β-环糊精修饰壳聚糖对刺梨果汁单宁和色素的吸附动力学研究

Studies on Adsorption Kinetics of β-Cyclodextrin Modified Chitosan to Tannin and Pigment of Rosa roxburghii Tratt Juice

为有效脱除刺梨果汁中的单宁和色素,提高刺梨果汁品质,选用β-环糊精、壳聚糖及β-环糊精修饰的功能化壳聚糖对刺梨果汁进行脱色和脱单宁处理。结果表明:色素和单宁在3种吸附剂上的吸附均符合吸附等温线,Langmuir和Freundlich方程,直线的相关系数R2均大于0.98,β-CS-CD的色素和单宁的Langmuir拟合参数分别为qm=32.61 mg/g,103×KL=52.85 L/mg,qm=22.37 mg/g,103×KL=29.90 L/mg;β-CS-CD的色素和单宁的Fre鄄undlich拟合参数分别为n=2.00,KF=3.611;n=1.18,KF=1.53。化学修饰的壳聚糖β-CS-CD比纯粹的壳聚糖CS和单纯的β-CD表现出较好的吸附效率。吸附动力学研究表明:色素和单宁的吸附过程符合假一级动力学模型。从假一级动力学常数k1可知,色素和单宁在β-CS-CD上吸附速率常数要大于在CS和β-CD上的吸附速率常数,特别是对于色素吸附表现得尤为明显。由此可见,β-CD的引入不仅增大了对色素和单宁的吸附容量和强度,而且加快了对其的吸附速率。β-CS-CD吸附剂能够有效脱除刺梨果汁中的单宁和色素类物质并改善其品质。

In order to effectively remove the tannin and pigment present in Rosa roxburghii Tratt juice and improve its quality,three kinds of adsorbent includingβ-CS-CD,β-CD and CS were studied.Results showed thatβ-CS-CD exhibited the best absorption performance and the removal rate of pigment and tannin.Moreover,the absorption isotherm ofβ-CS-CD,β-CD and CS were fitted to the Langmuir and Freundlich equations.The linear correlation coefficients R2 were greater than 0.98.The pigment and tannin fitting parameter of Langmuir ofβ-CS-CD were qm=32.61 mg/g,103×KL=52.85 L/mg,qm=22.37 mg/g,103×KL=29.90 L/mg,respectively.The pigment and tannin fitting parameter of Freundlich ofβ-CS-CD were n=2.00,KF=3.611,n=1.18,KF=1.53,respectively.The results indicated that the introduction ofβ-CD functional group could greatly increase the adsorption efficiency.Kinetic studies showed that the adsorption was fast and the adsorption process followed a pseudo-first-order kinetic model.We also find that forβ-CS-CD the adsorption kinetic rate constant(k2)value was much larger onβ-CD and CS.These results clearly indicate that the introduction of CD increases not only the adsorption capacity and intensity but also the adsorption rate of chlorophenol.Therefore,β-CS-CD was effective to remove tannin and pigment from Rosa roxburghii Tratt juice and therefore could improve its quality.