Synthesis of Resins with Ionic Liquids for Purification of Flavonoids from Hippophae rhamnoides L. Leaves

Abstract

The efficient purification method of high-purity flavonoids from Hippophae rhamnoides L. (sea buckthorn) is reported. A novel room temperature ionic liquid-based macroporous adsorption resin (MAR), N-methylimidazole/MARs (Mim/MARs), was prepared on the basis of the Friedel-Crafts-catalyzed and surface-modified technique. The material exhibited favorable characteristics for adsorption application, including high pore volume (1.90 cm(3)/g, 3 times as big as the optimal commercial adsorbent), good pore structure (type IV isotherm with an H1 hysteresis loop, the most favorable structure for adsorption purposes), narrow particle size and pore size distribution (1.2 mm with a standard deviation of 0.106 mm), and excellent chemical stability. This paper also presents the first experimental evidence that the functional groups of the modified materials and composite action of certain molecular interactions between the adsorbent and flavonoids affected the adsorption process. Moreover, a new sphere-size adsorption kinetics model in which the adsorption process contained three or more compartments and detailed parameters of sphere size was developed according to the multicompartment kinetics model and Karichhoff's theory by investigating the regression of the experimental results. The conclusion that the first compartment of the adsorption process onto Mim/MARs mainly occurred on spheres larger than 0.83 mm and the second and third ones mainly occurred on spheres of 0.46-0.83 and 0.22-0.46 mm, respectively, was drawn from this new sphere-size adsorption kinetics model.

Retracted: Analyzing the Effects of Sphere Size on the Adsorption Behavior of Flavonoids on Core‐Shell Ionic‐Liquid‐Based Resins

“…The isotherm for the DIm/MARs, an adsorption isotherm with an H1 hysteresis loop in accordance with IUPAC recommendations, [17] is shown in Figure 4a.The pore-size distribution of the DIm/MARs is displayed in Figure 4b.D etailed physiochemicalp roperties of the adsorbents used in this study are presented in Ta ble 1.…”

“…This model contains just two steps, and does not take into account the differences between fast adsorption,s low adsorption, and even slower adsorption. [17] In this work, considering the restriction above, an ew modified model of adsorption with sphere size was created according to Karickhoof's theory [23] and the multiparameter adsorption kinetics model. [21] Am odel in which the adsorption process contains more compartmentsw as proposed, the real sections were investigated through the polarity inductive effect model,a nd the effect of pore size on different layers was analyzed by using the new model on the experimental results.…”

“…[9,[13][14] The intrinsic nature of the adsorption process, however,r emains unclear.T hus, better knowledge of the adsorbate-adsorption process may help improve the properties of adsorption resins,a nd allow molecular design of their composition. [15][16][17] Our interest focusedo nt he adsorption of flavonoids from sea buckthorn leaves onto resins and on furtheri nvestigating the influence of the degree of matching of the structural paAn ovel room-temperature ionic-liquid-based adsorption resin, n-decylimidazolium/macroporous adsorptionr esin (DIm/MAR), consisting of micrometer-size MAR spheres with an anometersized n-decylimidazolium surfacec oating, was prepared. The materiale xhibits favorable characteristics for adsorption applications.E xisting adsorption modelsa nd methods fail to account for the effect of sphere size on adsorption kinetics.…”

Evaluation on the adsorption capability of chemically modified macroporous adsorption resin with ionic liquid

“…The abovementioned works emphasized that a novel type of embedded imidazolium phase increases the selectivity by interacting with analytes via multiple interactions, including hydrogen-bond, hydrophobic, -, and electrostatic interactions. Ionic liquids are used for the first time as adsorbent to modify MARs and to purify flavonoids from Hippophae rhamnoides L. leaves [19]. The results proved that the adsorption capacity of flavonoids on ionic liquid/MAR is better than that of original MARs.…”

Synthesis, characterization, and adsorption properties of ionic liquid-modified hypercrosslinked polystyrene resins

“…18 ILs can be dened as a class of ionic and nonmolecular solvents composed of large organic cations and small anions. In our previous studies, ILs are used for the rst time as adsorbent to modify macroporous adsorption resins and purify avonoids from Hippophae rhamnoides L. leaves.…”