摘要/Abstract
本工作旨在探索MOFs材料高效富集黄芩中黄芩苷的新方法，拓展MOFs在吸附领域的用途.溶剂热法合成了沸石咪唑酯骨架-8（ZIF-8），并进行了结构表征，以确保其准确合成.研究了ZIF-8对黄芩苷的吸附规律和作用机理：ZIF-8对黄芩苷的吸附符合准二级动力学方程，平衡吸附数据符合Langmuir吸附等温模型.采用响应面法（RSM）得到优化后的最佳吸附参数，在此条件下，ZIF-8对黄芩中黄芩苷的吸附率高达98.22%，且对黄芩中其它成分吸附效果不显著，以pH 6.8的PBS溶液作解吸液，ZIF-8对黄芩苷的解吸率为62.46%，而黄芩苷的纯度由吸附前的21.55%提高到解吸后的64.27%，且ZIF-8在吸附前后稳定性良好，回收率达到83.50%.因此，ZIF-8在吸附纯化黄芩苷方面具有潜在的应用价值.
关键词: 金属有机框架, 吸附, X射线光电子能谱(XPS)
This work aims to explore a new method for the efficient enrichment of baicalin in Scutellaria baicalensis Georgi by using metal organic frameworks (MOFs) materials, and to open up new applications for MOFs in the adsorption direction. The zeolitic imidazolate framework-8 (ZIF-8) was synthesized by solvothermal method and characterized by structure to ensure its accurate synthesis. Baicalin was extracted from Scutellaria baicalinsis Georgi by ethanol extraction and acid precipitation method. The ZIF-8 was used to carry out the static adsorption experiment on the crude extract of Radix Scutellariae. After the adsorption equilibrium was reached, the mixture was centrifuged, and the residual concentration of baicalin was detected by high performance liquid chromatography method (HPLC). The recovered saturated adsorbed ZIF-8 material was washed with water and dried, and the phosphate buffered saline (PBS) solution of pH 6.8 was used as a desorption solution, and the desorption was performed by shaking. The content of baicalin in the desorbed solution was determined by HPLC to calculate the desorption rate and achieve the purpose of adsorbent recovery. In the adsorbing process, the effects of adsorbent dosage, pH and adsorbate concentration of the crude extract of Radix Scutellariae were also optimized, and the response surface test (RSM) was performed using Design Expert software to obtain optimal adsorption conditions. Under these conditions, the adsorption rate of ZIF-8 to baicalin in Radix Scutellariae was as high as 98.22%, and the adsorption effect was not significant on other components in Radix Scutellariae. The desorption rate of ZIF-8 adsorbed baicalin in pH 6.8 solution was 62.46%, and the purity of baicalin increased from 21.55% before adsorption to 64.27% after desorption, and ZIF-8 had good stability before and after adsorption, and the recovery rate reached 83.50%. Therefore, ZIF-8 has potential application value in the adsorption and purification of baicalin. The adsorption law and mechanism of ZIF-8 on baicalin were studied:The adsorption of baicalin on ZIF-8 accorded with the quasi-second-order kinetic equation, and the equilibrium adsorption data accorded with the Langmuir adsorption isotherm model.
Key words: metal-organic framework, adsorption, X-ray photoelectron spectroscopy
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