Studies On The Separation And Purification Process Of Xylitol With Membrane And Chromatography

Xylitol is widely used as a functional additive,China is playing an important role in xylitol production,and more than 60%xylitol is produced in China. Unfortunately,most of the manufacturers are still applying the traditional synthesis process,which converts xylose to xylitol in high temperature as well as high pressure conditions,so it is not an energy-efficient and environmental-friendly process.Therefore,it is an interesting and exciting work to develop a new type xylitol production process based on biotransformation with innovative separation and purification technology based on membrane and chrotographic techniques, which would reduce resources consumption,improve product quality,increase production yield and minimize pollution.In this dissertation,a series of pilot-scae experiments have been carried out to obtain the optimized operation parameters and conditions,which are suitable for enlarging the pilot-scale results to industrial one,after separating cells by membrane, desalting and deeolorizing by resins,separating using continuous moving bed, xylitol solution in high purity can be continuously product.Firstly,choosing Flow-eel ultrafiltration system to reusing the cells,also getting the dialysate in high yield;secondly,using the typical ion exchange resin chromagraphy to desalting and decoloring,this process can improve the quality of xylitol and reduce the effects on the cycle of simulated moving bed for less salinity and pigments;then getting a high performance resin for separating xylitol fermentation,and directing how to get the operation parameters by pulse experiment and the "Triangle theory";finally, opetating the continuous moving bed actually to verify and optimize the operation parameters.At last,an integrated separation and purification process based on membrane and chromatography has been studied and the results have been successfully applied by a famous industrial enterprise in China.In the process of determinating operation parameters,this dissertation proposes a useful and simple calculation method which simplifies the process of parameters determination.