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|Other Titles: ||Use of cross-flow diafiltration & dialysis for glucose-xylose concentration|
|Authors: ||陳冠忠;Chen, Kuan-chung|
|Keywords: ||透析過濾;透析;葡萄糖;分離效率;Diafiltration;Dialysis;Glucose;Separation efficiency|
|Issue Date: ||2010-09-23 17:32:44 (UTC+8)|
In this study, sugars produced by enzyme hydrolysis of rice straw are separated by cross-flow diafiltration and dialysis. Three kinds of membranes, made of mixed cellulose ester with a mean pore size of 0.025 um and made of regenerated cellulose with MWCO of 5 kD and 10 kD, are used in experiments. The effects of filtration mode, membrane type and pore size, cross-flow velocity and filtration pressure on the filtration rate, sugar rejection and yield are discussed. In the first part, 0.025 um and 0.1 um membrane made of mixed cellulose ester are used to filter pure glucose suspension. Experimental results show that major filtration resistances are caused by the membrane, and the sugar rejections are less than 10% within the operating conditions of this study. Concentration polarization model, which parameters can be obtained using experimental data, is employed to estimate the filtration rate. In the second part, the suspension obtained from rice straw hydrolysis is used in diafiltration and dialysis after a pretreatment. The results show that the filtration rate in diafitration using 5 kD regenerated cellulose membrane is very low, the sugar yield in the filtrate is therefore low. When 10 kD regenerated cellulose membrane is used in diafitration, the sugar yield increases to 2.5% in 3 hours operation. The membrane resistances are the main resistance source under various cross-flow velocities and filtration pressure, and the yield of sugar is still lower than 3%. On the other hand, the results of filtration using 0.025 um mixed cellulose ester membrane indicate that no obvious improvements on the filtration rate and sugar yield can be found due to the formation of a fouled layer on the membrane surface. The resistance due to this fouled layer is as high as 72% of the total resistance. The filtration resistance increases from 66% to 72% as cross-flow velocity increases from 0.1 to 0.5 m/s. Filtration pressure plays more effects on the resistance, the resistance changes from 44% to 72% of the total resistance in the conditions of this study. In the dialysis experiments using 0.025 um mixed cellulose ester membrane, no fouled layer is formed on the membrane, and the collected sugar increases with increasing cross-flow velocity. The pseudo-steady state will be reached in 60 min. Comparing the yields obtained in diafitration and dialysis under the same cross-flow velocity, the diafitration using 10 kD regenerated cellulose membrane yields more sugars in 3 hours operations. However, the yield of sugar is lower than 3% due to the fouling resistance.
|Appears in Collections:||[化學工程與材料工程學系暨研究所] 學位論文|
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