A method for the production of a natural source porous water-absorbing mat

Abstract

The application provides a preparation method of a natural porous water-absorbing pad, which comprises the following steps: extracting cellulose and hemicellulose from natural plant raw materials, mixing and preparing a solution according to a certain proportion, and preparing a cellulose-based porous absorbing material by using a freeze-drying method. The cellulose can form a porous absorbing structure as a basic skeleton of the material, and the existence of the hemicellulose further increases the water-absorbing property and softness of the material; meanwhile, by adding natural nanocellulose and bacteriostatic and antioxidant substances, the water-absorbing pad is further endowed with more functions. The prepared porous water-absorbing pad is completely derived from nature, is safe and degradable, has excellent water-absorbing performance, stable mechanical performance, and the functions of bacteriostasis and oxidation resistance, can effectively maintain the quality of food and prolong the shelf life, and can be applied to the fields of absorbent sanitary products, medical treatment and the like.

Description

Technical Field

[0001] This invention relates to the field of porous absorbent materials technology, and more specifically, to a naturally sourced porous absorbent pad and its preparation method. Background Technology

[0002] With social development and technological advancements, people's living standards are constantly improving, and they are now pursuing fresh and healthy food and lifestyles. To meet consumer demand, food is packaged during storage and transportation, especially in the fresh food sector, where absorbent pads are often used to manage moisture in food packaging and ensure the freshness and safety of perishable foods.

[0003] Currently, common packaging methods for fresh produce include boxes, bags, or trays. Absorbent pads of a certain size are usually placed during the packaging process to absorb excess liquid produced by the food, which helps extend the shelf life of products such as meat, seafood, fruits, and vegetables.

[0004] Currently, the main materials used for absorbent pads on the market include polyethylene, non-woven fabric, paper-based materials, and superabsorbent resin, which are composed of multiple layers of composite materials. However, problems have also emerged, such as poor absorbency, safety concerns, and inability to preserve freshness. In addition, as disposable products, absorbent pads also present environmental issues due to their incomplete biodegradability.

[0005] Based on market demand and the goal of future sustainable development, there is an urgent need to develop a water-absorbing mat that is naturally sourced, biodegradable, and has excellent absorption properties. Summary of the Invention

[0006] The main objective of this invention is to provide a method for preparing a porous absorbent pad from a natural source, so as to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] S1. Place the plant material into a grinder and grind it. Take the ground plant material and react it with a benzene-ethanol mixture (volume ratio of 2:1) for 24 hours for extraction. The mass ratio is 1:50. Air dry at room temperature for 12-18 hours.

[0009] S2. The dried material is reacted with 4wt% NaClO2 solution in a 70℃ water bath for 4-5 hours at a mass ratio of 1:30-1:50. Acetic acid is added to adjust the pH value to 2-3. After the reaction is completed, the solution is repeatedly washed by vacuum filtration until it is neutral. The solution is then air-dried at room temperature for 12-18 hours to obtain component 1.

[0010] S3. Take the above component 1 and 5wt% KOH solution and react them at room temperature for 24 hours, with a mass ratio of 1:20-1:40; continue to treat for another 2 hours under a 90℃ water bath. After the reaction is completed, filter under vacuum and wash repeatedly until the solution is neutral. Air dry at room temperature for 12-18 hours to obtain component 2.

[0011] S4. Mix the above-prepared component 1 with component 2 in a mass ratio of 1:1 to 1:4, stir at high speed for 2-5 hours to prepare a 0.5-2wt% aqueous solution of the mixed components, and then disperse it using ultrasound for 0.5-1 hours.

[0012] S5. While stirring continuously, add 0.1-0.5 wt% nanocellulose, 0.5-2 wt% carboxymethyl chitosan, and 5-10% plant extract to the above solution.

[0013] S6. Pour the above-prepared mixed solution into a mold, freeze it in the freezer for 24 hours, and then dry it in a vacuum freeze dryer for 24-48 hours to obtain a porous absorbent pad of natural origin.

[0014] Furthermore, the plant material is derived from one or more of the following: coniferous wood, broadleaf wood, bamboo, sugarcane, flax, corn stalks, and reeds;

[0015] Furthermore, the nanocellulose is a rod-shaped nanomaterial extracted from natural plant fiber raw materials, with a diameter of less than 1 micrometer and a length of less than 100 micrometers;

[0016] Furthermore, the plant extract is one or more of the following: garlic extract, tea polyphenol extract, rosemary extract, grape seed extract, cinnamon extract, and ginger extract;

[0017] Furthermore, the main components of component 1 are hemicellulose and cellulose;

[0018] Furthermore, the main component of component 2 is cellulose.

[0019] The absorbent pad prepared by this invention is a naturally derived cellulose-based porous absorbent material. Using cellulose as the basic framework, water in the solution is first solidified and then sublimated under low pressure through freeze-drying, while the cellulose retains its original form, resulting in a porous absorbent material. The presence of hemicellulose further enhances the material's absorbency and increases its softness. During the absorption process, some bound water interacts with the components in the material through hydrogen bonds, while some bulk water is physically adsorbed within the pores of the porous material, exhibiting excellent absorbency. Simultaneously, the use of naturally derived nanocellulose to load natural components endows the absorbent pad with antibacterial and antioxidant properties, ensuring food safety and freshness, and extending the shelf life of food.

[0020] The beneficial effects of this invention are:

[0021] 1. The absorbent pad material prepared in this invention is derived from cellulose and hemicellulose extracted from natural plant raw materials. Cellulose is a long-chain polymer formed by a large number of glucose units, with a very regular structure. The glucose units are arranged in a planar, extended conformation, forming a highly ordered and crystalline microfiber structure, thus endowing the material with good mechanical strength. Furthermore, freeze-drying further forms a porous structure for adsorption. Hemicellulose is a complex polysaccharide composed of different sugar groups. Its structure is less regular than cellulose, and its crystallinity is lower. The presence of hemicellulose in porous materials has a significant impact on the material's absorption performance, leading to an increase in water absorption capacity. This is because hemicellulose is more hydrophilic and contains more free hydroxyl groups; cellulose exhibits a more crystalline structure with a greater degree of self-binding, while the amorphous structure of hemicellulose is the opposite of cellulose. The presence of hemicellulose also induces a more porous structure, further increasing the material's water absorption and storage space. In addition, the presence of hemicellulose and other residual lipids in component 1 contributes to the material's softness, providing a certain cushioning effect during use as an absorbent pad material.

[0022] 2. This invention loads carboxymethyl chitosan with antibacterial properties and plant extracts with antibacterial and antioxidant effects onto nanocellulose. The nanocellulose has good biocompatibility and can tightly bind to the cellulose, endowing the porous material with antibacterial and antioxidant functions. The addition of natural substances with antibacterial and antioxidant effects can, on the one hand, effectively inhibit bacterial growth and prevent food spoilage during transportation and preservation; on the other hand, it can prevent or slow down the oxidation process, which leads to the deterioration of components such as fats, proteins, and carbohydrates in food, affecting its nutritional value, taste, and safety. The presence of antioxidants can further ensure the freshness and quality of food.

[0023] 3. The components of the naturally derived porous absorbent pad prepared by this invention are all derived from natural substances. It is green, environmentally friendly, safe, and completely biodegradable. It can be used in the fields of food preservation, absorbent hygiene products, and medical applications. Detailed Implementation

[0024] The methods described in this invention are further illustrated below through specific embodiments, but this does not mean that the invention is limited to these embodiments.

[0025] Example 1

[0026] Coniferous wood chips were pulverized in a pulverizer. The pulverized plant material was then reacted with a benzene-ethanol mixture (volume ratio 2:1) for 24 hours for extraction (mass ratio 1:50), and air-dried at room temperature for 12 hours. The dried material was then reacted with a 4wt% NaClO2 solution at 70℃ for 4 hours (mass ratio 1:40). Acetic acid was added to adjust the pH to 2-3. After the reaction, the solution was repeatedly washed under vacuum until it was neutral and air-dried at room temperature for 12 hours to obtain component 1. Component 1 was then reacted with a 5wt% KOH solution at room temperature for 24 hours (mass ratio 1:30). The solution was further treated at 90℃ for 2 hours. After the reaction, the solution was repeatedly washed under vacuum until it was neutral and air-dried at room temperature for 16 hours to obtain component 2. The above-prepared component 1 and component 2 were mixed at a mass ratio of 1:1 and stirred at high speed for 3 hours to prepare a 2wt% aqueous solution of the mixed components. Then, the solution was dispersed by ultrasonication for 1 hour. While stirring continuously, 0.5wt% of nanocellulose, 0.5wt% of carboxymethyl chitosan, and 10% of tea polyphenol extract were added to the solution.

[0027] The above-prepared mixed solution is poured into a mold, placed in the freezer for 24 hours, and then placed in a vacuum freeze dryer for 48 hours to obtain a porous absorbent pad of natural origin.

[0028] Example 2

[0029] Hardwood chips were pulverized in a pulverizer. The pulverized plant material was then reacted with a benzene-ethanol mixture (volume ratio 2:1) for 24 hours for extraction (mass ratio 1:50), and air-dried at room temperature for 16 hours. The dried material was then reacted with a 4wt% NaClO2 solution at 70℃ for 4 hours (mass ratio 1:30). Acetic acid was added to adjust the pH to 2-3. After the reaction, the solution was repeatedly washed under vacuum until it was neutral and air-dried at room temperature for 12 hours to obtain component 1. Component 1 was then reacted with a 5wt% KOH solution at room temperature for 24 hours (mass ratio 1:20). The solution was further treated at 90℃ for 2 hours. After the reaction, the solution was repeatedly washed under vacuum until it was neutral and air-dried at room temperature for 14 hours to obtain component 2. The above-prepared component 1 and component 2 were mixed at a mass ratio of 1:2 and stirred at high speed for 2 hours to prepare a 1.5 wt% aqueous solution of the mixed components. Then, the solution was dispersed by ultrasonication for 1 hour. While stirring continuously, 0.1 wt% of nanocellulose, 2 wt% of carboxymethyl chitosan, and 5% of grape seed extract were added to the above solution.

[0030] The above-prepared mixed solution is poured into a mold, placed in the freezer for 24 hours, and then placed in a vacuum freeze dryer for 48 hours to obtain a porous absorbent pad of natural origin.

[0031] Example 3

[0032] Corn stalks were crushed in a pulverizer. The crushed plant material was then reacted with a benzene-ethanol mixture (volume ratio 2:1) for 24 hours for extraction (mass ratio 1:50), and air-dried at room temperature for 18 hours. The dried material was then reacted with a 4wt% NaClO2 solution at 70℃ for 5 hours (mass ratio 1:40). Acetic acid was added to adjust the pH to 2-3. After the reaction, the solution was repeatedly washed under vacuum until it was neutral and air-dried at room temperature for 12 hours to obtain component 1. Component 1 was then reacted with a 5wt% KOH solution at room temperature for 24 hours (mass ratio 1:30). The solution was further treated at 90℃ for 2 hours. After the reaction, the solution was repeatedly washed under vacuum until it was neutral and air-dried at room temperature for 18 hours to obtain component 2. The above-prepared component 1 and component 2 were mixed at a mass ratio of 1:3 and stirred at high speed for 5 hours to prepare a 1wt% aqueous solution of the mixed components. Then, the solution was dispersed by ultrasonication for 1 hour. While stirring continuously, 0.2wt% of nanocellulose, 1wt% of carboxymethyl chitosan, and 8% of garlic extract were added to the above solution.

[0033] The above-prepared mixed solution is poured into a mold, placed in the freezer for 24 hours, and then placed in a vacuum freeze dryer for 24 hours to obtain a porous absorbent pad of natural origin.

[0034] Example 4

[0035] Sugarcane stalks were crushed in a grinder. The crushed plant material was then reacted with a benzene-ethanol mixture (volume ratio 2:1) for 24 hours for extraction (mass ratio 1:50), and air-dried at room temperature for 18 hours. The dried material was then reacted with a 4wt% NaClO2 solution at 70℃ for 5 hours (mass ratio 1:50). Acetic acid was added to adjust the pH to 2-3. After the reaction, the solution was repeatedly washed under vacuum until it was neutral and air-dried at room temperature for 18 hours to obtain component 1. Component 1 was then reacted with a 5wt% KOH solution at room temperature for 24 hours (mass ratio 1:40). The solution was further treated at 90℃ for 2 hours. After the reaction, the solution was repeatedly washed under vacuum until it was neutral and air-dried at room temperature for 18 hours to obtain component 2. The above-prepared component 1 and component 2 were mixed at a mass ratio of 1:4 and stirred at high speed for 5 hours to prepare a 0.5 wt% aqueous solution of the mixed components. Then, the solution was dispersed by ultrasonication for 30 minutes. While stirring continuously, 0.25 wt% of nanocellulose, 0.8 wt% of carboxymethyl chitosan, and 8% of rosemary extract were added to the above solution.

[0036] The above-prepared mixed solution is poured into a mold, placed in the freezer for 24 hours, and then dried in a vacuum freeze dryer for 36 hours to obtain a porous absorbent pad of natural origin.

[0037] Table 1 shows the performance tests of the porous absorbent pads prepared in Examples 1, 2, 3, and 4, with the comparative examples being commonly used absorbent pad products on the market; the absorbent pads in the examples and comparative examples are 10*8cm in size.

[0038] Saturated water absorption test: Weigh the absorbent pad as m1, place it in a sufficiently deep tray, and pour about 500g of deionized water into the tray until the absorbent pad is completely submerged. After 1 hour, lift the absorbent pad out, hang it with a clip, and drip liquid for 10 minutes in a static state. Then weigh the absorbent pad as m2. Saturated absorption = m2 - m1.

[0039] Porosity testing instrument: Fully automated vacuum density analyzer.

[0040] Application performance test: Place the absorbent pad in the middle of the bottom of the 9L food storage container, place 200g of fresh pork on the absorbent pad, cover the container with the lid, and place the food storage container in the refrigerator compartment of a household refrigerator to observe the condition of the fresh pork.

[0041] Table 1. Test Results of Absorbent Pad Performance

[0042]

[0043]

[0044] As shown in Table 1, the absorbent pad prepared by the present invention has better water absorption performance than ordinary absorbent pads. It can effectively absorb the moisture generated during food preservation, while preventing food from spoiling and deteriorating, thus ensuring the quality of food.

[0045] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a porous absorbent pad from a natural source, characterized in that, The preparation method includes the following steps: S1. Place the plant material into a grinder and grind it. Take the ground plant material and react it with a benzene-ethanol mixture (volume ratio of 2:1) for 24 hours for extraction. The mass ratio is 1:

50. Air dry at room temperature for 12-18 hours. S2. The dried material is reacted with 4wt% NaClO2 solution in a 70℃ water bath for 4-5 hours at a mass ratio of 1:30-1:

50. Acetic acid is added to adjust the pH value to 2-3. After the reaction is completed, the solution is repeatedly washed by vacuum filtration until it is neutral. The solution is then air-dried at room temperature for 12-18 hours to obtain component 1. S3. Take the above component 1 and 5wt% KOH solution and react them at room temperature for 24 hours, with a mass ratio of 1:20-1:40; continue to treat for another 2 hours under a 90℃ water bath. After the reaction is completed, filter under vacuum and wash repeatedly until the solution is neutral. Air dry at room temperature for 12-18 hours to obtain component 2. S4. Mix the above-prepared component 1 with component 2 in a mass ratio of 1:1 to 1:4, stir at high speed for 2-5 hours to prepare a 0.5-2wt% aqueous solution of the mixed components, and then disperse it using ultrasound for 0.5-1 hours. S5. While continuously stirring, add 0.1-0.5 wt% nanocellulose, 0.5-2 wt% carboxymethyl chitosan, and 5-10% plant extract to the solution obtained in step S4 above. S6. Pour the mixed solution obtained in step S5 into a mold, freeze it in the freezer for 24 hours, and then dry it in a vacuum freeze dryer for 24-48 hours to obtain a porous absorbent pad of natural origin.

2. As described in claim 1, characterized in that, The plant material mentioned in step S1 is derived from one or more of the following: coniferous wood, broadleaf wood, bamboo, sugarcane, flax, corn stalks, and reeds.

3. As described in claim 1, characterized in that, The nanocellulose described in step S5 is a rod-shaped nanomaterial extracted from natural plant fiber raw materials. The nanocellulose has a diameter of less than 1 micrometer and a length of less than 100 micrometers.

4. As described in claim 1, characterized in that, The plant extract mentioned in step S5 is one or more of the following: garlic extract, tea polyphenol extract, rosemary extract, grape seed extract, cinnamon extract, and ginger extract.

5. As described in claim 1, characterized in that, The main components of component 1 are hemicellulose and cellulose.

6. As described in claim 1, characterized in that, The main component of component 2 is cellulose.

Images