水中镉对绿藻的毒性效应以及绿藻对镉的吸附效能研究

发布时间：2018-03-01 21:38

  本文关键词： 小球藻 Cd~(2+) 毒性效应 吸附效能 机理分析　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着近几十年社会经济的快速发展,环境问题受到了人们的关注,特别是近几年来,中央加大了对环境保护的力度。各种修复水体污染的方法被研制出来,其中利用藻类等生物修复水体重金属污染或者利用藻类生物吸附剂处理污水是一种具有广泛应用前景的技术。小球藻等绿藻广泛存在于水体中,并且生长繁殖速度快,很容易进行大规模养殖,同时对重金属具有一定的吸附能力,可以有效降低重金属的含量。但是,重金属对生活藻类的毒性作用影响了其的正常生长,在一定程度上抑制了藻类在水处理中的应用。同时,在重金属的胁迫下,藻细胞自身能够通过一系列生理活动来减轻重金属的毒害作用,这一特点对于活性藻体在重金属水体中的应用具有重要的实际意义。另外,死亡的藻体对重金属同样有一定的吸附能力。本研究采用静态实验的方法,选用水体中常见的绿藻(小球藻、斜生栅藻),对其毒理学进行研究。获得了Cd2+对两种藻的半数抑制浓度分别为5.94mg/L、4.13 mg/L。同时对不同镉胁迫下的小球藻和斜生栅藻的叶绿素a,胞内胞外可溶性糖和蛋白质的浓度变化进行了比较,获取了两种藻类对Cd2+的耐受性程度,结果显示小球藻对镉的耐受性更好。另外,镉的胁迫下,小球藻藻细胞本身的抗氧化酶发生了一系列的变化,如SOD随着镉浓度先升高后降低等,说明在此过程中,抗氧化酶确实起到了一定的解毒效果。在吸附实验中,研究了初始藻细胞密度,初始重金属浓度,酸碱性,以及温度对生活、死亡小球藻生物吸附效率的影响,结果显示小球藻对镉具有很好的吸附效能,且生活小球藻的吸附效率要高于死亡小球藻。同时采用批量平衡法研究了小球藻对镉的吸附动力学与热力学,并采用伪一级动力学方程、伪二级动力学方程、Langmuir等温线方程以及Freundlich等温线方程对实验数据进行了拟合。结果显示:在溶液中性偏酸性的条件下,吸附效果最好,在20-30℃温度范围内提高温度有利于吸附的发生,同时,藻的生物量及镉的初始浓度都在一定程度上影响到吸附效果。伪二级动力学方程、Langmuir等温线方程以及Freundlich等温线方程都可描述小球藻生物吸附镉的过程。通过红外光谱分析,发现了小球藻在吸附过程中是C-O、C=O、-COOH、-NH-等官能团发挥了重要的作用。
[Abstract]:With the rapid development of social economy in recent decades, people pay more attention to environmental problems, especially in recent years, the central government has stepped up its efforts to protect the environment. Various methods for remediation of water pollution have been developed. Among them, the use of algae and other biological remediation of heavy metal pollution or the use of algae biological adsorbent treatment of sewage is a technology with wide application prospects. Chlorella and other green algae widely exist in the water, and the growth and reproduction speed is fast. It is easy to breed on a large scale and has certain adsorption ability for heavy metals, which can effectively reduce the content of heavy metals. However, the toxicity of heavy metals to living algae affects their normal growth. At the same time, under the stress of heavy metals, algal cells can reduce the toxicity of heavy metals through a series of physiological activities. This feature has important practical significance for the application of active algae in heavy metal water. In addition, the dead algae also has certain adsorption capacity for heavy metals. Chlorella vulgaris (Chlorella vulgaris), which is common in water, The median inhibitory concentration of Cd2 on two species of algae was 5.94 mg / L, 4.13 mg / L, respectively. The chlorophyll a, extracellular soluble sugar and protein of Chlorella vulgaris and S. obliquus under different cadmium stress were also studied. Were compared with each other. The tolerance of two algae to Cd2 was obtained. The results showed that Chlorella microphylla had better tolerance to cadmium. In addition, under cadmium stress, the antioxidant enzymes of Chlorella vulgaris cells had a series of changes. For example, SOD increased first and then decreased with the concentration of cadmium, which indicated that antioxidant enzymes did play a certain detoxification effect in this process. In the adsorption experiment, the initial cell density of algae, the initial concentration of heavy metals, acid and alkalinity, and so on, were studied. And the effect of temperature on the biosorption efficiency of Chlorella mori showed that Chlorella sp. Has a good adsorption efficiency for cadmium. The adsorption efficiency of chlorella was higher than that of dead Chlorella. The adsorption kinetics and thermodynamics of cadmium by Chlorella microphylla were studied by batch equilibrium method, and the pseudo-first-order kinetic equation was used. The pseudo-second-order kinetic equation Langmuir isotherm equation and Freundlich isotherm equation were used to fit the experimental data. Increasing the temperature in the temperature range of 20-30 鈩，

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