Vitamin C primary crystallization mother liquor component recovery method

Abstract

The invention discloses a vitamin C primary crystallization mother liquor component recovery method, which comprises the following steps of: decoloring and concentrating a vitamin C primary crystallization mother liquor under reduced pressure, and recovering the vitamin C primary crystallization mother liquor by adopting a staged cooling crystallization method, so that vitamin C and gulonic acid in the vitamin C primary crystallization mother liquor are effectively separated; repeated thermal degradation of recycled materials (gulonic acid and vitamin C are equivalent in content) added into the previous process is avoided, and the production cost is reduced. According to the method, the optimal time and temperature for recycling and staged crystallization of the primary crystallization mother liquor of vitamin C are determined, so that the recycling process is simpler and easier to operate. In the recovery process of the primary crystallization mother liquor of the vitamin C, no other substances except for a vitamin C preparation process are introduced, an additional removal process is not needed, the quality of the recovered substance can be better ensured, and the quality of the finished product of the vitamin C can be ensured by incorporating the recovered substance into the preparation process of the vitamin C.

Description

Technical Field

[0001] The invention relates to the technical field of vitamin C production, and in particular to a method for recovering components of a vitamin C primary crystallization mother liquor. Background Art

[0002] Vitamin C (also known as L-ascorbic acid) is an essential vitamin for the human body and is widely used in the fields of medicine, food, feed, cosmetics, etc. There are two methods for producing vitamin C: the Lysenberg method and the two-step fermentation method. Currently, most vitamin C manufacturers use the two-step fermentation method to produce vitamin C. This method has a long process, many steps, and a low overall yield.

[0003] There are many types of intermediates and mother liquors in the production process of vitamin C. Therefore, the recovery rate of various mother liquors and the quality of the recovered products directly affect the production cost of vitamin C. However, due to the complex composition and high viscosity of the vitamin C primary crystallization mother liquor, in addition to the main components of gluconic acid and vitamin C, there are also a small amount of gluconic acid methyl ester and by-products produced during the extraction and synthesis process, resulting in poor quality of the recovered vitamin C primary crystallization mother liquor. The vitamin C mother liquor recovered product obtained by concentration, cooling crystallization and centrifugation of the vitamin C primary crystallization mother liquor has comparable vitamin C and gluconic acid contents, and the recovered product has poor color and low yield, and it is impossible to obtain qualified vitamin C products through refining.

[0004] Therefore, there is an urgent need for a method that can use the simplest method to separate the vitamin C and citric acid in the recycled vitamin C mother liquor as much as possible and put them into different steps of vitamin C production respectively to improve the quality of the recycled material and reduce production costs. Summary of the invention

[0005] The purpose of the present application is to provide a method for recovering components of a vitamin C primary crystallization mother liquor, wherein the vitamin C primary crystallization mother liquor is decolorized and separated by crystallization in stages to obtain two types of recovered products rich in vitamin C and citric acid, respectively, and different recovered products are incorporated into different production steps to avoid repeated heating and degradation of the materials, thereby improving the quality and yield of the product.

[0006] In order to solve the above technical problems, the present application provides a method for recovering components of a vitamin C primary crystallization mother liquor, comprising:

[0007] Decolorization: Take the mother liquor of vitamin C primary crystallization, add 0.5‰~3.0‰ of food-grade activated carbon, stir and decolorize for 1 hour to obtain the decolorized solution;

[0008] Concentration under reduced pressure: using a rotary evaporator to concentrate the decolorized solution to obtain a concentrated solution, and according to the total content of vitamin C and citric acid in the decolorized solution, controlling the specific gravity of the concentrated solution to be 1.35-1.42, the concentration pressure to be -0.080-0.085 MPa, and the water bath temperature to be 45-60° C.;

[0009] Staged cooling, crystallization and separation:

[0010] In the first stage, stirring is started, the temperature of the concentrated solution is controlled at 40°C to 50°C, and the concentrated solution is stirred and crystallized for 2-5 hours to obtain a crystal solution, and the crystal solution is filtered and separated to obtain a vitamin C mother wet product 1 and a vitamin C secondary crystal mother solution 1;

[0011] The second stage: the vitamin C secondary crystallization mother liquor 1 is further cooled and crystallized to obtain a crystal liquid, and the crystal liquid is filtered and separated to obtain a vitamin C mother wet product 2 and a vitamin C secondary crystallization mother liquor 2, wherein the temperature is lowered to 0-5°C, and the total crystallization time is 10-20h;

[0012] Destination of the recyclables: After recrystallization, the vitamin C mother wet product 1 is combined with the vitamin C crude product to obtain a recrystallization mother liquor, and the recrystallization mother liquor is combined with the citric acid mother liquor for recovery and used in the esterification reaction; the vitamin C mother wet product 2 is combined with citric acid and used in the esterification reaction to generate vitamin C sodium.

[0013] As a preferred embodiment, a method for recovering components of a vitamin C primary crystallization mother liquor further comprises, before the decolorization:

[0014] Sampling and testing: 2050 ml of vitamin C primary crystallization mother liquor was taken from the vitamin C production workshop, in which the vitamin C content was 14.90%, the citric acid content was 20.46%, and the extinction was 2.052-2.536.

[0015] What needs to be described in detail in the scheme is that a method for recovering components of a vitamin C primary crystallization mother liquor, after obtaining the decolorized liquid in the decolorization step, further comprises:

[0016] The decolorized liquid is filtered by using a 0.45 μm mixed fiber membrane, and the extinction of the decolorized liquid is 1.531-1.607.

[0017] Compared with the prior art, the present invention provides a method for recovering components of a vitamin C primary crystallization mother liquor. After the vitamin C primary crystallization mother liquor is decolorized and concentrated under reduced pressure, the vitamin C primary crystallization mother liquor is recovered by a staged cooling and crystallization method, thereby effectively separating the vitamin C and citric acid therein, avoiding the rapid thermal degradation of adding the recyclate (the citric acid and vitamin C contents are equivalent) to the previous process, thereby reducing production costs. The present invention determines the optimal time and temperature for the staged crystallization of the recovery of the vitamin C primary crystallization mother liquor, making the recovery process simpler and easier to operate. In the process of recovering the vitamin C primary crystallization mother liquor, no other substances other than the vitamin C preparation process are introduced, no additional removal process is required, and the quality of the recyclate can be better guaranteed. Incorporating it into the vitamin C preparation process can ensure the quality of the vitamin C finished product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without inventiveness.

[0019] Figure 1 A schematic diagram of a method for recovering components of a vitamin C primary crystallization mother liquor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings.

[0021] The core of the present application is to provide a method for recovering components of a vitamin C primary crystallization mother liquor, in which the vitamin C primary crystallization mother liquor is decolorized and separated by crystallization in stages to obtain two types of recovered products rich in vitamin C and citric acid, respectively. Different recovered products are incorporated into different production steps to avoid repeated heating and degradation of materials, thereby improving product quality and yield.

[0022] Figure 1 A schematic diagram of a method for recovering components of a vitamin C primary crystallization mother liquor provided in the embodiment of the present application is shown in FIG. Figure 1 shown.

[0023] A method for recovering components of a vitamin C primary crystallization mother liquor, comprising:

[0024] Decolorization: Take the mother liquor of vitamin C primary crystallization, add 0.5‰~3.0‰ of food-grade activated carbon, stir and decolorize for 1 hour to obtain the decolorized solution;

[0025] Concentration under reduced pressure: using a rotary evaporator to concentrate the decolorized solution to obtain a concentrated solution, and according to the total content of vitamin C and citric acid in the decolorized solution, controlling the specific gravity of the concentrated solution to be 1.35-1.42, the concentration pressure to be -0.080-0.085 MPa, and the water bath temperature to be 45-60° C.;

[0026] Staged cooling, crystallization and separation:

[0027] In the first stage, stirring is started, the temperature of the decolorized liquid and the concentrated liquid is controlled at 40°C to 50°C, and the crystallization is stirred for 2-5 hours to obtain a crystal liquid, and the crystal liquid is filtered and separated to obtain a vitamin C mother wet product 1 and a vitamin C secondary crystal mother liquid 1;

[0028] The second stage: the vitamin C secondary crystallization mother liquor 1 is further cooled and crystallized to obtain a crystal liquid, and the crystal liquid is filtered and separated to obtain a vitamin C mother wet product 2 and a vitamin C secondary crystallization mother liquor 2, wherein the temperature is lowered to 0-5°C, and the total crystallization time is 10-20h;

[0029] Destination of the recyclables: After recrystallization, the vitamin C mother wet product 1 is combined with the vitamin C crude product to obtain a recrystallization mother liquor, and the recrystallization mother liquor is combined and recovered with the gulonic acid mother liquor (the gulonic acid mother liquor here is produced in the process of preparing vitamin C) and used in the esterification reaction; the vitamin C mother wet product 2 is combined with gulonic acid, which is an intermediate in the preparation of vitamin C and is used in the esterification reaction to generate vitamin C sodium.

[0030] As a preferred embodiment, a method for recovering components of a vitamin C primary crystallization mother liquor, before the decolorization, also includes: sampling and testing: taking 2050 ml of vitamin C primary crystallization mother liquor from a vitamin C production workshop, wherein the vitamin C content is 14.90%, the citric acid content is 20.46%, and the extinction is 2.052-2.536.

[0031] As a preferred embodiment, a method for recovering components of a vitamin C primary crystallization mother liquor, after obtaining the decolorized liquid in the decolorization step, further comprises: filtering the decolorized liquid with a 0.45 μm mixed fiber membrane, and extincting the decolorized liquid to 1.531-1.607.

[0032] In order to enable those skilled in the art to better understand the present invention, the present invention is described in detail with specific embodiments below:

[0033] Embodiment 1:

[0034] (1) Sampling and testing: 2050 ml of vitamin C primary crystallization mother liquor was collected from the vitamin C production workshop, wherein the vitamin C content was 14.90%, the citric acid content was 20.46%, and the extinction was 2.052.

[0035] (2) Decolorization: Add 1 g of food-grade activated carbon to 2000 ml of vitamin C primary crystallization mother liquor and stir to decolorize for 60 min. Filter with a 0.45 μm mixed fiber membrane. The extinction of the decolorized liquid is 1.582.

[0036] (3) Concentration under reduced pressure: Set the water bath temperature of the rotary evaporator to 50°C, concentrate the vitamin C primary crystallization mother liquor decolorization liquid, and concentrate it at a pressure of -0.080 MPa until its specific gravity is 1.39, and then end the concentration.

[0037] (4) Staged cooling, crystallization and separation

[0038] The first stage: Start stirring, cool the concentrated solution to crystallize, slowly lower the temperature to 45°C, and stir for 5 hours. The crystallized solution is filtered and separated to obtain 250.2g of vitamin C mother wet product 1 (vitamin C content is 60.2%, gulonic acid content is 37.8%) and 530ml of vitamin C secondary crystallization mother liquor 1 (vitamin C content is 25.82%, gulonic acid content is 49.32%);

[0039] The second stage: 530 ml of vitamin C secondary crystallization mother liquor 1 was cooled and crystallized to 2°C, and the total crystallization time was 15 hours. The crystallization liquid was filtered and separated to obtain 310 g of vitamin C mother wet product 2 (vitamin C content 27.8%, gulonic acid content 60.6%) and 290 ml of vitamin C secondary crystallization mother liquor 2 (vitamin C content 19.28%, gulonic acid content 44.22%).

[0040] (5) Reprocessing of recycled materials: Dissolve 200 g of vitamin C mother wet product 1 (vitamin C content is 60.2%, gulonic acid content is 37.8%) in 196 ml of 80°C hot water for dissolution, decolorization and recrystallization to obtain 97.8 g of vitamin C mother refined wet product (vitamin C content is 98.5%, equivalent to that of crude vitamin C). Most of the recrystallization mother liquor is gulonic acid (gulonic acid content is 3 times that of vitamin C). Mix vitamin C mother wet product 2 (vitamin C content is 27.8%, gulonic acid content is 60.6%) with gulonic acid at a ratio of less than 30% for esterification reaction. The resulting vitamin C sodium wet product has a vitamin C content of 86%.

[0041] (6) Yield: The yield of vitamin C wet product 1 is 50.5% (yield of vitamin C), and the yield of vitamin C wet product 2 is 45.7% (yield of gulonic acid).

[0042] Embodiment 2:

[0043] (1) Sampling and testing: 2050 ml of vitamin C primary crystallization mother liquor was collected from the vitamin C production workshop, wherein the vitamin C content was 13.35%, the citric acid content was 24.88%, and the extinction was 2.536.

[0044] (2) Decolorization: Add 2 g of food-grade activated carbon to 2000 ml of vitamin C primary crystallization mother liquor and stir to decolorize for 60 min. Filter with a 0.45 μm mixed fiber membrane. The extinction of the decolorized liquid is 1.531.

[0045] (3) Concentration under reduced pressure: Set the water bath temperature of the rotary evaporator to 45°C, concentrate the vitamin C primary crystallization mother liquor decolorization liquid, and concentrate it at a pressure of -0.085 MPa until its specific gravity is 1.42, and then end the concentration.

[0046] (4) Staged cooling, crystallization and separation

[0047] Stage 1: Start stirring, control the temperature of the concentrated liquid at 50°C, and stir and crystallize for 2 hours. The crystallized liquid is filtered and separated to obtain 233.8g of vitamin C mother wet product 1 (vitamin C content is 63.8%, gulonic acid content is 35.1%) and 515ml of vitamin C secondary crystallization mother liquor 1 (vitamin C content is 21.67%, gulonic acid content is 64.68%);

[0048] The second stage: 515 ml of vitamin C secondary crystallization mother liquor 1 was cooled and crystallized to 5°C, and the total crystallization time was 20 hours. The crystallization liquid was filtered and separated to obtain 321.5 g of vitamin C mother wet product 2 (vitamin C content 23.1%, gulonic acid content 65.3%) and 275 ml of vitamin C secondary crystallization mother liquor 2 (vitamin C content 20.65%, gulonic acid content 52.17%).

[0049] (5) Reprocessing of recycled materials: Dissolve 200 g of vitamin C mother wet product 1 (vitamin C content is 63.8%, gulonic acid content is 35.1%) in 198 ml of 80°C hot water for dissolution, decolorization and recrystallization to obtain 99.1 g of vitamin C mother refined wet product (vitamin C content is 98.9%, equivalent to that of crude vitamin C). Most of the recrystallization mother liquor is gulonic acid (the gulonic acid content is 2.5 times that of vitamin C). Mix vitamin C mother wet product 2 (vitamin C content is 23.9%, gulonic acid content is 63.1%) with gulonic acid at a ratio of less than 30% for esterification reaction. The resulting vitamin C sodium wet product has a vitamin C content of 87.2%.

[0050] (6) Yield: The yield of vitamin C wet product 1 is 55.9% (yield of vitamin C), and the yield of vitamin C wet product 2 is 42.2% (yield of citric acid).

[0051] Embodiment 3:

[0052] (1) Sampling and testing: 2050 ml of vitamin C primary crystallization mother liquor was collected from the vitamin C production workshop, wherein the vitamin C content was 12.25%, the citric acid content was 22.07%, and the extinction was 2.195.

[0053] (2) Decolorization: Add 6 g of food-grade activated carbon to 2000 ml of vitamin C primary crystallization mother liquor and stir to decolorize for 60 min. Filter with a 0.45 μm mixed fiber membrane. The extinction of the decolorized liquid is 1.607.

[0054] (3) Concentration under reduced pressure: Set the water bath temperature of the rotary evaporator to 60°C, concentrate the vitamin C primary crystallization mother liquor decolorization liquid, and concentrate it at a pressure of -0.083 MPa until its specific gravity is 1.35, and then end the concentration.

[0055] (4) Staged cooling, crystallization and separation

[0056] Stage 1: Start stirring, control the temperature of the concentrated liquid at 40°C, and stir and crystallize for 4 hours. The crystallized liquid is filtered and separated to obtain 187.3g of vitamin C mother wet product 1 (vitamin C content is 68.3%, gulonic acid content is 30.2%) and 585ml of vitamin C secondary crystallization mother liquor 1 (vitamin C content is 20.65%, gulonic acid content is 63.84%);

[0057] The second stage: 585 ml of vitamin C secondary crystallization mother liquor 1 was cooled and crystallized to 0°C, and the total crystallization time was 10 hours. The crystallization liquid was filtered and separated to obtain 306.6 g of vitamin C mother wet product 2 (vitamin C content 25.7%, gulonic acid content 63.8%) and 305 ml of vitamin C secondary crystallization mother liquor 2 (vitamin C content 18.65%, gulonic acid content 55.70%).

[0058] (5) Reprocessing of recycled materials: 150 g of vitamin C mother wet product 1 (vitamin C content is 68.3%, gulonic acid content is 30.2%) is dissolved in 150 ml of 80°C hot water, decolorized and recrystallized to obtain 82.3 g of vitamin C mother refined wet product (vitamin C content is 99.2%, equivalent to that of crude vitamin C), most of which is gulonic acid (gulonic acid content is 2.3 times that of vitamin C); vitamin C mother wet product 2 (vitamin C content is 18.65%, gulonic acid content is 55.70%) is mixed with gulonic acid at a ratio of less than 30% for esterification reaction, and the resulting vitamin C sodium wet product has a vitamin C content of 86.8%.

[0059] (6) Yield: The yield of vitamin C wet product 1 is 52.2% (yield of vitamin C), and the yield of vitamin C wet product 2 is 44.3% (yield of gulonic acid).

[0060] The vitamin C wet product 1 and the vitamin C wet product 2 obtained in Examples 1 to 3 are reprocessed or incorporated into the vitamin C preparation step, and their quality meets the intermediate quality standard in the vitamin C preparation process. The present invention has the following advantages over conventional processes:

[0061] (1) The present invention adopts a staged cooling crystallization method to recover the vitamin C primary crystal mother liquor, effectively separating the vitamin C and gulonic acid therein, avoiding the rapid thermal degradation of the recovered product (gulonic acid and vitamin C content are equivalent) added to the previous process, thereby reducing the production cost;

[0062] (2) The present invention determines the optimal time and temperature for the phased crystallization of the mother liquor of the primary crystallization of vitamin C, making the recovery process simpler and easier to operate;

[0063] (3) During the recovery process of the vitamin C primary crystallization mother liquor, no other substances other than those in the vitamin C preparation process are introduced, no additional removal process is required, and the quality of the recovered material can be better guaranteed. It is incorporated into the vitamin C preparation process and has no effect on the quality of the vitamin C finished product.

[0064] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art disclosed in the present application. The specification and examples are to be regarded as exemplary only, and the true scope of the present application is indicated by the claims.

[0065] It should be understood that the present application is not limited to the precise structure described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The above-described embodiments of the present application do not constitute a limitation on the scope of protection of the present application.

Claims

1. A method for recovering components of a vitamin C primary crystallization mother liquor, characterized in that: include: Decolorization: Take the mother liquor of vitamin C primary crystallization, add 0.5‰~3.0‰ of food-grade activated carbon, stir and decolorize for 1 hour to obtain the decolorized solution; Concentration under reduced pressure: using a rotary evaporator to concentrate the decolorized solution to obtain a concentrated solution, and according to the total content of vitamin C and citric acid in the decolorized solution, controlling the specific gravity of the concentrated solution to be 1.35-1.42, the concentration pressure to be -0.080-0.085 MPa, and the water bath temperature to be 45-60° C.; Staged cooling, crystallization and separation: In the first stage, stirring is started, the temperature of the concentrated solution is controlled at 40°C to 50°C, and the concentrated solution is stirred and crystallized for 2-5 hours to obtain a crystal solution, and the crystal solution is filtered and separated to obtain a vitamin C mother wet product 1 and a vitamin C secondary crystal mother solution 1; The second stage: the vitamin C secondary crystallization mother liquor 1 is further cooled and crystallized to obtain a crystal liquid, and the crystal liquid is filtered and separated to obtain a vitamin C mother wet product 2 and a vitamin C secondary crystallization mother liquor 2, wherein the temperature is lowered to 0-5°C, and the total crystallization time is 10-20h; Destination of the recyclables: After recrystallization, the vitamin C mother wet product 1 is combined with the vitamin C crude product to obtain a recrystallization mother liquor, and the recrystallization mother liquor is combined with the gulonic acid mother liquor for recovery and used in the esterification reaction; the vitamin C mother wet product 2 is combined with gulonic acid and used in the esterification reaction to generate vitamin C sodium.

2. The method for recovering components of the vitamin C primary crystallization mother liquor according to claim 1, characterized in that: Before the decolorization, the method further comprises: Sampling and testing: 2050 ml of vitamin C primary crystallization mother liquor was taken from the vitamin C production workshop, in which the vitamin C content was 14.90%, the citric acid content was 20.46%, and the extinction was 2.052-2.

536.

3. The method for recovering components of vitamin C primary crystallization mother liquor according to claim 2, characterized in that: After the decolorizing step to obtain the decolorizing solution, the method further comprises: The decolorized liquid is filtered by using a 0.45 μm mixed fiber membrane, and the extinction of the decolorized liquid is 1.531-1.607.

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