【作者】 陈波；

【导师】 黄玉明；

【作者基本信息】 西南大学 ， 分析化学， 2012， 博士

【摘要】 环境介质中有机或无机污染物的分析测定是环境分析化学的一个重要分支。目前已经发展了一系列的仪器分析方法如高效液相色谱法、气相色谱法、毛细管电泳、化学发光法、电化学法、原子吸收光谱和原子发射光谱等用于环境基质中有机或无机污染物的残留测定。但复杂环境基体中有毒污染物的浓度通常较低且成分复杂,需要应用适当的前处理技术对样品进行分离、富集和净化才能进行分析检测。可以说,样品前处理技术的优劣决定了分析方法的可靠性,对于定性定量检测具有至关重要的意义。传统的样品前处理技术如液液萃取和索氏提取等操作繁琐,且消耗大量有毒有害有机溶剂,易对环境造成二次污染,不能满足环境分析工作的要求。因而有必要开发简单、快速、高效、绿色环保的样品前处理技术来促进分析技术的发展。近年来,新型样品前处理技术的开发已经成为环境科学领域的研究热点之一。目前已开发的新型样品前处理技术包括浊点萃取、固相萃取、固相微萃取、液相微萃取、加压流体萃取、基质固相分散、搅拌棒吸附萃取等,其中固相萃取技术由于富集效率高、有机溶剂用量少、易于自动化、操作模式多样化等优点而被用于环境及生物样品前处理。液相微萃取是最近几十年发展起来的一种新型样品前处理技术,因其微型化操作、萃取速度快、萃取效率高、萃取溶剂用量小等优点备受亲睐。对于固相萃取而言,吸附剂的选择是影响固相萃取效率最重要的因素之一,目前己实现商品化的固相萃取吸附剂有C8、C18、OasisHLB、石墨化碳黑等等,而近年来纳米材料和生物材料在固相萃取中的应用引起人们的广泛关注。对于液相微萃取而言,操作模式以及萃取溶剂的选择是萃取成功与否的关键。基于此,本文建立了一系列基于固相萃取技术和液相微萃取技术的新型分析方法,并考察其在环境有机污染物分析检测中的应用。论文共分为六章：第一章：综述了近年来新型样品前处理技术在环境污染物分析检测中的应用进展。第二章：本章采用香烟过滤嘴做为固相萃取吸附剂,结合反相高效液相色谱分析技术,建立了环境水样中六种氟喹诺酮类抗生素药物氟罗沙星(FLE)、左氧氟沙星(LEV)、诺氟沙星(NOR)、环丙沙星(CIP)、加替沙星(GAT)和莫西沙星(MOX)残留的同时分析新方法。实验系统考察了洗脱剂种类和体积、样品溶液流速、样品溶液酸度和样品体积等因素对固相萃取效率的影响。实验结果表明,在最佳固相萃取条件下六种目标分析物均能够得到有效富集。所建立分析方法的检测限为2-5ng L-1,重复实验相对标准偏差为4.1%-6.3%,实际样品加标回收率为76%-112%。实际水样检测结果表明,香烟过滤嘴材料可有效萃取水溶液中氟喹诺酮抗生素药物,所建立的分析方法简便、快速、准确、灵敏度高、重现性好,适用于环境水样中六种氟喹诺酮类抗生素药物残留分析。第三章：本章采用溶剂热共沉淀法成功制备了磁性多壁碳纳米管复合材料,以此作为磁性固相萃取吸附剂结合高效液相色谱法检测环境水样中阴离子表面活性剂线性烷基苯磺酸盐(LAS)。系统研究了影响萃取效率的因素如吸附剂用量、吸附时间及温度、样品溶液pH、离子强度、腐殖酸浓度以及共存污染物等。在最优萃取条件下,所建立分析方法的富集倍数为500,检测限为0.013-0.021μg L-1,线性范围为0.5-100μg L-1(LAS总浓度),线性相关系数为0.9938-0.9998。相同实验条件下6次平行测定相对标准偏差为2.4-5.6%。实际样品加标回收率高达87.3-106.3%。重复使用结果表明,50次吸附-解吸周期后,本文所合成磁性碳纳米管复合物对LAS的萃取回收率仍保持95%以上。最后,将本文所建立的分析方法用于环境水样包括废水样和河水样中线性烷基苯磺酸盐(LAS)的分析检测,实验结果令人满意。第四章：本章建立了分散辅助-悬浮固化-液相微萃取技术结合高效液相色谱-紫外方法检测环境水样及食品样品中的苏丹红染料(苏丹红Ⅰ-Ⅳ)的新方法。实验系统优化了萃取剂种类及体积、分散剂种类及体积、离子强度、萃取时间、萃取温度以及样品溶液pH等影响萃取效率的因素。得到的最佳萃取条件：离子强度,10%NaCl(w/v)；样品溶液pH,7.0；萃取时间,20min；萃取温度,70℃；样品体积,10mL；萃取剂种类及体积,100μL十二醇；分散剂种类及体积,400μL乙醇。在最佳实验条件下,四种目标分析物的检测限均为0.03μgL-1,线性范围为0.2-500μgL-1,六次重复实验的相对标准偏差为3.1-5.2%,实际水样及食品样品的加标回收率分别为91.1-108.6%和92.6-106.6%,三次测定结果的相对标准偏差小于10%。实验结果表明,本文所建立的分析方法具有快速、灵敏、操作简单等优点,可应用于环境水样和食品样品中苏丹红染料的分析测定,实验结果令人满意。第五章：本章通过戊二醛化学交联法将阳离子聚合物聚乙烯亚胺(Polyethylenimine, PEI)接枝到氨基化磁性纳米颗粒表面,制备得到对阴离子表面活性剂线性烷基苯磺酸盐(LAS)具有强烈吸附性能的复合吸附剂(Fe3O4/NH2/PEI)。利用傅立叶变换红外光谱(FT-IR)、X射线衍射(XRD)、热重分析(TGA)、BET比表面等分析手段对其进行了表征,并研究了其对水溶液中线性烷基苯磺酸盐(LAS)的吸附去除性能。考察了PEI负载量、吸附剂用量、吸附介质pH值以及离子强度等因素对LAS吸附容量的影响；系统研究了LAS在Fe304/NH2/PEI上的吸附动力学、吸附热力学以及吸附等温线。结果表明,PEI大分子链中大量质子化的胺基氮原子与线性烷基苯磺酸盐(LAS)分子结构中磺酸基阴离子之间产生的静电相互作用是Fe304/NH2/PEI对LAS吸附去除的主要机理。Fe3O4/NH2/PEI对LAS具有强烈的吸附去除能力,初始浓度为20和50mg L-1,吸附时间为3小时时LAS吸附去除率均可达100%。吸附动力学实验表明,LAS吸附反应过程符合准二级动力学方程。等温吸附数据符合Langmuir模型。该吸附剂具有超顺磁性以及良好的吸附能力,能有效去除水溶液中线性烷基苯磺酸盐(LAS),且吸附剂很容易从废水中分离出来。因此,该材料可作为高效吸附剂材料吸附去除水溶液中其他阴离子污染物。第六章：本章通过水热法合成磁性多壁碳纳米管复合物,并对其进行一系列的表征。以合成的磁性多壁碳纳米管为吸附剂进行水溶液中两种喹诺酮类抗生素(莫西沙星和诺氟沙星)的静态吸附试验,考查了吸附热力学、吸附动力学、吸附等温线以及水化学因素等对磁性碳纳米管吸附性能的影响。实验结果表明,磁性碳纳米管对莫西沙星和诺氟沙星的吸附是一个先快速后缓慢的过程,吸附过程均符合准二级反应动力学方程,10h可达吸附平衡；莫西沙星和诺氟沙星的等温吸附数据均能较好地用Langmuir吸附等温方程进行拟合；中性pH条件下吸附效果最佳,主要靠分子状态的莫西沙星和诺氟沙星与磁性多壁碳纳米管表面之间的疏水性相互作用以及碳纳米管表面与吸附质分子结构中芳香苯环之间的π-π相互作用机理而吸附去除。本文所合成的纳米复合物同时具有磁性材料易于分离以及多壁碳纳米管超强吸附性能的性质,操作简单、稳定、重复使用性好,是一种优良的吸附剂,可作为高效吸附剂用于水溶液中其他污染物的去除。更多还原

【Abstract】 The determination of organic and inorganic contaminants in environmental matrix has been an important branch in environmental analytical chemistry. Various instrumental analysis approaches such as high performance liquid chromatography (HPLC), gas chromatography (GC), chemiluminescence, electrochemical analysis, atomic absorption spectroscopy (AAS) and atomic emission spectroscopy (AES) have been developed to determine the residues of organic and inorganic contaminants. However, due to fact that the concentration level of the toxic contaminants in the complex matrix is low and the chemical compositions are rather complicated, it is impossible to directly determinate the real concentration of the target compounds. So the sample preparation steps including separation, enrichment and purification of the target from the studied matrix are so critical for quantitative analysis. In some sense, the reliability of the analytical method depends on the quality of the sample pretreatment procedures, and it is of vital significance to qualitative and quantitative detection.Traditional sample pre-treatment technologies, such as liquid-liquid extraction and Soxhlet extraction, is tedious and consume large amounts of toxic and hazardous organic solvents, easy to cause secondary pollution to the environment, and can not meet the requirements of the environmental analysis. So it is necessary to develop simple, rapid, efficient and green sample pretreatment techniques to promote the development of analytical technology. The study on the sample pretreatment has become one of the hotspots in the field of environmental science. So far, lots of novel sample preparation methods including cloud point extraction (CPE), solid-phase extraction (SPE), solid-phase microextraction (SPME), liquid-phase microextraction (LPME), pressuried fluid extraction (PFE), matrix solid-phase dispersion (MSPD), Stir Bar Sorptive Extraction (SBSE) have been widely used. Among which, SPE was usually used for the pretreatment of environmental and biological samples for its high efficient enrichment, low organic solvent consumption, ease automation, diversification of operation modes and other advantages. LPME is one of the newly developed sample pretreatment techniques, and has received great attention due to its characteristics of miniaturization operation, high enrichment efficiency, high extraction speed and little reagent-consuming. As for SPE, one of the key factors affecting extraction efficiency is the choice of adsorbents. Commercial SPE adsorbents including C8, C18, Oasis HLB, graphitizede carbonb, etc have shortcomings in adsorptive selection and reusability, which led to the demand of exploring new adsorptive materials. In recent years, nanomaterials and biomaterials have attracted widespread interest in the field of SPE due to their unique structures and properties. As for LPME, the operation mode and the choice of extraction solvent are keys to the success of extraction. In this thesis, we established a series of novel analytical methods based on SPE and LPME, and investigated their application in the determination of environmental organic pollutants. It is maily composed of six chapters:The first chapter:In this chapter, we summarized the applications of novel sample preparation techniques in the field of environmental analysis.The second chapter:In this chapter, the potential use of cigarette filters (CFs) as SPE adsorbents for the preconcentration of six fluoroquinolones (FQs) antibacterial agents prior to liquid chromatography was examined. In order to find a suitable procedure for extraction of the target FQs in one single step, various parameters probably affecting the extraction efficiency including the eluent kind and volume, sample flow rate, pH of sample solution, ion strength and sample volume were systematically optimized. Under the optimized conditions, the target FQs could be easily extracted by the proposed SPE cartridge. Combination of SPE with HPLC/UV provided detection limits for different FQs of2-5ng L-1when500mL of water sample was processed. The precision of the method, expressed as relative standard deviation, ranged from4.1to6.3%for2.5μg L-1FQs. The recoveries of FQs spiked in environmental water samples ranged from76to112%. The results obtained from the proposed method demonstrated that CFs-based solid-phase extraction combined with HPLC/UV was suitable for analyzing fluoroquinolones in water samples at ng L-concentration level.The third chapter:In this chapter, the magnetic multiwalled carbon nanotubes (MMWCNTs) have been successfully prepared using one-pot solvothermal coprecipitation method, in which magnetic nanoparticles (MNPs) were deposited onto multiwalled carbon nanotubes (MWCNTs) by in situ high temperature decomposition of the magnetic precursor of iron (III) in ethylene glycol media. A novel procedure for extraction of linear alkylbenzene sulfonates (LAS) as model compound was thus developed in an off-line extraction system with detection by HPLC. In order to achieve optimal preconcentration, predominant factors that probably affected the extraction efficiency including the type and volume of eluent solvent, pH of sample solution, sorption time and temperature, ultrasonification desorption time, the content of the electrolyte (NaCl), humic acid concentration, amount of adsorbents and the volume of sample solution were systematically investigated and optimized in terms of recoveries of target analytes. Under the optimized conditions, LAS homologues could be easily extracted by the proposed magnetic SPE. On the basis of high-performance liquid chromatography separation and UV detection of LAS homologues, the favorable limits of detection (LOD) for LAS homologues were in the range from0.013to0.021μg L-1with a linear calibration range from0.5to100μg L-1(total concentration of LAS), and the relative standard deviations (RSDs) were2.4-5.6%for50μg L-1LAS (n=6), and the recoveries of LAS homologues in the spiked environmental water samples ranged from87.3to106.3%. Stability testing demonstrated that the MMWCNTs remained95.0%recovery for the target LAS even after a run of50adsorption and desorption cycles, showing their super operational stability. The MMWCNTs are promising adsorbents, suitable for the long-term repetitive sorption/desorption of target compounds in environmental water samples.The fourth chapter:In this chapter, a novel analytical method based on dispersion assisted solidification of floating organic drop LPME coulped with high performance liquid chromatography (DLPME-SFO-HPLC) was established for the determination of Sudan (I-IV) dyes in environmental water samples and food samples. Predominant factors that probably affected the extraction efficiency including the extractant and its volumn, dispersant and its volume, ionic strength, extraction time and temperature, pH of sample solution and volume of sample solution were systematically investigated and optimized in terms of recoveries of target analytes. On the basis of the experimental obtained in the optimization procedures, the optimized conditions are as follows:100μL1-dodecanol as extractant,400μL ethanol as dispersant, sample solution pH7, extraction time20min, extraction temperature70℃, ionic strength (10%NaCl, w/v). Then the optimized extraction conditions were applied to evaluate the analytical performances such as linearity, detection limits and precision of the established method. On the basis of high-performance liquid chromatography separation and UV detection of sudan dyes, the favorable limits of detection (LOD) were0.03μg L-1with a linear calibration range from0.2to500μg L-1, and the relative standard deviations (RSDs) were below10%for20μg L-1sudan (I-IV)(n=6), and the recoveries of sudan (I-IV) in the spiked environmental water samples and food samples were in the range of91.1-108.6%and92.6-106.6%, respectively. The experimental results demonstrated that the established method exhibited high recovery of Sudan dyes. As well as the proposed method is a rapid, precise, green and convenient enrichment method, therefore, can be successfully applied for the analysis of sudan dyes in aqueous environmental samples and food samples.The fifth chapter:In this chapter, cationic polymer polyethylenimine (PEI) was grafed to the surface of aminated magnetic nanoparticles through PEl-glutaradehyde cross-linking reaction and the composite adsorbent (Fe3O4/NH2/PEI) were obtained. In order to demonstrate the reliability of the synthetic method, the products were characterized by FT-IR, XRD, TGA and BET surface area. Then the adsorption capacity of the obtained nanocomposite was evaluated for LAS in aqueous solution. Different factors which may affect the adsorption capacity have been taken into account, such as the amounts of PEI, the dosage of adsorbents, pH value of medium and ionic strength. The adsorption kinetics, adsorption thermodynamics and adsorption isotherm were studied systematically. The results showed that the Fe3O4/NH2/PEI has very high affinity to LAS. The removal rate could reach to100%within3h with the initial concentration of20or50mg L-1LAS. Based on the experimental results, we could speculate that the adsorption of LAS molecules on the surface of Fe3O4/NH2/PEI at acid medium was driven by electrostatic interaction between the aminated N atoms and the sulfonic group of LAS molecules. Because of its excellent magnetic properties and adsorption properties, the adsorbent can remove LAS from aqueous solution effectively. What’s more, the adsorbent can be separated from the waste water easily under extra magnet field. The represented parameters fitted using Langmuir and Freundlich adsorption models indicated that the Langmuir model effectively describes the adsorption data with larger R2, suggesting a better fit of the Langmuir isotherm with the experimental data compared to the Freundlich isotherm. The pseudo-first-order and pseudo-second-order equations were used to obtain the adsorption kinetic data. The results showed that the adsorption kinetics follows the pseudo-second-order model. The sixth chapter: In this chapter, the magnetic multiwalled carbon nanotubes (MMCNTs) were synthesized by a rapid hydrothermal method and then characterized using a series of analytical methods. The obtained magnetic nanocomposites were used to remove two fluoroquinolne antibiotics (moxifloxacin and norfloxacin) from aqueous media through static adsorption experimentals. The adsorption thermodynamics, adsorption kinetics, adsorption isotherm and effect of water quality parameter on adsorption were investigated systematically. The results obtained from adsorption kinetics turned out that the procedure of adsorption was very quickly at the first stage and then tend to slow down as the adsorption time increased. And the adsorption behavior of moxifloxacin and norfloxacin on MMWCNTs fitted the pseudo-second-order kinetics model. The adsorption isotherm of moxifloxacin and norfloxacin can well fit Langmuir model. The maximum adsorption capacity of moxifloxacin and norfloxacin on MMWCNTs were obtained at neutral pH conditions. The hydrophobic interaction between fluoroquinolne molecules and the surface of MMWCNTs dominates probably the adsorption process as well as strong π-π interaction between the benze of FQs and the surface of MMWCNTs. The fabricated magnetic nanocomposites, combining the magnetic properties of MNPs and the extremely high sorption capacity of MWCNTs, exhibited high adsorption efficiency to fluoroquinolne antibiotics and could be easily isolated from water solution after extraction. Thus, it is an excellent adsorbent and could be used as promising adsorbent for removal of other pollutants in aqueous solution.更多还原