环糊精聚氨酯磁性吸附剂制备、表征及对柯里拉京的吸附

以环糊精聚氨酯β-CDPU包覆Fe₃O₄磁核及SiO₂/Fe₃O₄复合粒子，制备出两种磁性吸附剂β-CDPU@Fe₃O₄和β-CDPU@（SiO₂/Fe₃O₄）。考察了吸附剂对多酚类天然产物柯里拉京的吸附，并结合磁分离技术，从珠子草粗提液中直接富集柯里拉京。采用FTIR、XRD、SEM及热重分析法对两种磁性吸附剂进行了结构表征，表明两种吸附剂中聚合物含量分别为41.5%和36.5%，β-CDPU的包覆未改变Fe₃O₄的晶型。吸附机理研究表明，二者对柯里拉京的吸附均符合Langmuir型等温线，但Fe₃O₄磁核对柯里拉京具有特殊的相互作用，造成柯里拉京洗脱困难，总洗脱率和回收率仅17.0%和10.5%。而磁核经SiO₂修饰后，可以阻碍Fe₃O₄对柯里拉京的接触，提高柯里拉京的洗脱率（41.0%）和回收率（22.8%），实现珠子草中柯里拉京的初步富集。

Synthesis and characterization of β-cyclodextrin polyurethane magnetic adsorbents and their adsorption on corilagin

Two magnetic adsorbents β-CDPU@Fe₃O₄ and β-CDPU@(SiO₂/Fe₃O₄) were synthesized by encapsulating Fe₃O₄ and SiO₂/Fe₃O₄ composite magnetic beads by β-cyclodextrin polyurethane polymer (β-CDPU), and adsorption and enrichment of polyphenolic natural product corilagin from Phyllanthus niruri L. herb plants by magnetic separation were studied. Both adsorbents were characterized by FTIR, XRD, SEM and TG/DTA techniques. The appearance of several new peaks in FTIR spectra around 1695, 1617, 1559, 1259 and 1033 cm^-1 was attributed to urethane and β-CD moiety. The adsorbent polymeric surface was rough with many protuberant lumps, folds and pores as observed by SEM. Both adsorbents were thermostable below 200℃, indicating suitability for separation usage at room temperature. Polymer content of the two adsorbents reached as high as 41.5% and 36.5%, respectively, based on the mass loss at high temperature in TG/DTA analysis. XRD showed that the crystal structure of Fe₃O₄ in both adsorbents was nearly the same as that of Fe₃O₄ and SiO₂/Fe₃O₄ composite beads. Hence, β-CDPU encapsulation did not alter crystal structure of Fe₃O₄. Adsorption of corilagin by both adsorbents followed Langmuir adsorption isotherm, which was expected from double adsorption sites in β-CDPU skeleton. But the special interaction between Fe₃O₄ magnetic-core and corilagin, probably due to the complex formation of Fe(Ⅲ) and phenolic hydroxyl groups in corilagin molecule, made it difficult to elute corilagin and resulted in low elution and recovery yield of corilagin at 17.0% and 10.5%, respectively. SiO₂ modification on Fe₃O₄ magnetic core was able to hinder such interaction and the adsorbent β-CDPU@(SiO₂/Fe₃O₄) exhibited more favorable performance for corilagin enrichment with the elution yield of 41.0% and recovery yield of 22.8%. The corilagin enrichment from Phyllanthus niruri L. showed the adsorbent β-CDPU@(SiO₂/Fe₃O₄) would find commercial application for recovery and enrichment of specific natural products from plant materials.