| Plant polyphenol is a kind of widely polyphenol which exist in plants, it is a general name for molecules with multiple phenolic hydroxyl, also called tannins. With more and more in-depth study of polyphenol, it is been found that plant polyphenol is widely used in the fields of medical, food, leather industry, daily-used chemicals etc. ,and the demand is also growing. It is necessary to develop new resources of polyphenol, because traditional polyphenol resources is not sufficient enough. In the same time, China is a major chestnut producer in the world, which contains a lot of polyphenol( about 18 %). Chestnut shell is typically abandoned in vain. It not only waste the resources, but also pollute the environment. If the chestnut shell has been well used, it is benefit for economic, ecological and social benefits, and the development of Chinese chestnut industry, even agricultural economical development.In this study, polyphenol was prepared from chestnut shell, ethanol solution as the extraction solvent, and then using membrane separation technology in order to increase its purity. Finally, the polyphenol of chestnut shell complexing Ge has been tested, and it turn out that we have a favorable outcome. Specific studies are as follows:1 polyphenol was prepared from chestnut shell abandoned in vain by ethanol solution as the extraction solvent. A method was established for analyzing polyphenol, standard curve were prepared. Curvilinear equation was established and the calculation method of extraction rate was listed. The effect of extraction solvent and its concentration, the extraction time and temperature, the ratio of solid to liquid and other factors on the extraction of polyphenol from chestnut shell as raw material was researched with the orthogonal experimental method for the optimal design of experimental factors. The optimum extraction conditions were as follows: ethanol solution was 40 % ; the ratio of solid to liquid was 1:20; and the mixture must be extracted in water-bathing at 80 oC for 120 minutes. Under the above conditions , the extraction amount of polyphenol was up to 71.28 %. So the extraction of the polyphenols from chestnut shell was feasible. 2 the polyphenol of chestnut shell were purified by membrane separation technology. The solution of chestnut shell polyphenol was treated by Polysulfone membrane. The effects of the molecular weight cutoff, trans-membrane pressure, flow velocity, and temperature on membrane property and product quality were studied with the orthogonal experimental method for the optimal design of experimental factor. The experimental results indicated that, under the conditions of molecular weight cutoff of 10000,tans-membrane pressure of 0.2 MPa,flow velocity of 2.0 m/s, and temperature of 40 oC, the chestnut shell polyphenol with turbidity≤0.8 NTU, and purity≥64 % was obtained. This method provides a technical reference for the further development of chestnut shell polyphenol.3 the application of chestnut shell polyphenol was research. The precipitation of germanium by complexing with chestnut shell polyphenol was study. First, the analyzing method of germanium was established; working curve was prepared at the maximum adsorption wavelength; curvilinear equation was obtained, and the calculation method of Ge concentration was determined. Second, the effects of pH value, amount of polyphenol, concentration of zinc sulfate and other factors on the rate of precipitation Ge were researched with the orthogonal method for the optimal design of experimental factor, and the optimum process parameters were obtained. The optimal operation conditions were the pH value of 2.5, the polyphenols/germanium content ratio of 36, zinc sulfate of 110 g/L. Under the above conditions, complex rate was up to 99.0 % in small scale experiment and was up to 98.6 % in experiment production after reaction 30 minutes at 25 oC. Compared with original tannic acid, the cost of production was greatly reduced with the polyphenol of chestnut shell. |
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