【作者】 刘慧君；

【导师】 张小平；

【作者基本信息】 安徽师范大学 ， 植物学， 2004， 硕士

【摘要】 环境问题已成为21世纪人们关注的焦点。环境污染是多方面的，重金属是其中的一个重要方面。重金属进入环境后不能被生物降解，参与食物链循环并最终在生物体内积累，破坏生物体正常生理代谢活动，危害人体健康，是对生态环境危害极大的一类污染物。目前，有各种物理、化学方法如中和沉淀法、电解法、蒸馏法及离子交换法等等用于重金属污水处理，但这些方法或者价格昂贵，或者不能有效处理低浓度的重金属污水，甚至造成二次污染。生物吸附技术应用于痕量重金属污水处理，效果较好，价格相对便宜，而引起人们的兴趣。利用藻类、细菌、真菌和酵母吸附污水中重金属已有很多报道。藻类资源丰富，易加工，经济，并具有高的吸附能力，而日益受到人们的重视。近年来，海洋养殖在全世界尤其亚洲昌盛起来，并且发现螺旋藻能在海水中生长良好，从而降低了培养成本。目前对极大螺旋藻吸附金属离子的研究还比较少。为探讨极大螺旋藻对水中金属离子的吸附特性，本文用非活性的极大螺旋藻和氯化钙预处理藻体对铅、铜、镉、锌四种离子进行批次吸附实验，并通过红外光谱法和化学处理法对藻体吸附金属离子的官能团进行研究，旨在探讨微生物的吸附机理。现结果如下：在pH5.5，吸附时间2小时，金属离子浓度50mg/l，藻体生物量2g/l的条件下，极大螺旋藻藻体对银、铅、锌、铜、锰、镍六种金属离子均有不同程度的吸附作用，对这六种离子的吸附能力依次为银>铅>锌>铜>锰>镍。极大螺旋藻吸附金属离子受多种因素的影响，pH值是重要的影响因素之一。在低pH值条件下（pH≤3），藻体对四种金属离子的吸附量都很小。在一定范围内，随着酸性的减弱，藻体对金属离子的吸附量增加。本实验条件下，当pH≥4，藻体对铅、镉、铜三种离子的吸附量较大，并且随pH值增大，吸附量增大不明显；而对锌离子的吸附<WP=5>量一直随pH的增大而增大。氯化钙预处理后的极大螺旋藻对四种金属离子的吸附产生不同的影响。预处理后的藻体对铅离子的吸附量明显高于天然藻体；对铜和镉离子的吸附量和天然藻体无显著差别；对锌的吸附量明显低于天然藻体。藻体生物量对金属吸附的影响主要是随着生物量的增加，藻体的单位金属吸附量减小，而吸附率升高。天然和预处理藻体对铅、镉、铜和锌四种金属离子的吸附都符合Freudlich方程，在相同条件下（pH5，金属离子浓度50mg/l，藻生物量1g/l），两者对铅、铜、锌三种离子的吸附强度均为铅>镉>铜。锌的吸附等温线实验是在pH6的条件下进行的，因而无法比较。 非活性的极大螺旋藻体对金属离子的吸附可分为三个阶段，首先为快速吸附阶段，其次是缓慢吸附阶段，最后是平衡阶段。第一阶段速度很快，15min时的金属吸附量可达到总吸附量的70%以上。用EDTA、硝酸和柠檬酸钠作为解吸剂洗脱吸附于藻体上的铅、镉离子，发现三种解吸剂对镉离子的解吸作用较好，而柠檬酸钠对铅离子的解吸效果不佳。混合金属离子溶液中，钾、钙、镁和钠四种离子对铜离子的吸附影响不大。藻体吸附镉、铜、锌三种离子后的红外图谱中，羟基和胺基的混合吸收峰、磺酸基特征吸收峰都减小，说明在吸附这三种金属离子时，胺基、羟基和磺酸基可能都参与了吸附作用。对藻体进行化学处理，使得藻体细胞成分的羧基、胺基和羟基被修饰，以了解这些官能团在吸附中的作用。藻体在化学处理后对四种离子的吸附量均有下降，说明这三种官能团在吸附过程中均有一定的作用，但对不同金属离子的作用各不相同。羧基和胺基是Zn2+吸附过程中的重要化学基团，而羟基在吸附中的作用不大；在Cu2+、Cd2+吸附过程中，羧基、胺基和羟基都参与吸附；而在Pb2+吸附过程中，羧基和羟基是吸附功能团，胺基的作用不大。更多还原

【Abstract】 With rapid development of industry, environmental pollution became more and more serious. Heavy metals are major resources of pollutants. These metals could be accumulated in organisms (including humans) through the food chain, and then do harm to human body. There are many different physical or chemical methods to remove metal pollutants from liquid waste when these metals are present in high concentration. since such methods as precipitation, evaporation, electroplating, ion exchange and membrane processes not only cost expensively, but also are unsatisfactory for removing such contaminants at very low concentration, even possibly make secondary environmental pollution, this has led to an increasing interest in the application of biosorption technology which is comparatively cheaper for the removal of trace amounts of toxic metals from dilute aqueous solutions.The accumulation of metals by algae, bacteria, fungi, and yeasts has been extensively studied and its application in the treatment of metal water was well documented. Of these studies, algae gained increasing attention due to the fact that not only the resource of algae is rich, but also algae are relatively cheap to be processed and able to accumulate high metal content. Mariculture is thriving all over the world, especially in Asia. More recently, it has been found that Spirulina could be adapted to grow well in seawater, thereby saving valuable farm land and expensive culture medium. However, metal ions adsorption by Spirulina has been rarely studied. The lack of information concerning Spirulina adsorption warrants detailed studies. In this paper, microalga Spirulina maxima was chosen for four metals accumulation studies. The objective was to study the effects of environmental transformation on metal-algae interactions and the mechanisms of metals <WP=7>adsorption by Spirulina maxima. The conditions of adsorption were tested by using batch tests. The role played by various functional groups in the cell wall of Spirulina maxima in adsorbing metal ions was investigated by using infrared spectroscopy and chemical treatment to modify the functional groups. Results were as follows:Many metals ions could be adsorbed by Spirulina maxima. Under the condition of pH5.5, 2h contact time, 50mg/l of the metal ions concentration, 2g/l biomass, the absorption ability of the alga from high to low was silver, lead, zinc, copper, manganese and nickel. The value of pH would have significant effect on the metal ions uptake by Spirulina maxima . The amount of metal biosorption was comparatively little when the value of pH was less than 3, and increased with pH rising. When pH ≥4, the amount of lead, cadmium and copper ions adsorption did not increased with rising of pH. The amount of zinc adsorption increased while the value of pH ranged from 2 to 6.The biomass of Spirulina maxima pretreated by CaCl2 would have different influences on the following four metals uptake. The amount of lead adsorption by raw spirulina mixama was less than that by pretreated biomass. There were no significant differences between raw and pretreated biomass adsorbing cadmium or copper. The amount of zinc adsorption by raw biomass was more than that by pretreated biomass. When the quantity of the biomass was increased, the adsorption amount reduced and the adsorption ratio added. Equilibrium isotherms of Freudlich for raw and pretreated biomass adsorbing metal ions were obtained from batch adsorption experiments. The intensity of Spirulina maxima adsorbing metal ions from high to low was lead, cadmium and copper in turn under the same conditions.There was a phase of rapid ions uptake in the first fifteen minutes of contact, followed by a period of slow ions uptake. Above 70% of metal ions uptake occurred at the phase of rapid ions uptake . Three desorbing agents EDTA, HNO3 and Sodium citrate were used in the <WP=8>ions desorption. All three desorbing agents were considered efficient on cadmium desorption , and sodium citrate couldn’t desorb lead well. Po更多还原