Adsorption and Desorption Characteristics of Maltooligosaccharide for the Surface Treated Activated Carbons
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Adsorption and Desorption Characteristics of Maltooligosaccharide for the Surface Treated Activated Carbons JUNG-WOOK YOO, TAE-YOUNG KIM, SUNG-YONG CHO AND SEON-GYUN RHO Department of Environmental Engineering, Chonnam National University, Gwangju 500-757, Korea SEUNG-JAI KIM∗ Department of Environmental Engineering, Chonnam National University, Gwangju 500-757, Korea; Environmental Research Institute, Chonnam National University, Gwangju 500-757, Korea [email protected]
Abstract. The adsorption and desorption characteristics of maltooligosaccharide for raw and surface treated activated carbons were studied experimentally. The TLC imaging densitometry method was used in determining the sugar concentration in the maltooligosaccharide. Adsorption amount of larger molecules, such as maltopentaose and maltoheptaose on F400 were greater than those of smaller molecules. On the other hand, Adsorption amount of smaller molecules, such as maltose and maltotriose on SLS103 were greater than those of larger molecules. Acid treatment of the GAC increases the carboxyl group, but did not affect much on the adsorption rate of saccharides. Heat treatment decreases the adsorption time of F400 due to substantial surface area increase. For the desorption of the adsorbed saccharides with ethanol, the amount of ethanol in the solution was more important than the concentration. Keywords: activated carbon, adsorption, desorption, maltooligosaccharide, thin-layer chromatography (TLC)
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Introduction
Oligosaccharides are carbohydrate compounds containing 2-20 sugar units, with molecular weights ranging between 300 and 2,000. Oligosaccharides are usually water soluble, have little influence on rheological properties of food, mild in sweetness, not degraded by human digestive enzymes. Oligosaccharides can be easily modified chemically and biochemically, and are highly stable, nontoxic, and hydrophilic. Maltooligosaccharide is a mixture of various glucose monosaccharide, which can be separated from maltooligosaccharide. It is useful in a wide variety of applications. For example, maltopentaose (G5) is used as a food additive, and it can restrain blood sugar and the cholesterol (Francesca et al., 2004). It can be used as ∗ To
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an aging agent for starch food and is highly functional material. For the separation of maltooligosaccharide, silica gel and ion exchange resin were used in general. However, it is too expensive for commercial scale application, thus an inexpensive separation method is required. Activated carbon is a powerful adsorbent because it has a large surface area and pore volume. The separation and quantitative analysis of oligosaccharides are important in a wide variety of applications such as food analysis and analysis of the products obtained from hydrolysis of polysaccharides. The quantitative determination of carbohydrate density directly from the “spots” on the TLC plate by densitometry has been appeared in the literature (Han and Robyt, 1998; Robyt and Rupendra, 1994), and rece
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