小球藻对重金属镉的耐受性及吸附研究

发布时间：2018-05-04 16:21

本文选题：小球藻 + 镉　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：重金属污染是危害最严重的水污染之一,对重金属废水和污染的水体进行处理和修复至关重要。传统的重金属污水的处理效率较低、成本较高、容易再次形成污染,而生物吸附则是一种高效、廉价的重金属处理方法,大量研究表明藻类对很多种金属都具有较强的吸附能力。本研究主要涉及两方面:一方面是以小球藻(Chlorella vulgaris)为研究材料,通过分析其在不同镉浓度下的生长情况,色素(叶绿素a、叶绿素b、类胡萝卜素)、可溶性蛋白、过氧化氢(H2O2)以及超氧化物阴离子(O2·-)含量的变化,并测定过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性的变化,判断小球藻对镉的耐受性。另一方面,通过研究小球藻活藻和死藻在不同接触时间、不同初始金属浓度、不同藻生物量以及在自然污水的不同条件下对重金属镉的吸附情况,确定小球藻对镉的吸附能力,同时对小球藻对镉吸附的动力学和热力学进行分析,为受重金属污染的水体利用藻类的生物修复提供理论依据。试验结果如下:1、在不同镉浓度(0 mg·L-1、0.5 mg·L-1、1 mg·L-1、3 mg·L-1、5 mg·L-1、7 mg·L-1)的影响下,镉对小球藻的抑制主要是在高浓度(3-7 mg·L-1)下,并且随着浓度的增大,对小球藻生长的抑制程度逐渐增大,小球藻生物量随着镉浓度的增大逐渐减少,在镉浓度为5 mg·L-1时,小球藻还可以生长,但在镉浓度为7 mg·L-1时,小球藻几乎不能生长。随着镉浓度的上升,叶绿素a、叶绿素b、类胡萝卜素的含量均减少,不同浓度的镉对叶绿素a、类胡萝卜素的含量均有显著影响(P≤0.05);而对叶绿素b影响不显著(P0.05)。可溶性蛋白含量随着镉浓度的上升先逐渐增大,其含量在镉浓度上升到3mg·L-1时达到最大,之后随着镉浓度的上升其含量逐渐减小。过氧化氢和超氧化物阴离子含量随着镉浓度的增大逐渐增大,且在高浓度下含量显著增加。随着镉浓度的增大,CAT、SOD、POD的活性逐渐增大,SOD和CAT活性在镉浓度为0.5 mg L-1时达到最大值,POD活性在镉浓度为5 mg L-1时达到最大值,随着镉浓度的继续增大,酶活性都逐渐减小。表明小球藻对镉有很好的耐受性。2、小球藻对镉的吸附受不同接触时间的影响。以100 mg·L-1作为初始镉浓度,死藻和活藻对重金属镉的吸附主要是在前5分钟内完成,在吸附5分钟时,活藻和死藻对重金属镉的吸附效率分别达到95.2%和96.8%,其吸附量分别为10.54 mg·g-1和10.77mg·g-1。随着时间的增加,死藻和活藻的吸附效率都逐渐增大,在吸附到105分钟时达到吸附平衡,此时死藻和活藻的吸附效率分别达到98.1%和96%,吸附量为10.88 mg·g-1和10.64 mg·g-1。因此可知,死藻对重金属镉的吸附效率和吸附量要稍高于活藻。3、小球藻对镉的吸附作用受不同初始镉浓度的影响。以5 mg·L-1、10 mg·L-1、50 mg·L-1、100 mg·L-1、150 mg·L-1作为初始镉浓度,在5 mg·L-1的镉浓度下,吸附平衡后,死藻和活藻对重金属镉的吸附效率分别达到89.7%和85.7%,吸附量为0.50 mg·g-1和0.48mg·g-1,随着初始镉浓度的增大,活藻和死藻的吸附效率和吸附量逐渐增大,在初始浓度为10-150 mg·L-1时,藻的吸附效率变化不大,但在初始浓度为150 mg·L-1时,死藻和活藻的吸附效率有轻微的下降,但其吸附效率也分别达到96.4%和96.1%,吸附量分别达到16.87 mg·g-1和16.02 mg·g-1。4、小球藻对镉的吸附作用受不同藻量的影响。不同藻生物量干重分别为0.18 mg、1.8 mg、18 mg,在藻生物量为0.18 mg时,吸附达到平衡后,死藻和活藻的吸附效率分别达到89.5%和87.3%,单位藻量的吸附量分别达到99.39 mg·g-1和97 mg·g-1,死藻的吸附效率明显高于活藻,随着藻生物量的增加,死藻和活藻的吸附效率都逐渐增大,但单位藻量的吸附量下降,在藻生物量为18 mg时,死藻和活藻对重金属镉的吸附效率可以达到95.5%和95.3%,单位藻量的吸附量为1.06 mg·g-1和1.05 mg·g-1。可以看出,此时死藻与活藻的吸附效率的差异不大。5、在自然污水中,小球藻对镉也有较高的吸附效率,但对镉的吸附量下降。在杨凌地区选取了某果厂、高干渠、后河和渭惠渠四处的污水,四个地区初始镉浓度的大小顺序为渭惠渠后河高干渠某果厂,在这四处污水样中,死藻和活藻对重金属镉的吸附效率都随镉浓度的增加逐渐增大,且死藻的吸附效率高于活藻,本次研究中,在污水中,死藻与活藻的吸附效率最低分别为85.1%和61.6%,吸附量分别为0.009 mg·g-1和0.006 mg·g-1,最高可分别达到96.4%和90.8%,吸附量为0.053 mg·g-1和0.050 mg·g-1。6、小球藻对重金属镉吸附的动力学和热力学分析,利用伪一阶、伪二阶和Elovich动力学方程对活藻和死藻对镉的吸附进行动力学分析,结果表明死藻的吸附符合伪二阶动力学方程,活藻的吸附则是符合伪一阶动力学方程;利用2个二参数的热力学方程(Langmuir和Freundlich方程)和2个三参数的热力学方程(Spis和Khan方程)对吸附的热力学进行分析,结果表明,死藻和活藻都符合三参数的Sips等温线模型。
[Abstract]:Heavy metal pollution is one of the most serious water pollution, it is very important to treat and repair heavy metal wastewater and polluted water body. The treatment efficiency of heavy metal wastewater is low, the cost is high, and it is easy to form the pollution again. The biological absorption is a high efficiency and low price heavy metal treatment method. A large number of studies show that algae are Many kinds of metals have strong adsorption capacity. This study mainly involves two aspects: one is using Chlorella vulgaris as the research material, by analyzing its growth in different concentrations of cadmium, pigment (chlorophyll a, chlorophyll b, carotenoid), soluble protein, H2O2, and superoxide anion (O2). The changes in content and changes in the activity of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) were measured to determine the tolerance of Chlorella to cadmium. On the other hand, the different initial metal concentration, different algae biomass and different conditions in natural sewage were studied at different contact time of Chlorella living algae and dead algae. The adsorption capacity of cadmium by Chlorella was determined, and the kinetics and thermodynamics of cadmium adsorption on Chlorella were analyzed in order to provide a theoretical basis for the bioremediation of algae contaminated by heavy metals. The results were as follows: 1, at different concentrations of cadmium (0 mg. L-1,0.5 mg. L-1,1 mg, L-1,3 mg. L-1,5 m) Under the influence of G. L-1,7 mg. L-1, the inhibition of cadmium to Chlorella was mainly at high concentration (3-7 mg. L-1), and with the increase of concentration, the inhibition of chlorella growth gradually increased. The biomass of Chlorella decreased gradually with the increase of cadmium concentration. When the concentration of cadmium was 5 mg. L-1, Chlorella could also grow, but the concentration of cadmium was 7 mg L. At -1, Chlorella could hardly grow. With the increase of cadmium concentration, the content of chlorophyll a, chlorophyll b and carotenoid decreased. The contents of cadmium on chlorophyll a and carotenoid were significantly affected by different concentrations (P < 0.05); but the effect on chlorophyll b was not significant (P0.05). The content of soluble protein increased gradually with the increase of cadmium concentration. The content of hydrogen peroxide and superoxide anion increase gradually with the increase of cadmium concentration, and the content of hydrogen peroxide and superoxide anion increases with the concentration of cadmium. The activity of CAT, SOD, POD increases gradually with the increase of cadmium concentration, and the activity of SOD and CAT increases with the increase of cadmium concentration. The maximum value was reached when the concentration of cadmium was 0.5 mg L-1. The activity of POD activity reached the maximum when the concentration of cadmium was 5 mg L-1. As the concentration of cadmium continued to increase, the enzyme activity decreased gradually. It indicated that Chlorella had a good tolerance to cadmium, and the adsorption of Chlorella on cadmium was affected by different contact time. 100 mg. L-1 as the initial cadmium concentration, dead algae and living algae. The adsorption of cadmium on heavy metals was achieved in the first 5 minutes. At 5 minutes, the adsorption efficiency of cadmium by living algae and dead algae reached 95.2% and 96.8% respectively. The adsorption capacity of the heavy metal cadmium was 10.54 mg. G-1 and 10.77mg g-1. respectively. The adsorption efficiency of dead algae and living algae increased gradually, and reached the absorption in 105 minutes. With equilibrium, the adsorption efficiency of dead algae and living algae reached 98.1% and 96%, respectively, and the adsorption amount was 10.88 mg. G-1 and 10.64 mg. G-1., therefore, the adsorption efficiency and adsorption capacity of dead algae to cadmium were slightly higher than that of living algae.3. The adsorption of Chlorella on cadmium was affected by different initial cadmium concentration. 5 mg. L-1,10 mg. L-1,50 mg. L-1100 mg L-1150 mg / L-1 as the initial cadmium concentration, the adsorption efficiency of cadmium in dead algae and living algae reached 89.7% and 85.7% respectively at the concentration of cadmium in 5 mg. L-1. The adsorption capacity was 0.50 mg g-1 and 0.48mg. G-1 respectively. With the increase of initial cadmium concentration, the adsorption efficiency and adsorption capacity of living algae and dead algae increased gradually, at the initial concentration of 10. When -150 mg / L-1, the adsorption efficiency of algae changed little, but when the initial concentration was 150 mg. L-1, the adsorption efficiency of dead algae and living algae decreased slightly, but the adsorption efficiency reached 96.4% and 96.1% respectively, and the adsorption capacity reached 16.87 mg g-1 and 16.02 mg. G-1.4 respectively. The adsorption of Chlorella on cadmium was affected by different algae quantity. The dry weight of the biomass was 0.18 mg, 1.8 mg and 18 mg respectively. When the algae biomass was 0.18 mg, the adsorption efficiency of dead algae and living algae reached 89.5% and 87.3% respectively. The adsorption capacity of unit algae reached 99.39 mg. G-1 and 97 mg g-1 respectively. The adsorption efficiency of dead algae was significantly higher than that of living algae. The adsorption efficiency increased gradually, but the adsorption capacity of unit algae decreased. When the biomass of algae was 18 mg, the adsorption efficiency of cadmium in dead algae and living algae could reach 95.5% and 95.3%. The adsorption capacity of unit algae was 1.06 mg. G-1 and 1.05 mg. G-1.. The difference of adsorption efficiency between dead algae and living algae was not.5, in natural sewage. Chlorella also had high adsorption efficiency to cadmium, but the adsorption of cadmium decreased. In the Yangling area, a certain fruit plant, the high dry canal, the back River and the Wei Hui canal were selected. The order of the initial cadmium concentration in the four regions was a certain fruit plant in the Weihui river high dry canal, and the adsorption effect of dead algae and living algae on the heavy metal cadmium in the four polluted water samples With the increase of cadmium concentration, the adsorption efficiency of dead algae is higher than that of living algae. In this study, the adsorption efficiency of dead algae and living algae is 85.1% and 61.6%, respectively, the adsorption capacity is 0.009 mg. G-1 and 0.006 mg. G-1 respectively, the highest can reach 96.4% and 90.8% respectively, the adsorption amount is 0.053 mg. G-1 and 0.050 mg g-1.6, pellet. Kinetic and thermodynamic analysis of cadmium adsorption on heavy metals, the adsorption of cadmium on living algae and dead algae was analyzed by pseudo first order, pseudo two order and Elovich kinetic equation. The results showed that the adsorption of dead algae conformed to pseudo two order kinetic equation, and the adsorption of living algae was in accordance with the pseudo first order kinetic equation, and the thermal power of 2 two parameters was used. The thermodynamic equations (Langmuir and Freundlich equations) and 2 three parameters thermodynamic equations (Spis and Khan equations) were used to analyze the thermodynamics of adsorption. The results showed that both dead algae and living algae were in accordance with the three parameter Sips isotherm model.

【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X173;X703

【参考文献】