Studies On The Optimization Of Preparation Of Xylose From The Hydrolysis Mother Liquor Of Cottonseed Hulls By Ethanol Solventing-out Crystallization

With the development of quality of people's lives, D-xylose is being a kind of main sweetener by replacing sucrose, and method of preparing xylose is constantly improved and perfected. However, it is not fundamentally improved the defects that the yield of xylose is lower and there is the high xylose residues in the xylose solution in the process of xylose's industrial applications, as a result, how to improve the xylose yield and extract effectively much xylose from the solution become a major problem. What is more , with the development of industrial crystallization, the market proposed a higher request for particle size and shape of xylose product in order to consider the convenience of transportation and storage. For these two main problems, this pape focused on two aspects of xylose yield and product size distribution as assessed by the entire process of producing xylose from cottonseed hulls.First of all, this paper accomplished and studied the whole process of preparation of D-xylose from the cottonseed hull, discussed many details in the xylose production process,such as cottonseed hull hydrolysis,neutralization,decolorization, concentration and ion exchange and so on, furthermore, a relatively new crystal method - solventing-out crystallization was used to get the white D-xylose product.After that, this paper made a detailed study on some factors affecting the yield of preparing xylose by ethanol solventing-out crystallization,focusing on effects to yield of factors of temperature, initial concentration of xylose solution, the quantity of the ethanol and seeds, stir rate, time, and which were made some quantitative curves with respective ocorresponding yields, based on this basis, the quasi—level uniform design U18 (1811) was used to optimize the yield, the following conclusion was obtained, that is, while the concentration of xylose solution is 72.22% , concentration of ethanol is 75.95%, added seeds 0.6g, and stirring 4 hours at 17℃, the recovery of xylose is 79.85%, which is much higher than 50% of the industrial product.Finally, the experiment made a research on the control of product size distribution in solventing-out crystallization process, and ultimately, some factors that were temperature, whether the addition of crystal seeds, stirring speed, initial concentration of xylose solution and so on was determined the quantitative relationship with product size distribution, which provides a guide to Industrial production.