Preparation Of Lead-imprinted Mesoporous Silicon Materials And CdSe Quantum Dots And Their Applications In Lead Ion Separation Detection

Lead ions are widely present in the environment,there are serious threats to human body and organism due to its toxicity and bioaccumulation.Currently,the methods used for the detection of lead ions often have the problem of complex,high limit of detection,poor selectivity.Therefore,it is important to establish a reliable,sensitive and highly selective method for the separation and determination of lead ions.In this paper,two types of functionalized nanomaterials were prepared: Pb???ion-imprinted materials based on bis-pyrazolyl functionalized mesoporous silica,and Mercapto propionic acid coated cadmium selenide quantum dots?Cd Se QDs?with optical properties.Functionalized mesoporous silica materials were used as solid phase extraction fillers for the selective separation of lead ions,then coupled with inductively coupled plasma-atomic mass spectrometry?ICP-MS?to realize the detection of lead ions.Next,the method for the determination of lead ions by liquid-phase ECL based on Cd Se QDs was initially established.The detailed work includes the following three aspects:1.Three types of bidentate functional group with nitrogen element modified Pb???ion-imprinted mesoporous silicas were designed and synthesized.For all ion-imprinted materials,we chose 4-?di?1H-pyrazol-1-yl?methyl?phenol?DPP?as functional monomer,lead ion as temple,3-?triethoxysilyl?-propyl-isocyanate as crosslinking agent,three kinds of mesoporous silicas SBA-15,MCM-41 and FDU-12 with different morphological characteristics as solid supports.By the surface imprinting technique,the ion-imprinted mesoporous materials Pb-IIMS-SBA-15,Pb-IIMS-MCM-41 and Pb-IIMS-FDU-12 were prepared through the elution of temple.Through the analyses of fourier transform-infrared spectroscopy?FT-IR?,solid-state29 Si and 13 C NMR spectra demonstrated that functional monomer DPP was successfully modified on the surface of mesoporous silicas.The characterizations of scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,N2adsorption–desorption analysis and small angel x-ray scattering?SAXS?proved the prepared materials were kept the morphologies of original mesoporous silicas.The elemental analysis by energy dispersive x-ray spectroscopy?EDX?indicating that Pb-IIMS-MCM-41 possessed the highest percentage of nitrogen.Moreover,three kinds of corresponding non imprinted materials were also successfully prepared.2.Researches of adsorption performance for Pb???ion-imprinted mesoporous silica and the application in water sample analysis.We investigated the adsorption capacity and selectivity of lead ion-imprinted and non-imprinted materials,results indicated that ion-imprinted mesoporous silicas did have the development of the adsorption capacity and selectivity for lead ions.The adsorption isotherms and adsorption kinetics experiments showed that three kinds of ion-imprinted materials had high adsorption capacity,fast adsorption rates for lead ions.The adsorption behavior was in accordance with Langmuir isotherm model and pseudo two order kinetics model.Among them,Pb-IIMS-MCM-41 possessed the best adsorption performances and excellent reusability.So,Pb-IIMS-MCM-41 were employed as packing material to construct a solid-phase extraction column,then coupled with ICP-MS for the determination of trace lead ion in water,limit detection?LOD?of the method is 0.015?g L^-1.The method has been applied to the detection of Pb???in the real water samples,the obtained results were satisfactory.It provides an effective method for selective removal and detection of lead ion in water.3.The synthesis of mercapto propionic acid as stabilizer coated CdSe QDs and the detection of Pb???.Water soluble Cd Se QDs were prepared by hydrothermal method,mercapto propionic acid as stabilizer,newly prepared Cadmium precursor and selenium precursor solution as raw materials.The ratio of cadmium and selenium precursors and the synthesis time were optimized.The fourier transform-infrared spectroscopy,ultraviolet spectrum and fluorescence spectrum were carried out to characterized Cd Se QDs.We investigated the effect of p H,potential sweep speed on Cd Se ECL signal.Under the optimal experimental conditions,the influence of Pb???for Cd Se QDs ECL signal was studied to initially build a liquid-phase ECL method for the determination of Pb???.The LOD of this method is 0.35 n M(0.072 ?g L^-1).