【作者】 李莹；

【导师】 费学宁；

【作者基本信息】 天津城市建设学院 ， 环境工程， 2008， 硕士

【摘要】 在全球性环境污染和能源危机日趋严重的今天,如何有效利用太阳能来治理污染已引起世界各国的广泛重视。TiO₂光催化氧化技术因其具有能耗低、反应条件温和、操作简便、可减少二次污染等突出优点而日益受到重视。具有高量子效率、能充分利用太阳能的高活性光、具有良好沉降性能催化剂的制备与应用,已成为环境科学领域广泛关注和研究的热点课题。采用溶胶-凝胶法制备多孔氧化钛,并耦合CdS,制备出对可见光有一定响应又易于分离的多孔耦合CdS/TiO₂催化剂。研究表明,采用煅烧—碱洗—浸渍的制备方法,CdS掺杂比例为3%,煅烧温度为700℃,煅烧时间为3h,碱洗时间为20h时,制备的多孔CdS/TiO₂催化剂性能较优。于太阳光下以溴氨酸溶液为底物,考察了光照方式、底物浓度、催化剂用量、pH值、氯化钠含量、降解时间等因素对降解过程的影响。试验表明,太阳光直射时,溶液的降解效果较好;对于30mg/L的溴氨酸溶液,催化剂的最佳用量为2g/L,最佳pH值为10,少量氯化钠的存在可提高反应体系的褪色效果,此外,当溴氨酸浓度高于50mg/L时,溶液的降解效果显著降低。多孔CdS/TiO₂催化剂的沉降性能优于P25,更易分离。溴氨酸水溶液在多孔CdS/TiO₂催化剂太阳光催化体系中降解脱色反应用L—H方程描述,反应级数为零级反应;随着初始浓度的增大,初始反应速率成增大趋势,催化剂投加量为2g/L时,反应速率最大,碱性条件下的降解反应速率较中性和酸性条件下快,少量氯化钠的存在可加快反应速率。更多还原

【Abstract】 As world wide enviornment pollution and energy resource crisis are graving gradually today, effective utilization of sunlight to solve pollution problems has became of great interest in many countries. The photocatalytic oxidation technique of TiO₂ has been paid more and more attention for the advantage of less energy cost, mild reaction condition, easy operation, less secondary pollution. The synthesis and applications of photocatalyst with high quantum-efficiency and high activity,which is easy to settle down and separate and can utilize sunlight efficiently, have became hot research topics in the field of environment science.Lacunaris coupling CdS/TiO₂ photocatalyst which can be activated by visible light and easily separated from liquor was prepared by coupling CdS with lacunaris TiO₂ by a sol-gel process. Primary research suggested that the optimal preparation condition is method of calcining-alkali marinating-coupling, calcining temperature 700℃, CdS adulterant proportion3%, and alkali marinating time 20h. The photocatalytic degradation by sunlight was investigated with bromamine acid as pollutant, and the manner of light, initial concentration of the pollutant, dosage of photocatalyst, pH value, sodium chloride concentration and reaction time on the photocatalytic degradation were discussed. The results suggested the optimal degradation condition is point-blank sunlight, dosage of photocatalyst 2g/L , and pH value 10 for the bromamine acid solution of 30mg/L. Meanwhile the existence of a few sodium chloride may enhance chroma degradation, furthermore, the degradation rate decreased distinctly when the concentration of bromamine acid is higher than 50mg/L. Comparing with P25, lacunaris coupling CdS/TiO₂ has better settlement and is easier to be seperated. For the system of degradation using lacunaris coupling CdS/TiO₂ with bromamine acid as pollutant by sunlight, chroma degradation can be discribed by L-H equation, it is zero kinetic reaction. The initial reaction rate constant increases, as initial concentration of the pollutant increasing. When dosage of photocatalyst is 2g/L, the initial reaction rate constant is the fastest. The reaction rate constant in the condition of alkali is faster than in the condition of neutral and acidic. Existence of a few sodium chloride may improve chroma degradation the reaction rate constant.更多还原