initial concentration, solution pH and synergistic effect factor on the photocatalytic reduction efficiency of Cr6+ in Cr6+-AA system were studied; The photocatalytic reduction mechanism and L-H kinetic mechanism of Cr6+ in Cr6+-CA system were also explored. The results showed that, the maximum rate of Cr6+ reduction was obtained for an initial CA/Cr6+ molar ratio, R=3.75, a further increment in R being disadvantageous; the initial concentration had a little influence on the photocatalytic reduction efficiency of Cr6+; the highest reduction efficiency and adsorption efficiency of Cr6+ were obtained at pH=2.5 and pH=1.5, respectively; with the increase of initial solution pH(pH=1.5-3.5), adsorption efficiency of Cr6+ decreased significantly, and yet photocatalytic reduction efficiency of Cr6+ decreased slightly; the photocatalytic reduction of Cr6+ in Cr6+-CA system also followed L-H kinetics. The synergistic effect factor is always greater than 6 in the compound system, indicating that a marked synergistic effect between the photocatalytic reduction of Cr6+ and citric acid.The feasibility of photocatalytic reduction of Cr6+ by STBBFS photocatalyst in Cr6+-CA-FN system was systematically studied. The effects of the molar ratio of Fe3+-CA/Cr6+, the initial concentration, solution pH and synergistic effect factor on the photocatalytic reduction efficiency of Cr6+ in Cr6+-CA-FN system were studied; The photocatalytic reduction mechanism and L-H kinetic mechanism of Cr6+ in Cr6+-CA-FN system were also explored. The results showed that, the maximum rate of Cr6+ reduction was obtained for an initial Fe3+-CA/Cr6+ molar ratio, R=0.019; the initial concentration had a great influence on the photocatalytic reduction efficiency of Cr6+; the highest reduction efficiency and adsorption efficiency of Cr6+ were obtained at pH=2.5 and pH=1.5, respectively; with the increase of initial solution pH(pH=1.5-3.5), photocatalytic reduction efficiency and adsorption efficiency of Cr6+decreased significantly; the photocatalytic reduction of Cr6+in Cr6+-CA-FN system also followed L-H kinetics. The synergistic effect factor is always greater than 1 in the compound system, indicating that a marked synergistic effect between the photocatalytic reduction of Cr6+, Fe3+ and citric acid.The feasibility of photocatalytic disposal of Cr6+-methyl orange (MO) system by STBBFS photocatalyst was systematically studied. The effects of the initial concentration, solution pH and synergistic effect factor on the photocatalytic disposal of Cr6+-MO system were studied; The mechanism of the photocatalytic disposal of Cr6+-MO system and L-H kinetic were also explored. The results showed that, the synergistic effect factor of MO is always greater than Cr6+ in Cr6+-MO system, indicating that a marked synergistic effect between the photocatalytic reduction of Cr6+ and the photocatalytic oxidation of methyl orange.更多还原