The Research On Separation And Analysis Of Dyes And Proteins Using Ionic Liquids And Deep Eutectic Solvents Combined With Magnetic Solid Phase Extraction

Magnetic solid phase extraction(MSPE)is a modern separation analysis technology using functionalized magnetic nanomaterials as adsorbents.It has the advantages of simple operation and rapid separation.It can also be combined with microfluidic chips for high throughput and automated detection analytes.Ionic liquid(IL)and deep eutectic solvent(DES)are widely regarded green solvents with extremely low vapor pressure and design structure and good biocompatibility.Modification of IL or DES on the surface of the magnetic adsorbent will enhance interactions with the analyte to achieve higher extraction performance.Therefore,combining magnetic solid phase extraction with deep eutectic solvent or ionic liquid may provide new ideas for the field of extraction separation.In this paper,two kinds of green solvents,ionic liquid and deep eutectic solvent,were successfully synthesized and combined with magnetic solid phase extraction technology.A new method for extracting and analyzing dyes and proteins was explored.The main research contents are as follows:(1)Ionic liquid modified molybdenum disulfide and reduced graphene oxide magnetic nanocomposite for separation and analysis of dyes from aqueous solutionAn imidazol-based ionic liquid(IL)was designed and synthesied.The magnetic nanocomposites(mag-MoS₂-RGO)composed of molybdenum disulfide(MoS₂)and reduced graphene oxide(RGO)was surface-modified as a magnetic extraction agent(mag-MoS₂-RGO-IL),combined with magnetic solid phase extraction technology(MSPE)for the extraction and separation of dyes in aqueous solutions.The physicochemical properties and morphology of mag-MoS₂-RGO-IL were systematically characterized by X-ray diffraction(XRD),vibrating sample magnetometer(VSM),thermo-gravimetric analysis(TGA),zeta potentials,fourier transform infrared spectrometry(FT-IR)and field emission scaning electron microscope(FESEM).In the screening experiment,mag-MoS₂-RGO-IL had better adsorption performance for different dyes(amaranth,orange II,methylene blue and methyl green)than mag-MoS₂-RGO,and the adsorption capacity was the highest for methylene blue.Therefore,the performance of mag-MoS₂-RGO-IL in the magnetic adsorption separation process was studied with methylene blue as the targeted analyte.In the experiment of influencing factors,the effects of initial concentration of dye solution,extraction time,p H value of solution and extraction temperature on extraction capacity were investigated.Under optimal conditions,the extraction capacity was 143.9 mg/g.Experimental results were imitated by adsorption isotherms and kinetic models,revealing a monolayer adsorption on the homogeneous surface governed by chemisorption.The removal rate was maintained 78%after 5 cycles of regeneration,indicating its good reutilization.Methodological study suggested that the method possessed excellent repeatability,precision and stability.The recoveries from the real samples were in the range of 87.0-98.8%with relative standard deviation of?5.2%.Benefiting from composite structure and magnetic Fe₃O₄,the stable magnetic adsorbent can be quickly separated from aqueous solution.All of above proves that the prepared mag-MoS₂-RGO-IL has great application potential in dye separation.(2)Polymerized deep eutectic solvent modified magnetic carbon nanotubes for separation and analysis of bovine serum albuminThis article described the fabrication of novel magnetic carbon nanotube modified with polymeric deep eutectic solvent(M-CNT@PDES)and its application as extractant for the magnetic solid phase extraction(MSPE)of bovine serum albumin(BSA).The physical properties and morphological characteristics of the extractant are systematically characterized.Afterwards,several parameters such as p H value,initial concentration of BSA,extraction time,ionic strength and extraction temperature were optimized.The results indicated that the modification of PDES significantly improved the extraction performance for BSA,and the maximum extraction capacity was 225.15mg/g under the optimized conditions.In addition,0.20 mol/L Na Cl-PBS solution was chosen as the appropriate eluent,and favourable elution rate(81.22%)was obtained.Circular dichroism spectroscopy(CD)indicated that the secondary structure of BSA has not changed during extraction and elution.The regenerative experiment and application in real calf serum confirmed the outstanding durability and practical application ability of M-CNT@PDES.All of above verified that the proposed M-CNT@PDES coupled with MSPE method has great application potential for the pre-concentration of biomolecules.(3)Deep eutectic solvent of methacrylic acid-benzyl quaternary ammonium salt series modified magnetic cyclodextrin for solid phase extraction of ovalbuminFirst,six kinds of methacrylic acid based deep eutectic solvents were synthesized by a typical heating and stirring method.The carbon chain length and halogen atom of the benzyl quaternary ammonium salt as hydrogen bond acceptors were different.The deep eutectic solvents were polymerized on the surface of the modified magnetic cyclodextrin nanomaterial,respectively,and used for the magnetic solid phase extraction of ovalbumin(OVA).The physical properties and morphological characteristics of the extractant are systematically characterized.The effects of M-?-CD@PDES on the extraction capacity of OVA under different extraction conditions(initial OVA concentration,extraction time,p H value and extraction temperature)were investigated.Under the optimal extraction conditions,the extraction capacity of M-?-CD@PDES for OVA can reach 151.62 mg/g.The results of regenerative experiment revealed that M-?-CD@PDES still maintained an extraction capacity of 108 mg/g for OVA after 6 cycles of regeneration.The gel electrophoresis experiment of extracting OVA from the actual sample of egg white confirmed the excellent practical performance of the synthesized extractant.In summary,the M-?-CD@PDES nanomaterial prepared in this section has ideal application potential for protein extraction.