BiOBr光催化降解苯系物及动力学研究

发布时间：2018-05-04 22:31

  本文选题：BiOBr + 光催化　； 参考：《山东大学》2017年硕士论文

【摘要】：近几年,随着中国经济和工业的高速发展,环境污染越来越严重,大气污染问题逐渐获得重视,其中,挥发性有机物(VOCs)更是受到了广大学者的关注。苯系物是VOCs的重要组成成分,其非常难降解、在环境空气中浓度较高且对环境和人体的危害较大。在苯系物的众多治理技术中,光催化氧化法具有操作过程简单、污染物去除效率高、运行能耗低、经济可行且无二次污染等优点,成为治理VOCs的新趋势。BiOBr是一种新型的光催化材料,由于其具有独特的层状结构和优良的光催化性能,得到了广大研究者的关注,BiOBr通过不同的方法制备,会得到不同的结构及性质。因此,此次研究的目的是寻找一种简单有效的方法制备出具有高的光催化性能的BiOBr催化剂,用制备出的BiOBr作为催化剂,在紫外光下催化降解气相苯系物并探讨降解过程中的影响因素及光催化降解动力学规律。本实验以Bi(N03)3·5H20为铋源,KBr为溴源,乙二醇为溶剂,利用溶剂热法来制备所需的BiOBr催化剂,实验发现:制备的BiOBr的催化活性受制备过程中的溶剂热温度和初始反应物中Bi与Br的摩尔比的影响。通过XRD、SEM和BET对制备的BiOBr催化剂进行了表征,发现Bi与Br的摩尔比为1:1时制备的BiOBr催化剂的结晶性最好;120℃溶剂热温度时制备的BiOBr催化剂微球具有结晶性好、尺寸均匀、分散良好、微球由较多的单片状催化剂构成、催化剂山中孔和微孔结构构成、比表面积大等优点。在光催化反应中,采用Bi与Br的摩尔比为1:1且120℃时制备的BiOBr作为催化剂,紫外光照射90min后,苯的降解率为82.86%,邻二甲苯的降解率为98.30%,结果表明,在紫外光下,苯系物的降解效果由大到小依次为二甲苯,甲苯和苯,而二甲苯的三种异构体的的降解效果山大到小为邻二甲苯,间二甲苯和对二甲苯。此次实验探讨了光催化过程中苯系物初始反应浓度和BiOBr投加量对催化反应的影响。结果表明,当BiOBr投加量一定时,随着苯系物初始反应浓度的增加,苯系物的降解率反而下降;BiOBr在低投加量下,随着BiOBr投加量的增加,苯系物的降解效率增大,当BiOBr的投加量达到一定量后,随着BiOBr投加量的增加,苯系物的降解效率变化不明显。本实验对苯系物光催化降解动力学规律进行研究,发现苯系物光催化降解过程符合一级反应动力学规律。对于催化反应来说,催化剂的使用寿命是衡量催化剂使用效果的一个重要指标。为了考察实验中制备的BiOBr的稳定性,确定其使用寿命,本实验以苯作为苯系物的代表物来考察BiOBr催化剂的稳定性,重复四次实验后,发现苯的降解率由82.86%下降至77.95%,降解率没有明显降低,结果表明:制备的BiOBr催化剂性质稳定,可以重复利用。
[Abstract]:In recent years, with the rapid development of economy and industry in China, environmental pollution is becoming more and more serious, and the problem of air pollution has been paid more and more attention. Benzene series is an important component of VOCs, which is very difficult to degrade, and has a high concentration in the ambient air and great harm to the environment and human body. Among the many treatment technologies of benzene series, photocatalytic oxidation has the advantages of simple operation, high pollutant removal efficiency, low energy consumption, economic feasibility and no secondary pollution. BiOBr is a new kind of photocatalytic material. Because of its unique layered structure and excellent photocatalytic performance, BiOBr has attracted the attention of many researchers in the preparation of BiOBr by different methods. Different structures and properties will be obtained. Therefore, the purpose of this study is to find a simple and effective method to prepare BiOBr catalyst with high photocatalytic performance, using the prepared BiOBr as catalyst. The catalytic degradation of gaseous benzenes under ultraviolet light was carried out and the influencing factors and kinetics of photocatalytic degradation were discussed. In this experiment, Bi(N03)3 5H20 was used as bismuth source and KBR as bromine source and ethylene glycol as solvent to prepare BiOBr catalyst by solvothermal method. It is found that the catalytic activity of the prepared BiOBr is affected by the solvothermal temperature and the molar ratio of Bi to Br in the initial reactants. The prepared BiOBr catalyst was characterized by XRDA SEM and BET. It was found that the crystallinity of the BiOBr catalyst prepared at 1:1 was the best when the molar ratio of Bi to Br was 1:1. The BiOBr catalyst microspheres prepared at 120 鈩，

本文编号：1844971