Application Study On Removal Of Pb²⁺ By Fe₃O₄@SA-Ca And Construction Of A Pb²⁺ Electrochemiluminescence Sensor

Due to the rapid development of the economy and industry,heavy metal pollution is serious.Lead(Pb)is one of the heavy metals.Excessive lead can lead to slow brain reactions and liver and kidney damage.Therefore,the removal and detection of heavy metal lead ions is very important for ecological environment protection and public health.This thesis aims to develop lead ion(Pb2+)adsorbent materials to remove lead ions and construct an electrochemiluminescence sensor to detect Pb2+.The specific work is as follows:1.The magnetic Fe3O4 nanoparticles were prepared by solvothermal method,then Fe3O4 nanoparticles were mixed with sodium alginate solution.The new magnetic sodium alginate-calcium(?)composite gel spheres were prepared by Ca2+as exchange ion..The adsorption behavior of Fe3O4@SA-Ca was analyzed by adsorption isotherm model and adsorption kinetics.In addition,multiple adsorption-analysis cycle experiments were performed to evaluate the recyclability of the Fe3O4@SA-Ca adsorbent.The research shows that the maximum adsorption capacity of the magnetic beads is 292.73 mg/g,and the adsorption rate is as high as 99.56%.The repeated utilization rate of the first five batches can reach more than 90%.After seven consecutive adsorption-analytical cycles,the adsorption capacity of Fe3O4@SA-Ca to Pb2+can be maintained by 79.50%.Therefore,Fe3O4@SA-Ca has good adsorptivity and reusability to Pb2+,and is an adsorbent for Pb2+in waste water with potential application.2.Preparation of nitrogen-doped carbon quantum dots(NCQDs)by pyrolysis of diethylenetriamine pentaacetic acid,using NCQDs as signal indicators,and modifying the "G-quadruplex" aptamers to NCQDs via amino and carboxyl groups.An ECL aptamer sensor was prepared.Studies have shown that the decline of ECL signal is linear with the logarithm of Pb2+concentration,the detection range is 0.05-387.9 nmol ·L-1,the linear regression equation can be expressed as follows:I=18463-2878.9 X Log(CPb2+)(pmol/L)(R2=0.998).Tthe detection limit is 18.9 pmol ·L-1,with wide detection range and low detection limit,and Has good selectivity and stability.Therefore,the new ECL aptamer sensor based on the design of nitrogen-doped carbon quantum dots obtained in this study can quickly and accurately detect Pb2+,providing a new idea for the rapid and efficient detection of Pb2+.