Preparation And Recognition Performance Of Imprinted Hydrogel Electrochemical Sensors

With the rapid development of industrialization and urbanization,the problem of environmental pollution is becoming more and more serious,and the rapid and effective detection of pollutants has become an urgent problem to be solved.Among them,heavy metal ions and dye wastewater pose a serious threat to human health and natural environment because of their huge use and complex post-treatment process.Electrochemical analysis has attracted much attention in the field of analysis and detection due to its advantages of low cost,wide detection range,simple operation and high selectivity.Imprinting technology has also attracted the attention of researchers due to its advantages of easy preparation,low price,stable performance,excellent selectivity and specific recognition function.Therefore,the electrochemical sensor prepared by imprinting technology shows a broad application prospect in the field of pollutant identification and detection.In this thesis,three different metal ions(Cu²⁺,Pb²⁺,Cd²⁺)imprinted hydrogels and dye-rhodamine B molecularly imprinted hydrogels were prepared by imprinting technique.Different types of imprinted hydrogel electrochemical sensors were prepared by using imprinted hydrogels as electrochemical sensor precursors.The response ability,selectivity,stability and reproducibility of the sensor to the target substance were investigated,and the minimum detection limit and linear detection range of the sensor were determined.At the same time,rhodamine B molecularly imprinted hydrogel loaded with silver nanoparticles was prepared on the basis of molecularly imprinted gel,and the effect of silver nanoparticles on the detection ability of rhodamine B hydrogel was discussed.The main research contents and results of this thesis are as follows:（1）The ion imprinted hydrogel was prepared by using PVA as raw material,chitosan andβ-cyclodextrin as functional monomers,Cu²⁺,Pb²⁺and Cd²⁺as templates,and glutaraldehyde as crosslinking agent.The results show that the prepared gels are porous materials,and the pyrolysis temperatures are 380℃、250℃and 280℃,respectively.They have abundant functional groups（-OH,-NH₂）that can interact with metal ions.The results of the prepared imprinted hydrogel electrochemical sensor showed that the three sensors had good sensitivity to the identified template ions and good selectivity to Cu²⁺,Pb²⁺and Cd²⁺.The linear detection ranges were2.5～40μmol/L,1～20μmol/L and 0.25～25μmol/L,respectively,and the detection limits were 0.5μmol/L,0.075μmol/L and 0.15μmol/L,respectively（S/N=3）.In addition,the modified electrode also showed good reproducibility and stability under certain conditions.（2）Rhodamine B molecularly imprinted hydrogel was prepared by using acrylic acid as functional monomer,N’N-methylenebisacrylamide（MBA）as crosslinking agent and potassium persulfate as initiator.The characterization analysis showed that the rhodamine B imprinted hydrogel was a porous material,the pyrolysis temperature was stable at 280℃,and it had abundant functional groups（-OH,-NH₂,-COOH）.The test results of the prepared imprinted hydrogel electrochemical sensor show that the rhodamine B imprinted hydrogel sensor has good sensitivity to rhodamine B and has certain selective recognition ability.The linear detection range is 0～30μmol/L,and the detection limit is 0.4μmol/L（S/N=3）.The sensor also showed good reproducibility and stability.Compared with the unloaded hydrogel,the hydrogel loaded with silver nanoparticles improves the electrochemical response ability,increases the linear detection range,reduces the minimum detection limit,and enhances the stability of the modified electrode.