活性氧成分对光照自然水体生物膜体系中SDBS降解的作用

发布时间：2017-12-28 18:45

本文关键词：活性氧成分对光照自然水体生物膜体系中SDBS降解的作用　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：自然水体生物膜作为复合微生物群落会对周围的微环境特征造成影响,通过富集、吸附、转化等作用改变自然水体中有机污染物的迁移和转化规律。相关研究表明,光照条件下藻类光合作用生成的活性氧(ROS)等活性物质会促进有机污染物的降解,由藻类释放到自然水体中的ROS种类繁多,各ROS在有机污染物降解过程中所起的作用不尽相同,对有机污染物的降解机制尚不清晰。本文为深入探究自然水体生物膜产生的ROS对有机污染物降解的作用,以十二烷基苯磺酸钠(SDBS)为有机污染物的代表来构建模拟实验体系,通过选择合适的活性氧清除剂(FRS)来清除特定的ROS,进而确定其在SDBS降解过程中发挥的作用。通过初步筛选,选择比较常见的FRS进行实验。在H_2O_2体系、SDBS体系以及H2O_2~-SDBS体系中选取FRS的最适浓度,然后在水-生物膜体系中分别测定·O_2~-、·OH、~1O_2三种ROS荧光探针的荧光强度,以此计算FRS的清除率,确定最适用于实验体系的FRS。同时验证添加时间对FRS活性的影响,确定各FRS的使用条件。选取·O_2~-、H_2O_2、·OH和~1O_2这四种代表性比较强的ROS,研究其在SDBS降解过程中的作用。通过仅保留水-生物膜体系中的某一种ROS和仅清除该种ROS,分别从直接和间接的角度研究单一ROS对SDBS降解的作用;此外,通过清除全部四种ROS及清除氧自由基,探究其他因素对SDBS降解的作用。为了深入研究ROS对SDBS降解的作用,通过清除水-生物膜体系中的某两种ROS,结合上述相关实验来确定各ROS对SDBS降解作用的大小。研究结果表明,各FRS最适浓度分别为:Vc和硫脲为0.5 mg/L,儿茶酚、CAT和IPA为0.7 mg/L,L-GSH、SOD、甘露醇、组氨酸和二苯胺为1.0 mg/L。荧光探针的荧光强度变化表明最适浓度的FRS可将水-生物膜体系中的ROS有效清除。通过对比清除率,最终选择SOD、CAT、甘露醇和组氨酸分别作为·O_2~-、H_2O_2、·OH和~1O_2的清除剂。水-生物膜体系中的实验证明了FRS在体系中的停留时间不会影响其活性。清除或保留水-生物膜体系中的·O_2~-、H_2O_2、·OH或~1O_2后,SDBS降解量都有不同的变化,这表明这四种ROS均通过直接或间接的方式参与到SDBS的降解过程中。H_2O_2浓度高、存在稳定,对SDBS的降解作用最大;·OH活性较强,在SDBS降解过程中比较重要;·O_2~-是最早生成的ROS,对SDBS降解也有一定作用;~1O_2对SDBS的降解作用最小。除ROS外,体系中存在其他因素(如生物膜上的细菌等)也会促进SDBS降解。清除两种ROS的相关实验可进一步证明各ROS对SDBS的降解有促进作用,单一ROS并不是导致SDBS降解的唯一因素。各ROS之间可以相互转化,但转化关系较为复杂。
[Abstract]:Natural water biofilm as a composite microbial community will affect the characteristics of the surrounding microenvironment. It can change the migration and transformation of organic pollutants in natural waters through enrichment, adsorption and transformation. Related research shows that light reactive oxygen species generated under the conditions of algae photosynthesis (ROS) and other active substances can promote the degradation of organic pollutants by algae released into the natural water ROS variety, the ROS in the degradation of organic pollutants in the process of action is not the same, the degradation mechanism of organic pollutants is not clear. This paper is to probe into the function of natural biofilm produced by ROS on the degradation of organic pollutants, with twelve sodium dodecyl benzene sulfonate (SDBS) as the representative of organic pollutants to construct the simulation system, by selecting appropriate scavengers of reactive oxygen species (FRS) to remove specific ROS, and then determine its play in the process of SDBS degradation effect. Through the preliminary screening, the more common FRS was selected to carry out the experiment. The optimum concentration of FRS was selected in H_2O_2 system, SDBS system and H2O_2~-SDBS system. Then, the fluorescence intensity of three ROS fluorescent probes, O_2~-, OH and ~1O_2, were measured in water biofilm system respectively, so as to calculate FRS scavenging rate and determine the most suitable FRS for experimental system. At the same time, the effect of addition time on the activity of FRS was verified, and the use conditions of each FRS were determined. Four representative ROS, such as O_2~-, H_2O_2, OH and ~1O_2, were selected to study the role of the ROS in the degradation of SDBS. By reservations of only one ROS in the water biofilm system and only removing the ROS, we studied the effect of single ROS on SDBS degradation from a direct and indirect perspective. In addition, we removed all four ROS and scavenged oxygen free radicals to explore the effect of other factors on SDBS degradation. In order to further study the effect of ROS on the degradation of SDBS, two kinds of ROS in water biofilm system were removed, combined with the above related experiments, to determine the size of ROS degradation to SDBS. The results showed that the optimum concentrations of FRS were Vc and thiourea, 0.5 mg/L, catechol, CAT and IPA were 0.7 mg/L, L-GSH, SOD, mannitol, histidine and two aniline were 1 mg/L. The fluorescence intensity changes of the fluorescent probe indicate that the optimum concentration of FRS can effectively remove the ROS in the water biofilm system. By comparing scavenging rates, SOD, CAT, mannitol and histidine were selected as the scavengers of O_2~-, H_2O_2, OH and ~1O_2 respectively. Experiments in the water biofilm system show that the retention time of FRS in the system does not affect its activity. After removal or retention of O_2~-, H_2O_2, OH or ~1O_2 in water biofilm system, the SDBS degradation amount varied differently, indicating that these four kinds of ROS were involved in the degradation process of SDBS through direct or indirect way. H_2O_2 concentration is high, stable, and has the greatest degradation effect on SDBS. OH activity is stronger, and it is more important in SDBS degradation process. O_2~- is the first generation of ROS, and also plays a role in SDBS degradation. ~1O_2 has the least degradation effect on SDBS. In addition to ROS, there are other factors in the system, such as bacteria on the biofilm, which can also promote the degradation of SDBS. The related experiments of eliminating two kinds of ROS can further prove that ROS can promote the degradation of SDBS, and single ROS is not the only factor that leads to the degradation of SDBS. Each ROS can be converted to each other, but the transformation relationship is more complex.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52

【相似文献】