Study On The Processing Technology Of Xylose Mother Liquor For Galactitol

Xylose mother liquor, as an important by-product of xylose productive process, contains xylose, glucose, arabinose, galactose and so on, all of them are high value-added monosaccharides. Besides, there is very complex colloid and pigment system in xylose mother liquor, so, the traditional separation method is limited to further purifying. The galactitose in xylose mother liquor can be used to product galactitol by hydrogenation catalytic reaction. As an important biochemistry preparation and medicine, galactitol has a bright market further. The traditional processing of galactitol is complicated and costly. In this paper, we aimed to find a new processing technology of galactitol from xylose mother liquor.First, the components of xylose mother liquor analysed by HPLC, to find the effect of different kinds ion-chromatography on separating; based on the SMB (simulated moving bed chromatography) technology, the separating of xylose mother liquor is researched, it is separated into two parts:xylose/glucose, arabinose/galactose; next, the whole processing of galactitol from xylose mother liquor is researched and optimized, and we attained the optimized parameters; at the end, based on all of the work above, the medium-scale experiment is conducted, and the possibility of the industrialized production is explored and evaluated.(1) the components analysis of xylose mother liquorIn the paper, we analysis the components of xylose mother liquor by HPLC, and investigate the separation effect of xylose, alabinose, galactose, and glucose. Compared and assessed the separation effect of Ca2+type exchange resin and Pb2+type exchange resin. It’s showed that not Ca2+type exchange resin but Pb2+type exchange can separate xylose and galactose effectively. We get the components of xylose mother liquor by comparing calculation:xylose, alabinose, galactose, and glucose account for97%of HPLC detection substance, xylose account for44.45%, alabinose27.75%, glucose13.05%, galactose11.75%.(2) Separating xylose mother liquor by SMB chromatographyBased on the experience of predecessors, by comparing the separation effect of cationic exchange resins and strong basic anionic exchange resins in chloride form, we find that Na+type, K+type, Pb+type and other cationic exchange resins cannot separate effectively. So, strong basic anionic exchange resin in chloride form is selected for stationary phase of SMB, it can separate galacose from xylose effectively. By comparing, we select0.1mol/L NaOH and0.02mol/L NaCl mixed half to half as the mobile phase.(3) Whole processing and parameters designWe explore the whole processing of galactitol from xylose mother liquor, and determine the process:Stockâ†'Dilute with waterâ†'Removal pigmentâ†'IX (Ion Exchange)â†'Deaeration and Ultra filtrationâ†'SMBâ†'Evaporationâ†'Hydrogenationâ†'Removal pigmentâ†'IX (Ion Exchange)â†'Evaporationâ†'Crystallizationâ†'Centrifugalizationâ†'Dryâ†'Packaging.The optimum processing parameters:(1) xylose mother liquor is diluted to20-40%with water;(2) the liquid luminousness after removal pigment process should be more than90%; the order of IX (Ion Exchange) system:anion exchange column with D301resin, cation exchange column with001X7resin, anion exchange column with D296resin. The conductivity of liquid after IX should be below than5us/cm, the luminousness should be more than99%; t0.1mol/L NaOH and0.02mol/L NaCl mixed half to half as the mobile phase; strong basic anionic exchange resin in chloride form is selected for stationary phase of SMB; the temperature range of separation is40-50℃. The SMB has12columns. The concentrations of product is3-10%, in which galactose account for30-60%, alabinose account for25-40%; the concentrations of by-product is10-30%, in which xylose account for60-90%, glucose account for5-20%. Evaporating by sheet evaporator to25%, and adjust the pH to7.5-8.0; the ratio of Raney nickel catalyst is2-5%of dry matter, the reaction temperate is stay within100-180℃and the press is stay within10.0-12.0MPa.(4) medium-scale experimentIn the paper, the medium-scale experiment is conducted in the above processing and parameters, the quality of obtained crystal galactitol product is up to the standard of galactitol production enterprises, and can meet the demands of biochemistry preparation and medicine stock.