Colorimetric Detection Of Trace UO₂²⁺ In Water Based On Functional Gold Nanoparticles

It is said that uranium are threatens to the ecology and environment for its high radioactivity and biological toxicity. In recent years, with the rapid development of the application in nuclear industry, It has caused serious radioactive contamination in groundwater, soil, atmosphere and many other issues. In this research paper, a new portable detector and three colorimetric sensors including ALD-AuNPs, 2-AP-AuNPs and 2-APM-AuNPs have been prepared for colorimetric detection of uranium（Ⅵ）. The structure of the functionalized gold nanoparticles are analyzed by the TEM, Uv-vis. and Zeta potentiostat. The factors that affect the colorimetric assay in aqueous such as initial p H values and contact time have been investigated by colorimetric experiments.（1） The second chapter introduces a selective colorimetric sensors based on gold nanoparticles cofunctionalized with Aledronate for UO₂²⁺ detection. The aggregation when the UO₂²⁺ bind with chelating ligands（ –PO43-）, yield a red-to-bule color change and could be monitored by naked eyes as well. By optimized the condition of p H and reaction time, ALD-AuNPs shows high selectivity to UO₂²⁺ in comparison with other 16 metal ions（Co2+,Cu2+, Hg2+ etc.,）. Under optimum conditions, the absorbance ratio（A680/A518） was linear with the UO₂²⁺ concentration in the range of 0.92-2.20 μmol/L（R2=0.991）, the detection limit of UO₂²⁺ could be as low as 2.36×10-8 mol/L.（2） The third chapter introduces 2-aminopyridine functionalized gold nanoparticles（2-AP-AuNPs） as selective a colorimetric sensor for UO₂²⁺ detection. The metal chelation of pyridine groups and UO₂²⁺ induces the aggregation of nanoparticles, which leads to the remarkable color change which can be easily observed by naked eyes from wine red to blue. 2-AP-AuNPs shows high selectivity to UO₂²⁺ in comparison with other 15 metal ions（Cu2+, Co2+, Mn2+ etc.,）. Under optimum conditions, the absorbance ratio（A610/A531） was linear with the UO₂²⁺ concentration in the range of 6.69-48.44 μmol/L μmol/L（R2=0.995）, the detection limit of UO₂²⁺ could be as low as 1.34×10-7 mol/L.（3） The fourth chapter introduces gold nanoparticles cofunctionalized with 2-aminopyrimidine used as selective colorimetric sensors for UO₂²⁺ detection. due to the UO₂²⁺ binding with pyrimidine groups, the aggregation yield a red-to-bule color change, and could be monitored by naked eyes as well. 2-APM-AuNPs shows high selectivity to UO₂²⁺ in comparison with other 16 metal ions（Cu2+, Co2+, Pb2+etc.,）. Under optimum conditions, the absorbance ratio（A630/A528） was linear with the UO₂²⁺ concentration in the range of 0.56-12.03 μmol/L μmol/L（R2=0.993）, the detection limit of UO₂²⁺ could be as low as 3.02×10-8 mol/L.（4） The fourth chapter introduces An instrument was designed for UO₂²⁺ determination in water environment.The instrument without external power supply has the advantages of fast detection,small volume, low cost, simple operation and good repeatability, etc.