【作者】 江用彬；

【导师】 季宏兵；

【作者基本信息】 首都师范大学 ， 环境科学， 2007， 硕士

【摘要】 重金属对水体的污染已成为全球性的环境问题，利用藻类生物修复重金属污染水体，因其有效、低廉和环保引起了国内外的广泛重视，并且取得了一定的成效。但目前这一领域的工作在机理研究、方法手段等方面均存在着不足。本研究通过建立莱茵衣藻(以下简称衣藻)(?)重金属镉吸附系统：从耐受性测试方面来了解重金属镉对衣藻的生理影响、评估其应用的可能性；从衣藻吸附镉的吸附动力学、热力学角度来解释衣藻生物吸附的行为、过程以及吸附潜力；建立金属浓度、藻量之间应用上的适宜的关系；从pH值、背景离子等外界条件入手来探讨不同环境因素对衣藻生物吸附的影响；运用化学修饰和物理吸附的方法研究了衣藻的吸附机理；比较分析各个洗脱试剂在衣藻吸附后的洗脱效能；从应用角度出发，利用固定化技术包埋衣藻，并同时评价环境因素对固定化衣藻吸附的影响。主要实验结果有：通过耐受性实验，得出衣藻能够耐受较高浓度的重金属镉，衣藻密度越大，耐受性个体越多，整体耐受性越强，有利于对污染水体进行生物修复，因此有着较大的应用前景。衣藻和固定化衣藻对重金属镉的吸附的动力学过程均可用Lagergren一级动力学模型和由Gauss-Newton及Levenberg-Marquardt所建立的方法推演出来的二级动力学模型进行很好的拟合，实验数据对模型的适应说明衣藻及固定化衣藻对镉离子的吸附遵循着一定的指数关系。由此，可以对吸附行为和过程进行可靠的预测，并对吸附条件进行优化。衣藻对镉的热力学等温吸附过程遵循着Langmuir等温吸附模型和Freundlich等温吸附模型，这两个模型对不同镉浓度与衣藻吸附能力之间的关系能够进行很好的解释。实际应用中，可以据此来判断吸附用的藻量和欲清除镉量之间的施用关系。衣藻和固定化衣藻对重金属镉的吸附在pH6.0左右达到最佳吸附，但pH的变化对衣藻吸附镉的影响较大；固定化衣藻则在极低pH值下吸附受到显著影响，在pH3-8的范围内，所受影响不大；背景阳离子的存在对二者吸附的影响非常显著，这从另一方面证明了离子交换为衣藻生物吸附的主要机制。通过化学修饰和物理吸附实验，揭示了在衣藻生物吸附过程中，功能基团如羧基、羟基和氨基等为吸附的主要位点，物理吸附量约占整个吸附量的5.5％，生物化学吸附过程为衣藻吸附镉的主要过程。衣藻吸附后的洗脱剂的选择，生活衣藻要选择如NaCl等物理化学性质比较温和的试剂，死亡衣藻则选用HCl比较合适，不过还需摸索其它更适宜的洗脱剂。更多还原

【Abstract】 Heavy metal pollution in aqueous system is a significant world-wide problem. Heavy metal ions which are present as ions in wastewater are toxic and can be readily absorbed into the human body through the food chain in aquatic ecosystem. The prevention of heavy metal contamination in aquatic environments is often performed by conventional methods. However, these methods have many disadvantages, such as incomplete metal removal, toxic sludge generation and cost inefficiency. Metal uptake by microorganisms has been studied for some years. Researches indicate that algae have the abilities to accumulate trace metal. Based on which, technologies of bioremediation of heavy metal contaminated water by algae in living and non-living form have been developed and got more and more attention around world-wide for its cost-effective and environmentally friendly characteristics. However, there still exist some deficiencies in mechanism and application of bioremediation. So, further investigation is still needed to elucidate the process of bioremediation and optimize the maximum efficiency of removal. In this thesis, we established an adsorption system of Chlamydomonas reinhardtii and cadmium to study the tolerance of C. reinhardtii to cadmium through testing the toxic effects of cadmium and evaluate the practical prospect of the microalgae, use the adsorption isotherms models and biosorption kinetic models to fit the experiment data, study the influence from the surroundings factors such as pH, anions and cations, block groups of the microalgae chemically and identify the physical adsorption ability, study the method of immobilization of C. reinhardtii and the factors which affect the adsorption of the immobilized microalgae. Through our researches, several conclusions can be safely reached:C. reinhardtii was able to survive even at a very high cadmium concentration, especially the higher density the microalgae gathered together in, the more tolerant individuals of the microalgae survived, which will help to utilize the microalgae to remove heavy metals from polluted water.From the study of the microalgae adsorption isotherms and biosorption kinetics, Langmuir equation and Freundlich equation fitted very well the adsorption isotherms, Lagergren equation known as a first order kinetic model and the second kinetic model which based on a combination of Gauss-Newton and Levenberg-Marquardi methods both described the biosorption process andsimulated the experimental transient profiles, but the latter was better.The optimal pH, which was the major factor influencing the adsorption of cadmium, was around 6.0; and the higher concentration of cations such as K⁺, Na⁺, Ca²⁺, Mg²⁺, the lower the sorbing capacity of the microalgae; This effect, on the other hand, also illustrated that the ion-exchange was the main adsorption mechanism.Chemical modification and physical adsorption experiments demonstrated that the dominant functional groups which present on the cell surface are the carboxyl, amide and hydroxyl. They play major roles in the complexation of heavy metal; the maximum contribution of physical adsorption in the overall biosorption process is about 5.5%.C. reinhardtii can be reused several times through desorption, the living microalgae should be eluded with mild chemical reagents such as NaCl. 0.1mol/L HC1 was one of optimal selection for non-living microalgae.更多还原