【作者】 于新意；

【导师】 张高科；

【作者基本信息】 武汉理工大学 ， 环境工程， 2006， 硕士

【摘要】 染料废水具有成分复杂、色度高、排放量大、可生化性差的特点,一直是废水处理中的难题。采用光催化氧化法处理有机废水,具有处理效率高、工艺设备简单、操作条件容易控制、无二次污染等突出优点,为染料废水的工业化处理提供了新思路和新途径。本文以SrCO₃,Bi₂O₃和La₂O₃为原料,采用固相法制备Sr₂Bi₂O₅和掺杂La₂O₃的Sr₂Bi₂O₅化合物,并利用X射线衍射（XRD）、扫描电镜（SEM）等测试方法对样品进行了表征,同时以酸性红G为对象,模拟染料废水进行了催化降解实验。XRD和SEM分析结果表明,在900℃焙烧4h时可合成纯度很高具有氧位缺的Sr₂Bi₂O₅粉末晶体,该化合物为属于正交晶系,所属空间群为Pnma[62],晶胞参数是a=1.430nm b=0.6172nm c=0.7625nm。合成的晶体晶粒均匀,结晶度较好。掺杂La₂O₃并没有改变Sr₂Bi₂O₅的结构和晶体形貌。进行了Sr₂Bi₂O₅对酸性红G模拟的染料废水的光催化降解实验。考察了光源,合成温度及时间,反应物的初始浓度,催化剂的投加量等因素对光催化降解的影响。实验表明,在荧光灯（λ=365nm）照射下,用900℃焙烧4h制得的Sr₂Bi₂O₅样品,降解浓度为50mg/L酸性红G溶液,2h后的降解率即可达到98.6%,其光催化活性高于公认的对比样德国P25-TiO₂;当酸性红G初始浓度为90mg/L时,2h后降解率也可达77.0%;光催化降解率与溶液初始浓度成反比,催化剂的最佳投加量为3.0mg/L左右。掺杂适量的La₂O₃能够使Sr₂Bi₂O₅光催化活性略有提高,但是当掺杂La₂O₃量较大时,反而会使Sr₂Bi₂O₅光催化活性降低。最佳掺镧量为0.4 wt.%。动力学研究表明,在本实验条件下,Sr₂Bi₂O₅和掺杂La₂O₃的Sr₂Bi₂O₅光催化降解酸性红G的反应属于一级反应,可以用L-H动力学方程描述。通过紫外-可见光谱和红外光谱分析,初步探讨了Sr₂Bi₂O₅降解酸性红G的机理以及酸性红G脱色历程,发现酸性红G溶液的脱色最终不是被催化剂所吸附,而是在荧光灯照射下被Sr₂Bi₂O₅的催化降解。最后还分析了掺杂La₂O₃对Sr₂Bi₂O₅光催化活性的影响。更多还原

【Abstract】 It is difficult for dye effluent to be treated because of its complex component,high chroma,increasing amount and non-biodegradability. Photocatalytic oxidation technology for treating dye effluent has a lot advantages such as high efficiency,facile operation,lower cost and non-secondary contamination,and has attracted more and more attentionsIn the paper,Sr₂Bi₂O₅ and La-doped Sr₂Bi₂O₅ were synthesized with SrCO₃,Bi₂O₃ and La₂O₃ by solid-state reaction.The samples obtained were characterized by X-ray diffraction（XRD）,scan electron microscopy （SEM）.The photocatalytic activities of the Sr2Bi₂O₅ samples prepared were evaluated by the photodegradation of azo dye acid red G on the catalysts.The results of X-ray and SEM analyses showed that the single-phase, homogeneous microcrystalline Sr₂Bi₂O₅ powders were synthesized successfully at temperature 900℃for a short holding time（4h）in static air.The reflections of the powders obtained were indexed in the orthorhombic space group Pnma[62]with Z = 4 and X-ray cell parameters a = 1.4261nm,b = 0.6172nm,c = 0.7625nm.The samples obtained were with the homogenous distribution of particles.La-doped Sr₂Bi₂O₅ was not changed the structure and the morphology of the compound Sr₂Bi₂O₅ crystal.The influences of the calcining temperature and time of the catalysts, irradiation intensity,the dosage of the catalysts and the initial concentration of acid red G solution on the photocatalytic degradation rate of acid red G were studied.The results showed that the Sr₂Bi₂O₅ sample by solid-state method at 900℃for 4h showed a higher photocatalytic activity than P25-TiO₂.50mg/L of acid red G solution could be decoloured completely by using Sr₂Bi₂O₅ as photocatalyst within 120min under fluorescent irradiating（λ=365nm）.The best degradation effect can be obtained when the dosage of the photocatalyst Sr₂Bi₂O₅ is 3.0g/L.The photocatalytic activity of the La-doped Sr₂Bi₂O₅ is slightly higher than that of Sr₂Bi₂O₅ when the doping amount of La and decreases with increasing the doping amount of La.The photocatalytic degradation reactions of acid red G solution on the catalyst Sr₂Bi₂O₅ comply with the first order kinetics equation and could be characterized by L-H equation.The photodegradation mechanisms of acid red G on the catalyst were analyzed by infrared analysis（IR）and ultraviolet-visible light analysis（UV-Vis）.In conclusion,the degradation of acid red is as a result of catalyst and irradiation but adsorption action. The effect of La203 doping on the photocatalysis was discussed as well.更多还原