Preparation Of Norfloxacin-Pickering Emulsion Molecularly Imprinted Polymers And Its Adsorption And Solid-phase Extraction Properties

Norfloxacin is a highly effective bactericidal drug and has a good killing effect on various pathogenic bacteria.It is widely used in medical and aquaculture.In recent years,as people's demand for antibiotics continues to increase,more and more studies have found that norfloxacin residues are detected in water.Residues of norfloxacin in the environment will threaten the health of people and animals.Therefore,it is very necessary to find a simple and effective method to deal with norfloxacin pollution in the environment.Molecularly imprinted polymers have the characteristics of high selectivity,good stability,and can be used as adsorbents to separate and remove norfloxacin from the environment.In this study,Norfloxacin-MIP was synthesized by Pickering emulsion polymerization,and its structure was characterized by SEM and FT-IR.The effect of different adsorption conditions on the adsorption capacity of the molecularly imprinted polymer was studied.The adsorption process and adsorption mechanism of the material were analyzed using the isothermal adsorption model,adsorption kinetics model,and adsorption thermodynamic function.The polymer's selective identification of norfloxacin was explored by competitive adsorption experiments.At the same time,the synthesized molecularly imprinted polymer was used as the packing material to obtain the solid phase extraction cartridge,the elution conditions were optimized,the effect of extraction conditions on the extraction performance of solid phase extraction column was analyzed,and the extraction performance of the solid phase extraction column was studied.Finally,the solid phase extraction column was combined with high performance liquid chromatography to detect norfloxacin in simulated wastewater.The following conclusions have been obtained:?1?Nofloxacin molecularly imprinted polymers were prepared by pickering emulsion polymerization with norfloxacin,methacrylic acid,ethylene glycol dimethacrylate,azobisisobutyronitrile and nano-SiO₂ as template molecules,functional monomers,cross-linking,initiators and Pickering emulsion stabilizers.SEM and FT-IR characterization results show that the synthesized materials are spherical particles,and there are a large number of binding sites and abundant pore structure on the surface.?2?When the dosage of the polymer was 100 mg,the initial concentration of norfloxacin was 100 mg/L,the pH of the solution was 6,the adsorption temperature was 30°C,the adsorption of norfloxacin by the prepared molecularly imprinted polymer could reach an equilibrium in 80 minutes,and the maximum adsorption amount was 181.45 mg/g.In the competitive adsorption experiments,the relative selectivity coefficients of polymer to norfloxacin/levofloxacin and norfloxacin/ciprofloxacin were 3.77 and 1.81,respectively,indicating that the material has good selectivity for norfloxacin.?3?The adsorption data of the polymer to norfloxacin in water accorded with the Freundlich adsorption model.The adsorption process could be described by the pseudo-second-order kinetics model.The results showed that the adsorption of norfloxacin on the material belongs to multi-layer adsorption,and the chemical adsorption process is the rate-limiting step.The intraparticle diffusion model indicated that the adsorption of NOR on MIP can be divided into three stages:rapid adsorption,slow adsorption and equilibrium adsorption.The Elovich model showed that the adsorption energy of the MIP surface is uniform during the adsorption process.Thermodynamic parameters indicated that the imprinted polymer's adsorption of norfloxacin is a spontaneous endothermic process.?4?The optimal eluent composition for the molecularly imprinted polymer-solid phase extraction column was 9:1 methanol/acetic acid,and the optimal amount was 3 ml.When the concentration of norfloxacin in the sample solution was 2?g/ml and the solution pH was 7,the extraction efficiency of norfloxacin on the SPE column was not less than 97%.And after the solid phase extraction column was reused for 6 times,the extraction efficiency of norfloxacin could still be maintained above 90%.?5?Combining the solid phase extraction column with high performance liquid chromatography could reduce the interference of impurities in the sample,and could also greatly reduce the detection limit of the device.This method was used to detect norfloxacin in water with good accuracy and high credibility,and the limited detection range of norfloxacin was 1-5?g/ml.