Cupriavidus gilardii CR3对铜的吸附及其生物膜—多孔介质中铜迁移的研究

发布时间：2018-02-27 04:31

本文关键词： Cupriavidus gilardii CR3 铜离子吸附生物膜迁移　出处：《东北师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：重金属铜离子进入地下环境的第一道天然屏障是含有多孔介质的土壤水带层,也是微生物主要存在和运动的区域。在地下环境中,微生物通常以生物膜形式存在,并且微生物的生物膜影响重金属铜在地下环境中的迁移。本文以具有天然铜抗性的细菌(Cupriavidus gilardii CR3)活细胞为研究对象,探讨了C.gilardii CR3对重金属铜的吸附特性和机理,及重金属铜对C.gilardii CR3生物膜的影响,同时,研究了不同铜离子浓度在C.gilardii CR3生物膜-石英砂柱中的迁移。在此基础上,研究了生物膜对重金属铜迁移的影响及其生物膜胞外聚合物(EPS)作用。主要研究结论如下:(1)C.gilardii CR3对重金属铜的吸附特性。利用重金属抗性细菌C.gilardii CR3吸附重金属铜离子,研究pH、初始铜离子浓度和吸附时间对C.gilardii CR3吸附铜的影响,采用等温吸附和动力学模型拟合实验结果。发现C.gilardii CR3对铜离子吸附量随pH的增加而增加,最适的pH为5.0,实际最大吸附量是18.33mg/g;吸附过程符合Langmuir模型,理论预测的最大吸附量是18.25 mg/g,与实测数值接近;吸附过程分两步进行,即初始的快速反应和后续的缓慢反应;吸附过程符合二级动力学和颗粒内扩散方程,这些结果表明该吸附过程是单分子化学吸附和物理内部扩散共同作用。(2)C.gilardii CR3对重金属铜的吸附机理。通过Zeta电位、扫描电子显微镜-X射线能量散射能谱(SEM-EDX)和傅里叶红外光谱(FTIR)方法对吸附铜离子前后的C.gilardii CR3形貌和结构进行表征。Zeta电位表明静电引力使官能团发生去质子化,C.gilardii CR3表面负电荷吸附铜离子。SEM-EDX证明C.gilardii CR3对铜离子的吸附为表面吸附。FTIR结果显示参与吸附的官能团主要有羟基、羧基、磷酸和氨基等。此外,当铜离子存在时,C.gilardii CR3具有自我保护能力,分泌网状的EPS保护细胞受到破损,在实际应用中具有潜在的应用价值。(3)重金属铜对C.gilardii CR3生物膜的影响。利用不同浓度的LB培养基模拟细菌地下环境生存的营养条件,运用结晶紫染色方法分析确定C.gilardii CR3生物膜形成的最适营养条件,发现20%LB可以使C.gilardii CR3形成较好的生物膜。通过结晶紫染色法和CLSM分析32 mg/L铜离子可以促进抗性菌C.gilardii CR3分泌较多的蛋白和多糖,形成的生物膜面积最大。(4)重金属铜在C.gilardii CR3生物膜-石英砂柱中的迁移。在C.gilardii CR3生物膜-石英砂柱中注入12 h的20%LB使C.gilardii CR3短期饥饿,形成均匀稳定生物膜。生物膜柱对三种浓度的铜离子迁移都有影响,并且6.4 mg/L、32 mg/L和64 mg/L铜离子的穿透曲线(BTCs)在生物膜柱中呈现不规则的“几”字形,随着铜离子浓度升高,生物膜柱对铜离子的截留越小,穿透能力越大。另外,生物膜柱对铜离子的截留和生物量分布趋势一致,即实验柱两端较多,中间最少,并且铜离子在柱中截留主要是EPS对铜离子的吸附作用。
[Abstract]:The first natural barrier for copper ions to enter the underground environment is the soil water belt layer containing porous media, which is also the main area where microorganisms exist and move. In the underground environment, microorganisms usually exist in the form of biofilms. The biofilm of microorganism affected the migration of heavy metal copper in underground environment. In this paper, the adsorption characteristics and mechanism of C. gilardii CR3 on copper were studied in the living cells of Cupriavidus gilardii CR3, a bacterium with natural copper resistance. And the effect of heavy metal copper on C. gilardii CR3 biofilm. The migration of copper ions in C. gilardii CR3 biofilm-quartz sand column was studied. The effects of biofilm on the migration of heavy metal copper and the effect of biofilm extracellular polymer (EPS) on copper transfer were studied. The main conclusions were as follows: 1. The adsorption characteristics of heavy metal copper by CR3. Heavy metal copper ions were adsorbed by heavy metal resistant bacteria C. gilardii CR3. The effects of pH, initial copper concentration and adsorption time on the adsorption of copper by C. gilardii CR3 were studied. The experimental results were fitted by isothermal adsorption and kinetic model. It was found that the adsorption capacity of C. gilardii CR3 increased with the increase of pH. The optimum pH value is 5.0, the actual maximum adsorption capacity is 18.33 mg / g, the adsorption process accords with Langmuir model, and the predicted maximum adsorption amount is 18.25 mg / g, which is close to the measured value, and the adsorption process is divided into two steps, that is, the initial rapid reaction and the subsequent slow reaction. The adsorption process accords with the second-order kinetics and intraparticle diffusion equation. These results indicate that the adsorption process is the adsorption mechanism of heavy metal copper by means of monolayer chemisorption and physical internal diffusion. SEM and FTIR methods for characterizing the morphology and structure of C.gilardii CR3 before and after copper ion adsorption. Zeta potential indicates that electrostatic gravitation results in deprotonation of functional groups by deprotonation of C. gilardii CR3 table. Surface negative charge adsorption of copper ions. SEM-EDX showed that the adsorption of copper ions by C.gilardii CR3 was surface adsorbed. FTIR results showed that the functional groups involved in the adsorption were mainly hydroxyl groups. In addition, when copper ions exist, C. gilardii CR3 has the ability to protect itself, secreting reticular EPS to protect cells from being damaged. The effect of heavy metal copper on C. gilardii CR3 biofilm was studied. The nutrient conditions of bacteria in underground environment were simulated by using different concentration LB medium. The optimum nutritional conditions for the formation of C. gilardii CR3 biofilm were determined by crystal violet staining. It was found that 20LB could make C.gilardii CR3 form a better biofilm. The copper ions of 32 mg/L could be detected by crystal violet staining and CLSM analysis, which could promote the secretion of protein and polysaccharide by C. gilardii CR3. The migration of heavy metal copper in C. gilardii CR3 biofilm-quartz sand column was the largest in the biofilm formed. 20 LB was injected into C. gilardii CR3 biofilm-quartz sand column for 12 hours to cause C. gilardii CR3 to starve for a short time. A uniform and stable biofilm was formed. The biofilm column had an effect on the migration of copper ions at all three concentrations, and the penetration curves of 6.4 mg / L ~ (32 mg/L) and 64 mg/L Cu ~ (2 +) were irregular in the biofilm column, with the increase of Cu ~ (2 +) concentration. The smaller the cupric ion interception, the greater the penetration ability of the biofilm column. In addition, the biofilm column has the same trend of cupric ion interception and biomass distribution, that is, there are more ends of the experimental column, and the middle of the column is the least. The adsorption of copper ions in the column was mainly due to the adsorption of EPS to copper ions.
【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X14;O647.3

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