Preparation And Properties Of Rare Earth Fluorescent Probe Materials And Their Application In Fe³⁺ Detection

Iron is one of the most abundant and important metal ions in living organisms and plays an important role in the human body as a trace element essential for various vital activities.There are a growing number of reports on the detection of Fe³⁺and although these methods are capable of high sensitivity and quantitative detection,they require expensive and delicate instrumentation and complex procedures,among other things,and are highly demanding on the experimenter.Inorganic fluorescence probes based on lanthanide ions have narrow emission bands and long luminescence lifetimes,and their detection is unaffected by the shape and size of the ligand field,leading to high detection sensitivity and reusability.When using lanthanide ion inorganic fluorescence probes for detection,no complex instrumentation is required,the operation is fast and simple,the reagents are inexpensive,and the response is fast.The research work presented in this paper consists of three main parts:1)A simple hydrothermal method was used to synthesize GdF₃:Tb³⁺fluorescence material with good dispersion for the determination of Fe³⁺in water.XRD and SEM were used to study the phase structure and properties of the materials.It was found that the morphology of the materials did not change greatly under the action of different additives（CTAB,Gly,EDTA and CA）.The optical properties of the material were measured by fluorescence spectrum.It was found that the luminescence intensity reached the maximum when the doping concentration of Tb³⁺was 8 mol%.The Fe³⁺detection performance of GdF₃:Tb³⁺fluorescent materials was analyzed by metal ion fluorescence quenching test and interference ion competition test.It was proved that the fluorescence probe has the advantages of fast response,good selectivity,good anti-interference and high sensitivity for detecting Fe³⁺,and its detection limit was calculated to be 2.9×10^-5 mol/L.2)BaMoO₄:Eu fluorescent probe with good crystallinity and dispersibility was successfully synthesized by one-step hydrothermal method for sensitive detection of Fe³⁺in water.The average particle size of BaMoO₄ crystals with octahedral structure is about 6.6μm in length and 1.8μm in width.The coordination number of Ba²⁺ion and Mo⁶⁺ion is 8 and 4,respectively,and Ba²⁺ion is right in the center of the octahedron.BaMoO₄:Eu fluorescent probe has excellent luminescence performance.At the excitation wavelength of 365 nm,it exhibits four characteristic emission peaks of Eu³⁺,and the strongest emission peak is located at 652 nm,indicating that the phosphor mainly presents red emission,which is the result of magnetic dipole transition.The fluorescence spectra of Eu³⁺at 652 nm were measured after the probe was placed for a period of time.It was found that the relative intensity of Eu³⁺at 652 nm only changed slightly with the increase of time,indicating that the probe has good photostability and is suitable for use as a fluorescence probe in water medium.The fluorescence test was carried out by mixing different metal ions with fluorescent powder detection solution.It was found that Fe³⁺could cause a large degree of fluorescence quenching of Eu³⁺,and the fluorescence quenching degree of Eu³⁺increased with the increase of Fe³⁺concentration.The calculated detection limit of Eu³⁺was 0.12μM,which was obviously better than many other fluorescence probes used for detecting Fe³⁺.In addition,the fluorescence probe is reusable.Under the action of NH₄F,the fluorescence quenching effect of Fe³⁺will disappear,because F^-ion will form stable[Fe F₆]^3-complex with Fe³⁺.3)Cubic phase ScF₃:Ce³⁺,Tb³⁺crystals were prepared by hydrothermal method.The luminescence properties and energy transfer of Ce³⁺→Tb³⁺crystals were investigated deeply,and it was proved that the energy transfer process was realized by dipole-dipole electric multipole interaction mechanism,and its energy transfer efficiency is as high as 94.12%.The concentration of Fe³⁺detected by the fluorescence probe was 4.15×10^-4 mol/L,which was very close to the 4×10^-4 mol/L calculated by ICP,indicating its feasibility in the actual detection environment.