【作者】 栗荣贺；

【导师】 王君；

【作者基本信息】 辽宁大学 ， 无机化学， 2008， 硕士

【摘要】 随着工业化进程的发展,人们的生活水平得到较大幅度的提高,但与此同时我们也面临着巨大的能源短缺和环境污染问题,给人类的生存带来了负面的影响。大量的含有机污染物的工业废水未被处理直接排入江河湖海,给我们人类的健康和其他生物的生存带来了极大的威胁。如何有效地去除残存在工业废水中的有毒污染物如表面活性剂、染料、贵金属离子等已成为人们研究的重点。为了解决这一问题,人们做了大量的研究工作,采用了各种不同的方法如物理吸附、生物降解、半导体催化、气提法等来去除水中的有毒物质。但由于工业废水中的有毒化合物大多含有苯环分子结构,目前所使用的物理和生物等处理方法效果均不佳,而近年来兴起的可以将有毒污染物完全破坏掉的高级氧化技术则愈来愈受到人们的重视。在高级氧化技术中TiO₂作为光催化剂,具有化学性质稳定、价廉易得、无毒、催化效率高等优点,因而得到广泛的研究和应用。但是,由于TiO₂的带隙较宽（Eg = 3.2 eV）,可利用的激发光仅限于紫外光（λ< 387 nm）,而太阳光中仅含3 %⁵ %左右的紫外光,使用紫外光降解各种废水需耗费大量能源,而且还需要昂贵的设备。所以近年来,人们就如何提高TiO2的光催化活性做了大量的研究工作。通过改性TiO2,如:表面敏化、表面有机改性、过渡金属离子掺杂、非金属元素掺杂、半导体复合、酸碱改性等一些修饰技术以提高TiO₂对可见光的利用率。通常,作为光催化剂来说,混晶TiO₂比锐钛型TiO₂和金红石型TiO₂的光催化活性都要高,通过热处理使部分TiO₂从亚稳态的锐钛型向稳态的金红石型转化,从而得到具有高光催化活性的混晶TiO₂。同时,研究人员发现,某些过渡金属离子掺杂同样可以提高TiO₂的光催化活性。我们通过溶胶-凝胶和热处理的方法实现了以上两种方法的结合,合成了Fe、Co、Cr离子掺杂的混晶TiO2粉末,并利用XRD、TEM、TG-DTA、FT-IR等表征手段对制备的过渡金属掺杂混晶TiO2粉末进行了表征。以制备的过渡金属掺杂混晶TiO₂粉末为光催化剂,在太阳光/可见光照射下降解染料废水,并考察了过渡金属离子掺杂量、热处理温度、热处理时间、催化剂加入量、染料浓度、溶液pH值、照射时间对降解率的影响。结果表明:合成的过渡金属掺杂混晶TiO₂具有很高的光催化活性,在太阳光/可见光照射下降解染料废水溶液,取得了很好的效果,达到了在太阳光照射下降解工业废水的目的,为大规模利用太阳光降解工业废水开辟了新的道路,具有很好的应用前景。更多还原

【Abstract】 With the development of industrial course, people’s life has been improved dramatically. Meantime, people face the problem of energy sources lacking and environmental pollution that cause negative influence on our survival. Lots of industrial wastewaters containing high concentration organic pollutants are discharged into river and sea without treatment, which seriously damage the health of human being. How efficiently to eliminate the toxic and hazardous substances such as organic surfactant, dyestuff, noble metal ion from industrial waste effluents has become a major concern. In order to solve this problem, people do a lot of researches and adopt kinds of methods such as physical adsorption, biological degradation, semi-conductor catalysis and gas extraction to eliminate the hazardous chemical compounds from wastewater. However, these organic pollutants can not be decomposed easily and completely by physical and biological methods, because these organic dyestuff compounds in wastewater usually contain one or several benzene molecule rings. In recent years, the advanced oxidation processes which can completely decompose these hazardous organic pollutants have drawn more and more attentions.Among the advanced oxidation processes, the TiO2 as photocatalyst is studied and applied extensively by researchers because it is chemical stable, cheap, non-toxic and catalytic activity high. However, the band-gap of TiO2 (Eg =3.2 eV) is broad, so only under ultraviolet light (λ< 387 nm) irradiation TiO2 catalyst can effectively decompose the organic pollutants in wastewaters. In general, the sunlight only contains 3 %~5 % ultraviolet light, so it will consume large numbers of energy source and need costly equipments to treat wastewaters. Recently, people perform a lot of researches to improve the photocatalytic activity of TiO2. The visible light utilization efficiency of TiO2 is enhanced by modification methods such as surface sensitization, surface organic modification, transition metal ion doping, nonmetal doping, narrow semiconductor coupling and acid or base pretreatment. In general, the photocatalytic activity of the mixed crystal TiO2 is better than that of anatase and rutile TiO2. By heat-treatment, the anatase TiO2 will transform to rutile TiO2 and then the mixed crystal TiO2 is obtained. Meanwhile, researchers found that some transition metal ion doping can also improve the photocatalytic activity of TiO2. The preparation of Fe, Co, Cr ions doped mixed crystal TiO2 is realized by sol-gel and heat-treatment methods. The prepared catalysts were characterized by XRD, TEM, TG-DTA and FT-IR. The experiments of photocatalytic degradation of dyestuff wastewaters using the transition metal doped mixed crystal TiO2 as photocatalyst under sunlight or visible light irradiation were conducted and the influence factors such as dopant content, heat-treatment temperature, heat-treatment time, catalyst addition amount, dyestuff concentration, solution pH and irradiation time were investigated. The results revealed that the prepared photocatalysts behaved high photocatalytic activity under sunlight or visible light irradiation, which can completed decomposed dyestuff molecules. Thus, the experiments explore the way of large-scale using sunlight to treat dyestuff wastewater and the method has a good application future.更多还原