Multifunctionalized Nanomaterials And Application For Uranyl Ion Adsorption And Detection

Uranium,as the most basic raw material for the nuclear industry,is crucial to building an economically reliable,green and efficient energy security system in China.However,along with the rapid development of the nuclear industry,there is a risk of uranium leaking into the natural environment during mining,processing and disposal,which can then enter the human body through water and food and be deposited in the liver,kidneys and bones,causing acute or chronic poisoning,inducing various diseases and even death.Therefore,the development of new material systems capable of detecting and adsorbing uranium is of great importance for the sustainable development of the nuclear industry and the protection of the environment.This thesis is divided into three parts as follows.（1）ZnS:Mn quantum dot modified Zn₂GeO₄ nano-ellipsoid and its functionalized test paper for selective detection of uranyl ions over a wide concentration range.The conventional fluorescent colorimetric test paper,with a single signal response material and a narrow dynamic detection range,does not meet the requirements of a wide detection range in a practical environment.In this paper,a new method for the detection of uranyl ions(UO₂²⁺)over a wide concentration range was developed using synthesized ZnS:Mn quantum dot modified Zn₂GeO₄ nanoellipsoids（Zn₂GeO₄@ZnS:Mn NEs）.The ellipsoid contains mainly two signal-responsive materials with different fluorescence responses at different UO₂²⁺concentrations.At low concentrations（0-100μM）,a photo-induced electron transfer effect between ZnS:Mn quantum dots and UO₂²⁺occurred,causing a fluorescence burst in the red light of the modified ZnS:Mn quantum dots.When the concentration of UO₂²⁺was further increased（100-1000μM）,the green fluorescence of UO₂²⁺itself was gradually revealed and the fluorescence color changed from red to green due to the strong interaction between the Ge-O-H groups present on the surface of Zn₂GeO₄ nanoellipsoid and UO₂²⁺based on the antenna effect.Furthermore,by embedding Zn₂GeO₄@ZnS:Mn NEs on the microporous structural membrane,a low-cost and effective fluorescent test paper was prepared,which can have a simple and effective colorimetric response to UO₂²⁺in real samples,such as lake water and seawater,with a wide dynamic range.Therefore,it has a strong practical application for the detection of UO₂²⁺in real time/in situ under unexpected situations.（2）Pyrophosphate-functionalized magnetic nanoporous silica(Fe₃O₄@mSiO₂-Zn²⁺/P₂O₇^4-NPs)and its simultaneous application in the adsorption,separation and detection of uranyl ions.The pyrophosphate-functionalized magnetic nanoporous silica is based on the magnetic separation function of Fe₃O₄ nanoparticles and the abundant specific surface area,while the functionalized modified P₂O₇^4-enhances the fluorescence intensity of UO₂²⁺while improving the adsorption performance of UO₂²⁺to achieve simultaneous adsorption,separation and detection of uranyl ions.The detection limit of this nanoparticle for UO₂²⁺ion is:0.0048μM,and the adsorption capacity for UO₂²⁺ion is:515 mg/g.Finally,combined with the magnetic separation function of the nanoparticle,the interference of interfering components in the actual sample on the adsorption and detection of uranyl ion can be excluded,and the selective adsorption and detection of P₂O₇^4-can be realized,which has a strong practical application value.（3）Ethylenediamine-hybridized zinc germanate nanoribbons（NH₂-Zn₂GeO₄ NRs）and their simultaneous application in the adsorption and detection of uranyl ions.The surface of the ethylenediamine-hybridized zinc germanate nanoribbons is rich in amino groups,which greatly improves the dispersion of the nanoribbons and facilitates the coordination of uranyl ions with the amino groups on the surface of the zinc germanate nanoribbons and the adsorption of uranyl ions;at the same time,there are a large number of-Ge-O-H groups on the surface of the zinc germanate nanoribbons,and the interaction between them and UO₂²⁺,based on the antenna effect,makes the green color of UO₂²⁺itself fluorescence significantly enhanced to achieve the fluorescence detection of uranyl ions.Thus,the ethylenediamine-hybridized zinc germanate nanoribbons(NH₂-Zn_2Ge O₄ NRs)can selectively and efficiently adsorb uranyl ions with a maximum adsorption capacity of 190 mg/g.On the other hand,the ethylenediamine-hybridized zinc germanate nanoribbons show good linearity for uranyl ions in the concentration range of 0-45μM with a minimum detection limit of 0.202μM.In addition,the NH₂-Zn₂GeO₄ NRs were successfully used for the detection of uranyl ions in real water samples,demonstrating their potential application in aqueous environmental systems.