Treatment method of xylose / glucose hydrolysate

Abstract

The invention relates to the technical field of membrane separation, in particular to a treatment method of xylose / glucose hydrolysate. The invention provides a xylose / glucose hydrolysate treatment method, which comprises: sequentially carrying out pretreatment and membrane deacidification concentration on a xylose / glucose hydrolysate to obtain a xylose / glucose concentrated liquid and a membrane deacidification concentration system filtrate; carrying out organic acid and inorganic acid separation on the filtrate of the membrane deacidification concentration system to obtain an inorganic acid concentrated solution and an organic acid permeable solution; and carrying out reverse osmosis treatment on the organic acid permeable liquid to obtain an organic acid salt concentrated liquid and pure water. The method provided by the invention has the advantages of high recycling rate of xylose / glucose and low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of membrane separation technology, and particularly relates to a treatment method of xylose / glucose hydrolysate. BACKGROUND

[0002] Corn cob is rich in a large amount of lignocellulose. Lignocellulose is mainly composed of cellulose, hemicellulose and lignin. After biochemical treatment under certain conditions, a series of high value-added products such as monosaccharides, oligosaccharides, liquid fuels, and chemical products such as formaldehyde and lactic acid can be obtained, which can be widely used in food, chemical, vehicle and power generation industries.

[0003] Glucose and xylose can be prepared by a series of biochemical processes under different conditions. Xylose / glucose is mainly obtained by hydrolysis of xylose / glucose polymers. Xylose / glucose polymers are hydrolyzed by acid, alkali and corresponding hydrolytic enzymes to obtain xylose / glucose hydrolysate. Then, the xylose / glucose hydrolysate is filtered, purified, crystallized, separated and dried to obtain the final xylose / glucose product. In actual production, different processes and equipment affect the purity of the final xylose / glucose product. Commonly used xylose / glucose purification methods that have been applied in commercial production include microbial enzyme method, ion exchange method, evaporation crystallization method and the like. The current process method has problems such as high energy consumption, large amount of waste water in ion exchange resin regeneration, large equipment area and large amount of waste heat, which need to be solved urgently.

[0004] Meanwhile, the separation and purification of xylose / glucose hydrolysate is an important step in the production of xylose or glucose products. At present, the separation and purification methods of xylose / glucose hydrolysate in the industry mainly include neutralization and deacidification, electrodialysis deacidification, membrane separation technology, activated carbon decolorization and ion exchange desalination. The general process for purifying xylose / glucose hydrolysate using membrane separation technology is as follows: hydrolysate-neutralization process-activated carbon decolorization-plate and frame filtration-first ion exchange resin-ultrafiltration membrane filtration-reverse osmosis membrane concentration-second activated carbon decolorization-acid and alkali neutralization process-second ion exchange resin-evaporation crystallization-xylose / glucose product. In the acid and alkali neutralization process in the above existing process, the calcium ion content in the hydrolysate increases during the deacidification process, causing a large amount of scale accumulation in the subsequent heating pipeline, low heat transfer efficiency, frequent cleaning of the equipment, high consumption of acid and alkali, and a large amount of waste water, which increases the equipment cost and operating cost. At the same time, the content of organic acid / inorganic acid in the product increases, and the acid and alkali neutralization process is still needed at the back end, which consumes a large amount of acid and alkali. In view of the above problems, the process of using ultrafiltration system + nanofiltration dialysis concentration system to purify xylose / glucose hydrolysate can separate organic acids, and the subsequent neutralization process can be omitted. However, the traditional nanofiltration membrane used in this process has low rejection rate, and compared with reverse osmosis membrane separation technology, the xylose / glucose yield of the system is low, part of the xylose / glucose contained in the permeate water is not recycled, which causes great waste. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for treating xylose / glucose hydrolysate. The method described in this invention enables efficient and low-cost recovery and utilization of xylose / glucose.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for processing xylose / glucose hydrolysate, comprising the following steps: The xylose / glucose hydrolysate was pretreated and then concentrated via membrane deacidification to obtain xylose / glucose concentrate and membrane deacidification concentration system filtrate. The filtrate from the membrane deacidification and concentration system is separated into organic and inorganic acids to obtain a concentrated inorganic acid solution and an organic acid permeate solution. The organic acid permeate was subjected to reverse osmosis treatment to obtain a concentrated organic acid salt solution and pure water. The membrane deacidification and concentration uses a fouling-resistant and acid-resistant composite nanofiltration membrane, which is uncharged or weakly charged.

[0007] Preferably, the pretreatment includes sequential activated carbon decolorization, plate and frame filtration, and cation exchange resin treatment.

[0008] Preferably, the membrane deacidification and concentration process is as follows: The filtrate obtained from the pretreatment is concentrated and separated once by passing it through a nanofiltration membrane to obtain a nanofiltration membrane concentrate and a nanofiltration membrane filtrate. The primary nanofiltration membrane concentrate is further concentrated and separated by a secondary nanofiltration membrane to obtain a secondary xylose / glucose concentrate and a secondary nanofiltration membrane filtrate. The primary nanofiltration membrane filtrate and the secondary nanofiltration membrane filtrate are mixed to obtain the filtrate of the membrane deacidification and concentration system.

[0009] Preferably, the molecular weight cutoff of the primary nanofiltration membrane and the secondary nanofiltration membrane is independently 100~300 Da.

[0010] Preferably, the primary nanofiltration membrane and the secondary nanofiltration membrane are of model SANF2-8040.

[0011] Preferably, the operating pressure of the primary concentration separation and the secondary concentration separation are independently 4~6.3MPa, the temperature is independently ≤70℃, and the average unit membrane flux is independently 5~18LMH.

[0012] Preferably, the operating pressure for separating the organic and inorganic acids is ≤8.3MPa, the temperature is ≤45℃, and the average unit membrane flux is 5~22LMH.

[0013] Preferably, the secondary nanofiltration membrane used for separating the organic and inorganic acids is SANF1-8040, with a molecular weight cutoff of 100~200 Da.

[0014] Preferably, before performing the reverse osmosis treatment, the pH value of the organic acid permeate is adjusted to 4.0~7.0.

[0015] Preferably, after obtaining the xylose / glucose concentrate, the method further includes subjecting the xylose / glucose concentrate to secondary activated carbon decolorization, and then subjecting the decolorized solution to ion exchange resin and evaporation crystallization in sequence to obtain refined xylose / glucose.

[0016] This invention provides a method for treating xylose / glucose hydrolysate, comprising the following steps: pretreating the xylose / glucose hydrolysate sequentially and then performing membrane deacidification and concentration to obtain a concentrated xylose / glucose solution and a filtrate from the membrane deacidification and concentration system; separating the filtrate from the membrane deacidification and concentration system into organic and inorganic acids to obtain a concentrated inorganic acid solution and an organic acid permeate; subjecting the organic acid permeate to reverse osmosis treatment to obtain a concentrated organic acid salt solution and pure water; the membrane deacidification and concentration uses an antifouling and acid-resistant composite nanofiltration membrane, which is uncharged or weakly charged. The pure water obtained by the method of this invention has a pH of 4.0~7.0, a conductivity (25℃) ≤50μS / cm, and a TDS ≤20ppm, meeting the water quality requirements for xylose / glucose processes, and achieving a xylose / glucose yield of over 99% for the overall process.

[0017] Compared with the prior art, the antifouling and acid-resistant composite nanofiltration membrane of the present invention has the following beneficial effects: 1) The membrane deacidification and concentration method described in this invention employs a fouling-resistant and acid-resistant composite nanofiltration membrane that is uncharged or weakly negatively charged, exhibiting extremely low rejection rates for organic / inorganic acids and a rejection rate of over 99% for xylose / glucose. The composite nanofiltration membrane demonstrates high sugar rejection and high acid permeability, enabling sugar-acid separation. 2) According to the embodiment, when the xylose / glucose mass-volume ratio in the raw material is greater than 4%, a high-concentration xylose / glucose concentrate with a xylose / glucose mass-volume ratio >20%, refractive index >25%, and conductivity <3000μs / cm can be obtained after concentration. The organic acid removal rate can reach more than 85%, and the inorganic acid removal rate can reach more than 90%. Therefore, when the concentrate treated by the anti-fouling and acid-resistant composite nanofiltration membrane undergoes further purification, the acid-base neutralization process can be omitted, reducing the operating load of the ion exchange resin column, reducing the amount of ion exchange resin used, reducing the amount of resin regeneration wastewater, and reducing equipment investment and operating costs. 3) The antifouling and acid-resistant composite nanofiltration membrane of this invention can operate stably for a long time in acidic environments: for example, at an operating temperature of 25°C, under acidic conditions (30wt% phosphoric acid, 10wt% hydrochloric acid, 20wt% sulfuric acid, or 10wt% nitric acid), the service life is ≥1 year. The antifouling and acid-resistant composite nanofiltration membrane of this invention is suitable for the separation of organic acids and inorganic acids from acidic organic matter, and for the purification of inorganic acids. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of the method for processing xylose / glucose hydrolysate provided by the present invention. Detailed Implementation

[0019] like Figure 1 As shown, the present invention also provides a method for processing xylose / glucose hydrolysate, comprising the following steps: The xylose / glucose hydrolysate was pretreated and then concentrated via membrane deacidification to obtain xylose / glucose concentrate and membrane deacidification concentration system filtrate. The filtrate from the membrane deacidification and concentration system is separated into organic and inorganic acids to obtain a concentrated inorganic acid solution and an organic acid permeate solution. The organic acid permeate was subjected to reverse osmosis treatment to obtain a concentrated organic acid salt solution and pure water. The membrane deacidification and concentration uses a fouling-resistant and acid-resistant composite nanofiltration membrane, which is uncharged or weakly charged.

[0020] In this invention, "xylose / glucose" in the xylose / glucose hydrolysate can be understood as xylose or glucose.

[0021] This invention involves pretreating xylose / glucose hydrolysate sequentially and then performing membrane deacidification and concentration to obtain xylose / glucose concentrate and membrane deacidification and concentration system filtrate.

[0022] In this invention, the pretreatment preferably includes sequential activated carbon decolorization, plate and frame filtration, and cation exchange resin treatment. The primary activated carbon decolorization is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring process; any process well-known to those skilled in the art can be used. Similarly, this invention does not impose any special limitations on the plate and frame filtration process; any process well-known to those skilled in the art can be used. In this invention, the primary activated carbon decolorization serves to adsorb any organic pollutants that may be present during decolorization.

[0023] In this invention, the cation exchange resin used for the treatment is preferably the D001 macroporous strong acid cation exchange resin from Xi'an Lanxiao New Material Technology Co., Ltd. This invention does not impose any special limitations on the process of the cation exchange resin treatment; any process well-known to those skilled in the art can be used.

[0024] In this invention, the function of the cation exchange resin treatment is to adsorb cations (calcium ions) in the pretreated xylose / glucose hydrolysate to prevent membrane fouling caused by excessive calcium sulfate concentration during the subsequent concentration process.

[0025] In this invention, the preferred method for membrane deacidification and concentration is: The filtrate obtained from the pretreatment is concentrated and separated once by passing it through a nanofiltration membrane to obtain a nanofiltration membrane concentrate and a nanofiltration membrane filtrate. The primary nanofiltration membrane concentrate is further concentrated and separated by a secondary nanofiltration membrane to obtain a secondary xylose / glucose concentrate and a secondary nanofiltration membrane filtrate. The primary nanofiltration membrane filtrate and the secondary nanofiltration membrane filtrate are mixed to obtain the filtrate of the membrane deacidification and concentration system.

[0026] In this invention, the molecular weight cutoff of the primary nanofiltration membrane and the secondary nanofiltration membrane is preferably 100~300 Da, more preferably 150~300 Da.

[0027] In this invention, the primary nanofiltration membrane and the secondary nanofiltration membrane are preferably of the independent type, SANF2-8040.

[0028] In this invention, the operating pressure of the primary concentration separation and the secondary concentration separation is preferably 4~6.3MPa, the temperature is preferably ≤70℃, and the average unit membrane flux is preferably 5~18LMH.

[0029] In this invention, the membrane deacidification and concentration system employs the antifouling and acid-resistant composite nanofiltration membrane described herein, which achieves high sugar retention and high acid permeability, thus separating sugar and acid to obtain a xylose / glucose concentrate. The xylose / glucose concentrate has a conductivity <3000 μs / cm and a refractive index >25%, with a mass (kg) to volume (L) ratio >20%. After membrane deacidification and concentration, the removal rate of organic acids is greater than 85%, the removal rate of inorganic acids is greater than 90%, and the yield of xylose / glucose can reach over 99%.

[0030] After obtaining the xylose / glucose concentrate and the filtrate from the membrane deacidification and concentration system, the present invention separates the organic acid and inorganic acid from the filtrate of the membrane deacidification and concentration system to obtain an inorganic acid concentrate and an organic acid permeate; the xylose / glucose concentrate is subjected to secondary activated carbon decolorization, and the resulting decolorized liquid is passed through an ion exchange resin and evaporated for crystallization to obtain refined xylose / glucose.

[0031] In this invention, the xylose / glucose concentrate is subjected to secondary activated carbon decolorization, and the resulting decolorized solution is then passed through an ion exchange resin and evaporative crystallization to obtain refined xylose / glucose. This method eliminates the need for conventional refining processes involving alkali neutralization, ion exchange resins, and evaporative crystallization to produce xylose / glucose.

[0032] In this invention, the operating pressure for separating the organic and inorganic acids is preferably ≤8.3MPa, the temperature is preferably ≤45℃, and the average unit membrane flux is preferably 5~22LMH.

[0033] In this invention, the secondary nanofiltration membrane used for separating the organic and inorganic acids is preferably SANF1-8040, and the molecular weight cutoff is preferably 100~200 Da.

[0034] In this invention, the process of separating organic and inorganic acids separates organic and inorganic acids, and the resulting system concentrate is rich in inorganic acids (i.e., inorganic acid concentrate), which can be used in the process of hydrolyzing xylose / glucose polymers to prepare xylose / glucose hydrolysate.

[0035] After obtaining the inorganic acid concentrate and the organic acid permeate, the present invention performs reverse osmosis treatment on the organic acid permeate to obtain an organic acid salt concentrate and pure water.

[0036] Before performing the reverse osmosis treatment, the present invention preferably adjusts the pH value of the organic acid permeate, and the adjusted pH value is preferably 4.0~7.0.

[0037] The present invention does not impose any special limitations on the reverse osmosis process; any process known to those skilled in the art can be used.

[0038] The pure water obtained after the reverse osmosis treatment has a pH of 4.0~7.0, a conductivity (25℃) ≤50μS / cm, and a TDS ≤50ppm, which meets the requirements for xylose / glucose process water.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1 Prepare 3ml of xylose hydrolysate. 3 The electrical conductivity is 14630 μS / cm, the xylose content (by mass / volume) is 5.2%, the refractive index is 6.5%, the pH is 1.4, the organic acid content is 9.0 g / L, and the inorganic acid content is 9.0 g / L. 1.5m 3 Pure water: pH=6.5~7.5, conductivity <50μs / cm; 3 g / L of activated carbon was added to the xylose hydrolysate and stirred for 30 min. The mixture was then pumped into a plate and frame filter. The residual solids were sent for external treatment. The filtrate was pumped into a macroporous strong acid cation exchange resin system (D001 macroporous strong acid cation exchange resin from Xi'an Lanxiao New Material Technology Co., Ltd.) to remove cations (calcium ions, magnesium ions, etc.) to obtain Ca. 2+ <30ppm resin exchange filtrate; The resin exchange filtrate was pumped into a primary nanofiltration membrane (model SANF2-8040, performance parameters: molecular weight 150~300 Da, test unit water flux of more than 50 LMH) for primary concentration and separation (specific operating parameters are shown in Table 1), to obtain primary nanofiltration membrane concentrate (containing 20.65% xylose by mass / volume, refractive index 23.2%, conductivity 9280 μs / cm, organic acid content 18.9 g / L, inorganic acid content 4.9 g / L, organic acid deacidification rate 55.45%, inorganic acid deacidification rate 78.91% (based on concentrate)) and primary nanofiltration membrane filtrate; The primary nanofiltration membrane concentrate was pumped into a secondary nanofiltration membrane (model SANF2-8040, performance parameters: molecular weight 150~300 Da, test unit water flux above 50 LMH) for secondary concentration and separation (specific operating parameters are shown in Table 1). After washing and filtration with water, a secondary xylose / glucose concentrate (containing 20.65% xylose by mass / volume, refractive index 25.8%, conductivity 3021 μs / cm, organic acid content 3.8 g / L, inorganic acid content 0.9 g / L, organic acid deacidification rate 89.17%, inorganic acid deacidification rate 95.98% (based on concentrate)) and secondary nanofiltration membrane filtrate were obtained. The primary nanofiltration membrane filtrate and the secondary nanofiltration membrane filtrate were mixed to obtain 3.75m. 3 The filtrate from the membrane deacidification and concentration system contained 11.20 g / L of organic acids and 5.40 g / L of inorganic acids; the xylose recovery rate was 99.28%. The permeate from the membrane deacidification and concentration system was pumped into an organic acid and inorganic acid separation system (two-stage nanofiltration membrane, model SANF1-8040, with performance parameters of molecular weight of 100~200 Da and a water flux of more than 50 LMH per unit) to separate organic acids and inorganic acids (specific operating parameters are shown in Table 1), resulting in an inorganic acid concentrate (concentration of 20.7 g / L) and an organic acid permeate (concentration of 6.7 g / L). After adjusting the pH of the organic acid permeate to 7, it was pumped into a reverse osmosis system (RO system, specific operating parameters are shown in Table 1) for reverse osmosis treatment to obtain pure water with a pH of 6.8 and a conductivity of 43 μs / cm.

[0041] Table 1 Operating parameters of Example 1

[0042] Example 2 Prepare 3ml of xylose hydrolysate. 3 The electrical conductivity is 19870 μS / cm, the xylose content (by mass / volume) is 5.9%, the refractive index is 7.2%, the pH is 1.5, the organic acid content is 8.8 g / L, and the inorganic acid content is 10.6 g / L. 1.6m 3 Pure water: pH=6.5~7.5, conductivity <50μs / cm; 3 g / L of activated carbon was added to the xylose hydrolysate and stirred for 30 min. The mixture was then pumped into a plate and frame filter. The residual solids were sent for external treatment. The filtrate was pumped into a macroporous strong acid cation exchange resin (D001 macroporous strong acid cation exchange resin from Xi'an Lanxiao New Material Technology Co., Ltd.) to remove cations (calcium ions, magnesium ions, etc.) to obtain Ca. 2+ <30ppm resin cation column filtrate; The resin cation column filtrate was pumped into a primary nanofiltration membrane (model SANF2-8040, performance parameters: molecular weight 150~300Da, test unit water flux above 50LMH) for primary concentration and separation (specific operating parameters are shown in Table 2), yielding a primary nanofiltration membrane concentrate (containing 22.0% xylose by mass / volume, refractive index 26.8%, conductivity 9586μs / cm, organic acid content 14.2g / L, inorganic acid content 7.59g / L, organic acid deacidification rate 56.7%, inorganic acid deacidification rate 79.25% (based on concentrate)) and the primary nanofiltration membrane filtrate; The primary nanofiltration membrane concentrate was pumped into a secondary nanofiltration membrane (model SANF2-8040, performance parameters: molecular weight 150~300 Da, test unit water flux above 50 LMH) for secondary concentration and separation (specific operating parameters are shown in Table 2). After washing and filtration with water, a secondary xylose / glucose concentrate (containing 22.0% xylose by mass / volume, refractive index 26.8%, conductivity 2150 μs / cm, organic acid content 2.8 g / L, inorganic acid content 1.0 g / L, organic acid deacidification rate 88.64%, inorganic acid deacidification rate 94.29% (based on concentrate)) and secondary nanofiltration membrane filtrate were obtained. The primary nanofiltration membrane filtrate and the secondary nanofiltration membrane filtrate were mixed to obtain 3.75m. 3The filtrate from the membrane deacidification and concentration system contained 6.1 g / L of organic acids and 8.0 g / L of inorganic acids; the xylose recovery rate was 99.44%. The permeate from the membrane deacidification and concentration system was pumped into an organic acid and inorganic acid separation system (two-stage nanofiltration membrane, model SANF1-8040, with performance parameters of molecular weight of 100~200 Da and a water flux of more than 50 LMH per unit) to separate organic acids and inorganic acids (specific operating parameters are shown in Table 2), resulting in inorganic acid concentrate (concentration of 24.2 g / L) and organic acid permeate (concentration of 6.0 g / L). After adjusting the pH of the organic acid permeate to 4.5, it was pumped into a reverse osmosis system (RO system, specific operating parameters are shown in Table 2) for reverse osmosis treatment to obtain pure water with a pH of 4.6 and a conductivity of 55 μs / cm.

[0043] Table 2 Operating parameters of Example 2

[0044] Example 3 Prepare 3ml of glucose hydrolysate 3 The conductivity is 2790 μS / cm, the glucose mass-volume percentage is 7.31%, the refractive index is 8.6%, the pH is 2.1, the organic acid content is 5.89 g / L, and the inorganic acid content is 0.39 g / L. 2.0m 3 Pure water: pH=6.5~7.5, conductivity <50μs / cm; 3 g / L of activated carbon was added to the xylose hydrolysate and stirred for 30 min. The mixture was then pumped into a plate and frame filter. The residual solids were sent for external treatment. The filtrate was pumped into a macroporous strong acid cation exchange resin (D001 macroporous strong acid cation exchange resin from Xi'an Lanxiao New Material Technology Co., Ltd.) to remove cations (calcium ions, magnesium ions, etc.) to obtain Ca. 2+ <30ppm resin cation column filtrate; The resin cation column filtrate was pumped into a primary nanofiltration membrane (model SANF2-8040, performance parameters: molecular weight 150~300Da, test unit water flux above 50LMH) for primary concentration and separation (specific operating parameters are shown in Table 3), yielding a primary nanofiltration membrane concentrate (containing 21.80% glucose by mass / volume, refractive index 25.6%, conductivity 2440μs / cm, organic acid content 7.1g / L, inorganic acid content 0.21g / L, organic acid deacidification rate 58.21%, inorganic acid deacidification rate 82.31% (based on concentrate)) and the primary nanofiltration membrane filtrate; The primary nanofiltration membrane concentrate was pumped into a secondary nanofiltration membrane (model SANF2-8040, performance parameters: molecular weight 150~300 Da, test unit water flux above 50 LMH) for secondary concentration and separation (specific operating parameters are shown in Table 3). After washing and filtration with water, a secondary xylose / glucose concentrate (containing 21.80% glucose by mass / volume, refractive index 25.6%, conductivity 2440 μs / cm, organic acid content 2.5 g / L, inorganic acid content 0.1 g / L, organic acid deacidification rate 85.85%, inorganic acid deacidification rate 91.45% (based on concentrate)) and the secondary nanofiltration membrane filtrate were obtained. The primary nanofiltration membrane filtrate and the secondary nanofiltration membrane filtrate were mixed to obtain 4m 3 The filtrate from the membrane deacidification and concentration system contained 3.8 g / L of organic acid and 0.27 g / L of inorganic acid; the xylose recovery rate was 99.41%. The permeate from the membrane deacidification and concentration system was pumped into an organic and inorganic acid separation system (two-stage nanofiltration membrane, model SANF1-8040, performance parameters: molecular weight 100~200 Da, test unit water flux exceeding 50 LMH) for separation of organic and inorganic acids (specific operating parameters are shown in Table 3), yielding a concentrated inorganic acid solution (concentration 2.0 g / L) and 3.6 m 3 Organic acid permeate (concentration 3.72 g / L); After adjusting the pH of the organic acid permeate to 6.0, it was pumped into a reverse osmosis system (RO system, specific operating parameters are shown in Table 3) for reverse osmosis treatment to obtain pure water with a pH of 6.2 and a conductivity of 40 μs / cm.

[0045] Table 3 Operating parameters of Example 3

[0046] Example 4 Prepare 1.8 ml of glucose hydrolysate. 3 The conductivity is 2150 μS / cm, the glucose mass-volume percentage is 4.0%, the refractive index is 4.9%, the pH is 2.0, the organic acid content is 3.41 g / L, and the inorganic acid content is 0.26 g / L. 0.6m 3 Pure water: pH=6.5~7.5, conductivity <50μs / cm; 3 g / L of activated carbon was added to the xylose hydrolysate and stirred for 30 min. The mixture was then pumped into a plate and frame filter. The residual solids were sent for external treatment. The filtrate was pumped into a macroporous strong acid cation exchange resin (D001 macroporous strong acid cation exchange resin from Xi'an Lanxiao New Material Technology Co., Ltd.) to remove cations (calcium ions, magnesium ions, etc.) to obtain Ca. 2+<30ppm resin cation column filtrate; The resin cation column filtrate was pumped into a primary nanofiltration membrane (model SANF2-8040, performance parameters: molecular weight 150~300Da, test unit water flux above 50LMH) for primary concentration and separation (specific operating parameters are shown in Table 4), yielding a primary nanofiltration membrane concentrate (containing 20.5% glucose by mass / volume, refractive index 25.1%, conductivity 1760μs / cm, organic acid content 6.95g / L, inorganic acid content 0.2g / L, organic acid deacidification rate 57.23%, inorganic acid deacidification rate 81.59% (based on concentrate)) and the primary nanofiltration membrane filtrate; The primary nanofiltration membrane concentrate was pumped into a secondary nanofiltration membrane (model SANF2-8040, performance parameters: molecular weight 150~300 Da, test unit water flux above 50 LMH) for secondary concentration and separation (specific operating parameters are shown in Table 4). After washing and filtration with water, a secondary xylose / glucose concentrate (containing 20.5% glucose by mass / volume, refractive index 25.1%, conductivity 1760 μs / cm, organic acid content 1.9 g / L, inorganic acid content 0.08 g / L, organic acid deacidification rate 89.17%, inorganic acid deacidification rate 94.02% (based on concentrate)) and secondary nanofiltration membrane filtrate were obtained. The primary nanofiltration membrane filtrate and the secondary nanofiltration membrane filtrate were mixed to obtain 2.1m... 3 The filtrate from the membrane deacidification and concentration system (containing 2.64 g / L of organic acids and 0.21 g / L of inorganic acids) showed a glucose recovery rate of 99.65%. The permeate from the membrane deacidification and concentration system was pumped into an organic and inorganic acid separation system (two-stage nanofiltration membrane, model SANF1-8040, performance parameters: molecular weight 100~200 Da, test unit water flux exceeding 50 LMH) for separation of organic and inorganic acids (specific operating parameters are shown in Table 4), yielding a concentrated inorganic acid solution (concentration 1.72 g / L) and 1.85 m 3 Organic acid permeate (concentration 2.8 g / L); After adjusting the pH of the organic acid permeate to 5.5, it was pumped into a reverse osmosis system (RO system, specific operating parameters are shown in Table 3) for reverse osmosis treatment to obtain pure water with a pH of 5.8 and a conductivity of 44 μs / cm.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for processing xylose / glucose hydrolysate, characterized in that, Includes the following steps: The xylose / glucose hydrolysate was pretreated and then concentrated via membrane deacidification to obtain xylose / glucose concentrate and membrane deacidification concentration system filtrate. The filtrate from the membrane deacidification and concentration system is separated into organic and inorganic acids to obtain a concentrated inorganic acid solution and an organic acid permeate solution. The organic acid permeate was subjected to reverse osmosis treatment to obtain a concentrated organic acid salt solution and pure water. The membrane deacidification and concentration uses a fouling-resistant and acid-resistant composite nanofiltration membrane, which is uncharged or weakly charged.

2. The processing method as described in claim 1, characterized in that, The pretreatment includes sequential activated carbon decolorization, plate and frame filtration, and cation exchange resin treatment.

3. The processing method as described in claim 1 or 2, characterized in that, The membrane deacidification and concentration process is as follows: The filtrate obtained from the pretreatment is concentrated and separated once by passing it through a nanofiltration membrane to obtain a nanofiltration membrane concentrate and a nanofiltration membrane filtrate. The primary nanofiltration membrane concentrate is further concentrated and separated by a secondary nanofiltration membrane to obtain a secondary xylose / glucose concentrate and a secondary nanofiltration membrane filtrate. The primary nanofiltration membrane filtrate and the secondary nanofiltration membrane filtrate are mixed to obtain the filtrate of the membrane deacidification and concentration system.

4. The processing method as described in claim 3, characterized in that, The molecular weight cutoffs of the primary and secondary nanofiltration membranes are independently 100~300 Da.

5. The processing method as described in claim 4, characterized in that, The primary and secondary nanofiltration membranes are of model number SANF2-8040.

6. The processing method as described in claim 1, characterized in that, The operating pressure for the primary and secondary concentration separations is 4~6.3MPa, the temperature is ≤70℃, and the average unit membrane flux is 5~18LMH.

7. The processing method as described in claim 1, characterized in that, The operating pressure for separating organic and inorganic acids is ≤8.3MPa, the temperature is ≤45℃, and the average unit membrane flux is 5~22LMH.

8. The processing method as described in claim 1 or 7, characterized in that, The secondary nanofiltration membrane used for separating the organic and inorganic acids is model SANF1-8040, with a molecular weight cutoff of 100~200 Da.

9. The processing method as described in claim 1, characterized in that, Before performing the reverse osmosis treatment, the pH value of the organic acid permeate is adjusted to 4.0~7.

0.

10. The processing method as described in claim 1, characterized in that, After obtaining the xylose / glucose concentrate, the process further includes secondary activated carbon decolorization of the xylose / glucose concentrate, followed by sequential ion exchange resin treatment and evaporation crystallization to obtain refined xylose / glucose.

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