A method for preparing renewable food-grade activated carbon

Abstract

This invention relates to the field of adsorption material preparation, specifically disclosing a method for preparing renewable food-grade activated carbon. First, the fruit shells are biodecomposed to form more fine fibers. After being pounded to loosen the fibers, they are rinsed with water to remove pigments and other impurities. Then, they are soaked in a safe and harmless activator to further remove impurities. Next, they are directly carbonized to promote the penetration reaction of the activator. Finally, they are hydrothermally treated with a terpineol solution. The resulting activated carbon has low moisture absorption and desiccant capacity, maintains good adsorption performance even in high humidity environments, and is recyclable, meeting the decolorization and adsorption requirements of different types of food.

Description

Technical Field

[0001] This invention relates to the field of adsorption material preparation, specifically to a method for preparing renewable food-grade activated carbon. Background Technology

[0002] With rapid economic development and the rise of renewable, environmentally friendly, and green concepts, the treatment of many industrial and domestic wastes has become a serious problem. For example, fruit shells are byproducts and wastes generated after fruit processing and consumption. The amount generated is large, which can easily cause environmental pollution. The treatment is not only energy-intensive but also troublesome. However, as a renewable energy source, fruit shells contain a large amount of fiber and other active substances, which have good economic benefits.

[0003] In the current preparation of food-grade activated carbon, chemical reagents are generally used to enhance adsorption and other properties. However, this process requires reagent removal and can easily leave chemical residues. Commonly used chemical reagents include organic acids, organic bases, and oxidants, which are unsuitable for food-grade products and do not conform to the concept of safety and environmental protection. While activated carbon adsorbents are widely used in the food and other fields, their hygroscopic properties weaken their adsorption performance, making them unsuitable for use in high-humidity environments. This limits the application of activated carbon in wet products and also hinders the recycling and reuse of activated carbon. Summary of the Invention

[0004] To address the above problems, the present invention aims to provide a method for preparing renewable food-grade activated carbon.

[0005] The technical content of this invention is as follows:

[0006] This invention provides a method for preparing renewable food-grade activated carbon, comprising the following steps:

[0007] (1) Wash the fruit shells 1-3 times, add water at a solid-liquid ratio of 1:5-7g / ml, heat to boiling, keep at a constant temperature for 10-15 minutes, dry, crush, and then sieve to remove impurities to obtain fruit shell particles.

[0008] The sieving process involves passing through a 200-300 mesh sieve.

[0009] The shells include those of nuts.

[0010] (2) After the fruit shell particles obtained in step (1) are fermented and pretreated, they are rinsed with water, stirred for 30-50 minutes under a pressure of 0.1-0.4 MPa, and then filtered.

[0011] The fermentation pretreatment involves adding 30-40 wt% of the fruit shell particles to the fermentation broth, mixing thoroughly, and then carrying out constant-temperature fermentation at 30-40℃.

[0012] The fermentation broth is composed of plant microbial solution, potassium dihydrogen phosphate, urea and calcium carbonate in a ratio of 11-15ml:2-3g:1g:1g.

[0013] The plant culture solution is a mixture of Monascus purpureus culture solution that has been activated and cultured for 8-10 hours and yeast powder, with a mass ratio of Monascus purpureus to yeast of 2-4:2.

[0014] The fermentation pretreatment involves the preliminary decomposition of activated carbon by food bacteria, which can decompose coarse fiber and other substances in the fruit shell particles, forming a loose and porous structure.

[0015] (3) The fruit shells obtained in step (2) are mixed with an active agent at a ratio of 60-70 wt% and then soaked and filtered.

[0016] The active agent is food-grade hydrogen peroxide;

[0017] The activator can further remove impurities and increase the adsorption capacity of activated carbon through activation;

[0018] (4) Carbonize and hydrothermally treat the fruit shells obtained in step (3), and finally crush and dry them to obtain activated carbon;

[0019] The carbonization process involves treating the carbon at a temperature of 400-500℃ for 55-75 minutes to obtain an activated carbon precursor.

[0020] The hydrothermal treatment involves spraying the activated carbon precursor with terpineol solution for the first time, then placing the moistened activated carbon precursor in a high-temperature heat treatment furnace and heating it to 180-220℃ for 80-100 minutes, spraying it with terpineol solution for the second time, continuously cooling it to 60-70℃, and then placing it in a nitrogen atmosphere for 6-10 hours.

[0021] The activated carbon sprayed with the terpineol solution for the first time had a liquid content of 17-18%.

[0022] The liquid content of the activated carbon precursor sprayed with the terpineol solution in the second spray was 6-8%.

[0023] The hydrothermal treatment involves introducing a thiol-based structure into the activated carbon structure for modification, which increases its water-repellent properties. Furthermore, physical treatment alters the water-absorbing groups of the activated carbon, thereby increasing its moisture-proof capabilities.

[0024] The beneficial effects of this invention are as follows: The preparation method provided by this invention is simple, using food-grade raw materials to prepare activated carbon without generating harmful chemical waste, making it safe and environmentally friendly. First, the fruit shells are biodecomposed to form more fine fibers. After pressure stirring, they are rinsed with water to remove pigments and other impurities. Then, they are soaked in a safe and harmless activator to further remove impurities. Next, direct carbonization promotes the penetration reaction of the activator. Finally, hydrothermal treatment with terpineol solution yields activated carbon with low moisture absorption and desiccation capabilities. It still exhibits good adsorption performance in high humidity environments. When placed at temperatures above 70°C, the activated carbon can release organic matter with a release rate of over 95%. It has good recyclability and adsorption efficiency, which is of great significance for reducing resource waste, lowering usage costs, and protecting the environment. Furthermore, it can meet the decolorization and adsorption requirements of different types of food. Detailed Implementation

[0025] The present invention will be further described in detail below through specific implementation examples. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope of the appended claims.

[0026] Unless otherwise specified, all raw materials and reagents used in this invention are from the conventional market.

[0027] Example 1

[0028] A method for preparing renewable food-grade activated carbon includes the following steps:

[0029] (1) Wash the peanut shells twice, add water at a solid-liquid ratio of 1:6 g / ml, heat to boiling, keep at a constant temperature for 12 minutes, dry, crush, and then pass through a 200-300 mesh sieve to remove impurities to obtain shell particles.

[0030] (2) After the fruit shell particles obtained in step (1) are fermented and pretreated, they are rinsed with water, stirred for 30-50 minutes under a pressure of 0.1-0.4 MPa, and then filtered.

[0031] The fermentation pretreatment involves adding 35wt% of the fruit shell particles to a fermentation broth containing 13ml:2g:1g:1g of plant microbial solution, potassium dihydrogen phosphate, urea, and calcium carbonate, mixing thoroughly, and then carrying out constant-temperature fermentation at 5°C.

[0032] The plant culture solution is a mixture of Monascus purpureus cultured for 9 hours after activation and yeast powder, with a mass ratio of Monascus purpureus to yeast of 3:2.

[0033] (3) The fruit shells obtained in step (2) are mixed and soaked with food-grade hydrogen peroxide activator at a ratio of 65wt%, and then filtered.

[0034] (4) The fruit shells obtained in step (3) are carbonized at 450℃ for 65 minutes to obtain activated carbon precursor. The activated carbon precursor is sprayed with terpineol solution for the first time, and then the activated carbon precursor with a liquid content of 17% is placed in a high-temperature heat treatment furnace and heated to 200℃ for 90 minutes. Then, the terpineol solution is sprayed for the second time, and the liquid content of the activated carbon precursor is 7%. After that, the temperature is continuously reduced to 65℃, and it is placed in a nitrogen atmosphere and left to stand for 8 hours. Finally, it is crushed and dried to obtain activated carbon.

[0035] Example 2

[0036] A method for preparing renewable food-grade activated carbon includes the following steps:

[0037] (1) Wash the cashew shells twice, add water at a solid-liquid ratio of 1:5g / ml, heat to boiling, maintain the temperature for 10 minutes, dry, crush, and then pass through a 200-mesh sieve to remove impurities to obtain shell particles; as described above;

[0038] (2) After the fruit shell particles obtained in step (1) are fermented and pretreated, they are rinsed with water, stirred for 30-50 minutes under a pressure of 0.1-0.4 MPa, and then filtered.

[0039] The fermentation pretreatment involves adding 30wt% of fruit shell particles to a fermentation broth containing 11ml:2g:1g:1g of plant culture, potassium dihydrogen phosphate, urea, and calcium carbonate, mixing thoroughly, and then conducting constant-temperature fermentation at 30℃. The plant culture is a mixture of Monascus purpureus activated and cultured for 8 hours and yeast powder, with a mass ratio of Monascus purpureus to yeast of 2:2.

[0040] (3) The fruit shells obtained in step (2) are mixed and soaked with food-grade hydrogen peroxide at a ratio of 60 wt%, and then filtered.

[0041] (4) The fruit shells obtained in step (3) are carbonized at 400℃ for 55 minutes to obtain activated carbon precursor. The activated carbon precursor is sprayed with terpineol solution for the first time, and then the activated carbon precursor with a liquid content of 17% is placed in a high-temperature heat treatment furnace and heated to 180℃ for 80 minutes. Then, the terpineol solution is sprayed for the second time, and the liquid content of the activated carbon precursor is 6%. After that, the temperature is continuously reduced to 60℃, and it is placed in a nitrogen atmosphere and left to stand for 6 hours. Finally, it is crushed and dried to obtain activated carbon.

[0042] Example 3

[0043] A method for preparing renewable food-grade activated carbon includes the following steps:

[0044] (1) Wash the peanut shells three times, add water at a solid-liquid ratio of 1:7g / ml, heat to boiling, keep at a constant temperature for 15 minutes, dry, crush, and then pass through a 300-mesh sieve to remove impurities to obtain shell particles.

[0045] (2) After the fruit shell particles obtained in step (1) are fermented and pretreated, they are rinsed with water, stirred for 30-50 minutes under a pressure of 0.1-0.4 MPa, and then filtered.

[0046] The fermentation pretreatment involves adding 40wt% of the fruit shell particles to a 15ml:3g:1g:1g fermentation broth containing plant microbial solution, potassium dihydrogen phosphate, urea, and calcium carbonate, and then thoroughly mixing the mixture before constant-temperature fermentation at 40℃. The plant microbial solution is a mixture of Monascus purpureus activated and cultured for 10 hours and yeast powder, with a mass ratio of Monascus purpureus to yeast of 4:2.

[0047] (3) The fruit shells obtained in step (2) are mixed and soaked with food-grade hydrogen peroxide at a ratio of 70 wt%, and then filtered.

[0048] (4) Carbonize the fruit shells obtained in step (3) at 500℃ for 75 min to obtain activated carbon precursor. Spray the activated carbon precursor with terpineol solution for the first time, and then put the activated carbon precursor with a liquid content of 18% into a high-temperature heat treatment furnace and heat it to 220℃ for 100 min. Then spray it with terpineol solution for the second time. The liquid content of the activated carbon precursor is 8%. Then continuously cool it down to 70℃, place it in a nitrogen atmosphere and let it stand for 10 h. Finally, pulverize and dry to obtain activated carbon.

[0049] Example 4

[0050] A method for preparing renewable food-grade activated carbon includes the following steps:

[0051] (1) Wash the cashew shells three times, add water at a solid-liquid ratio of 1:5g / ml, heat to boiling, keep at a constant temperature for 11 minutes, dry, crush, and then pass through a 220-mesh sieve to remove impurities to obtain shell particles.

[0052] (2) After the fruit shell particles obtained in step (1) are fermented and pretreated, they are rinsed with water, stirred for 30-50 minutes under a pressure of 0.1-0.4 MPa, and then filtered.

[0053] The fermentation pretreatment involves adding fruit shell particles at 32 wt% to a fermentation broth containing 11 ml of plant culture medium, 3 g of potassium dihydrogen phosphate, urea, and calcium carbonate, mixing thoroughly, and then fermenting at a constant temperature of 32°C. The plant culture medium is a mixture of Monascus purpureus activated and cultured for 8 hours and yeast powder, with a mass ratio of Monascus purpureus to yeast of 4:2.

[0054] (3) The fruit shells obtained in step (2) are mixed and soaked with food-grade hydrogen peroxide at a ratio of 63 wt%, and then filtered.

[0055] (4) The fruit shells obtained in step (3) were carbonized at 420℃ for 58 minutes to obtain activated carbon precursor. The activated carbon precursor was sprayed with terpineol solution for the first time. The activated carbon precursor with a liquid content of 17% was placed in a high-temperature heat treatment furnace and heated to 190℃ for 85 minutes. Then, terpineol solution was sprayed for the second time. The liquid content of the activated carbon precursor was 8%. After that, the temperature was continuously reduced to 63℃ and placed in a nitrogen atmosphere for 7 hours. Finally, it was crushed and dried to obtain activated carbon.

[0056] Example 5

[0057] A method for preparing renewable food-grade activated carbon includes the following steps:

[0058] (1) Wash the peanut shells three times, add water at a solid-liquid ratio of 1:7g / ml, heat to boiling, keep at a constant temperature for 14 minutes, dry, crush, and then pass through a 280-mesh sieve to remove impurities to obtain shell particles.

[0059] (2) After the fruit shell particles obtained in step (1) are fermented and pretreated, they are rinsed with water, stirred for 30-50 minutes under a pressure of 0.1-0.4 MPa, and then filtered.

[0060] The fermentation pretreatment involves adding fruit shell particles at 38 wt% to a 15 ml: 2 g: 1 g: 1 g fermentation broth containing plant microbial solution, potassium dihydrogen phosphate, urea, and calcium carbonate, mixing thoroughly, and then conducting constant-temperature fermentation at 38°C. The plant microbial solution is a mixture of Monascus purpureus activated and cultured for 9 hours and yeast powder, with a mass ratio of Monascus purpureus to yeast of 3:2.

[0061] (3) The fruit shells obtained in step (2) are mixed and soaked with food-grade hydrogen peroxide at a ratio of 68 wt%, and then filtered.

[0062] (4) The fruit shells obtained in step (3) were carbonized at 480℃ for 62 minutes to obtain activated carbon precursor. The activated carbon precursor was sprayed with terpineol solution for the first time. The activated carbon precursor with a liquid content of 17% was placed in a high-temperature heat treatment furnace and heated to 210℃ for 95 minutes. Then, the terpineol solution was sprayed for the second time. The liquid content of the activated carbon precursor was 8%. After that, the temperature was continuously reduced to 68℃ and placed in a nitrogen atmosphere for 9 hours. Finally, it was crushed and dried to obtain activated carbon.

[0063] Example 6

[0064] A method for preparing renewable food-grade activated carbon includes the following steps:

[0065] (1) Wash the walnut shells twice, add water at a solid-liquid ratio of 1:6 g / ml, heat to boiling, keep at a constant temperature for 10 minutes, dry, crush, and then pass through a 300-mesh sieve to remove impurities to obtain shell particles.

[0066] (2) After the fruit shell particles obtained in step (1) are fermented and pretreated, they are rinsed with water, stirred for 30-50 minutes under a pressure of 0.1-0.4 MPa, and then filtered.

[0067] The fermentation pretreatment involves adding 35wt% of fruit shell particles to a 13ml:2g:1g:1g fermentation broth containing plant microbial solution, potassium dihydrogen phosphate, urea, and calcium carbonate, and mixing thoroughly before constant-temperature fermentation at 30℃. The plant microbial solution is a mixture of Monascus purpureus activated and cultured for 9 hours and yeast powder, with a mass ratio of Monascus purpureus to yeast of 2:2.

[0068] (3) The fruit shells obtained in step (2) are mixed and soaked with food-grade hydrogen peroxide at a ratio of 65 wt%, and then filtered.

[0069] (4) Carbonize the fruit shells obtained in step (3) at 400℃ for 75 min to obtain activated carbon precursor. Spray the activated carbon precursor with terpineol solution for the first time, and then put the activated carbon precursor with a liquid content of 17% into a high-temperature heat treatment furnace and heat it to 180℃ for 100 min. Then spray it with terpineol solution for the second time. The liquid content of the activated carbon precursor is 8%. Then continuously cool it down to 60℃, place it in a nitrogen atmosphere and let it stand for 10 h. Finally, pulverize and dry to obtain activated carbon.

[0070] Comparative Example 1

[0071] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not undergo fermentation pretreatment, while everything else remains the same.

[0072] Comparative Example 2

[0073] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 does not undergo hydrothermal treatment, but everything else remains the same.

[0074] Comparative Example 3

[0075] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 is not soaked in the activator, but everything else remains the same.

[0076] I. The pore size and specific surface area of ​​the activated carbon prepared in Example 1 and Comparative Example 1 were characterized by testing, and the test results are shown in Table 1.

[0077] Table 1. Pore size and specific surface area of ​​activated carbon

[0078]

[0079] As shown in Table 1, the method for preparing activated carbon in this invention involves fermenting the fruit shells to pre-treat them, which decomposes and loosens the pores, resulting in activated carbon with large pore size and high specific surface area.

[0080] 2. The activated carbon prepared in the examples and comparative examples was placed in a microemulsion solution of edible oil with an initial COD of 200 mg / L and adsorbed at 30°C for 2 hours. The adsorption rate of the activated carbon was measured. Then, it was taken out and regenerated at 70°C. The release rate of the activated carbon was measured. The results are shown in Table 2.

[0081] Table 2 Adsorption and Release Amounts of Activated Carbon

[0082]

[0083]

[0084] As shown in Table 2, the activated carbon prepared by this invention has hydrophobic and recyclable properties, making it a renewable material. The process involves pre-treatment with fermentation to decompose the fruit shell, forming a loose and porous structure, and using an activator to remove impurities, thereby improving the adsorption performance of the activated carbon. Furthermore, hydrothermal treatment with chemical reagents combined with temperature and liquid content differences further modifies the activated carbon to achieve hydrophobicity. The resulting activated carbon exhibits good adsorption and desorption capabilities and regeneration performance.

Claims

1. A method for preparing renewable food-grade activated carbon, characterized in that, Includes the following steps: (1) Clean the fruit shells, add water at a solid-liquid ratio of 1:5-7 g / ml, heat to boiling, keep at a constant temperature for 10-15 minutes, dry, crush, and then sieve to remove impurities to obtain fruit shell particles. (2) After the fruit shell particles obtained in step (1) are fermented and pretreated, they are rinsed with water, stirred for 30-50 minutes under a pressure of 0.1-0.4 MPa, and then filtered. (3) The fruit shells obtained in step (2) are mixed with an active agent at a ratio of 60-70 wt% and soaked, then filtered; (4) Carbonize and hydrothermally treat the fruit shells obtained in step (3), and finally crush and dry them to obtain activated carbon; The hydrothermal treatment involves spraying the activated carbon precursor with terpineol solution for the first time, then placing the moistened activated carbon precursor in a high-temperature heat treatment furnace and heating it to 180-220℃ for 80-100 minutes, spraying it with terpineol solution for the second time, continuously cooling it down to 60-70℃, and then placing it in a nitrogen atmosphere for 6-10 hours. The activated carbon sprayed with terpineol solution for the first time had a liquid content of 17-18%. The liquid content of the activated carbon precursor after the second spraying of terpineol solution was 6-8%.

2. The method for preparing renewable food-grade activated carbon according to claim 1, characterized in that, The fermentation pretreatment involves adding 30-40 wt% of the fruit shell particles to the fermentation broth, mixing thoroughly, and then carrying out constant-temperature fermentation at 30-40℃.

3. The method for preparing renewable food-grade activated carbon according to claim 2, characterized in that, The fermentation broth is composed of plant microbial solution, potassium dihydrogen phosphate, urea and calcium carbonate in a ratio of 11-15ml:2-3g:1g:1g.

4. The method for preparing renewable food-grade activated carbon according to claim 3, characterized in that, The plant culture solution is a mixture of Monascus purpureus solution (after activation and expansion culture for 8-10 hours) and yeast powder, with a mass ratio of Monascus purpureus to yeast of 2-4:

2.

5. The method for preparing renewable food-grade activated carbon according to claim 1, characterized in that, The active agent is food-grade hydrogen peroxide.

6. The method for preparing renewable food-grade activated carbon according to claim 1, characterized in that, The carbonization process involves treating the carbon at 400-500℃ for 55-75 minutes to obtain an activated carbon precursor.

7. The method for preparing renewable food-grade activated carbon according to claim 1, characterized in that, The sieving process involves passing the material through a 200-300 mesh sieve.

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