藻体对水环境中N、P及重金属Cu2+、Pb2+、Cd2+、Cr6+的吸附特征研究

IOCAS-IR > 海洋环流与波动重点实验室

	藻体对水环境中N、P及重金属Cu2+、Pb2+、Cd2+、Cr6+的吸附特征研究
其他题名	Bioaccumulation and biosorption of nitrogen, phosphorus and heavy metal ions Cu2+, Pb2+, Cd2+ and Cr6+
	邓莉萍
学位类型	博士
导师	朱校斌
	2008-06-03
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
学位专业	环境科学
关键词	藻体刚毛藻褐藻渣营养盐重金属饲料
摘要	随着全球生态环境的恶化，各国日益重视对水体中各种污染物的治理。利用藻类的吸收、富集和降解作用，可以去除污水中的营养物质、重金属离子和有机污染物，与其他物理、化学及工程的方法相比，该技术具有以下优点：成本低、能耗小、治理效果较好，对环境污染小，有利于资源化，有利于整体生态环境的改善，是治理水质污染的新途径。本文利用几种大型海藻对富营养化海水进行处理，结果发现孔石莼、刚毛藻均有很强的吸收N、P的能力，吸收能力依次为褶曲刚毛藻>束生刚毛藻>孔石莼。水体中褶曲刚毛藻3 g/L含量，在3～5小时之内，可把中等以上富营养化海水中的N、P降低至一类海水水平。利用刚毛藻处理富营养化地下海水和养殖废水，进行海参和大菱鲆养殖试验，探索藻类净化水质和废水循环利用的新模式，使水体保持较低的营养盐状态，减轻养殖废水对环境的影响，实现了海水养殖业与环境的可持续发展。刚毛藻在我国近海滩涂分布广泛，利用它来处理富营养化水体，并和水产养殖业相结合，既净化水体，使养殖废水能循环利用，满足水产养殖的需求，又改善水产业生态环境。同时，将回收藻体生产优质饲料、食品和药物等，实现藻类资源的高值利用。刚毛藻营养丰富，用其替代鼠尾藻作海参饲料，资源丰富，成本低，效果好，是一种值得加以开发利用的宝贵资源，具有广泛的应用前景。生物吸附法是一种经济有效的移除废水中有害重金属离子的方法。由于藻类细胞壁中的多聚糖可提供吸附重金属的位点，廉价而蕴藏丰富的海藻对多种重金属表现出很强的吸附能力。所以本文通过分批实验，研究了非活体刚毛藻对水体中重金属Cu2+、Pb2+和Cd2+的吸附影响因子、吸附热力学、吸附动力学及吸附机理，得到了平衡等温线及动力学数据。吸附过程的最佳pH值为5.0，吸附量随温度的升高而增加，水体中常见的Na+、K+、Ca2+、Mg2+阳离子及Cl-、NO3-、SO42-、C2O42-等阴离子的存在对吸附的影响并不显著。EDTA存在时，吸附百分率大大降低。吸附等温线符合Langmuir和Freundlich方程。刚毛藻对重金属Cu2+、Pb2+和Cd2+的吸附容量很高，25℃时，对Cu2+、Pb2+和Cd2+的最大吸附容量分别为1.61 mmol/g、0.96 mmol/g和0.98 mmol/g，且吸附过程为吸热反应。刚毛藻对重金属Cu2+、Pb2+和Cd2+的吸附过程为化学吸附，在吸附过程中藻体表面的官能团可能与金属离子发生了螯合作用。吸附动力学过程符合pseudo-二级动力学模型，在初始的30min内，吸附速率很快，随后速率逐渐降低。解吸试验表明，用EDTA可以对重金属进行回收，刚毛藻可以循环利用。实验结果表明刚毛藻是一种高效、经济实用的生物吸附材料，可用来吸附回收水体中的重金属Cu2+、Pb2+和Cd2+等。通过非活体刚毛藻对重金属Cr6+的吸附影响因子、吸附动力学、吸附机理的研究发现，刚毛藻对Cr6+具有很强的还原能力，对电镀废水中的Cr6+的还原去除提供了非常好的方法。吸附过程的最佳pH值为2～3，实际电镀废水通常在此pH范围，因此处理实际废水时，首先在原酸性条件下，对Cr6+进行还原去除，然后调废水pH至5.0，继续进行吸附，去除其他二价离子及被还原的三价Cr离子，实现了利用同一材料还原Cr6+为Cr3+，并将Cr3+和其他重金属离子同时去除。通过对机理的讨论，认为刚毛藻对Cr6+的生物吸附过程不是一个简单的“离子交换过程”，而是一个“吸附还原过程”。在海藻量足够的前提下，只要时间足够长，Cr6+可被彻底还原去除。利用工业废弃物褐藻渣，对水体中重金属离子Cu2+、Pb2+、Cd2+及Cr6+的生物吸附特性分别进行了讨论，结果表明褐藻渣对重金属离子的吸附特性与刚毛藻一致，吸附等温线符合Langmuir和Freundlich方程，在25℃时，pH为5.0时，由Langmuir方程求出褐藻渣对Cu2+、Pb2+和Cd2+的最大吸附容量分别为4.20 mmol/g、3.13 mmol/g和2.97 mmol/g。褐藻渣对低、高浓度的重金属Cr6+都具有很强的吸附能力，且移除效果比较彻底。实际应用结果表明，褐藻渣是一种高效、经济实用的生物吸附材料，可用来吸附回收水体中的重金属离子，具有广泛的应用前景。
其他摘要	As more and more attention is paid to environment, it is important to remove pollutants in aqueous solution. Conventional wastewater treatment methods are either inefficient or expensive, and they may also generate secondary wastes, which are difficult to treat. Consequently, it is urgent to find new technologies or materials for removing pollutants from wastewater. Biosorption and bioaccumulation are two kinds of valuable biological processes for pollutants removal from industrial waste streams and natural water. The method using alga to adsorb, accumulate and degrade of N, P, heavy metals, and organic compounds is effective and economical. The biomass can be used in animal feeds, industry materials and potential food for human beings. It has wide foreground, especially in our development country. In this work, some kinds of algae were used to treat eutrophic underground seawater. The results proved that Cladophora sp could absorb and remove N and P efficiently. The sea cucumber and turbot was breed in the treated underground seawater by Cladophora sp. The mode of alga cleansing fishery seawater can decrease N and P evidently, lessen the environmental infection of fishery wastewater, and increase the economy export of the fishery system, then realize sustainable development of the fisheries resources and the environment in mariculture. Biosorption utilizes the ability of certain materials to accumulate heavy metals from aqueous solutions by either metabolically mediated or physico-chemical pathways of uptake. In this study, biosorption of Cu2+, Pb2+ and Cd2+ by Cladophora fascicularis were investigated as a function of environment effects, biosorption equilibriums, biosorption kinetics and biosorption mechanism. Adsorption equilibriums were well described by Langmuir and Freundlich isotherm models. The maximum adsorption capacities were1.61 mmol/g for Cu2+, 0.96 mmol/g for Pb2+ and 0.98 mmol/g for Cd2+，and adsorption processes were endothermic. The biosorption kinetics followed the pseudo-second order model. The removal rate was rapid in the first 30 min, and leveled off after 1 to 2 h. With high metal ions biosorption and desorption capacities, the biomass has the potential to be used as an effective and economic biosorbent for the removal and recovery of heavy metals Cu2+, Pb2+ and Cd2+ from wastewater. Bosorption of Cr6+ from aqueous solutions by nonliving green algae C. fascicularis was investigated as a function of pH, initial Cr6+ concentration, and temperature. The removal rate increased with decreasing pH, increasing Cr6+ concentration and temperature. The mechanism of Cr6+ removed by C. fascicularis was discussed by analyzing the Cr6+ and total Cr in the solution at different time. Actual industry wastewater was used to evaluate the practicality of the biomass. The result showed that C. fascicularis could be used for removal of Cr6+ from wastewater by the reduction of toxic Cr6+ to nontoxic Cr3+. The utilization of C. fascicularis in industry was discussed in this study. The resource of C. fascicularis is abundant and economic, and the nutrition is rich, so it can be used in the sea cucumber feeds. The results showed that C. fascicularis was a kind of invaluable resource. Bosorption of Cu2+, Pb2+, Cd2+ and Cr6+ from aqueous solutions by algae residues was investigated. The biosorption characteristics of algal residues were consistent with C. fascicularis. At pH 5, the maximum adsorption capacities were 4.20 mmol/g for Cu2+, 3.13 mmol/g for Pb2+ and 2.97 mmol/g for Cd2+. Algal residues have high reduction capacity for low and high initial concentration Cr6+. From a practical viewpoint, the abundant and economic biomass algal residues could be used for removal of heavy metals from wastewater.
页数	125
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1387
专题	海洋环流与波动重点实验室
作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	邓莉萍. 藻体对水环境中N、P及重金属Cu2+、Pb2+、Cd2+、Cr6+的吸附特征研究[D]. 海洋研究所. 中国科学院海洋研究所,2008.