The production process steps of D(+)-Xylose are as follows:
1) Grinding: Take 1000kg of corn cobs after dedusting and impurity removal, transfer them to the universal grinder, start the motor, adjust the frequency conversion power to 50Hz, and grind the corn cobs to 2cm, and set aside;
2) High-temperature water cooking: import the crushed corn cobs into a high-temperature water cooking tank, add evaporative condensed water according to 1:5 of the dry weight of corn cobs, and turn on the stirring device, control the stirring speed to 100 rpm, and use steam to raise the temperature After heating at 80°C for 3 hours, it is sent to a crawler-type solid-liquid separator for solid-liquid separation. The separated high-temperature cooking liquid enters a settling tank, and its supernatant is used for pretreatment of corn cobs outside the tank to save industrial water resources. ;The separated high-temperature cooking slag enters the hydrolysis kettle for hydrolysis operation;
3) Hydrolysis: Pour the high-temperature cooking slag into the hydrolysis kettle, add fresh water treated by reverse osmosis equipment according to 1:12 of the dry weight of the high-temperature cooking slag, and add 320kg of concentrated hydrochloric acid with a concentration of 30% to make the mixed liquid in the hydrolysis kettle The concentration of hydrochloric acid is 0.8%, start the stirring device, control the stirring speed to 10 rev/min, then pass in steam, raise the temperature to 100°C, keep warm for 4 hours, then send it to the crawler type solid-liquid separator for solid-liquid separation, after separation, get The xylose hydrolyzate has a refractive concentration of 6%, a light transmittance of 36%, and an acidity of 0.65%, and then enters the hydrolyzate tank for subsequent refining treatment; the separated hydrolyzate enters the slag-coal mixed-fired biomass boiler for combustion Prepare steam for evaporation and concentration of the process of the present invention; repeat the above-mentioned hydrolysis process once until the hemicellulose in the corn cob is fully converted into a single xylose molecule;
4) Decolorization: Pump the xylose hydrolyzate in the hydrolyzate tank into the decolorization kettle, control the decolorization temperature to 70°C, the stirring speed to 200 rpm, and the heat preservation and stirring time for 40 minutes. The pigment in the sugar hydrolyzate is removed to obtain a xylose decolorization solution with a light transmittance of 70%;
5) Refining: Pass the D(+)-Xylose decolorization solution through an ion exchange column equipped with 001×7 type cation exchange resin, D301 type anion exchange resin, and 001×7 type cation exchange resin in series to decolorize the xylose solution Carry out refining treatment to reduce the conductivity to below 50 μs/cm to obtain a D(+)-Xylose refined solution with a refractive concentration of 4%;
6) Continuous membrane concentration: use nanofiltration membrane to concentrate xylose refined solution to obtain xylose membrane concentrated solution with a dry matter concentration of 10%;
7) Steam evaporation and concentration: use a multi-effect steam evaporator to evaporate and concentrate the xylose film concentrate again until the dry matter concentration is 80% to obtain xylose massecuite;
8) Crystallization, centrifugation, and drying: cooling crystallization is adopted, and cooling crystallization is carried out at a cooling rate of 1°C/h, so that the xylose massecuite changes from an unsaturated solution to a saturated solution and then to a supersaturated solution. The sugar crystals grow and precipitate continuously. The xylose crystals are separated from the mother liquor by a three-legged centrifuge to obtain 95kg of xylose crystals and 90kg of xylose mother liquor with a dry matter concentration of 60%. The xylose crystals are then passed through a steam drying device. The moisture in the xylose crystals is removed to obtain a crystalline xylose product with a moisture mass percentage of 0.35%; the xylose mother liquor is sold as a by-product and used as a raw material for preparing caramel pigment products.
Research on the technology of extracting D(+)-Xylose from xylose mother liquor, including steps:
(1) The xylose mother liquor is diluted to a refractive index of 35%, wherein the xylose content is 53.84%, the glucose content is 20.16%, the arabinose content is 17.63%, and the galactose content is 5.03%. Add 0.4% activated carbon according to the volume of the xylose mother liquor for decolorization, the decolorization time is 30min, and the decolorization temperature is 80°C.
(2) The decolorized xylose mother liquor is processed through a plate and frame filter screen with a pressure of 0.2Mpa.
(3) The filtered xylose mother liquor is subjected to ion exchange treatment to ensure that the conductance of the ion-exchanged xylose mother liquor is less than or equal to 20 μs/cm, and the pH is 4-5.
(4) Concentrate the xylose mother liquor after separation to a refractive index of 50%.
(5) The concentrated xylose mother liquor is filtered, and the filtration pressure is 0.2Mpa.
(6) The filtered xylose mother liquor is preheated to 62°C for chromatographic separation, the ratio of feed water to material is 1:2.3, and the output is xylose-rich extract, arabinose-rich raffinate A, extract Remaining liquid B.
(7) The extract and raffinate A after chromatographic separation are pre-distilled respectively, and the refractive index is 52%.
(8) The pre-steamed extract and raffinate A are decolorized through an activated carbon column, and the light transmission is 88%.
(9) The decolorized extract and raffinate A are evaporated and concentrated, and the output refraction is 82%, and the temperature is 70°C.
(10) The concentrated extract and raffinate A are cooled to crystallize, the temperature is lowered at 1°C/h, and the temperature is lowered to 30°C to stop.
(11) Centrifuge the crystallized xylose massecuite and arabinose massecuite at a speed of 1000 r/min to obtain crystalline xylose and crystalline arabinose.
The purity of crystalline xylose in (11) was 98.13%, and the yield was 47.33%. The purity of crystalline arabinose was 98.33%, and the yield was 35.95%.
