Preparation And Application Of Novel Imprinted Solid Extraction Materilas Based On Carbon Nanotubes Surface

Carbon nanotubes (CNTs) possess unique mechanical performance and highspecific surface area, which exhibited broad application prospect in the field ofmolecularly imprinted technology. The paper prepared a series of surface molecularlyimprinted materials based on modified carbon nanotube. The synthetized imprintedmaterials were applied to the extraction of natural products and detection ofenvironmental pollutants. The results showed that the imprinted materials couldeffectively separate and enrich the template molecules. The content of this research is asfollows:1. A novel molecularly imprinted polymers based on multi-walled carbonnanotubes synthesized by precipitate polymerization was applied as a selective sorbentfor separation and determination of rhein (4,5-dihydroxyanthraquinone-2-carboxylicacid) from the root of kiwi fruit samples coupled with high performance liquidchromatography. The molecularly imprinted polymers were prepared with methacrylicacid and4-vinylpyridine as bifunctional monomers. The chemical structure of themolecularly imprinted polymers was characterized by Fourier transform infraredspectrometer. The equilibrium rebinding experiment and competitive adsorptionexperiment showed that these imprinted polymers exhibited good adsorption abilitytoward rhein. The Langmuir adsorption equilibrium constant, Km, and theoreticalmaximum adsorption capacity, Qm, were estimated to be0.43and6.77mg g1,respectively. Compared with molecularly imprinted polymers prepared with methacrylicacid or4-vinylpyridine solely, the molecularly imprinted polymers synthesized withbifunctional monomers showed enhanced molecular imprinting effect and higheradsorption capacity for the template rhein. The performances of the molecularlyimprinted polymers utilized as solid phase extraction sorbent were investigated in detail.The molecularly imprinted polymers prepared by the method proposed in this workcould successfully apply to extraction and determination of rhein from the root of kiwifruit samples coupled with high performance liquid chromatography.2. This study describes the synthesis of novel molecularly imprinted polymersbased on multi-walled carbon nanotubes (MWNTs@MIPs) using oleanolic acid as thetemplate,4-vinylpyridine as the functional monomer and divinylbenzene as thecross-linker by heat-induced polymerization. The MWNTs@MIPs were characterizedwith Fourier transform infrared (FT-IR) spectrometry and scanning electron microscopy(SEM). The adsorption process of the MWNTs@MIPs towards oleanolic acid wasinvestigated in detail. The properties of MWNTs@MIPs for solid-phase extraction (SPE)were also evaluated. The results demonstrated the good imprinting effect and thecomparable selectivity of MWNTs@MIPs. The optimized molecularly imprinted solid-phase extraction (MISPE) procedure was applied to extract oleanolic acid from theextracts of the roots of kiwi fruit samples. The recoveries of spiked oleanolic acid inkiwi fruit samples were in the range of84%~92.6%with relative standard deviationsbelow5%, and its limit of detection reached2.56μg L1.3. Magnetic molecularly imprinted polymers based on multiwalled carbonnanotubes (MWNTs@MMIPs), which have specific selectivity toward bisphenol A(BPA), were synthesized using BPA as the template molecule, methacrylic acid (MAA)as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as thecross-linker. The MWNTs@MMIPs were characterized by Fourier transform infrared(FT-IR) analysis, vibrating sample magnetometer (VSM) and transmission electronmicroscopy (TEM). MWNTs were grafted with an imprinted polymer film (10.0-20.0nm) and MWNTs@MMIPs exhibited magnetic property (Ms=41.18emu g-1). Batchmode adsorption studies were carried out to investigate the performance of the specificadsorption equilibrium and kinetics. The imprinted polymers exhibited good affinityand excellent selectivity for BPA. The capacity of the MWNTs@MMIPs for BPAretention was also evaluated, and MWNTs@MMIPs showed a maximum specificcapacity of49.26μmol g-1. And the detection limit (3S/N) was7.99×10-6mg L-1. Testfor recoveries of spiked tap water, lake water and rain samples were conducted at3concentration levels, values of recoveries found were in the range of89.8-95.4%,89.9-93.4%and87.3-94.1%, respectively with RSD less than6%. The trace amounts ofBPA in tap water, rain and lake water were determined by the magnetic solid extractioncombined with liquid chromatography and the satisfactory results were obtained.4. A novel magnetic molecularly imprinted polymers (MWNTs/MMIPs) based onphenyl-functionlized multiwalled carbon nanotubes was synthesized using curcumin asthe template, methacrylic acid (MAA) as the functional monomer and ethylene glycoldimethacrylate (EGDMA) as the cross-linker. MWNTs/MMIPs were characterized byscanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) analysis andvibrating sample magnetometer (VSM). Adsorption studies demonstrated that theMWNTs/MMIPs possessed excellent adsorption and selective recognition abilitytowards curcumin with a maximum capacity of7.3mg g-1. And the selectivity factor ofMWNTs/MMIPs towards curcumin, demethoxycurcumin and bisdemethoxycurcuminwas2.04,1.02and1.02, respectively. Combined with high performance liquidchromatography analysis technology, the MWNTs/MMIPs were successfully appliedfor separation and enrichment curcumin in real samples.