Study on the isotherm adsorption characteristics of activate charcoal on functional oligosaccharides

• Main Authors: Tzu-hao Wu, 吳子顥
• Other Authors: Phoency Lai
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/67155670684660261477

碩士 === 靜宜大學 === 食品營養研究所 === 95 === Adsorption isotherms can be used to describe the interactions between oligosaccharides and activate charcoals. Empirical equations for equilibrium adsorption facilitate the determination of activate charcoal consumption during oligosaccharide preparation. Therefore, this study was to adopt two commonly-used adsorption isotherm models (Langmuir isotherm and Freundlich isotherm) in describing the adsorption behaviors of five functional oligosaccharides onto nine activate charcoals, in order to figure out the roles of oligosaccharide and activate charcoal property therein. The results indicated that the optimal pre-dehydration for all activate charcoals examined was 120 ℃ for 40 min. The iodine number was in the range of 660 ~ 950 mg/g, following the order of CNPC (920 ~ 950 mg/g)＞COPC (800 ~ 930 mg/g)＞BPC (870 mg/g)＞WPC (660 ~ 820 mg/g). Based on the adsorption isotherms applied, fructo-oligosaccharide (FOS), isomalto-oligosaccharide (IMO), galacto- oligosaccharide (GOS) and xylo-oligosaccharide (XOS) showed a Langmuir isotherm kL = -2.11*10-5 ~ 2.57*10-3，qm = -1428.6 ~ 2500 (r2 = 0.909 ~ 0.995) and Freundlich isotherm kF = 0.004 ~ 58.75，n = 0.065 ~ 1.249 (r2 = 0.908 ~ 0.996), suggesting good, favorable adsorption onto activate charcoals. But, chito-oligosaccharide (COS) was in unfavorable balanced state for all activate charcoals detected, due to of Langmuir isotherm kL = -1.05*10-4 ~ -1*10-5，qm = -526.3 ~ -54.9 (r2 = 0.886 ~ 0.995) and Freundlich isotherm kF = 1.58*10-17 ~ 6.95*10-3，n = 2.038 ~ 4.914 (r2 = 0.940 ~ 0.987). COS was therefore unsuitable for further purification by using a prepared activate charcoal column. According to the results of Freundlich isotherm, coal powder activate charcoal (COPC-3) displayed a superior absorbing ability to the other charcoals for most of the oligosaccharides examined at 25 ℃, and hence being the best choice as packing materials of prepared columns in elucidating the effect of ethanol concentration for desorption and purification of oligosaccharides. Eluted by 5 ~ 50% ethanol on an activate charcoal column, totally 7.9 ~ 9.2 g of oligosaccharides could be collected from 30 g activate charcoal adsorbent, quite close to the theoretical quantity (9.6 ~ 12.1 g) estimated by Freundlich isotherm. The oligosaccharide recovery was high up to 75 ~ 97%. The regeneration rate of the activate charcoal column by 95% ethanol and DI water was also high up to 90%. Conclusively, the desorption ability and resolution power of ethanol was: GOS and XOS > FOS and IMO.