Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB23RA, UK.
J Chromatogr A. 2009 Dec 11;1216(50):8730-40. doi: 10.1016/j.chroma.2009.02.092. Epub 2009 Mar 6.
The suitability of the use of macroporous adsorbent Amberlite XAD7HP in expanded bed adsorption processes for the isolation of flavonoids from crude extracts of Ginkgo biloba L. has been assessed. The expansion and hydrodynamic properties of expanded beds were investigated and analyzed. The bed expansion as a function of operational fluid velocity was measured and correlated with the Richardson-Zaki equation. Theoretical predictions of the correlation parameters (the terminal settling velocity u(t) and exponent n) were improved by modifying equations in the literature. Residence time distributions (RTDs) were studied using acetone as a tracer. Three measures of liquid phase dispersion (the height equivalent of theoretical plate, Bodenstein number and axial distribution coefficient) were investigated and compared to values previously obtained with commercial EBA adsorbents developed for protein purification. A suitable bed expansion ratio was found to be 1.25 times the settled bed height, which occurred at a corresponding flow velocity of 183 cm/h. For an initial settled bed height of 42 cm, the mean residence time of liquid in the expanded bed was around 28 min. Under these flow conditions, the axial mixing coefficient D(ax) was 7.54 x 10(-6) m(2)/s and the Bodenstein number was 28; the number of theoretical plates (N) was 19 and the height equivalent of a theoretical plate (HETP) was 2.77 cm. Rutin trihydrate was used as a model flavonoid for the characterization of the adsorption properties of Amberlite XAD7HP. Adsorption was observed to reach equilibrium within 3 h with 70% of the adsorption capacity being achieved within 30 min. The estimated maximum equilibrium adsorption capacity for rutin was estimated to be 43.0 mg/(gresin) when the results were fitted to Langmuir isotherms. The adsorption performance was not seriously impaired by the physical presence of G. biloba leaf powders. Assessment of the kinetics of the adsorption of rutin revealed that the rate constant for adsorption was only reduced by 15% in the presence of leaf powders at a concentration of 50 mg/mL. The results demonstrated that Amberlite XAD7HP should be suitable for expanded bed adsorption of flavonoids from crude extracts of G. biloba L.
已评估大孔吸附剂 Amberlite XAD7HP 在用于从银杏 crude 提取物中分离类黄酮的膨胀床吸附工艺中的适用性。研究和分析了膨胀床的膨胀和流体力学特性。测量了作为操作流体速度函数的床膨胀，并与 Richardson-Zaki 方程相关联。通过修改文献中的方程，改进了关联参数（终端沉降速度 u(t)和指数 n）的理论预测。使用丙酮作为示踪剂研究停留时间分布（RTD）。研究了三个液相分散度（理论塔板高度当量、Bodenstein 数和轴向分布系数）的措施，并与先前用为蛋白质纯化开发的商业 EBA 吸附剂获得的值进行了比较。发现合适的床膨胀比为settled 床高度的 1.25 倍，在相应的流速为 183 cm/h 时发生。对于初始 settled 床高度为 42 cm，液体在膨胀床中的平均停留时间约为 28 min。在这些流动条件下，轴向混合系数 D(ax)为 7.54 x 10(-6) m(2)/s，Bodenstein 数为 28；理论板数（N）为 19，理论板高度当量（HETP）为 2.77 cm。芦丁三水合物用作 Amberlite XAD7HP 吸附性能表征的模型类黄酮。观察到吸附在 3 h 内达到平衡，70%的吸附容量在 30 min 内达到。当结果拟合 Langmuir 等温线时，芦丁的估计最大平衡吸附容量估计为 43.0 mg/(gresin)。物理存在银杏叶粉末不会严重损害吸附性能。芦丁吸附动力学的评估表明，在 50 mg/mL 浓度下存在叶粉时，吸附速率常数仅降低了 15%。结果表明，Amberlite XAD7HP 应该适合从银杏 crude 提取物中吸附黄酮类化合物。
