复合钨酸铋光催化材料的制备及其光催化性能的研究

发布时间：2018-04-23 20:05

  本文选题：Bi_2WO_6 + 半导体复合　； 参考：《宁夏大学》2017年硕士论文

【摘要】：钨酸铋(Bi2WO6)是最简单的Aurivillius型氧化物,有特殊的钙钛矿层状结构、较好的稳定性和光催化活性受到广泛的关注。但Bi2WO6仍存在一些缺点:Bi2WO6内部的光生电子-空穴对的复合几率较高、对降解物没有选择性、与反应体系分离困难等。本论文将针对Bi2WO6材料的一些缺点进行改性研究,具体内容如下:(1)以Bi(NO3)3·5H2O和Na2WO4·2H2O分别作为Bi源和W源,水为溶剂,水热法合成Bi2WO6。采用单一因素法来研究反应液的pH对Bi2WO6活性的影响。通过XRD、SEM、UV-VisDRS等表征手段对合成材料的组成、形貌、光学性质进行表征,并通过降解罗丹明B、泰勒菌素溶液来评价对Bi2WO6的光催化活性。实验结果表明:反应液的pH为9、反应时间20h、反应温度160℃时制备Bi2WO6的光催化活性最好,在可见光下光照80min时,Bi2WO6对罗丹明B、泰勒菌素溶液的降解率都能达到90%以上。(2)为了解决Bi2WO6光催化活性低的问题,本文将在Bi2WO6上复合半导体BiOCl,采用水热-溶剂热法制备BiOCl/Bi2WO6。以罗丹明B溶液为降解物,研究不同BiOCl的复合量对BiOCl/Bi2WO6的光催化活性的影响,实验结果表明:15%BiOCl/Bi2WO6的光催化活性最好,在光照20min时其对罗丹明B溶液的降解率可达99%以上,且4次循环利用后,仍很稳定且对罗丹明B的降解率仍可达98%。在可见光下,对印染废水罗丹明B、抗生素泰勒菌素都具有降解性。与Bi2WO6相比,15%BiOCl/Bi2WO6的光吸收能力增强,带隙降低,PL发射峰强度降低,且比表面积提高了400%。(3)为了解决光催化剂在降解时对降解物没有选择性的问题,本文以泰勒菌素为模板剂,BiOCl/Bi2WO6为载体,采用表面聚合法合成了分子印迹型BiOCl/Bi2WO6(MIP-BiOCl/Bi2WO6)。光降解表明:在单一溶液中,MIP-BiOCl/Bi2WO6对泰勒菌素和罗丹明B溶液的降解率在60min时分别为90%、17.2%,而BiOCl/Bi2WO6在20min时对罗丹明B的降解率和在40min时对泰勒菌素的降解率均可达100%;在泰勒菌素和罗丹明B的混合溶液中,MIP-BiOCl/Bi2WO6在60min时对泰勒菌素的降解率在90%以上,对罗丹明B的降解率仅达20.1%,BiOCl/Bi2WO6在60min时对泰勒菌素的降解率在92%以上,对罗丹明B的降解率则可达100%。实验结果验证了MIP-BiOCl/Bi2WO6对模板分子泰勒菌素具有优先降解能力。(4)为了解决Bi2WO6的光催化活性低的问题,本文还尝试使用稀土离子掺杂的方式提高Bi2WO6的光催化活性。在Bi2WO6的基础上掺杂稀土金属离子La3+,采用水热法合成La/Bi2WO6。实验结果表明:La3+修饰Bi2WO6后会导致其晶格参数d(hkl)值增加而使2θ的值就会相应的减小,La/Bi2WO6的禁带宽度增加,PL发射峰强度降低,比表面积提高了550%。5%La/Bi2WO6的光催化活性最好,光照25min时其对罗丹明B降解率为98%,在可见光下,对印染废水罗丹明B、抗生素泰勒菌素都具有降解性,且循环利用3次后,其仍很稳定且对罗丹明B的降解率仍可达97%。(5)为了解决光催化剂在降解污染物后不能及时分离、回收再利用的问题,本文将La/Bi2WO6与磁性的γ-Fe2O3复合来制备磁性γ-Fe2O3/La/Bi2WO6复合光催化剂,利用外加磁场使光催化剂与反应体系能够快速、有效的分离。5%γ-Fe2O3/La/Bi2WO6的光催化活性最好,光降解70min时其对罗丹明B的降解率可达98.6%。在可见光下,对印染废水罗丹明B、抗生素泰勒菌素都具有降解性,且循环利用3次后,其对罗丹明B的降解率仍可达95.3%。通过VSM和外磁场的分离实验可知,5%γ-Fe2O3/La/Bi2WO6的比饱和磁化强度是8.19emu·g-1,通过外加磁场作用使5%γ-Fe2O3/La/Bi2WO6与反应溶液快速的分离,达到分离回收的目的。
[Abstract]:Bismuth tungstate (Bi2WO6) is the simplest Aurivillius type oxide, with a special calcium and titanium layer like structure. The good stability and photocatalytic activity are widely concerned. But there are still some shortcomings in Bi2WO6: the recombination probability of the photoelectron electron hole pair in Bi2WO6 is higher, the degradation is not selective, and the separation of the reaction system is difficult. This paper will study some defects of Bi2WO6 materials. The specific contents are as follows: (1) Bi (NO3) 3. 5H2O and Na2WO4. 2H2O are used as Bi source and W source, water as solvent and hydrothermal method to synthesize Bi2WO6. to study the effect of pH on Bi2WO6 activity. The composition, morphology and optical properties of the material were characterized, and the photocatalytic activity of Bi2WO6 was evaluated by the degradation of Luo Danming B and Taylor bacterin. The results showed that the pH of the reaction liquid was 9, the reaction time was 20h, and the reaction temperature was 160, and the photocatalytic activity of Bi2WO6 was best. When the light illumination was 80min, the Bi2WO6 was to Luo Danming B, Taylor bacteria. The degradation rate of the prime solution can reach more than 90%. (2) in order to solve the problem of low photocatalytic activity of Bi2WO6, this paper will compound semiconductor BiOCl on Bi2WO6, use hydrothermal solvothermal method to prepare BiOCl/Bi2WO6. with Luo Danming B solution as degrading substance, and study the effect of the compound amount of different BiOCl on the photocatalytic activity of BiOCl/Bi2WO6, the experimental result table Ming: 15%BiOCl/Bi2WO6 has the best photocatalytic activity. The degradation rate of Luo Danming B solution can reach more than 99% when light is 20min, and after 4 cycles, it is still stable and the degradation rate of Luo Danming B can still be 98%. in visible light, the Luo Danming B and antibiotic Taylor bacteriocin in printing and dyeing wastewater are all degrading. Compared with Bi2WO6, 15%BiOCl/Bi2WO The light absorption capacity of 6 is enhanced, the band gap is reduced, the intensity of PL emission peak is reduced, and the specific surface area is increased by 400%. (3) in order to solve the problem that the photocatalyst is not selective in degradation. This paper uses Taylor as a template, BiOCl/Bi2WO6 as the carrier, and uses the surface polymerization to synthesize the molecularly imprinted BiOCl/Bi2WO6 (MIP-BiOCl/Bi2WO6). Photodegradation showed that in a single solution, the degradation rate of MIP-BiOCl/Bi2WO6 to Taylor and Luo Danming B was 90%, 17.2% respectively at 60min, while the degradation rate of Luo Danming B and the degradation rate of Taylor to Taylor were 100% at 20min, and MIP-BiOCl/Bi2WO6 in the mixed solution of Taylor and Luo Danming B, MIP-BiOCl/Bi2WO6. At 60min, the degradation rate of Taylor was above 90%, the degradation rate of rhodamine B was only 20.1%, the degradation rate of Taylor was more than 92% at 60min, and the degradation rate of rhodamine B could reach 100%. test results that MIP-BiOCl/Bi2WO6 had the ability to degrade the template molecule Taylor bacteria. (4) to solve Bi2WO 6 of the problem of low photocatalytic activity, this paper also tries to improve the photocatalytic activity of Bi2WO6 by doping rare earth ions. On the basis of Bi2WO6, doping rare earth metal ions La3+ and using hydrothermal method to synthesize La/Bi2WO6. experiment results show that La3+ modified Bi2WO6 will lead to the increase of the lattice parameter d (hkl) value, and the value of 2 theta will be corresponding. Decrease, the width of the band gap of La/Bi2WO6 is increased, the intensity of PL emission peak is reduced, the photocatalytic activity of 550%.5%La/Bi2WO6 is better than the surface area, and the degradation rate of Luo Danming B is 98% when light is 25min. Under visible light, the Luo Danming B and the antibiotic Taylor bacteriin are all degrading, and after 3 cycles, it is still very stable and opposite. The degradation rate of B is still up to 97%. (5). In order to solve the problem that the photocatalyst can not be separated in time and reused after the photocatalytic degradation of pollutants, the La/Bi2WO6 and magnetic gamma -Fe2O3 are combined to prepare the magnetic gamma -Fe2O3/La/Bi2WO6 composite photocatalyst. Using the applied magnetic field, the photocatalyst and the reaction system can quickly and effectively separate.5%. The photocatalytic activity of gamma -Fe2O3/La/Bi2WO6 is the best, and the degradation rate of Luo Danming B can reach 98.6%. when 70min is degraded in visible light. The degradation of Luo Danming B and antibiotic Taylor bacteria in printing and dyeing wastewater, and after 3 cycles of recycling, the degradation rate of Luo Danming B can still be up to 95.3%. through the separation experiment of VSM and external magnetic field, and it can be found that 5% y -Fe2 The specific saturation magnetization of O3/La/Bi2WO6 is 8.19emu g-1. The purpose of separation and recovery is achieved by separating 5% gamma -Fe2O3/La/Bi2WO6 from the reaction solution by the effect of applied magnetic field.

【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O644.1

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