Synthesis,Optimization And Property Study Of Fe₃O₄@TA@P?NVP-co-NIPAM? Magnetic Polyphenol Adsorption Microsphere

In this study,Fe3O4@TA@P(NVP-co-NIPAM)and its modification Fe3O4@TA@P(NVP-co-NIPAM)@PNIPAM were constructed for magnetic soild-phase extraction(M-SPE)as polyphenol absorbent.Methods including fourier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA),magnetic intensity analysis,BET surface area analysis,ultra high performance liquid chromatography(UHPLC)were used for analysis,and the composition,magnetic property,adsorption and desorption ability of Fe3O4@TA@P(NVP-co-NIPAM)were analysized.Moreover,Fe3O4@TA@P(NVP-co-NIPAM)was applied for polyphenol M-SPE from plants.Main achievements were listed as follows:(1)Fe3O4@TA@P(NVP-co-NIPAM)microsphere was fabricated.The individual microsphere was 50?m in diameter,core-shell structured,with a magnetic Fe3O4 core and a polymer shell copolymerized by N-Vinyl-2-pyrrolidone(NVP)and N-Isopropylacrylamide(NIPAM).The microsphere exhibited good magnetic property(with saturation induction density of 15.0 emu/g),excellent adsorption ability to polyphenols(145.4 mg/g to EGCG under test condition),and polyphenols were absorbed as a monolayer,following Langmuir adsorption model.Absorbed polyphenol could be desorbed by ethanol,and the desorption ratio for EGCG was 49.0%.The reusability of the absorbent was also good.Thus,the Fe3O4@TA@P(NVP-co-NIPAM)was an outstanding absorbent for polyphenol M-SFE.(2)To construct the core-shell structure,tannic acid(TA)was employed for directing copolymerization of two amide monomers.The TA guided copolymerization preferentially on the surface of the magnetic core and facilitated formation of the shell for coating the magnetic core.(3)It was unveiled that proper amount of TA(43 mg per gram of Fe3O4)helped formation of core-shell structure;Too low ratio between NVP and NIPAM(<2:1)would cause caking,and too high ratio(>2:1)would cause low adsorption ability of synthesized product;Synthesizing with proper amount of surfactant(0.5 mg/mL of sodium dodecyl benzene sulfonate)resulted in microspheres with diameter of 50 ?m;Vigurous shaking promoted chance of successing of the structure formation.(4)Excellent selectiveness to polyphenol of Fe3O4@TA@P(NVP-co-NIPAM)was observed through polyphenol M-SPE from green tea extract and peanut shell extract,as polyphenols increased from 82.4%to 92.1%and from 80.5%to 91.4%for green tea extract and peanut shell extract,respectively after M-SPE.Meanwhile,an adsorption preference for lower polarity polyphenol was observed during the extraction.(5)To further improve the adsorption ability,Fe3O4@TA@P(NVP-co-NIPAM)@PNIPAM was fabricated by modification of Fe3O4@TA@P(NVP-co-NIPAM)with NIPAM through polymerization.The new absorbent possessed better adsorption ability to polyphenols(176.2 mg/g to EGCG)and better desorption rate in ethanol(76.3%for EGCG).Fe3O4@TA@P(NVP-co-NIPAM)@PNIPAM was applied for purification of chlorogenic acid in sunflower seed shell extract,utilizing its selectiveness adsorption to polyphenols to remove the unwanted polyphenols.