Chitosan oligosaccharide mother liquor purification treatment method

Abstract

The invention relates to a chitosan oligosaccharide mother liquor purification treatment method, and belongs to the technical field of separation and purification. The chitosan oligosaccharide mother liquor purification treatment method comprises the following steps: adjusting the pH value of a chitosan oligosaccharide mother liquor to 5.0-6.5, then adding a flocculating agent, carrying out a flocculation reaction, and carrying out solid-liquid separation to obtain a chitosan oligosaccharide solution. The chitosan oligosaccharide mother liquor purification treatment method provided by the invention can realize the purification of the chitosan oligosaccharide mother liquor in a low-cost and high-yield manner, has the remarkable advantages of simple equipment process, simplicity, convenience and rapidness in operation and large material treatment capacity in unit time, and can effectively reduce the cost of chitosan oligosaccharide mother liquor purification and improve the economic benefits of enterprises.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of separation and purification, and particularly relates to a chitosan oligosaccharide mother liquor purification treatment method. BACKGROUND

[0002] Chitosan oligosaccharide is an oligomer obtained by degrading chitosan, and generally has a degree of polymerization of 2-20. Chitosan oligosaccharide has a wide application prospect in the fields of medicine, food, agriculture and the like due to its good water solubility and high biological activity. In the industrial production of chitosan oligosaccharide, the method of degrading chitosan by using enzymes or acid is usually adopted. After the obtained chitosan oligosaccharide mixture is preliminarily separated, a large amount of chitosan oligosaccharide mother liquor is generated. The chitosan oligosaccharide mother liquor contains not only the target product chitosan oligosaccharide, but also incompletely degraded chitosan, proteins, pigments, inorganic salts and other suspended impurities and colloidal substances generated in the reaction process, resulting in turbidity and deep color of the mother liquor, which directly affects the purity and quality of the subsequent product.

[0003] With the increasing application of chitosan oligosaccharide, the requirements for its purity and quality are also becoming higher and higher. The purification treatment of chitosan oligosaccharide mother liquor has become a key link for preparing high-quality chitosan oligosaccharide. At present, the purification treatment technologies of chitosan oligosaccharide mother liquor mainly include membrane separation technology and traditional filtration and precipitation technology. However, the traditional membrane separation technology has many limitations in the industrial production of chitosan oligosaccharide mother liquor purification process.

[0004] Firstly, the high cost is a big problem. The purchase cost of membrane separation equipment is high, and the service life of membrane components is limited and needs to be replaced regularly. The energy consumption in the membrane separation process is also large, and special pressurization equipment and circulation system need to be equipped to maintain the pressure difference on both sides of the membrane to ensure the smooth progress of the separation process, which makes the energy consumption cost high. Secondly, the yield of the traditional membrane separation technology is low. In the membrane separation process, due to the interaction between chitosan oligosaccharide molecules and membrane materials, part of the chitosan oligosaccharide will be adsorbed on the membrane surface or clog the membrane pores, resulting in loss of chitosan oligosaccharide that cannot pass through the membrane. This loss not only reduces the yield of chitosan oligosaccharide, but also increases the production cost. Thirdly, the equipment and process of the traditional membrane separation technology are complex, and the requirements for environment and operation are high. The membrane separation equipment needs to be operated under specific temperature, pressure and flow conditions, and the stability of the environment is required to be high. If the environmental conditions fluctuate greatly, the performance and separation effect of the membrane will be affected. Fourthly, the unit time material processing capacity of the traditional membrane separation technology is small, and the production efficiency is low. Due to the limited flux of the membrane, it takes a long time to complete the separation process when treating large-scale chitosan oligosaccharide mother liquor, which is difficult to meet the needs of industrial large-scale production. This limits the development scale and speed of chitosan oligosaccharide industry to some extent. Therefore, it is necessary to develop a new chitosan oligosaccharide mother liquor purification treatment process with low cost, high yield, simple equipment and process, high treatment efficiency and suitable for industrial large-scale production in the field. SUMMARY

[0005] To address the problems of high cost, low yield, complex equipment and processes, and small material throughput per unit time in existing chitosan oligosaccharide mother liquor purification methods, this invention provides a chitosan oligosaccharide mother liquor purification method to solve the above problems.

[0006] The technical solution of this invention is as follows: A method for purifying chitosan oligosaccharide mother liquor includes the following steps: First, adjusting the pH of the chitosan oligosaccharide mother liquor to 5.0-6.5. This pH range allows the charge distribution and structural state of chitosan oligosaccharide molecules to reach a relatively stable state, reducing the loss of chitosan oligosaccharides during subsequent processing. Simultaneously, this pH environment also affects the properties of impurities, reducing the solubility of some impurities or altering their surface charge, creating favorable conditions for subsequent flocculation and separation. Then, a flocculant is added, and after the flocculation reaction, solid-liquid separation is performed to obtain a clear chitosan oligosaccharide solution.

[0007] Furthermore, the flocculant includes at least one of polyacrylamide or polyferric sulfate. The polynuclear hydroxyl complexes produced by the hydrolysis of polyferric sulfate can neutralize the charge of colloidal impurities in the water, causing the colloidal particles to lose stability and aggregate to form precipitates. Polyacrylamide utilizes the charge on its molecular chains to electrostatically attract charged impurity particles, and simultaneously, through the bridging effect of its molecular chains, connects multiple particulate impurities together to form larger flocs. In this way, impurities originally dispersed in the chitosan oligosaccharide mother liquor are flocculated into larger particles, facilitating subsequent separation.

[0008] Furthermore, the molecular weight of the polyacrylamide is 8 million to 20 million; the basicity of the polyferric sulfate is 8% to 16%.

[0009] Furthermore, the amount of polyacrylamide added is 80-100 ppm. The amount mentioned here refers to the mass concentration of polyacrylamide in the chitosan oligosaccharide mother liquor.

[0010] Furthermore, the amount of polyferric sulfate added is 40-60 ppm. The amount mentioned here refers to the mass concentration of polyferric sulfate in the chitosan oligosaccharide mother liquor.

[0011] Furthermore, the flocculant is polyacrylamide and polyferric sulfate.

[0012] Furthermore, the stirring speed increases after adding polyferric sulfate, while the stirring speed decreases after adding polyacrylamide.

[0013] Furthermore, after adding polyferric sulfate, polyacrylamide is added; the above steps can be performed once or multiple times.

[0014] Furthermore, the solid-liquid separation employs a bag filter. The bag filter utilizes the sieving action of the filter bag to intercept impurity particles larger than the filter bag pore size, thereby obtaining a clear chitosan oligosaccharide solution.

[0015] Furthermore, the filter pore size of the bag filter is 0.5~20 μm.

[0016] The beneficial effects of this invention are as follows: Compared with existing methods for purifying chitosan oligosaccharide mother liquor, this invention has the following advantages: (1) Cost Advantage: Compared with traditional membrane separation technology, this process has a significant cost advantage. Regarding raw material costs, the flocculants used in this process, such as polyacrylamide and polyferric sulfate, are inexpensive and require only small amounts, significantly reducing raw material costs. In contrast, traditional membrane separation technology involves expensive membrane separation equipment and high replacement costs for membrane modules. Regarding equipment costs, the bag filters used in this process are inexpensive, simple in structure, and have low maintenance costs. A medium-sized bag filter system costs only 1 / 5 to 1 / 10 of traditional membrane separation equipment, greatly reducing equipment purchase and maintenance expenses. Regarding operating costs, this process is simple to operate and requires no complex professional training, reducing labor costs. Traditional membrane separation technology requires professional technicians for operation and maintenance, resulting in higher labor costs.

[0017] (2) High yield advantage: The yield of this process is as high as 97% or more, while the yield of traditional membrane separation technology is generally less than 90%.

[0018] (3) Technological and operational advantages: The equipment of this invention has a simple process and is easy to build and maintain. The bag filter has a simple structure and is easy to install, requiring no complex supporting facilities. Moreover, during use, only the filter bag needs to be replaced periodically, making maintenance simple and quick. The operation of this process is simple and fast; operators only need to adjust the pH and add flocculant according to the set steps, and then perform the filtration operation, without the need for lengthy professional training. This not only reduces labor costs but also reduces the risk of production accidents caused by operational errors, improving the stability and reliability of production. (4) Material handling advantages: This process has a large material handling capacity per unit time, which can meet the needs of large-scale industrial production. The bag filter has a large filtration area, and by reasonably selecting the specifications and number of filters, it is possible to quickly process a large amount of chitosan oligosaccharide mother liquor. In actual production, the adoption of this process can greatly improve production efficiency and shorten the production cycle, thereby providing strong support for the large-scale industrial production of chitosan oligosaccharides and meeting the growing market demand for high-quality chitosan oligosaccharides.

[0019] In summary, the chitosan oligosaccharide mother liquor purification method provided by this invention can achieve the purification of chitosan oligosaccharide mother liquor in a low-cost and high-yield manner. It also has significant advantages such as simple equipment and process, easy and fast operation, and large material processing capacity per unit time. It can effectively reduce the cost of chitosan oligosaccharide mother liquor purification and improve the economic benefits of enterprises. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a comparison chart of the clarity of the chitosan oligosaccharide solutions prepared in Examples 1-8 and the comparative example. In the chart, A is the chitosan oligosaccharide solution prepared in Example 1; B is the chitosan oligosaccharide solution prepared in Example 2; C is the chitosan oligosaccharide solution prepared in Example 3; D is the chitosan oligosaccharide solution prepared in Example 4; E is the chitosan oligosaccharide solution prepared in Example 5; F is the chitosan oligosaccharide solution prepared in the comparative example; G is the chitosan oligosaccharide solution prepared in Example 6; H is the chitosan oligosaccharide solution prepared in Example 7; and I is the chitosan oligosaccharide solution prepared in Example 8. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0022] In the following examples and comparative examples, polyacrylamide and polyferric sulfate were purchased from Henan Saike Environmental Protection Technology Co., Ltd., and the other reagents were commercially available and readily accessible to those skilled in the art.

[0023] In this embodiment, the polyacrylamide was added as follows: a 0.2% polyacrylamide aqueous solution was first prepared, and then added to the chitosan oligosaccharide mother liquor in the prescribed amount. The polyferric sulfate was added as follows: a 5% polyferric sulfate aqueous solution was first prepared, and then added to the chitosan oligosaccharide mother liquor.

[0024] The amount of polyacrylamide added is 80-100 ppm; the amount of polyferric sulfate added is 40-60 ppm. The amounts mentioned here refer to the mass concentration of polyacrylamide or polyferric sulfate in the mixed system after being added to the chitosan oligosaccharide mother liquor.

[0025] Example 1 A method for purifying chitosan oligosaccharide mother liquor includes the following steps: The pH of the chitosan oligosaccharide mother liquor was adjusted to 5.0 using a 20% sodium hydroxide solution. Under stirring, 60 ppm of polyferric sulfate (PFC) was added first, and the mixture was stirred rapidly for 2 minutes. Then, 100 ppm of polyacrylamide (PAM) was added, and the mixture was stirred slowly for 10 minutes. After standing for 30 minutes, obvious floc formation was observed. Finally, the solution was filtered through a 10 μm bag filter to obtain a clear and transparent chitosan oligosaccharide solution. The yield of chitosan oligosaccharide was measured to be 97.4%.

[0026] Example 2 A method for purifying chitosan oligosaccharide mother liquor includes the following steps: The pH of the chitosan oligosaccharide mother liquor was adjusted to 5.5 using a 20% sodium hydroxide solution. Under stirring, 60 ppm of polyferric sulfate (PFC) was added first, followed by rapid stirring for 2 minutes. Then, 100 ppm of polyacrylamide (PAM) was added, and the mixture was stirred slowly for 10 minutes. After standing for 30 minutes, obvious floc formation was observed. Finally, the solution was filtered through a 10 μm bag filter to obtain a clear and transparent chitosan oligosaccharide solution. The yield of chitosan oligosaccharide was measured to be 97.2%.

[0027] Example 3 A method for purifying chitosan oligosaccharide mother liquor includes the following steps: The pH of the chitosan oligosaccharide mother liquor was adjusted to 6.0 using a 20% sodium hydroxide solution. Under stirring, 50 ppm of polyferric sulfate (PFC) was added first, followed by rapid stirring for 2 minutes. Then, 90 ppm of polyacrylamide (PAM) was added, and the mixture was stirred slowly for 10 minutes. After standing for 30 minutes, obvious floc formation was observed. Finally, the solution was filtered through a 10 μm bag filter to obtain a clear and transparent chitosan oligosaccharide solution. The yield of chitosan oligosaccharide was measured to be 97.8%.

[0028] Example 4 A method for purifying chitosan oligosaccharide mother liquor includes the following steps: The pH of the chitosan oligosaccharide mother liquor was adjusted to 6.5 using a 20% sodium hydroxide solution. Under stirring, 40 ppm of polyferric sulfate (PFC) was added first, and the mixture was stirred rapidly for 2 minutes. Then, 80 ppm of polyacrylamide (PAM) was added, and the mixture was stirred slowly for 10 minutes. After standing for 30 minutes, obvious floc formation was observed. Finally, the solution was filtered using a 10 μm bag filter to obtain a clear and transparent chitosan oligosaccharide solution. The yield of chitosan oligosaccharide was measured to be 98.2%.

[0029] Example 5 A method for purifying chitosan oligosaccharide mother liquor includes the following steps: The pH of the chitosan oligosaccharide mother liquor was adjusted to 6.5 using a 20% sodium hydroxide solution. Under stirring, 30 ppm of polyacrylamide (PAM) was added first, followed by slow stirring for 10 minutes and standing for 10 minutes, during which floc formation was observed. Then, 40 ppm of polyferric sulfate (PFC) was added, followed by rapid stirring for 2 minutes. Next, 50 ppm of polyacrylamide (PAM) was added, followed by slow stirring for 10 minutes and standing for 20 minutes, during which obvious floc formation was observed. Finally, the solution was filtered using a 10 μm bag filter to obtain a clear and transparent chitosan oligosaccharide solution. The yield of chitosan oligosaccharide was measured to be 98.6%.

[0030] Example 6 A method for purifying chitosan oligosaccharide mother liquor includes the following steps: The chitosan oligosaccharide mother liquor (pH=3.8) was taken without pH adjustment. Under stirring, 60 ppm of polyferric sulfate (PFC) was added, and the mixture was stirred rapidly for 2 minutes. Then, 100 ppm of polyacrylamide (PAM) was added, and the mixture was stirred slowly for 10 minutes. After standing for 30 minutes, the resulting flocs were small and loose, with poor sedimentation after standing. After filtration through a 10 μm bag filter, the filtrate remained turbid, with a clarity lower than in Example 1. The chitosan oligosaccharide yield was determined to be 98.0%.

[0031] Example 7 A method for purifying chitosan oligosaccharide mother liquor includes the following steps: The chitosan oligosaccharide mother liquor was taken, and the pH was adjusted to 5.0 using 20% ​​sodium hydroxide solution. 60 ppm polyferric sulfate (PFC) was added, and the mixture was rapidly stirred for 2 minutes to induce flocculation. The results showed poor flocculation; after filtration through a 10 μm bag filter, the filtrate remained turbid, with a clarity lower than in Example 1. The chitosan oligosaccharide yield was determined to be 98.5%.

[0032] Example 8 A method for purifying chitosan oligosaccharide mother liquor includes the following steps: The chitosan oligosaccharide mother liquor was taken, and the pH was adjusted to 5.0 using 20% ​​sodium hydroxide solution. 100 ppm of polyacrylamide (PAM) was added, and the mixture was stirred slowly for 10 minutes and allowed to stand for 30 minutes. The results showed poor flocculation; after filtration through a 10 μm bag filter, the filtrate remained turbid, with a clarity lower than in Example 1. The chitosan oligosaccharide yield was determined to be 98.2%.

[0033] Comparative Example The traditional membrane separation method was used to purify the chitosan oligosaccharide mother liquor, as detailed below: The same chitosan oligosaccharide mother liquor as in Example 1 was first subjected to coarse filtration and centrifugation pretreatment, and then filtered using a ceramic membrane ultrafiltration system with a pore size of 50 nm at an operating pressure of 0.3 MPa. During the process, the membrane flux gradually decreased, and the filtration time was relatively long. After the treatment was completed, the ceramic membrane was cleaned, and the chitosan oligosaccharide yield was found to be 89.5%.

[0034] The yields of the chitosan oligosaccharide solutions prepared in Examples 1-8 and the comparative examples were tested, and the results are shown in the table below: Table 1 - Test results of chitosan oligosaccharide mother liquor prepared in Examples 1-8 and comparative examples

[0035] As can be seen from the yield comparison in Table 1, compared with the traditional membrane separation method (comparative example), the yield of Examples 1 to 8 of the present invention is significantly improved, and problems such as membrane fouling, long filtration time and high energy consumption are avoided.

[0036] Compared to Example 6, adjusting the pH to the specific range of this invention (5.0~6.5) is crucial for achieving good flocculation, which affects the clarity of the final chitosan oligosaccharide solution, as some impurities cannot be effectively removed.

[0037] Compared with Examples 7 and 8, this demonstrates that the synergistic flocculation effect of using polyferric sulfate (PFC) in combination with polyacrylamide (PAM) is far superior to that of using a single flocculant.

[0038] The clarity of the chitosan oligosaccharide solutions prepared in Examples 1-8 and the comparative examples was compared. For detailed results, please refer to [link to relevant documentation]. Figure 1 .

[0039] from Figure 1 As can be seen, the chitosan oligosaccharide solution prepared by the purification method of the present invention has significantly better clarity, while the filtrate obtained by purification has significantly poorer clarity when the pH of the mother liquor is not adjusted before purification and only a single flocculant is used.

[0040] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this invention should be included within the protection scope of this invention.

Claims

1. A method for purifying chitosan oligosaccharide mother liquor, characterized in that, The pH of the chitosan oligosaccharide mother liquor was adjusted to 5.0-6.5, then a flocculant was added. After flocculation, solid-liquid separation was performed to obtain the chitosan oligosaccharide solution.

2. The method for purifying chitosan oligosaccharide mother liquor as described in claim 1, characterized in that, The flocculant includes at least one of polyacrylamide or polyferric sulfate.

3. The method for purifying chitosan oligosaccharide mother liquor as described in claim 2, characterized in that, The polyacrylamide has a molecular weight of 8 million to 20 million; the basicity of the polyferric sulfate is 8% to 16%.

4. The method for purifying chitosan oligosaccharide mother liquor as described in claim 2, characterized in that, The amount of polyacrylamide added is 80~100 ppm.

5. The method for purifying chitosan oligosaccharide mother liquor as described in claim 2, characterized in that, The amount of polyferric sulfate added is 40~60 ppm.

6. The method for purifying chitosan oligosaccharide mother liquor as described in claim 2, characterized in that, The stirring speed increases after adding polyferric sulfate; the stirring speed decreases after adding polyacrylamide.

7. The method for purifying chitosan oligosaccharide mother liquor as described in claim 2, characterized in that, The flocculant is polyacrylamide and polyferric sulfate.

8. The method for purifying chitosan oligosaccharide mother liquor as described in claim 7, characterized in that, After adding polyferric sulfate, add polyacrylamide.

9. The method for purifying chitosan oligosaccharide mother liquor as described in claim 1, characterized in that, The solid-liquid separation is achieved using a bag filter.

10. The method for purifying chitosan oligosaccharide mother liquor as described in claim 1, characterized in that, The filter pore size of the bag filter is 0.5~20 μm.

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