【作者】 孟庆海；

【导师】 周国伟；

【作者基本信息】 山东轻工业学院 ， 制浆造纸工程， 2007， 硕士

【摘要】 二氧化钛在空气净化、水的杀菌消毒和含有机污染物的废水光催化降解中有重大的应用,且无二次污染,成为目前最引起科学家关注的绿色环保型催化剂之一。介孔TiO₂由于具有很高的比表面积和规整的介孔孔道,具有比TiO₂更优越的物理和化学性能,通过掺杂过渡金属离子制备介孔复合材料,能有效提高其光催化活性和反应效率,在处理废水有机污染物等方面具有广阔的应用前景。本项研究以三嵌段共聚物P123作模板,采用溶胶–凝胶法制备掺杂Mn²⁺和Yb³⁺的介孔TiO₂复合材料,利用X–射线衍射（XRD）、透射电子显微镜（TEM）、扫描电子显微镜（SEM）、N₂吸附-解吸分析和傅里叶变换红外光谱分析（FT–IR）等手段对样品进行表征。结果表明:金属离子的掺杂对改性介孔二氧化钛的晶型和平均粒径有很大的影响;Mn²⁺和Yb³⁺离子起到了光生电子捕获剂的作用,减少了光生电子–空穴对的复合几率;金属离子的掺杂量对TiO₂的光催化活性有一定的影响,掺杂量过大时,会有多余的金属离子包裹在TiO₂的表面,阻碍了紫外线对TiO₂的照射,影响TiO₂的光催化活性。适量Mn²⁺和Yb³⁺掺杂能有效抑制纳米TiO₂晶粒的成长,使晶体发育良好,粒度分布均匀,产物分散性较好;Mn²⁺和Yb³⁺均匀分散在TiO₂中;金属离子掺杂使TiO₂粒子表面含有大量羟基,有利于提高TiO₂的光催化活性,提高TiO₂对太阳光的利用率。以对氯苯酚为目标降解物,考察了掺杂过渡金属离子后介孔TiO₂光催化性能的变化。发现掺杂后的介孔TiO₂复合材料比纯的介孔TiO₂有更好的光催化性能,能有效提高对氯苯酚的光催化降解。介孔TiO₂复合材料光催化氧化降解反应受温度、催化剂用量、通氧方式、光照时间的影响较大:温度升高有利于目标降解物的去除;催化剂用量存在一个最佳值。用量过多或过少都会影响光催化反应的降解率。过少的催化剂不足以完全降解有机物,过多则会使溶液变的混浊,使紫外光难以透过,阻碍紫外线对TiO₂的照射,从而降低TiO₂的催化效率;通氧方式对降解效果也有很大的影响,通入工业氧时,降解效果最佳,通空气次之,不通气,降解效果最差;光催化反应的降解率随光照时间的增长而增大,反应速率均是先快后慢。分别以Mn²⁺/TiO₂和Yb³⁺/TiO₂介孔复合材料作催化剂处理造纸废水,考察了光催化体系中光照时间、催化剂的用量、初始pH值、通氧方式等对降解造纸废水的影响因素,探明了在反应条件为:催化剂用量为1.5 g/L、初始pH = 12、连续通氧条件下降解效果最佳,在紫外光照射下,反应12 h后,废水的CODCr去除率分别达到78.3%和75.3%,色度去除率分别达到92.5%和91.4%。与纯的介孔TiO₂相比均有了很大提高。更多还原

【Abstract】 Titanium dioxide （TiO₂） is one of the green catalysts, which has attracted much attention due to its promising applications in the purification of air, the bactericidal action of water, and environmental photocatalytic degradation of organic pollutant compounds in waste water. The mesoporous TiO₂ has the better physical and chemical properties than TiO₂ because of its high specific surface area and well-regulated pore structure. The photocatalytic activity and efficiency of TiO₂ can be enhanced obviously and the degradation of organic wastewater has a promising future by doping some transitional metal ions.In this work, Mn²⁺-doped and Yb³⁺-doped TiO₂ were prepared by a sol–gel process and triblock copolymer P123 as the templates. The composition, micro-structure and properties of the prepared TiO₂ powders were characterized by X–ray diffraction （XRD）, Transmission electron microscopy （TEM）, Scanning electron microscope （SEM）, N2 adsorption-desorption and Fourier transform infrared spectrophotometer （FT–IR）, and so on. The results indicated that the crystallographic forms and diameter of the samples were greatly affected by doping of transitional metal ions. Mn²⁺ and Yb³⁺ could be an effective capturer of photo–induced electron and reduced the recombination of photo–generated holes and electrons. The amount of doping has effect on the photocatalytic activity of mesoporous TiO₂: redundant metal ions may surround the TiO₂ to block the ultraviolet irradiation, which depress the activities of samples. The suitable doping of Mn²⁺ and Yb³⁺ could decrease the growth of anatase grains and could effectively improve the dispersion of grains. Doped ions had not been found in FT–IR of complex TiO₂ materials and there were an amount of hydroxyl groups on surface of the samples.The photocatalytic activity of metal ions-doped TiO₂ was much better than the pure mesoporous TiO₂ in degradation of P-chlorophenol. The effects of temperature, amount of catalysts, the different modes of oxygen aeration and irradiation time on the photocatalytic degradation were great. The high temperature was advantaged the removal of P-chlorophenol. The lacking catalysts could not degraded P-chlorophenol completely, while the overabundance would make the solution turbid, blocking the ultraviolet irradiation. The removal rate received the maximum when the oxygen was aerated. The degradation rate increased as the irradiation time.The Mn²⁺/TiO₂ and Yb³⁺/TiO₂ were used as catalysts to treat the papermaking wastewater. The influencing factors of the weight of photocatalysts, the irradiation time, the initial pH value and different modes of oxygen aeration were examined. The removing rate of CODCr of papermaking wastewater was up to 78.3 % and 75.3%, the removing rate of chroma was 92.5% and 91.4% respectively. The best parameters during the photocatalysis processes were determined also, its best conditions were photocatalyst amount 1.5 g/L, pH = 12, bulling with oxygen ultraviolet irradiation and reaction time 12h. There were great improvements compared with the pure mesoporous TiO₂.更多还原