KR101073726B1 - Economical manufacturing process of xylose from biomass hydrolysate using electrodialysis and direct recovery method - Google Patents

Abstract

The present invention relates to an xylose manufacturing process that is environmentally friendly and simple in process, and more particularly, the present invention relates to a high concentration xylose extract by countercurrent extraction of tropical fruit biomass by sulfuric acid hydrolysis. Steps for getting it; b) adjusting the pH of the extract to 1.5-2.5, bleaching and filtration; c) desalting the decolorizing and filtrate by introducing the electrodialysis apparatus; d) the sulphate waste recovered in step c) is recycled to step a), and the desalted organics are concentrated and directly recovered to obtain xylose crystals. It relates to a manufacturing process of.

Tropical fruit biomass by-product, xylose, electrodialysis, sulfate recovery, direct determination

Description

ECONOMICAL MANUFACTURING PROCESS OF XYLOSE FROM BIOMASS HYDROLYSATE USING ELECTRODIALYSIS AND DIRECT RECOVERY METHOD}

The present invention eliminates the process of generating a large amount of waste water, such as the neutralization and ion purification process in the existing xylose manufacturing process, not only environmentally friendly, but also economical xylose manufacturing process reduced production cost due to the simplified process It is about.

As a method of purifying a useful sugar component including xylose from a conventional sulfuric acid hydrolysis solution, a precipitation method and an ion exchange resin method are most used. Among them, the ion exchange resin method is widely used because of its low cost and traditionally used process. However, since a large amount of wastewater containing a high concentration of salt is generated during the regeneration of the ion exchange resin, the burden of wastewater treatment is greatly increased, and thus, an alternative technique for reducing the amount of chemicals and the amount of wastewater generated is required.

Recently, as a new separation technique, a method of desalting molasses and fermentation broth by electrodialysis and effectively utilizing resources is well known. Korean Patent Publication No. 2008-0074687 discloses a method for preparing xylose from the step of hydrolysis, neutralization, precipitation, filtration, electrodialysis and ion exchange resin from tropical fruit biomass. However, it is well known that the problem of such an electrodialysis apparatus is the contamination of the ion exchange membrane, and this contamination phenomenon not only reduces the efficiency of the apparatus but also shortens the life of the membrane.

In order to avoid this problem, pretreatment such as treatment with a hard water softening device or an anion exchange resin has been attempted (Japanese Patent Application Laid-Open No. 54-67093), but the disadvantage is that the cost is high because it is necessary to go through various stages of pretreatment and use a subsidiary material. There is a limit of industrial application. Korean Laid-Open Patent No. 2001-0107331 relates to a method for recovering lactic acid by an electrodialysis process, and describes the recycling process of some of the separated substances (ammonium sulfate) and the advantages (efficiency and environmental friendliness) by the electrodialysis process. . However, electrodialysis still has problems with membrane cost, membrane fouling and long term stability in industrial applications.

Accordingly, the inventors of the present invention have made a lot of research, and provide a range of pH that can prevent scale, which is the cause of contamination of the ion exchange membrane during electrodialysis, thereby preventing a decrease in productivity due to membrane contamination. And it was possible to overcome the limitations of the industrial application of electrodialysis by removing the burden such as and operating costs. In addition, by removing the ion exchange resin process through a direct recovery process that maximizes the advantages of high-purity extraction, to remove the burden on the waste water treatment of high concentration salt to complete the simple xylose manufacturing process.

Accordingly, an object of the present invention is to completely extract soluble components from tropical fruit biomass through countercurrent extraction, while selectively separating and recovering sulfate ions from high concentration extracts, and reusing them repeatedly in the extraction process. By preventing the ion exchange membrane contamination of the dialysis device can be operated for a long time without chemical cleaning, the organic matter separated sulfuric acid is concentrated to provide a process to recover directly to crystals.

In order to achieve the above object, the present invention comprises the steps of countercurrent extraction of tropical fruit biomass by sulfuric acid hydrolysis reaction to obtain a high concentration xylose extract; b) adjusting the pH of the extract to 1.5-2.5, bleaching and filtration; c) desalting the filtrate by introducing it into an electrodialysis apparatus; d) the process for producing xylose, comprising the step of recycling the sulphate waste recovered in step c) to the step a) and concentrating and directly recovering the desalted organics to obtain xylose crystals. To provide.

When xylose is produced using an electrodialysis apparatus and a direct recovery process according to the xylose production method of the present invention, not only the environmental burden for wastewater treatment can be reduced, but also the production cost reduction effect due to the simplification of the process can be expected. . Therefore, the present invention can provide a low pollution pollution-free xylose manufacturing process that can be actively substituted for reducing raw material costs and environmental pollution.

The present invention comprises the steps of: a) countercurrent extraction of tropical fruit biomass by sulfuric acid hydrolysis to obtain a high concentration xylose extract; b) adjusting the pH of the extract to 1.5-2.5, bleaching and filtration; c) desalting the filtrate by introducing it into an electrodialysis apparatus; d) the sulphate waste recovered in step c) is recycled to step a), and the desalted organics are concentrated and directly recovered without further ionic refining and decolorizing to obtain xylose crystals. It is characterized by providing a process for producing xylose.

The xylose manufacturing process of the present invention is shown in Figure 2, it will be described in detail with reference to the accompanying drawings.

The tropical fruit biomass 9 may be a dried coconut shell, palm bark or oil palm empty fruit bundle (OPEFB).

The hydrolysis was performed by adding 2,000-50,000 ppm of sulfuric acid solution 10 to the tropical fruit biomass 9, and reacting at a reaction temperature of 100-200 ° C. and a reaction pressure of 0-10 kgf / cm ² for 0.5 to 10 hours. Can be carried out.

Extraction is performed under the hydrolysis reaction conditions, and countercurrent extraction may be performed using the extractor 1 shown in FIG. 2.

The sugar composition ratio of the extract 11 obtained by the countercurrent extraction process is preferably 60 to 90%, preferably 80 to 90% of the separated mixed sugar solution.

The extract 11 is decolorized using activated carbon and filtered by a filter press 2 or an ultrafiltration device 2 to remove suspended matter. As a specific example of the present invention, a filter cloth having a 0.5 μm pore is used to filter by a filter press or an ultrafiltration device.

The pH of the filtrate 12 from which the suspended solids is removed is adjusted to 1.5-2.5. This is to prevent contamination of the ion exchange membrane by preventing scale from forming in a hydrolysis solution containing a substance that contaminates an electrodialysis membrane such as a protein, a pigment, and a humus.

In step c), the recovered sulfuric acid waste solution (13) may be recycled to the extraction process of step a) and reused for the next extraction. The recovered sulfuric acid can be reused continuously and repeatedly. Preferably, 2,000 to 4,000 ppm of sulfuric acid is further added to the recovered sulfuric acid waste solution, and more preferably, the final extracted sulfuric acid concentration is added to be 25,000 ppm. Can be.

In step b), the pH-adjusted decolorizing and filtrate 12 is introduced into the dilution tank of the electrodialysis apparatus 3, and the electrical conductivity of the organic material 14 is 1,500 uS / cm or less, preferably Desalting until less than 1,000 uS / cm.

The desalted organics 14 are sent to a concentrator 4, concentrated to a sugar concentration of 50-70 brix (Bx), and then recovered directly by vacuum crystallization or cooling of the concentrated concentrate 15 through a recovery process to recover xylose. It was. The direct recovery process may be preferably performed in three steps (5, 6, 7).

The following examples are intended to illustrate the present invention in more detail, and these examples do not limit the technical scope of the present invention.

Example  1: Preparation of sulfuric acid hydrolysis solution

Tropical fruit by-products of coconut shells, palm husks and palm trees (OPEFB) are ground to an average area of 0.5-5.0 cm ² or an average length of 0.1-5.0 cm and then 12-24 at 40-80 ° C. Dried over time.

Acid hydrolysis is performed by adding 2,000-50,000 ppm sulfuric acid solution to 100 g of dried coconut shell, palm bark or palm tree hollow fruit bunch (OPEFB), and the ratio of acid hydrolysis solvent and biomass is 1: 1-1 It was made to be: 20, the reaction temperature 100-200 ℃, the reaction pressure 0-10 kgf / cm ² , it was carried out by reacting for 0.5-10 hours.

Xylose Sugar Concentration and Electrical Conductivity of Hydrolyzate Item Coconut shell Palm shell OPEFB Xylose Sugar Composition Rate (%) 95.2 94.8 96.1 Electrical conductivity (uS / cm) 45,000 48,000 43,000

Example  2 : In countercurrent extraction  High concentration Xylose  production

The simplest method of extraction is to extract repeatedly with a pure solvent, but in the present invention, countercurrent extraction was performed in order to extract soluble components from raw materials as completely as possible and to obtain a high concentration of extract.

When the tropical fruit biomass and sulfuric acid solution is reacted in the extractor for a predetermined time, the solution is separated into the upper layer and the slurry in the lower layer and sequentially moved in the opposite direction. That is, the solution primary extract (b) and the secondary extract (c) composed of a solvent and a solute move each stage in the opposite direction to the solid phase, and dissolve and extract the solute during the movement of each stage. The flow chart of countercurrent multistage extraction is shown in FIG. 3.

Specifically, the extractor consists of a stage 1 extraction reactor and a stage 2 extraction reactor, and the method of the continuous countercurrent multistage extraction process is as follows: Low concentration of Brix 3-7 obtained from the stage 1 extraction reactor. Transferring the primary extract (b) to a stage 2 extraction reactor; The transferred low concentration primary extract (b) consists of obtaining a high concentration and high purity xylose secondary extract (c) of Brix 10-20 through a stage 2 extraction reactor.

Under the same conditions as in Example 1, the extraction yield by a simple batch extraction method repeatedly extracted with a pure solvent and multistage countercurrent extraction were compared. By multi-stage countercurrent extraction, high extraction yield of 90-80% was obtained.

Comparison of Extraction Yields by Countercurrent Extraction division Extraction yield (%) Biomass Hemicellulose Content (%) Batch Extraction 60 to 70 15-30     Multistage countercurrent extraction 90 to 80

The acid hydrolyzate (c) having a pH of 0.8-1.2 obtained by countercurrent extraction was adjusted to pH 1.5-2.5 with caustic soda, and then decolorized by filtration with a filter press using a filter cloth having 0.5 um pores with activated carbon. Suspended matter was removed.

Example  3: Desalination  Electrodialysis ( Electrodialysis )

When the acid hydrolysis liquid produced through the countercurrent extraction process was purified through the desalination electrodialysis apparatus, the organic matter (sugar) using the desalination electrodialysis process according to the present invention, such as the desalination rate of sulfate ions and the loss rate of organic matter (sugar) and Current efficiency and energy consumption were investigated to investigate the possibility of sulfuric acid separation and economic feasibility.

The sugar concentration of the desalted and filtered reaction solution was Brix 10-15, pH 1.5-2.5. The voltage was maintained at a constant voltage condition of 40-70V using a DC power supply (120V, 30A) and the temperature of the solution was kept constant at about 40-70 ° C using a heat exchange coil. At a flow rate of 6-8 L / min, desalination was performed for 100-150 minutes until the electrical conductivity became less than 1,500 uS / cm.

At this time, the electrodialysis machine used a 3-compartment type device, and the ion membrane was composed of a total effective membrane area of 0.6 m ² composed of a strong acid cation exchange membrane and a strong base anion exchange membrane. Table 3 shows the results of electrodialysis.

Desalting Electrodialysis Desalination Time
(min) Conductivity (uS / cm) Sugar Concentration (Brix) Current efficiency
(%) Energy consumption
(kWh / kg sugar) Dilution tank Thickener Dilution tank Thickener 0 50,000 200 15.0 0 - - 120 1,000 48,000 14.5 0.5 95 0.2

Sulfuric acid desalination rate can be determined by the electrical conductivity value of the dilution tank, and the loss rate of organic matter can be confirmed by the change of Brix value of the dilution tank.

Sulfuric acid desalination rate = 100-{(end value of electrical conductivity / initial value of electrical conductivity) * 100}

Loss of organics = 100-{(final brix value / initial brix value) * 100}

As a result, the desalination rate of sulfuric acid was 98%, and the loss rate of organic matter (sugar) was 3.4%.

Example  4: Measurement of contamination indicators of ion exchange membrane

Under the same conditions as in Example 3, ion exchange capacity and performance according to pH adjustment of the acid hydrolysis solution were measured. In the case of pH 1.5-2.5, the deterioration of the ion exchange capacity and the performance of the membrane was remarkably small, indicating that the membrane contamination hardly occurred. The results are shown in Table 4.

Membrane Pollution Indicators Membrane ion exchange capacity
(L) Membrane ion exchange performance
(L / m ² -hr) pH 0.8 ~ 1.2 (Source Extract) 60 8 pH 1.5 ~ 2.5 300 or more 30

Example  5: reuse of recovered sulfuric acid

In order to evaluate the reusability and economic feasibility of sulfuric acid recovered from the electrodialysis process, the yield of xylose extraction when the recovered sulfuric acid was reused in the next extraction process was measured.

As a result, as shown in Table 5, the extraction yield using only the recovered sulfuric acid was 10.61%, and when the concentration was increased by mixing sulfuric acid and recovered sulfuric acid, the extraction yield was 12.80%, similar to the control. Table 4 also shows the extraction yield when the sulfuric acid recovered was reused repeatedly by adding minimal sulfuric acid. The average yield was 12.57% for the extraction experiments with sulfuric acid 6 times. The results are shown in Table 6. It was found that the recovered sulfuric acid could be reused continuously and repeatedly.

Effect of Extraction Yield on Recovery and Addition of Sulfuric Acid division Sulfuric acid concentration composition Extraction yield
(%) Sulfuric acid recovery rate
(%) Recovered sulfuric acid (ppm) Sulfuric acid (ppm) Control 0 25,000 12.04 0 Example 1 22,000 0 10.61 88 Example 2 22,000 3,000 12.80 88

Result of using recovered sulfuric acid repeatedly for hydrolysis division Sulfuric acid concentration composition Extraction yield
(%) Sulfuric acid recovery rate
(%) Recovered sulfuric acid (ppm) Sulfuric acid (ppm) Reuse1 22,000 3,000 12.80 88 Reuse 2 21,750 3,250 12.80 87 Reuse 3 21,750 3,250 12.71 87 Reuse 4 22,250 2,750 12.32 89 Reuse 5 21,500 3,500 12.79 86 Reuse 6 21,750 3,250 12.04 87

Example  6: through a direct recovery process Xylose  collection

In order to determine the direct crystal recovery rate of the desalted organic matter from the electrodialysis process, the recovery yield of xylose was measured by concentrating the recovered sugar concentration from 10-15 Brix to 50-70 Brix through a three-step direct recovery process. .

As a result, as shown in Table 6, the recoveries of recovered xylose (5, 6, and 7 in Fig. 2) were 33.5%, when the second and third crystal mother liquors (16 and 17 in Fig. 2) were recovered. The total recovery of xylose was 87%, which was similar to that of the conventional ion purification process.

Direct recovery method Xylose
Recovery rate (%) Xylose
Purity (%) Sugar composition ratio of separated mixed sugar solution (%) Xylose Glucose Galactose Arabinos DR _ 1 Step 87 95 70 7 6 17 DR _ 2 Step 70 98 92 - - 8 DR _ 3 Step 55 99 99 - - -

1 shows a comparative diagram of a conventional xylose manufacturing process schematic diagram using a neutralization and ion exchange method, an electrodialysis process, and a xylose manufacturing process schematic diagram using a simplified process using an electrodialysis and direct recovery method according to the present invention.

Figure 2 shows a detailed process of separating the organic matter and sulfuric acid through the electrodialysis process according to the present invention and at the same time to reuse the recovered sulfuric acid while producing the xylose through the organic crystals directly.

Figure 3 shows the process flow details of the countercurrent multi-stage extraction used in the present invention.

Figure 4 shows a graph showing the change in electrical conductivity with treatment time in the electrodialysis apparatus used in the present invention.

Claims (4)

In producing xylose by hydrolysis of tropical fruit biomass, a) countercurrent extraction of the hydrolyzate obtained after sulfuric acid hydrolysis of the tropical fruit biomass; b) adjusting the pH of the extract to 1.5-2.5, bleaching and filtration; c) desalting the filtrate by introducing it into an electrodialysis apparatus; And d) the sulphate recovered in step c) is recycled to step a), and the desalted organics are concentrated and crystallized to obtain xylose crystals. Xylose manufacturing method comprising a. The method of claim 1, The method for producing xylose, characterized in that the addition of 2,000 to 4,000ppm sulfuric acid to the sulfuric acid waste liquid recovered in step c) to recycle to step a). The method of claim 1, The xylose sugar composition ratio of the filtrate in step b) is a method for producing xylose, characterized in that more than 80 wt% based on the separated mixed sugar solution. The method of claim 1, In the step c) desalination until the electrical conductivity of the filtrate is 1,000 uS / cm or less, characterized in that the manufacturing method of xylose.

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