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电化学富集转移技术用于近岸海水中铜离子的检测研究
陆妍
Subtype硕士
Thesis Advisor潘大为
2018-05-23
Training institution中国科学院烟台海岸带研究所
Degree Grantor中国科学院大学
Place of Conferral中国科学院烟台海岸带研究所
Degree Name理学硕士
Degree Discipline海洋化学
Keyword海水 电化学富集/转移 多功能电化学池 铜离子 Seawater Electrochemical preconcentration/transfer Multifunctional electrochemical cell Copper ions
Abstract海洋拥有优越的资源和环境条件,与人类的生存发展息息相关。近岸海域由于受陆地、海洋和人类活动的多重影响,成为污染最严重的海洋区域。铜作为一种生命必需元素,广泛参与海洋生物体内各种酶的形成,同时也会参与海洋系统中的碳氮循环以及铁运输等过程。因此,为更深入探究铜离子(Cu2+)在海洋系统尤其是近岸海域中的循环变化情况,需要发展灵敏准确的方法对Cu2+进行分析检测。 目前,国际上已有多种检测水体中Cu2+的方法,例如紫外-可见分光光度法、原子吸收光谱法、原子荧光光谱法、电感耦合等离子体质谱法、离子色谱法和电化学方法等。但大多数方法都需要一定的样品前处理,如去浊去色、提纯、富集等。常用的富集方法有吸附法、萃取法、沉淀与共沉淀等等,但这些方法都存在需要大量的化学试剂,操作繁琐费时,重现性不好,不易实现自动化分析等缺点。电化学方法除了灵敏度高、分离性好以及仪器能小型化、便携化等特点外,作为预处理方法也具有一定优势,如增强分析信号,减小基质干扰等。目前电化学方法作为前处理富集手段已被用来和紫外分光光度法、无火焰原子吸收光谱法、阳极溶出伏安法和电感耦合等离子体质谱法等方法联用。 本论文针对目前海水中Cu2+检测所存在的介质背景干扰严重、富集效率低下、仪器大型化和前处理过程操作复杂等问题,研发了两种电化学富集/介质转移便携装置,并将其应用于紫外分光光度法和电化学溶出伏安法定量检测实际样品的前处理过程,实现对海水中Cu2+的灵敏准确分析。研究工作内容主要涉及以下三个方面: 1.电化学介质转移用于混浊水体中铜离子的检测研究。采用电化学和标准比色法联用检测Cu2+。电化学沉积作为预处理及介质转移分离步骤,分光光度法作为Cu2+定量检测方法。联用方法能消除Cu2+所在介质的背景干扰,检测浑浊或有色水样中的Cu2+。在电化学介质转移过程中,Cu2+在电位从10 mL浑浊有色水样中被转移到10 mL空白缓冲溶液中,继而用国标二乙基二硫代氨基甲酸钠法(HJ 485-2009)进行定量检测。在使用裸玻碳电极的实验条件下,检测Cu2+的线性范围是16 ~ 160 mol/L,检出限为2.5 mol/L。该方法具有良好的重现性和重复性,同时通过加标回收率实验证明了该方法的准确性,并已成功应用于实际混浊水体中Cu2+的测定。 2. 电化学富集用于标准海水中铜离子的检测研究。为了进一步提高电极的富集效率,设计了包含一个内置大直径工作电极(9 mm的玻碳片电极,GCP)的大体积电解池。同时,为了进一步提高工作电极的有效面积,在电极上修饰上平均粒径为40 nm金纳米颗粒(AuNPs)。对富集前后的溶液进行检测的结果表明:利用该电解池,裸玻碳片富集600 s的效率从先前体系的1%提高为9.4%,修饰上AuNPs的玻碳片富集600 s的效率提高为18.6%。在最优实验条件下,标准曲线的线性范围分别是10 ~ 100 nmol/L和100 ~ 1000 nmol/L,检测限是6.5 nmol/L。该方法已被成功应用于不同盐度标准海水样品中Cu2+的检测。 3. 电化学富集/转移用于实际海水中铜离子的检测研究。为了进一步提高检测体系的富集效率,设计了集富集溶出于一体的多功能电化学池,并用于海水中Cu2+的检测研究。多功能电化学池主要包括大体积富集池、小体积溶出池和大直径工作电极三个部分,先采用修饰金纳米颗粒的玻碳片(AuNPs/GCP)为工作电极(工作直径9 mm),在富集池中对100 mL水样富集600 s,然后于溶出池中以700 L的溶出液中进行溶出,再用二甲酚橙(XO)作为显色剂进行吸光度的测定。对显色剂的显色时间、显色pH和显色剂的用量等条件进行了优化。在最优条件下结合富集和介质转移方法之后,介质中的Cu2+浓度约提升为原溶液中的30倍,该体系被成功应用于实际海水中Cu2+的检测,检测结果与ICP-MS具有较好的一致性,并已成功应用于黄海海水连续8天的定点检测。
Other AbstractThe ocean has superior condition of environment and resources, which is closely related to the survival and development of mankind. Due to the multiple impacts of the land, sea and human activities, the offshore area becomes the most polluted ocean area. As an essential element, copper plays an important role in the process of carbon and nitrogen cycle and iron transport in ocean system. Meanwhile, it will also participate in the synthesis of various enzymes maintaining the organisms’ living activities. Thus, in order to further explore the changes and cycle of copper ions (Cu2+) in ocean systems, especially in the offshore seawater, it is necessary to develop sensitive and accurate methods to detect and analyze Cu2+. Lots of techniques have been developed to determine the copper ions in water samples so far. However, most of them need pretreatment steps such as purification, removing turbidity and color, enrichment and so on. Common methods include adsorption, extraction, precipitation and co-precipitation, etc. However, these methods are limited to use because of many disadvantages such as vast need of chemical reagents, complexity and poor reproducibility, time-consuming and so on. Electrochemical method has many advantages such as portability, indigenous miniaturization, high selectivity, great sensitivity, and time-saving when it is used as a preconcentration process. The electro-deposition process also can enhance the analytical signal and eliminate interference from sample matrices. Just because of those, electrochemical enrichment has already been employed to provide concentrations required for analysis by flameless atomic absorption spectrometry, anodic stripping voltammetry, and inductively coupled plasmas mass spectroscopy. In view of the present problems, such as serious background interference of the medium, the low enrichment efficiency, large-scale instrument and complex operation of pretreatment process in the determination of copper ions in seawater, a series of pint-sized electrochemical preconcentration/media transfer equipment was set up and used as the pretreatment process for the quantitative determination of copper ions in seawater by ultraviolet-visible spectrophotometry and stripping voltammetry. The research work of this paper mainly involves the following three aspects: 1. Electrochemical medium transition procedure used to detect copper ions in turbid water. In this part, electrochemistry and UV-visible spectrophotometry method was combined to detect copper ions in turbid or colored water. The electrochemical deposition process served as medium shift pretreatment step while the spectrophotometric analysis was in charge of the quantitative analysis. This combination would give the chance to measure Cu2+ in water samples under conditions without interferences of turbidity, color or high salinity due to the advantages of electrodeposition. Under the optimized conditions, a linear relationship between the absorbance and the concentration of Cu2+ was obtained in the range of 16 μmol/L to 160 μmol/L with a detection limit of 2.5 μmol/L. This method had excellent reproducibility and selectivity and was applied to the determination of Cu2+ in actual turbid water with satisfactory results. 2. Electrochemical preconcentration method used to detect copper ions in standard seawater. In this part, a large volume electrochemical cell was designed to improve the enrichment efficiency and applied to detect Cu2+ in artificial seawater and standard seawater. The cell contained an inner large size working electrode, namely a glass carbon piece electrode (GCP) with effective diameter of 9 mm. To further increase the effective working surface area of the electrode, 40 nm gold nanoparticles (AuNPs) were electrochemically deposited onto the electrode surface (AuNPs/GCP). According to the Cu2+ concentration before and after the preconcentration, the enrichment efficiency of GCP and AuNPs/GCP was improved to 9.4% and 18.6% respectively. Under the optimized conditions, the liner range was segmented (0.01 ~ 0.1 μmol/L and 0.1 ~ 1 μmol/L) with a low detection limit of 6.5 nmol/L (S/N=3). It has been successfully applied to determine copper ions in standard seawater with different salinity and the result showed great accuracy. 3. Electrochemical enrichment/transition technique used to detect copper ions in real seawater. In this part, a multifunctional electrochemical cell was designed on the basis of the large size cell mentioned above and applied to detect Cu2+ in coastal seawater samples. The cell consisted of three main parts: a large enrichment cell, a mini stripping cell and an interior three-electrode system with a large-sized glassy carbon piece electrode (GCP) (9 mm in diameter). The enrichment step was acted in the large enrichment cell and the stripping step was in the mini stripping cell. The working electrode was AuNPs modified glassy carbon piece electrode (AuNPs/GCP) and xylenol orange (XO) was chosen as the color developing agent for spectrophotometry. The conditions such as acidity, developer dosage and developing time were optimized. After combining the preconcentration and transfer method under optimal conditions, the concentration of Cu2+ was 30 times higher than that in the original solution. Moreover, this system has been successfully applied to the detection of copper ions in actual seawater, the results are in good agreement with ICP-MS, and it had been successfully applied to the detection of Cu2+ in sea water for 8 consecutive days.
Subject Area海洋化学
Pages73
Language中文
Document Type学位论文
Identifierhttp://ir.yic.ac.cn/handle/133337/25310
Collection中科院烟台海岸带研究所知识产出_学位论文
Recommended Citation
GB/T 7714
陆妍. 电化学富集转移技术用于近岸海水中铜离子的检测研究[D]. 中国科学院烟台海岸带研究所. 中国科学院大学,2018.
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