Study On Detection And Enrichment Of Rare Earth And Heavy Metal Ions In Polluted Water

In recent years,with the rapid development of industry,heavy metal ions and rare earth ions emitted to the environment have been increasing,and the health problems that accompany them have been a challenge.Therefore,it is important to develop an effective monitoring and pretreatment of heavy metals and rare earth ions.Although methods such as atomic absorption spectrometry,atomic emission spectrometry,fluorescence method,ultraviolet spectrometry,and high-performance liquid chromatography have been developed and matured,they have the disadvantages of high price and incapability of real-time on-site detection.Electrochemistry,with its high sensitivity,long life,and certain anti-interference ability,fast response,can be used for on-site analysis,and is increasingly used for ion detection in water.Chemically modified electrodes can also be used to pre-enrich analytes of interest prior to voltammetry through selective interactions between electrodes and metal ions.So it is very important to develop a suitable active material for the target analyte.This paper mainly synthesizes two materials used to modify the surface of glassy carbon electrodes.The materials are carbon dots and bimetal oxide Co Fe₂O₄ crystals.Carbon dots are typical zero-dimensional nanospheres,which have excellent water solubility and biocompatibility.High fluorescence and low toxicity have aroused great interest.It is widely used in fluorescence detection,molecular detection,enzyme detection,etc.Carbon ion materials are rarely used in ion detection.Due to their synergistic effect,bimetal oxides can provide single-metal oxides with better electronic and oxygen vacancies,which have been preliminary explored.This paper mainly has the following two work directions.The research results of materials and corresponding electrode behavior are as follows:1.Using extensive anthracite as raw material,carbon dots were synthesized by chemical oxidation method,and through transmission electron microscope（TEM）,X-ray diffraction（XRD）,Fourier infrared transform Carbon is characterized by Fourier transform infrared（FT-IR）,X-ray photoelectron spectrometer（XPS）,cyclic voltammetry（CV）,Electrochemical impedance（EIS）,etc.Physical and chemical information of the point.The carbon dot material was loaded onto the surface of the glassy carbon electrode（GCE）by the method of drop coating to form CDs/GCE for detecting Eu（Ⅲ）and Ce（Ⅲ）in water.Subsequent optimization experiments were conducted to explore the amount of modified materials,supporting electrolyte,solution p H,enrichment voltage,enrichment time,etc.to obtain the highest response current and high sensitivity.Based on the optimized conditions,it is obtained that Eu（Ⅲ）is within the detection range of 1-1200μM,and the response current is proportional to the concentration of Eu（Ⅲ）.The linear fitting equation is:Ip=0.033C_Eu+0.290,R²=0.997,LOD=0.68μM（based on the 3σalgorithm）.Ce（Ⅲ）ion has a linear response in the concentration range of 1-100μM,the response equation is:Ip=0.015 C_Ce+0.406,R²=0.999,LOD=0.72μM（based on 3σalgorithm）.Subsequently,the selectivity,anti-interference,stability and service life of the modified electrode CDs/GCE were explored.The results show that in 16 rare earth ion solutions,CDs/GCE has high selectivity for rare earth Eu（Ⅲ）and Ce（Ⅲ）,and has good anti-interference for common heavy metals and rare earth ions.Finally,it is applied to the spiked recovery test of Eu（Ⅲ）ions in actual lake water to detect the possibility of practical application.2.Porous sponge-like Co Fe₂O₄ crystals were synthesized by sol-gel method followed by calcination.The surface morphology and physical and chemical properties were characterized by SEM,XRD,BET,CV,EIS,etc.Use cationic polymer Nafion to improve the efficiency of electron transmission and increase the service life.The Co Fe₂O₄/Nafion modified electrode was subsequently used for the individual detection of Pb（Ⅱ）,Cd（Ⅱ）,Hg（Ⅱ）,Cu（Ⅱ）,As（Ⅲ）plasma in water,and the anti-interference ability of the electrode was subsequently evaluated.Stability and testing in actual lake water to test the possibility of active materials in practical applications.