A copper-based deoxidizer based on waste textiles and preparation method thereof

Abstract

The present invention discloses a copper-based deoxidizer based on waste textiles and a preparation method thereof. Specifically, the method comprises dissolving a copper salt in an ammoniacal alkaline solution to prepare a copperammonia solution, adding an inhibitor and dissolving the waste textiles, and then dripping the mixture into an acidic solution to form a granular precursor. The precursor is filtered and replaced with an acidic solution, washed, freeze-dried, and subjected to a two-step heat treatment to obtain the copper-based deoxidizer. The present invention prepares a copper-loaded porous copper-based deoxidizer using waste textiles as raw materials, achieving high-value utilization of waste resources. During the carbonization process, carbon thermal reduction is used to reduce the copper source to elemental copper in situ, reducing energy consumption in the subsequent reduction process. The granular copper-based deoxidizer prepared by this process avoids the agglomeration and recycling difficulties of powdered deoxidizers during use.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling waste textiles, and particularly relates to a copper-based deoxidizer based on waste textiles and a preparation method thereof. Background Art

[0002] Deoxidizers play a vital role in petrochemicals, food preservation, and the use of precision instruments. Currently, deoxidizers can be mainly divided into two categories: inorganic deoxidizers and organic deoxidizers. Organic deoxidizers mainly include enzymes and reducing organic acid reagents such as ascorbic acid and oleic acid. However, since enzyme deoxidizers are very sensitive to changes in factors such as pH, salt content, and temperature, and organic deoxidizers have high operating costs and complex production processes, they are difficult to apply on a large scale. Therefore, current deoxidizers are mainly inorganic materials. However, inorganic deoxidizers based on reduced iron powder require the participation of water during the deoxidation process. Excessive moisture content will undoubtedly cause food and equipment to become damp. Therefore, it is still necessary to explore new deoxidizers that can be used on a large scale.

[0003] Copper metal readily reacts with oxygen in air at room temperature to form copper oxide, exhibiting excellent deoxidation properties. However, copper-based deoxidizers still suffer from issues such as large copper particle size, small active surface area, high cost, and difficulty in mass production. Dispersing copper metal on porous materials is an effective means of improving copper dispersion, but copper / carbon deoxidizers prepared by impregnation methods have large copper particles and low copper content, making it difficult to achieve highly dispersed copper nanoparticles. Therefore, new synthesis processes for copper / carbon deoxidizers are still needed.

[0004] Cuprammonia solution, a mixed solution made by dissolving copper ions in concentrated ammonia, can dissolve cellulosic materials, particularly cotton, and is commonly used in the production of cuprammonia fibers. The copper ions in cuprammonia solution possess four coordination bonds, allowing for the dispersion of copper through significant steric hindrance. Furthermore, recycling waste cotton fabrics through cuprammonia solution can add new value to waste resources, making it an environmentally friendly material production process. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a copper-based deoxidizer based on waste textiles and a preparation method thereof. The preparation method uses waste textiles as raw materials, the preparation process is simple and easy to operate, and can achieve small-sized copper particles and high deoxidation efficiency, while effectively solving the problem of difficulty in high-value utilization of textile solid waste.

[0006] The specific technical solutions of the present invention are as follows:

[0007] A method for preparing a copper-based deoxidizer based on waste textiles comprises the following steps:

[0008] 1) dissolving a copper salt in an ammoniacal alkaline solution to prepare a copper ammonia solution, adding an inhibitor and waste textiles, and stirring uniformly to obtain a mixture;

[0009] 2) adding the mixture in step 1) dropwise into the acidic solution, letting it stand for 0.5-12 hours and then filtering, then adding the particle precursor to the acidic solution and performing multiple replacements;

[0010] 3) The particle precursor after the replacement treatment is filtered, washed, dried, and then subjected to a two-step heat treatment to prepare the copper-based deoxidizer.

[0011] Furthermore, the waste textiles are textiles with a cotton content exceeding 70%.

[0012] Furthermore, the copper salt in step 1) is one or more of basic copper carbonate, copper sulfate, copper nitrate, copper hydroxide and copper chloride, and the solid-liquid mass ratio of the copper salt to the ammonia-containing alkaline solution in the copper ammonia solution is 1:10-30.

[0013] Furthermore, the solute of the ammonia-containing alkaline solution is ammonium chloride, ammonium oxalate, ammonium carbonate, ammonium bicarbonate or ammonia water, the solvent is water, the ratio of solute mass to solvent volume is 1-2:1, the mass unit is g, and the volume unit is mL, and the pH value of the above solution is adjusted to 12-14 with 1-20 mL of sodium hydroxide or potassium hydroxide solution with a molar concentration of 1 mol / L.

[0014] Furthermore, the solid-liquid mass ratio of the waste cotton fabric and the copper ammonia solution is 0.1-1:10.

[0015] Furthermore, the inhibitor in step 1) is sodium sulfite, ammonium bicarbonate, ammonium carbonate, or ammonium persulfate, and the volume ratio of the inhibitor mass to the copper ammonia solution is 0.1-1:10.

[0016] Furthermore, the acidic solution in step 2) is one or more aqueous solutions of nitric acid, hydrochloric acid, sulfuric acid, acetic acid, and phosphoric acid, the mass fraction of the acid is 10-30%, the number of replacements is 1-10 times, and the replacement interval is 1-24 hours.

[0017] Furthermore, the drying temperature in step 3) is -196 to -30°C, and the drying time is 12-24 hours.

[0018] Through the low-temperature drying process, the water in the precursor can be condensed into ice, which in turn promotes the separation of cellulose and causes a large number of ice crystals to appear in the precursor. These ice crystals can easily sublime under low pressure, thereby creating a large number of pores and channels, thereby increasing the specific surface area of the product.

[0019] Furthermore, the temperatures of the two heat treatment steps in step 3) are: 150-350° C. for the first step, and 400-900° C. for the second step, and the time for both heat treatment steps is 0.5-12 h.

[0020] To further enhance the anchoring of metal ions and their dispersion in the product, the precursor must be heat treated before carbonization. Heat treatment in air introduces a large number of oxygen-containing functional groups into the precursor. These oxygen-containing groups facilitate metal ion chelation, making it difficult for the metal ions to sinter and grow during the subsequent carbonization process, thus promoting their dispersion. Furthermore, these oxygen-containing functional groups facilitate cross-linking between cellulose molecules, thereby increasing the yield and strength of the final carbon.

[0021] A copper-based deoxidizer prepared by the above preparation method, wherein the copper-based deoxidizer is a porous carbon material uniformly loaded with copper, and its specific surface area is 200 to 600 m 2 / g; pore volume is 0.1~0.5cm 3 / g; the average particle size of the copper particles loaded on the copper-based deoxidizer is 10-30nm, and the copper-based deoxidizer is made from waste textiles.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The tetracoordinate structure of the copper-ammonia complex can be used to coordinate with the hydroxyl groups in waste textiles, thereby achieving uniform dispersion of copper particles on the porous carbon by constructing a large steric hindrance;

[0024] 2) A porous carbon-supported copper-based deoxidizer was prepared using waste textiles as raw materials, achieving high-value utilization of waste resources. At the same time, the rich pore structure of the porous carbon was utilized to enhance the mass transfer of oxygen.

[0025] 3) During the carbonization process, the copper source is reduced to elemental copper in situ by carbon thermal reduction, which reduces the energy consumption of the subsequent reduction process;

[0026] 4) This process can be used to prepare granular copper-based deoxidizers, avoiding the agglomeration and recovery difficulties of powdered deoxidizers during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the appearance morphology of the deoxidizer.

[0028] Figure 2 Transmission electron microscopy image of the deoxidizer.

[0029] Figure 3 This is a graph showing the relationship between the oxygen content in the mixed gas and the deoxidation time after treatment with different deoxidizers. DETAILED DESCRIPTION

[0030] To further describe the present invention, the present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention is not limited thereto.

[0031] Example 1

[0032] 20 g of 30% ammonia solution was diluted in 10 mL of deionized water and the pH was adjusted to 13 with 10 mL of 1 mol / L potassium hydroxide solution to obtain the ammoniacal alkaline solution. 2 g of basic copper carbonate was dissolved in the ammoniacal alkaline solution, 1 g of sodium sulfite was added, and the mixture was stirred at 30°C. 1 g of long-staple cotton (100% cotton content) was added to the solution and stirred until completely dissolved to obtain a mixture. The mixture was then added dropwise to a 20% nitric acid solution to obtain a granular precursor. The precursor was allowed to stand for 2 hours and then filtered. The granular precursor was then added back to the nitric acid solution for replacement. The nitric acid solution was then filtered and replaced every hour. After repeated replacement three times, the precursor was filtered and washed, and then dried at -30°C for 12 hours. The dried sample was subjected to a two-step heat treatment: a first step of heat treatment at 260°C for 6 hours and a second step of heat treatment at 600°C for 1 hour to obtain copper-based deoxidizer 1.

[0033] Example 2

[0034] The copper ammonia solution is prepared in the same manner as in Example 1. 1 g of cotton cloth (100% cotton content) is added to the solution and stirred until completely dissolved to obtain a mixture. The above mixture is then added dropwise to a 20% by mass nitric acid solution to obtain a granular precursor, which is then allowed to stand for 2 hours and then filtered. The granular precursor is added back to the above nitric acid solution for replacement, and then filtered and the nitric acid solution is replaced every hour. After repeating the replacement three times, the precursor is filtered and washed, and then dried at -30°C for 12 hours. The two-step heat treatment process is the same as in Example 1 to obtain a copper-based deoxidizer 2.

[0035] Example 3

[0036] The copper ammonia solution was prepared as in Example 1. 1 g of polyester-cotton blend (70% cotton content) was added to the solution and stirred until completely dissolved to obtain a mixture. The mixture was then added dropwise to a 20% by mass nitric acid solution to obtain a granular precursor. The precursor was allowed to stand for 2 hours and then filtered. The granular precursor was added back to the nitric acid solution for replacement. The nitric acid solution was then filtered and replaced every hour. After repeating the replacement three times, the precursor was filtered and washed, and then dried at -30°C for 12 hours. The two-step heat treatment process was the same as in Example 1 to obtain a copper-based deoxidizer 3.

[0037] Example 4

[0038] The copper ammonia solution is prepared in the same manner as in Example 1. 1 g of ammonia cotton (70% cotton content) is added to the solution and stirred until completely dissolved to obtain a mixture. The above mixture is then added dropwise to a 20% by mass nitric acid solution to obtain a granular precursor, which is then allowed to stand for 2 hours and then filtered. The granular precursor is re-added to the above nitric acid solution for replacement, and then filtered and the nitric acid solution is replaced every hour. After repeating the replacement three times, the precursor is filtered and washed, and then dried at -30°C for 12 hours. The two-step heat treatment process is the same as in Example 1 to obtain a copper-based deoxidizer 4.

[0039] Example 5

[0040] The copper ammonia solution was prepared as in Example 1. 1 g of cotton cloth (100% cotton content) was added to the solution and stirred until completely dissolved to obtain a mixture. The mixture was then added dropwise to a 20% by mass nitric acid solution to obtain a granular precursor. The precursor was allowed to stand for 2 hours and then filtered. The filtrate was washed until its pH value was 6 and the resulting precursor was dried at -30°C for 12 hours. The two-step heat treatment process was the same as in Example 1 to obtain a copper-based deoxidizer 5.

[0041] Comparative Example 1

[0042] 20g of 30% ammonia solution was diluted in 10mL of deionized water and the pH was adjusted to 13 with 10mL of 1mol / L potassium hydroxide solution to obtain the ammoniacal alkaline solution. 2g of basic copper carbonate was dissolved in the ammoniacal alkaline solution and stirred at 30°C. 1g of cotton cloth (100% cotton content) was added to the solution and stirred until completely dissolved to obtain a mixture. The mixture was then added dropwise to a 20% by mass nitric acid solution to obtain a granular precursor, which was then allowed to stand for 2h and filtered. The granular precursor was re-added to the nitric acid solution for replacement, and the nitric acid solution was then filtered and replaced every 1h. After repeating the replacement three times, the precursor was filtered and washed and then dried at -30°C for 12h. The two-step heat treatment process was the same as in Example 1 to obtain copper-based deoxidizer 6.

[0043] Comparative Example 2

[0044] The preparation of the copper ammonia solution is the same as that of Example 1. 1 g of cotton cloth (100% cotton content) is added to the solution and stirred until completely dissolved to obtain a mixture. The above mixture is then added dropwise to a 20% by mass nitric acid solution to obtain a granular precursor, which is then filtered after standing for 2 hours. The granular precursor is added back to the above nitric acid solution for replacement, and then the nitric acid solution is filtered and replaced every 1 hour. After repeating the replacement three times, the precursor is filtered and washed and dried at -30°C for 12 hours. The dried sample is placed in a corundum porcelain boat and heat-treated at 600°C for 1 hour to obtain a copper-based deoxidizer 7.

[0045] Comparative Example 3

[0046] The copper ammonia solution was prepared in the same manner as in Example 1. 1 g of cotton cloth (100% cotton content) was added to the solution and stirred until completely dissolved to obtain a mixture. The mixture was then added dropwise to a 20% by mass nitric acid solution to obtain a granular precursor, which was allowed to stand for 2 hours and then filtered. The granular precursor was added back to the nitric acid solution for replacement, and then filtered and the nitric acid solution was replaced every hour. After repeating the replacement three times, the precursor was filtered and washed, and then dried at 100°C for 12 hours. The two-step heat treatment process was the same as in Example 1 to obtain a copper-based deoxidizer 8.

[0047] Application Examples

[0048] 5g of the dried copper-based deoxidizer prepared in Examples 1-5 and Comparative Examples 1-3 were respectively ground to 60-80 mesh and placed in a fixed-bed reactor. Before the reaction, the deoxidizer was dried at 200°C for 1.5h under a nitrogen atmosphere. The reactor temperature was subsequently raised to 350°C, and an oxygen / nitrogen mixture (oxygen concentration of 20ppm) was introduced at 100mL / min to test the deoxidation performance. After the test, the tail gas was first passed through anhydrous calcium chloride to absorb the water vapor brought out in the gas, and finally, color-changing silica gel was used to ensure that the moisture in the product gas was completely absorbed. The remaining tail gas was analyzed for oxygen content by online gas chromatography.

[0049] The physical properties of the copper-based deoxidizers prepared in Examples 1-5 and Comparative Examples 1-3 are shown in Table 1 below. As shown in Table 1, the specific surface areas of the deoxidizers 1 and 2 prepared from long-staple cotton (100% cotton content) and cotton cloth (100% cotton content) are both above 400 m 2 / g, with a copper content of 3wt% and copper particle sizes ranging from 22-24nm, indicating that copper-based deoxidizers with smaller copper particles can be prepared using this method. Deoxidizers 3 and 4, prepared using polyester-cotton and spandex-cotton textiles with 70% cotton content, exhibited further increases in specific surface area compared to deoxidizer 2. This is likely due to the fact that polyester fibers readily decompose at high temperatures, producing large amounts of CO2. This CO2 acts as an activating gas to increase the specific surface area of the cotton-based carbon material. Furthermore, the copper particle sizes of deoxidizers 3 and 4 are comparable to those of deoxidizers 1 and 2, indicating that cotton blends can also be prepared using this method for copper-based deoxidizers. Deoxidizer 5, obtained by reducing the number of displacements, exhibited a significantly higher copper content than the aforementioned four samples, but its copper particle size also increased, resulting in a deoxidizer with a much lower specific surface area than the aforementioned four samples. This suggests that multiple displacements are necessary to prepare small-particle copper-based deoxidizers.

[0050] Table 1 Summary of physical properties of deoxidizers prepared in Examples 1-5 and Comparative Examples 1-3

[0051]

[0052] Deoxidizer 6, prepared without the addition of an inhibitor, exhibited significantly larger particle sizes than the sample with an inhibitor, demonstrating that the addition of an inhibitor effectively reduces copper particle agglomeration and reduces copper particle size within the deoxidizer. Deoxidizer 7, prepared without heat treatment, and deoxidizer 8, prepared using high-temperature drying, both exhibited lower specific surface areas and larger copper particle sizes, falling short of the method proposed in this invention.

[0053] Figure 1 In Figure 1, a is a transmission electron micrograph of deoxidizer 1, and b is a transmission electron micrograph of deoxidizer 3. As can be seen in Figure a, the cotton-based deoxidizer 1 prepared using the method of the present invention exhibits a smooth spherical shape. In contrast, deoxidizer 3, prepared using polyester-cotton textiles, exhibits an irregular morphology and is accompanied by a small amount of powder. This is primarily due to the activation of the polyester in the polyester-cotton textile during the carbonization process, which increases the specific surface area of the deoxidizer while also destroying its morphology. Therefore, the cotton content in the textile should be no less than 70%.

[0054] Figure 2 In the figure, a is the transmission electron micrograph of deoxidizer 1, and b is the transmission electron micrograph of deoxidizer 5; Figure 2 From the transmission electron microscope image, it can be seen that the diameter of the copper nanoparticles on the deoxidizer 1 prepared by the method of the present invention is about 20 nm, while the copper nanoparticles of the deoxidizer 5 prepared by the direct impregnation method are all larger than 100 nm.

[0055] The deoxidation performance of the 8 deoxidizers obtained above was tested. Figure 3 The vertical axis is the oxygen content in the tail gas after deoxidation. The higher the value, the lower the efficiency of the deoxidizer in removing oxygen from the oxygen-nitrogen mixture. Figure 3 As can be seen from the results, deoxidizers 1 and 2, prepared using long-staple cotton and cotton cloth as raw materials, exhibited high deoxidation efficiency, reducing the oxygen content in the air from 20 ppm to approximately 3 ppm. The oxygen content in the tail gas remained stable during the subsequent deoxidation process. Deoxidizers 3 and 4, prepared using polyester-cotton and spandex with a cotton content of 70%, even outperformed deoxidizers 1 and 2. The oxygen content in the tail gas of deoxidizer 5 increased rapidly with operating time, indicating poor deoxidation stability due to the presence of larger copper particles. Deoxidizers 6 and 7, prepared without the addition of inhibitors or heat treatment, also exhibited poor operational stability due to their larger copper particles. Deoxidizer 8, prepared using direct high-temperature drying, had a lower specific surface area and larger copper particles, resulting in lower mass transfer capacity for air. This resulted in poor initial deoxidation performance for both deoxidizers. However, after 3-5 hours of deoxidation, the tail gas oxygen content was essentially equivalent to that in the feed gas.

[0056] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a copper-based deoxidizer based on waste textiles, characterized in that The steps include: 1) dissolving a copper salt in an alkaline solution containing ammonia to prepare a copper ammonia solution, adding an inhibitor and waste textiles, and stirring to obtain a mixture; 2) adding the mixture in step 1) dropwise into the acidic solution to obtain a particle precursor, allowing it to stand for 0.5-12 hours and then filtering it, then adding the particle precursor to the acidic solution and performing multiple replacements; 3) filtering, washing, and drying the particle precursor after the replacement treatment, and then performing a two-step heat treatment to prepare the copper-based deoxidizer; Waste textiles are textiles with a cotton content of more than 70%; The inhibitor in step 1) is sodium sulfite, and the volume ratio of the inhibitor mass to the copper ammonia solution is 0.1-1:10; The acidic solution in step 2) is one or more aqueous solutions of nitric acid, hydrochloric acid, sulfuric acid, acetic acid, and phosphoric acid, with a mass fraction of the acid being 10-30%, and the replacement interval being 1-24 hours; The temperatures of the two heat treatment steps in step 3) are: 150-350°C for the first step, and 400-900°C for the second step. The time for both heat treatment steps is 0.5-12 hours.

2. The preparation method according to claim 1, wherein The copper salt in step 1) is one or more of basic copper carbonate, copper sulfate, copper nitrate, copper hydroxide and copper chloride, and the solid-liquid mass ratio of the copper salt to the ammoniacal alkaline solution in the copper ammonia solution is 1:10-30.

3. The preparation method according to claim 1, wherein The solute of the ammonia-containing alkaline solution is ammonium chloride, ammonium oxalate, ammonium carbonate, ammonium bicarbonate or ammonia water, the solvent is water, the ratio of solute mass to solvent volume is 1-2:1, the mass unit is g, and the volume unit is mL. The pH value of the ammonia-containing alkaline solution is adjusted to 12-14 using 1-20 mL of sodium hydroxide or potassium hydroxide solution with a molar concentration of 1 mol / L.

4. The preparation method according to claim 2, wherein The solid-liquid mass ratio of the waste cotton fabric and the copper ammonia solution is 0.1-1:

10.

5. The preparation method according to claim 1, wherein The drying temperature in step 3) is -196 to -30°C, and the drying time is 12-24 hours.

6. A copper-based deoxidizer prepared by the preparation method according to any one of claims 1 to 5, characterized in that Copper-based deoxidizer is a porous carbon material uniformly loaded with copper, with a specific surface area of 200~600 m 2 / g; pore volume is 0.1~0.5 cm 3 / g; the average particle size of the copper particles loaded on the copper-based deoxidizer is 10-30 nm, and the copper-based deoxidizer is made from waste textiles.

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