大孔树脂对竹叶总黄酮的吸附平衡和动力学

摘要

考察了7种大孔树脂对竹叶总黄酮的吸附及解吸特性,发现AB-8大孔树脂具有较高的吸附选择性和良好的脱附性能,并采用静态吸附实验研究了AB-8大孔树脂对竹叶总黄酮的吸附平衡和动力学特性。结果表明,Freundlich方程可较好地描述竹叶总黄酮在AB-8树脂上的吸附平衡;吸附自由能变？G〈0,熵变？S〉0,吸附为自发的熵增过程,升高温度有利于吸附分离。焓变？H为13.45 kJ/mol,在氢键键能范围内;吸附竹叶总黄酮前后树脂的红外谱图也表明,AB-8树脂对竹叶总黄酮分子的吸附是以氢键形式发生的物理吸附。动力学研究表明,吸附过程符合二级动力学方程,颗粒外的液膜扩散是决定吸附速率的主要步骤。%Seven types of macroporous resin were selected to compare their performances in adsorbing and desorbing bamboo flavonoids.AB-8 macroporous resin showed high selectivity and good desorption property.Static sorption experiments were carried out to study the adsorption equilibrium and kinetics of bamboo flavonoids on AB-8 macroporous resin at different temperatures.The results indicated that Freundlich equation was the best for the description of the adsorption equilibrium of bamboo flavonoids on AB-8 resin,the negative value of ΔG and the positive value of ？S showed that the adsorption was a spontaneous process of increased entropy,and the increase of temperature would benefit the adsorption process.The adsorption heat ？H was 13.45 kJ/mol within the range of hydrogen bond energy;and the FT-IR spectra of AB-8 resins before and after bamboo flavonoids adsorption further suggested that the adsorption of bamboo flavonoids on AB-8 resin was a type of physical adsorption with hydrogen bond.The kinetics results revealed the adsorption followed a pseudo-second-order reaction,and the adsorption rate was mainly decided by the film diffusion.