两种碳纳米点的绿色合成及其分析应用

发布时间：2018-06-14 14:37

本文选题：碳纳米点 + 亚硫酸盐　；参考：《华中科技大学》2015年硕士论文

【摘要】：碳点或碳量子点,包括石墨烯量子点、碳纳米点和聚合物量子点,是一种近球形结构的新型碳纳米材料,具有诸多独特的发光性能,包括发光稳定、耐光漂白、荧光发射可调谐、低毒性、良好的生物相容性。目前,碳点已在诸如生物成像、化学传感、纳米药物、光催化等领域得以成功应用。本论文主要针对碳纳米点的绿色合成和分析传感应用,开展了以下研究工作:首先,以丝氨酸、聚乙二醇600和丙三醇为原料微波辅助合成碳纳米点1,以柠檬酸和乙二胺为原料利用消解仪水热法一步合成碳纳米点2。实验分别对两种碳点进行了形貌和结构表征进而研究了两种碳纳米点的发光性能。实验证明,碳纳米点1粒径约为2~3 nm,单分散性好,稳定性好,保存时间长;碳纳米点2粒径在20至30 nm之间,单分散性较碳纳米点1差;两种碳点均含有碳、氮、氧三种元素,分别以羟基、羧基和氨基等官能团形式存在于碳点表面,碳纳米点1中碳元素含量更高而碳纳米点2表面分布有更多的羧基官能团;两种碳点均具有良好的发光性能,pH、浓度和保存时间均会对碳点荧光造成影响。本文进一步探讨了碳点的发光机理,推断碳点发光主要源于碳点表面电子-空穴的复合。依据碳纳米点1在酸性条件(0.9 mol L-1HCl)下可有效敏化Na2SO3-KMnO4体系的化学发光,构建了一种检测亚硫酸盐含量的化学发光新方法。方法的线性范围是1.0×10-4~1.0×10-3 mol L-1,检出限为5.1×10-5 mol L-1。此方法应用于银耳样品中亚硫酸盐含量的检测,方法加标回收率为78%至88.3%。在研究Hg2+与纳米点2相互作用时发现,与文献报道类似,Hg2+可选择性猝灭碳纳米点2位于448 nm处的荧光,且荧光猝灭程度(F0/F)与Hg2+浓度成正比;此外,我们还发现纳米点2在302nm处的吸收与溶液中所含Hg2+浓度亦成正比,这也是首次发现碳点的该性质。据此,建立了荧光/比色法测定Hg2+的新方法。荧光法线性范围是7.0×10-9~7×10-7 mol L-1,检出限(3σ)为5.5×10-10mol L-1;比色法线性范围1.0×10-9~7.0×10-7 mol L-1,检出限(3σ)为5.7×10-10 mol L-1,分析性能堪比荧光法。将两种方法应用于水样中Hg2+检测,两种方法获得的实验结果与原子吸收法实验结果相一致。加标回收实验表明,荧光法回收率为99.8~100.2%,比色法回收率为100.2~101.4%。本文进一步探讨了化学发光法的增敏机理和荧光猝灭的机理。认为碳点作为敏化剂,可有效吸收反应能量,作为发光体发出明亮的化学发光,有效提升化学发光效率。可能的化学发光机理是:KMnO4为碳点注入空穴,同时,高锰酸钾自身被还原,生成Mn(II)*。Mn(II)*可与HSO3-反应生成激发态HSO3-*,进一步生成激发态SO2*。由于碳点具有独特的表面性质,可以与上述激发态活性中间体发生反应,形成激发态碳点,进而产生明亮的化学发光。Hg2+与碳点之间的荧光猝灭作用为静态猝灭。经计算,它们之间的表观结合常数K=1.29×108 L mol-1。汞离子与碳点之间可能发生了络合作用,形成了全新的络合物,从而使体系紫外光谱出现新的吸收峰,同时该过程消耗了部分碳点,使得碳点荧光逐渐猝灭,表现为302 nm处的紫外吸收与448 nm处的荧光发射呈现此消彼长的关系。
[Abstract]:Carbon dots or carbon quantum dots, including graphene quantum dots, carbon nanoscale points and polymer quantum dots, is a new type of carbon nanomaterials with near spherical structures. It has many unique luminescence properties, including luminescence stability, photobleaching, fluorescence emission tunable, low toxicity and good biocompatibility. At present, carbon points have been in biological imaging, chemistry. Sensing, nanometers, photocatalytic and other fields have been successfully applied. This paper focuses on the green synthesis and sensing applications of carbon nanodots. The following research work has been carried out. First, the microwave assisted synthesis of carbon nanoscale points with serine, polyethylene glycol 600 and glycerol as raw materials and the use of citric acid and ethylenediamine as raw materials for the digestion of water and heat. The morphology and structure of two carbon dots were characterized by the one step synthetic carbon nanodot 2. experiment. The luminescence properties of the two carbon nanodots were studied. The experimental results showed that the 1 particle size of carbon nanodots was about 2~3 nm, with good monodispersity, good stability and long preservation time; 2 particle size of carbon nanodots was 20 to 30 nm, and the monodispersity was worse than that of carbon nanoscale 1; two Three elements of carbon, nitrogen and oxygen are contained in the carbon, nitrogen and oxygen species, which exist on the surface of carbon point with hydroxyl group, carboxyl group and amino group respectively. The carbon nano point 1 has higher carbon content and more carboxyl functional groups on the surface of carbon nano point 2, and the two kinds of carbon points have good luminescence properties. PH, concentration and preservation time are all made to carbon point fluorescence. The luminescence mechanism of carbon point is further discussed. It is concluded that the luminescence of carbon point is mainly derived from the recombination of electron hole on the surface of carbon point. The chemiluminescence of Na2SO3-KMnO4 system can be sensitized effectively under the acid condition (0.9 mol mol), and a new chemiluminescence method for detecting sulfite content is constructed. The sex range is 1 x 10-4~1.0 x 10-3 mol L-1 and the detection limit is 5.1 x 10-5 mol L-1.. The method is applied to the determination of sulfite content in the samples of Tremella. The recovery rate of the method is 78% to 88.3%. when the interaction between Hg2+ and nanometer point 2 is studied. Similar to the literature report, the selectivity of Hg2+ is located at 448 nm at 448 nm. And the degree of fluorescence quenching (F0/F) is directly proportional to the concentration of Hg2+. In addition, we also found that the absorption of nanometer point 2 at 302nm is also proportional to the concentration of Hg2+ in the solution. This is the first discovery of the carbon point. According to this, a new method of fluorescence / colorimetric determination of Hg2+ is established. The linear range of fluorimetry is 7 * 10-9~7 x 10-7 mol L-1, detection limit (3). It is 5.5 x 10-10mol L-1; the linear range of the colorimetric method is 1 x 10-9~7.0 x 10-7 mol L-1, the detection limit (3 sigma) is 5.7 * 10-10 mol L-1, and the analysis performance can be compared to the fluorescence method. Two methods are applied to the Hg2+ detection in water samples. The experimental results obtained by the two methods are in accordance with the experimental results of the atomic absorption method. For 99.8~100.2%, the recovery rate of colorimetric method is 100.2~101.4%., the mechanism of sensitization and fluorescence quenching of chemiluminescence method is further discussed. It is considered that carbon point as a sensitizer can effectively absorb the reaction energy, emit bright chemiluminescence as a luminescent body and improve the efficiency of chemiluminescence. The possible chemiluminescence mechanism is KMnO4 The carbon point is injected into the hole, and at the same time, the Potassium Permanganate itself is reduced to produce Mn (II) *.Mn (II) *, which can react with HSO3- to generate excited state HSO3-* and further generate the excited state SO2*. because of its unique surface properties, which can react with the active intermediate of the excited state to form the excited state carbon point and then produce bright chemiluminescent.Hg2+. The fluorescence quenching between carbon points is static quenching. It is calculated that the apparent binding constant between them, K=1.29 * 108 L mol-1. mercury ion and carbon point may be complex, forming a new complex, which makes the UV spectra of the system new absorption peak, and the process consumes part of the carbon point, making the carbon point fluorescence by fluorescence. The gradual quenching shows that the ultraviolet absorption at 302 nm is related to the fluorescence emission at 448 nm.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O613.71;TB383.1

【参考文献】