| 题名 | 食用菌废弃物对镉和铅的生物吸附研究 |
| 作者 | 高庭艳 |
| 学位类别 | 硕士 |
| 答辩日期 | 2008 |
| 授予单位 | 中国科学院水利部成都山地灾害与环境研究所 |
| 授予地点 | 成都 |
| 导师 | 张丹 |
| 关键词 | 重金属 金针菇 生物吸附 |
| 学位专业 | 土壤学 |
| 中文摘要 | 生物吸附技术是近年来环境领域里迅速发展起来的处理工业污染废水的新技术，它利用各种生物(微生物)吸附废水中的重金属离子。与传统的离子交换等技术相比，生物吸附具有以下优点：原材料来源广泛，投资小，运行费用低；不会产生第二次污染；吸附容量大，金属去除率高；能选择性吸附金属离子，不容易受到钙，镁离子影响；反应pH值和温度条件范围宽；适用于处理浓度较低（<100 mg•L-1）的重金属废水；被吸附的金属离子容易洗脱下来，可以重复利用。为了寻找性能优良，成本低廉的生物吸附剂，本文研究了食用菌加工废弃物的吸附能力。用金针菇脚作为生物吸附剂，对pH、重金属离子的起始浓度、生物吸附剂浓度以及共存金属离子相互作用等四个生物吸附影响因子进行了研究，并对吸附反应的热力学和动力学过程做了分析。为提高吸附剂的吸附能力，采用包埋技术对吸附剂进行固定化处理，用扫描电镜对金针菇脚吸附Cd2+和Pb2+前后的细胞壁变化作了观察，取得以下实验结果。1.四种食用菌不同部位对Cd2+和Pb2+的吸附能力没有显著差异四种不同种类的高等真菌其不同部位对Cd2+和Pb2+的生物吸附能力无明显差异。在初始Cd2+和Pb2+浓度为10 mg•L-1的溶液中，对Cd2+的吸附范围在1.62～1.90 mg•g-1，对Pb2+的吸附范围为1.40～2.01 mg•g-1，可以认为对Pb2+的吸附范围更为广。从子实体的菌盖，菌柄和菌脚三个不同部位吸附能力差异不显著来考虑，可将食用菌废弃部分作为新的吸附材料。选取金针菇废弃部分进一步研究对Cd2+和Pb2+的生物吸附。2.pH值对吸附的影响较大pH值是影响金针菇菌脚生物吸附金属离子的主要因素。在pH2～4的条件下，金针菇对Cd2+和Pb2+的吸附效率较低，最低分别为33.50%和37.3%。随着溶液的pH升高吸附效率升高，对Cd2+和Pb2+的最大吸附率出现在pH值7，分别为63.1 %和77.6%， pH值5～7是金针菇菌脚对Cd2+和Pb2+离子吸附的最适合范围。溶液pH值的变化，对金针菇脚吸附Cd2+的影响比对Pb2+的影响显著。3. 初始重金属离子浓度对吸附有显著影响初始重金属离子浓度对金针菇脚吸附Cd2+和Pb2+的效果有明显影响， 随着初始重金属离子浓度增加，单位质量金针菇脚对Cd2+和Pb2+的吸附量上升，变化幅度分别为1.496 mg•g-1～5.573 mg•g-1和1.427 mg•g-1～22.045 mg•g-1。Pb2+的吸附随初始浓度变化的曲线比Cd2+的吸附随初始浓度变化的曲线走势更陡，表明初始重金属离子浓度影响金针菇脚对Pb2+的吸附比对Cd2+的吸附更为明显。4. 生物吸附剂浓度增加，吸附率增加，吸附量下降金针菇脚对Cd2+和Pb2+的吸附效率随菌粉投入量的增加而增加，但不明显，Cd2+增加了24%，Pb2+增加了29%。就吸附效率而言，菌粉投入量对Pb2+的影响大于Cd2+。菌粉浓度的改变对Cd2+的吸附效率影响不大；从成本的角度考虑，在室温，Cd2+和Pb2+浓度为10 mg•L-1，pH5～7，振荡吸附0.5 h的条件下，投入浓度为4 g•L-1的生物吸附剂为宜。5. 共存金属离子的浓度变化影响金属的吸附量溶液中Pb2+的存在抑制了金针菇脚对Cd2+的吸附，当Pb2+的浓度为0～30 mg•L-1时，Cd2+的吸附率为61.6%～52.2%；Cd2+的存在促进了Pb2+的吸附，当Cd2+的浓度为0～30mg•L-1时，Pb2+的吸附率为65.3%～70.1%。6. Langmuir方程能很好地描述金针菇脚生物吸附重金属离子的热力学过程Langmuir方程能够很好地表达金针菇菌脚对Pb2+和Cd2+的吸附热力学过程，说明金针菇生物吸附金属离子的反应主要是一个单层吸附反应，吸附作用主要发生在金针菇脚细胞表面。对平衡数据做的Langmuir方程回归分析，得到了25℃条件下，金针菇脚对Pb2+和Cd2+的最大吸附容量分别为13.61 mg•g-1和6.84 mg•g-1。7. 一级动力学方程能很好地描述金针菇脚对Cd2+的吸附，二级动力学方程能很好地描述金针菇脚对Pb2+的吸附金针菇对Cd2+和Pb2+两种金属离子的吸附反应非常迅速，在前10 min内，金针菇脚对Pb2+和Cd2+吸附量均达到了总吸附量的70%以上。吸附30 min左右达到平衡。一级反应方程适用于对Cd2+吸附过程的描述，说明吸附过程可能只有单个官能团参与了反应，而对Pb2+的吸附则符合二级反应方程，由于细胞壁上存在多种官能团参与了反应，生物吸附不是单纯的一级反应，而是多个一级反应的混合，情况更为复杂。8. 包埋可提高金针菇脚的吸附能力采用海藻酸钠对金针菇菌脚进行包埋处理后，能够有效地提高对Cd2+和Pb2+的吸附量，对Cd2+的增幅为3％～6％，对Pb2+的增幅达到4％～10％。9. 真菌细胞壁的变化是吸附机理的表现形式之一用扫描电镜对金针菇菌体吸附Cd2+和Pb2+前后微观形态进行观测，发现，吸附后，细胞壁明显增厚，在细胞壁表面形成了明显的沉淀或晶体。目前，高等真菌生物吸附技术的发展正方兴未艾，本文的理论研究挖掘了其在工业上的应用潜力，为该项技术的进一步研究打下了理论基础。生物技术具有广阔的应用前景，但目前重金属的生物吸附还处于实验室阶段，实际应用不多。阐明与生物吸附作用有关的细胞壁成分、确定生物吸附剂内的金属结合位点与理解金属吸附机理，研究开发新的生物吸附剂及其固定化技术，研究增强生物吸附剂吸附性质的化学或生物学方法等都是寻找具有高选择性和高吸附能力的高效生物吸附剂的关键，必将会使生物吸附剂在将来有广泛的应用。 |
| 英文摘要 | Biosorption as a novel technique that utilizes inexpensive active/dead biomass to remove heavy metal is becoming more and more popular．It is particularly useful for the removal of contaminants from industrial effluents. Compared with conventional methods such as ion exchange, the biosorption process offers the advantages of low operating cost, minimization of the volume of chemical and biological sludge to be treated, high efficiency in detuning very dilute effluents, and could be reused etc. These advantages have served as the primary incentives for developing full-scale biosorption processes to clean up heavy-metal pollution of water. In this paper, waste of edible mushrooms after processing was taken as biosorbent, and effect factors, isotherm and kinetic of biosorption were studied. The results were below.1.Comparison of different parts of four edible mushrooms on Cd2+ and Pb2+ biosorptionThere was no distinct difference between the different parts of the four species edible mushroom, Pholiota nameko Ito ex Imai，Pleutotus ostreatus，Agrocybe Aegerila and Flammulina velutipes. When initial concentration of Cd2 + and Pb2+ was 10 mg•L-1, the biosorption quantity of F. velutipes of Cd2+ was 25.73%～32.55%, while biosorption quantity of Pb2+ was 1.86 mg•g-1～0.58 mg•g-1. Because of the same ability, the waste of mushroom could be used to be a new effective bioasrbent. Then take F. velutipes for example to farther studies.2. Effect of pH on biosorptionpH was the key factor affecting biosorption of heavy metal ions. When pH was between 2 to 7, the adsorption ratios of Cd2+ and Pb2+ were very low, only 33.50% and 37.3%, respectively. Along with increasing of pH, the adsorption ratio also increased, the maximal ratio was 63.1 % and 77.6% ,respectively when pH reached 7, so pH 5~7 could be the most suitable range. Biosorption of Cd2+ was more influenced by Changing of pH value than Pb2+ .3.Effect of initial heavy metal concentration on biosorptionBy initial heavy metal concentration raising, the biosorption quantity of Cd2+ was enhanced from 1.496 mg•g-1 ～5.573 mg•g-1 , while that of Pb2+ was from 1.427 mg•g-1 to 22.045 mg•g-1.4.Effect of biomass concentration on biosorptionWhen biomass concentration enhanced from 4 mg•L-1 to 16 mg•L-1, the adsorption ratios of Cd2+ and Pb2+ increased 24% and 29%, respectively, the change was not markbleness. We came to the conclusion that 4 mg•L-1 was the best biomass concentration in order to lower cost。5.Effect of co-exist heavy metal ions on biosorption each otherPb2+ restrained the biosorption of Cd2+ by F. velutipes. When Pb2+ concentration raised from 1 mg•L-1 to 30 mg•L-1, Cd2+ biosorption ratios droped(61.6%～52.2%); While Cd2+ was helpful to biosorption of Pb2+. When Cd2+ concentration increased from 1 mg•L-1 to 30 mg•L-1, Pb2+ biosorption ratios were enhanced(65.3%～70.1%).6.Isotherm of heavy metal biosorption by Flammulina velutipes Langmuir equation fitted the data of isotherm of heavy metal biosorption very well. Acording to analyzing, the maximum biosorption quantity(qmax) of Cd2+ and Pb2+ were abtained(25℃), which were 13.61 mg•g-1 and 6.84 mg•g-1, respectively. When temperature of biosorption reaction increased(from 25℃ to 35℃), qmax of Cu2+ didn’t change dramatically.7.Study of kinetic characters of biosorption processThe biosorption process was quite fast. During the first 10 minute, it had finished more than 70% of the total biosorption quantity. The process reached balance at 30 minute of adsorption. The frist degree reaction equation fit the kinetic data of Cd2+, while biosorption of Pb2+ fitted the second degree reaction equation very well, which suggested that the biosorption process was not only a frist degree reaction, but also a second degree reaction and many different groups on the cell wall participated in the reaction.8.Effect of immobilization on biosorptionAfter immobilized by Sodium alginate, the biosorption quantity of microfungi biomass of Cd2+ and Pb2+ were significant increased(from 3％ to 10％).9.Mechanism of biosorption The microcosmic configuration of Flammulina velutipes biomass after biosorption were observed by SEM. We can see that, the cell wall got thicker and formed deposition or crystal on cell wall after biosorption. This paper was just made a primary research about mechanism of biosorption, there is a need to make farther study using IR spectrum, X-ray diffractometry(XRD). Although the researchers on new and innovative treatment technologies had paid much more attention to metal binding capacities of various biomass, the exact interaction between the ligands of the metal uptake process and the description of the thermal properties of the biosorption was still unknown. So it is attractting more and more attention of scientists all over the world. Biosorption technology is just developing rapidly and this work would be helpful for the development of the new technology in improving polluted environment by heavy metal. |
| 语种 | 中文 |
| 学科主题 | 微生物学 |
| 公开日期 | 2010-10-14 |
| 分类号 | O64;X70 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/2205]  |
| 专题 | 成都山地灾害与环境研究所_成都山地所知识仓储（2009年以前） |
| 推荐引用方式 GB/T 7714 | 高庭艳. 食用菌废弃物对镉和铅的生物吸附研究[D]. 成都. 中国科学院水利部成都山地灾害与环境研究所. 2008. |
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