Preparation Of Ion Imprinted Polymers And CdTe Quantum Dots And Their Use In The Determination Of Cadmuium And Copper Ions

Due to the discharge of non-conforming industrial wastewater,the content of heavy metals in nature is far higher than before.Cadmium and copper are two typical heavy metal ions,which are common in industrial production.The heavy metal ions discharged into the environment will accumulate in the human body through the biological chain.When the cadmium content in human body is too high,it will damage blood vessels and system,even cancer.Although copper is a trace element needed by human body,it can also lead to diarrhea,vomiting and neurological disorders.Therefore,rapid and effective detection of heavy metal ions in the environment is of great significance.In this paper,the adsorption process and colorimetric detection are combined to achieve rapid adsorption and visual detection of cadmium and copper ions respectively.Firstly,cadmium ion imprinted polymers(Cd(II)-IIPs)were prepared by bulk polymerization using Cd(II),IA,EGDMA,AIBN and PAR as template ions,functional monomers,crosslinkers,initiators and chromogenic ligands,respectively.The preparation conditions of Cd(II)-IIPs were optimized,including the type of functional monomer,the optimization of functional monomer amount,the amount of crosslinking agent,the cross-linking time,the proportion of solvent and and the amount of PAR.Subsequently,Cd(?)-IIPs were characterized by FT-IR,SEM and XPS.And their performance was investigated.The results show that Cd(?)-IIPs can reach adsorption equilibrium at pH 7.0 in 10 min,and the maximum adsorption capacity is 50.542 mg·g-1.In the presence of Ni(?),Fe(?)and Co(?)ions,it has a certain selectivity to Cd(?)ions,and after 8 "adsorption-desorption"cycles,it still has an adsorption capacity of more than 90%.The detection limits of DIC and UV-Vis were 1.74 and 1.2 ?g/L,respectively.And the quantitative detection range was 8-100 ?g/L.At the same time,Cd(II)-IIPs detection has obvious color gradient change,which can be used for semi-quantitative colorimetric detection in a certain range.In order to better realize the detection of heavy metal ions,semiconductor quantum dots are selected.Compared with the traditional chromogenic reagent,the optical properties of QDs are better.In this paper,quantum dots with different emission wavelengths were synthesized by aqueous phase method,and the experimental temperature was controlled to distinguish the nucleation and growth process of the crysta.Then,the prepared quantum dots were embedded using the Sol-gel method to prepare fluorescent probes to detect copper ions.In order to further improve the detection effect,a ratiometric fluorescence probe(G-QDs and R-QDs)was constructed.The results show that the ratiometric fluorescent probe has a good detection effect for copper ions.In the Cu(?)concentration range of 0-1 mg/L,the detection limit is 0.13?g/L,which is far lower than the detection standard of copper ion in water.