聚乙烯醇接枝微粒对黄酮类物质的吸附特性

以硅胶表面接枝有聚乙烯醇(PVA)的接枝微粒PVA/SiO₂为固体吸附剂, 对槲皮素和芦丁2种黄酮类化合物进行了吸附研究, 结果表明, 由于接枝微粒PVA/SiO₂表面含有高密度的羟基, 使得该接枝微粒与黄酮类化合物分子之间可形成多位点的常规氢键和π型氢键, 溶剂的竞争吸附对黄酮化合物的吸附容量产生很大的影响. 以弱极性的1,2-二氯乙烷(DCE)为溶剂时, 几乎不存在溶剂的竞争吸附, 槲皮素和芦丁具有最高的吸附容量, 分别为0.32 mmol/g(96 mg/g)和0.23 mmol/g(140 mg/g); 而在质子溶剂乙醇中, 强烈的溶剂竞争吸附使两者的吸附容量降至0.22 mmol/g(65 mg/g)和0.14 mmol/g(87 mg/g). 升高温度会减弱氢键作用, 甚至使氢键断裂, 导致吸附容量减小. 质子溶剂中电解质的存在, 对吸附作用产生负性影响. 功能微粒PVA/SiO₂对黄酮类化合物的吸附为放热过程, 且为焓驱动的吸附过程.

Adsorption Character of Polyvinyl Alcohol-grafted Particles for Flavonoids by Driving of Hydrogen Bond Interaction

The adsorption characters of two kinds of flavonoids, quercetin and rutin, were conducted by polyvinyl alcohol(PVA)-grafted silica gel particles PVA/SiO2 as solid adsorbent. The research results show that the conventional hydrogen bond with multiple sites and π type hydrogen bond can be formed between the hydroxyl groups with high density on the surfaces of the functional composite particles PVA/SiO2 and the hydroxyl groups and the conjugated aromatic rings in the molecules of flavonoid compounds. The competing adsorption of the solvent will produce great negative effects on the adsorption capacity of the flavonoids. In 1,2-dichloroethane(DCE) as a weak polarity solvent, the competing adsorption of the solvent barely exists. Therefore, when DCE is used as solvent, quercetin and rutin have very high adsorption capacities, and they are 0.32 mmol/g(96 mg/g) and 0.23 mmol/g(140 mg/g), respectively. While in ethanol as a protic solvent, the adsorption capacities of quercetin and rutin decline greatly as a result of the strong competing adsorption of the solvent, and they are 0.22 mmol/g(65 mg/g) and 0.14 mmol/g(87 mg/g), respectively. Rising temperature will weaken the hydrogen bond interaction between the functional composite particles PVA/SiO2 and quercetin or rutin, and even makes the hydrogen bond rupture, leading to the decrease of the adsorption capacity. The existence of electrolytes in the protic solvent will influence the adsorption negatively. The adsorption process of the functional composite particles PVA/SiO2 for flavonoids is exothermic and driven by enthalpy.