A culture medium carrier, its preparation method and its application

Abstract

This invention discloses a culture medium carrier, its preparation method, and its application, belonging to the field of microbial detection technology. The culture medium carrier comprises a double-layer structure consisting of a composite nonwoven fabric layer and a cellulose acetate nanofiber membrane layer fixed together. The composite nonwoven fabric is made from wood pulp fiber (weight ratio 1-1.5:1) and recycled polyester staple fibers prepared from waste polyester textiles with a polyester weight content of 65%-95%. The cellulose acetate nanofiber membrane is made from cellulose diacetate filter rods after impurities have been removed, and the resulting cellulose diacetate fibers are produced through electrospinning. The culture medium carrier and its preparation method provided by this invention effectively solve the problems of traditional culture medium carriers, such as easy wrinkling, poor water retention, and double-sided colony growth. Simultaneously, it achieves the resource-based reuse of waste polyester textiles and cellulose diacetate filter rods, resulting in energy conservation and environmental protection. When applied to microbial detection slides, the average microbial detection rate reaches over 96%.

Description

Technical Field

[0001] This invention belongs to the field of microbial detection technology, and relates to a culture medium carrier, specifically a culture medium carrier, its preparation method, and its application. Background Technology

[0002] Waste textiles refer to textile materials and products discarded during production and use. Waste textiles are typically disposed of through landfill or incineration. However, because synthetic fibers such as polyester, nylon, and acrylic are not easily degraded, direct landfilling causes significant harm to the soil environment, while incineration produces large amounts of toxic gases, leading to air pollution. From the perspective of building an environmentally friendly and resource-saving society and developing a circular economy, the recycling and high-value reuse of waste textiles is of paramount importance.

[0003] my country's tobacco industry requires a large amount of cellulose diacetate tow annually to produce cigarette filters. Cellulose diacetate tow is relatively expensive, costing approximately 60,000 yuan per ton. According to a survey of several domestic cigarette filter and cigarette manufacturers, approximately 2.0-3.0% of cellulose diacetate filter rods (referred to as waste filter rods) are generated during the filter rod and cigarette manufacturing processes due to factors such as fluctuations in the operation of molding equipment. Based on the current annual national consumption of 330,000 tons of cellulose diacetate tow, this translates to approximately 6,600-9,900 tons of waste filter rods generated annually. Currently, these waste filter rods are mainly disposed of by transporting them to waste treatment plants for incineration or discarding them into the environment. Incineration costs approximately 300 yuan per ton and causes resource waste and environmental pollution during the process. Therefore, recycling and reusing waste filter rods is of great significance.

[0004] Traditional microbial detection uses the agar plate counting method, which requires extensive preparation before testing, such as preparing culture media, high-temperature steam sterilization, pouring plates, waste disposal, and cleaning equipment. This process is not only cumbersome but also demands high skill from both the equipment and the operator; improper operation can severely affect the accuracy of the results. Microbial detection strips, as a novel detection method, combine traditional culture methods with specific enzyme colorimetric reactions and are made into a readily usable, disposable product. Due to their simplicity, cost-effectiveness, and short culture cycle, they have significant application value. Developed countries such as the United States and the European Union began researching microbial detection earlier. In the 1950s, German scientists invented a rapid detection method for coliform bacteria. This method is simple to operate, significantly reducing the detection time from 72 hours to 15 hours, and the cost is only one-quarter of the traditional agar plate counting method. Microbial detection strips have become a research hotspot in my country in recent years.

[0005] Microbial detection strips typically use filter paper, soluble cold hydrogel, or non-woven fabric instead of agar as a carrier, detecting microorganisms in samples through color development based on microbial growth. In the 1980s, 3M made a breakthrough in developing coliform bacteria test strips. These strips used soluble cold hydrogel as a carrier, incorporating modified VRB medium and a chromogenic agent. While 3M's microbial detection strips were fast, convenient, highly sensitive, and specific, they still had limitations, such as colony diffusion and reduced counting when bacteria produced gas or organic solvents were present in the sample.

[0006] In the 1990s, Sanita Kun of Chisso Corporation in Japan and RIDACOUNT of R-BIOPHARM Corporation in Germany used non-woven fabric and selective chromogenic culture medium as carriers to produce microbial detection strips. The principle was based on the specific colorimetric reaction between enzymes and substrates, creating a clear color distinction between target and non-target bacteria. In my country, companies such as Guangzhou Oasis Biochemical Technology Co., Ltd. and Beijing Zhongwei Biotechnology Development Co., Ltd. also produce test strips using non-woven fabric as a carrier. However, non-woven fabric is prone to wrinkling when absorbing sample liquid, making counting difficult and preventing the picking of colonies for further verification experiments. Furthermore, the material has poor water retention, which hinders bacterial growth during cultivation due to the inability to maintain humidity.

[0007] In the 1980s, the Tianjin Health and Epidemic Prevention Station developed a series of test strips using filter paper as a carrier. The principle involves sterilized filter paper adsorbing culture medium and colorimetric reagents, allowing bacteria to expand and become fixed and multiply. While the filter paper-based test strips are simple and inexpensive to manufacture, the filter paper has relatively large gaps, making it easy for bacterial colonies to grow on both sides and between the fibers, making it impossible to accurately judge with the naked eye and affecting the accuracy of the test results. Summary of the Invention

[0008] The purpose of this invention is to provide a culture medium carrier, preparation method, and application to solve the problems of easy wrinkling, poor water retention, and double-sided growth of colonies in existing microbial detection strips, while realizing the resource utilization of waste textiles and waste filter rods.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A culture medium carrier comprising a bilayer structure of a composite nonwoven fabric layer and a cellulose acetate nanofiber membrane layer fixed together;

[0011] The weight ratio of the composite nonwoven fabric to the cellulose acetate nanofiber membrane is (8-10):1;

[0012] The raw material of the composite nonwoven fabric is wood pulp fiber with a weight ratio of (1-1.5):1 and recycled polyester staple fiber prepared from waste polyester textiles with a PET weight content of 65%-95%.

[0013] The cellulose acetate nanofiber membrane is made by removing impurities from waste cellulose diacetate filter rods and then electrospinning the resulting cellulose diacetate fibers.

[0014] As a limitation, the recycled polyester staple fiber has a length of 56-78 mm, a linear density of 1.56-2.22 dtex, and a breaking strength ≥4.85 cN / dtex.

[0015] As another limitation, the length of the wood pulp fiber is 2-3 mm; the porosity of the cellulose acetate nanofiber membrane is 0.5-5 μm.

[0016] As a third limitation, its liquid absorption capacity is ≥400%, and its weight is 40-60 g / m³. 2 .

[0017] The present invention also provides a method for preparing the above-mentioned culture medium carrier, comprising the following steps performed sequentially:

[0018] S1. Waste polyester textiles are decolorized and alcoholized to obtain BHET crystals, and the BHET crystals are polycondensation reaction to prepare recycled polyester staple fibers.

[0019] S2. Recycled polyester staple fiber is carded into a web, combined with wet-laid wood pulp fiber, and then hydroentangled to form a composite nonwoven fabric;

[0020] S3. After removing impurities from waste cellulose diacetate filter rods, cellulose diacetate fibers are obtained. Using composite nonwoven fabric as the receiving base fabric of the electrospinning device, cellulose diacetate nanofiber membranes are prepared by electrospinning and embedded on the cellulose diacetate fibers to obtain the culture medium carrier.

[0021] As a limitation, the decolorization in step S1 specifically includes: adding 1%-5% by weight of polyethylene glycol-silica composite phase change material to waste polyester textiles, mixing evenly, and then performing steam decolorization using dimethyl sulfoxide for 2 hours.

[0022] As another limitation, the alcoholysis in step S1 specifically includes: adding potassium carbonate and ethylene glycol at a weight of 4-6 times that of PET to the decolorized waste polyester textiles, reacting at a temperature of 185-195°C for 10-15 minutes, filtering while hot, cooling the filtrate to 8-12°C, and filtering to obtain pre-depolymerized PET solids; adding potassium carbonate and ethylene glycol at a weight of 4-6 times that of PET to the pre-depolymerized PET solids, reacting at a temperature of 230-260°C for 1-2 hours, filtering while hot, cooling the filtrate to 8-12°C, and crystallizing to obtain purified BHET crystals.

[0023] As a third limitation, in step S3, the waste cellulose diacetate filter rod is cleaned of impurities to obtain cellulose diacetate fiber, specifically including: peeling off the forming paper from the surface of the waste cellulose diacetate filter rod, immersing it in water at a temperature of 70-90℃ for 40-60 minutes, and dehydrating it for 1 minute; immersing the product in water at a temperature of 60-70℃ for a first rinse for 8-10 minutes, and dehydrating it for 1 minute; immersing the product in water at a temperature of 60-70℃ for a second rinse for 8-10 minutes, and dehydrating it for 1 minute; dehydrating the product at a high speed of 1500-2000 rpm for 4 minutes, and drying it at 90-100℃ for 40-60 minutes to obtain cellulose diacetate fiber.

[0024] As a fourth limitation, in step S2, the hydroentangling process includes pre-hydroentangling, flat-net hydroentangling, and rotary drum hydroentangling;

[0025] The pressure for pre-hydraulic spraying is 1.5-2.0 MPa, the pressure for flat-net hydraulic spraying is 2.5-3.5 MPa, and the pressure for rotary drum hydraulic spraying is 4-5 MPa.

[0026] In step S3, the electrospinning process parameters are: temperature 20-30℃, relative humidity 35-48%, voltage 25-28kV, injection rate 0.003mm / s, and receiving distance 10-12cm.

[0027] The present invention also provides an application of the above-mentioned culture medium carrier, which is used to prepare microbial detection slides.

[0028] By adopting the above technical solution, the technical progress achieved by this invention compared with the prior art is as follows:

[0029] ① The culture medium carrier provided by this invention uses recycled polyester short fibers as a skeleton, giving the culture medium carrier a certain strength, making it less prone to wrinkling when absorbing sample liquid compared to traditional non-woven culture medium carriers; wood pulp fibers have good water absorption, low cost, and are completely degradable, playing a role in absorbing and locking water in the culture medium carrier, making it better at retaining water than traditional non-woven culture medium carriers; at the same time, the recycled polyester short fibers and wood pulp fibers are combined to form a wood pulp hydroentangled composite non-woven fabric, which can reduce the gaps in the culture medium carrier and solve the problem that traditional filter paper culture medium carriers have large gaps, which easily lead to the growth of colonies between the two sides of the filter paper and the fibers;

[0030] ② The culture medium carrier provided by this invention has finer cellulose acetate nanofiber membrane fibers that are embedded on the surface of composite nonwoven fabric. This can reduce the porosity of traditional culture medium carriers, solve the problem of double-sided growth of microorganisms, and at the same time play the role of loading and slow-release of culture medium.

[0031] ③ The present invention provides a method for preparing a culture medium carrier, which uses waste polyester textiles and waste cellulose diacetate filter rods as raw materials, realizing the resource-based reuse of waste polyester textiles and waste cellulose diacetate filter rods, greatly saving production costs, improving economic benefits, and being more environmentally friendly.

[0032] ④ The present invention provides a method for preparing a culture medium carrier, in which polyethylene glycol-silica composite phase change material with phase change properties is added to waste polyester textiles. When the decolorizing agent vapor (dimethyl sulfoxide vapor) rises, the temperature of the waste polyester textile pile increases, and the phase change material inside the pile reaches the phase change temperature and undergoes a phase change, forming a local temperature difference. This guides the decolorizing agent vapor to penetrate the pile with a high pile thickness or a high fabric knitting density, so that the decolorizing agent vapor can fully contact the waste polyester textiles, thereby improving the decolorization uniformity and increasing the decolorization rate to over 97%.

[0033] ⑤ The present invention provides a method for preparing a culture medium carrier, which uses potassium carbonate as a catalyst and combines it with ethylene glycol to obtain BHET with a purity greater than 98.0% through stepwise reaction and gradual crystallization.

[0034] ⑥ The present invention provides a method for preparing a culture medium carrier, which uses a combined cleaning process of high-temperature washing, first rinsing, and second rinsing. On the one hand, the high-temperature washing destroys the molecular structure of triacetin, thereby effectively separating and removing most of the triacetin from the waste cellulose diacetate filter rods; on the other hand, the two rinsing processes further separate and remove the residual triacetin from the waste cellulose diacetate filter rods, increasing the removal efficiency to 99%. At the same time, no surfactants or other additives are used, which saves costs and is more environmentally friendly, making it suitable for industrial applications.

[0035] ⑦ The present invention provides an application of a culture medium carrier for preparing microbial detection strips, which can achieve efficient detection of microorganisms such as Escherichia coli, Staphylococcus aureus, and Salmonella.

[0036] The culture medium carrier and preparation method provided by this invention effectively solve the problems of traditional culture medium carriers being prone to wrinkling, having poor water retention, and exhibiting double-sided colony growth. At the same time, it realizes the resource-based reuse of waste polyester textiles and waste cellulose diacetate filter rods, which is energy-saving and environmentally friendly. When applied to microbial detection slides, the average microbial detection rate reaches over 96%. Attached Figure Description

[0037] Figure 1 This is a K / S value-wavelength diagram of waste polyester textiles before and after decolorization treatment in Example 2;

[0038] Figure 2 The HPLC spectrum of BHET crystals obtained by alcoholysis in Example 2 is shown below.

[0039] Figure 3 The image shows the microstructure of the cellulose acetate nanofiber membrane prepared in Example 2. Detailed Implementation

[0040] The present invention will be further described in detail below through specific embodiments. It should be understood that the described embodiments are only for explaining the present invention and do not limit the present invention.

[0041] Example 1: A culture medium carrier

[0042] This embodiment discloses a culture medium carrier comprising a bilayer structure of a composite nonwoven fabric layer and a cellulose acetate nanofiber membrane layer fixed together. The weight ratio of the composite nonwoven fabric to the cellulose acetate nanofiber membrane is 8:1. The two layers are interlocked by using the composite nonwoven fabric as the receiving substrate for the electrospinning process of the cellulose acetate nanofiber membrane. Alternatively, the two layers can be bonded together by hot pressing.

[0043] In addition, culture medium carriers can be prepared by using composite nonwoven fabrics and cellulose acetate nanofiber membranes in a weight ratio of (8-10):1.

[0044] The liquid absorption capacity of this culture medium carrier is 400%, and its weight is 40 g / m³. 2 .

[0045] In addition, the liquid absorption capacity of the culture medium carrier is ≥400%, and the basis weight is 40-60 g / m³. 2 Both can meet the requirements.

[0046] The composite nonwoven fabric is made of wood pulp fiber and recycled polyester staple fiber in a weight ratio of 1:1 through a hydroentangling process; the recycled polyester staple fiber has a length of 56 mm, a linear density of 1.56 dtex, and a breaking strength of 4.85 cN / dtex; the wood pulp fiber has a length of 2 mm.

[0047] Furthermore, composite nonwoven fabrics can be prepared with a weight ratio of wood pulp fiber and recycled polyester staple fiber between (1-1.5):1; the recycled polyester staple fiber has a length between 56-78 mm, a linear density between 1.56-2.22 dtex, and a breaking strength ≥4.85 cN / dtex, all of which meet the requirements for preparing composite nonwoven fabrics; the wood pulp fiber has a length of 2-3 mm, which also meets the requirements for preparing composite nonwoven fabrics.

[0048] The recycled polyester staple fiber is made from waste polyester textiles with a PET weight content of 65%. Furthermore, waste polyester textiles with a PET weight content between 65% and 95% can also meet the requirements for preparing recycled polyester staple fiber.

[0049] The cellulose acetate nanofiber membrane is made by electrospinning cellulose diacetate fibers obtained by removing impurities from waste cellulose diacetate filter rods; the porosity of the cellulose acetate nanofiber membrane is 0.5 μm.

[0050] In addition, the porosity of cellulose acetate nanofiber membranes can meet the requirements in the range of 0.5-5 μm.

[0051] Example 2: A method for preparing a culture medium carrier

[0052] This embodiment discloses a method for preparing a culture medium carrier, comprising the following steps performed sequentially:

[0053] S1.

[0054] Colored waste polyester textiles containing 2.5 kg of PET (65 wt% PET, 33 wt% spandex, and 2 wt% dye) were uniformly mixed with 25 g of powdered polyethylene glycol-silica composite phase change material (1% of the PET weight in the waste polyester textiles) to obtain waste polyester textiles to be decolored; the waste polyester textiles to be decolored were placed in a metal mesh for steam decolorization treatment, and steam decolorization was carried out using 60 L of dimethyl sulfoxide as the decolorizing agent;

[0055] The specific steps of steam decolorization are as follows: stir and heat the decolorizing agent to the boiling point of the decolorizing agent 189°C, maintain this temperature for 2 hours to ensure that the decolorizing agent vapor comes into contact with the waste polyester textiles to be decolorized, stop heating, and wait for the decolorizing agent solution to cool to room temperature to complete the steam decolorization of waste polyester textiles.

[0056] The decolorization rate of waste polyester textiles before and after treatment was measured, and the K / S value-wavelength diagrams before and after treatment were obtained, as shown in the figure. Figure 1 As shown, the decolorization rate is calculated by the change in K / S value before and after processing. The formula for calculating the decolorization rate is as follows:

[0057] △K / S = (K / S value before decolorization - K / S value after decolorization) ÷ K / S value before decolorization × 100%

[0058] The calculated decolorization rate was 97.1%;

[0059] Add 75g of potassium carbonate and 10kg of ethylene glycol (4 times the weight of PET) to the decolorized waste polyester textiles, react at 185℃ for 10min, filter while hot, cool the filtrate to 12℃, and filter to obtain pre-depolymerized PET solid; add 75g of potassium carbonate and 15kg of ethylene glycol (6 times the weight of PET) to the pre-depolymerized PET solid, react at 230℃ for 1h, filter while hot, cool the filtrate to 8℃, and crystallize to obtain BHET;

[0060] Using potassium carbonate as a catalyst, the first alcohol treatment at 185-195℃ decomposes impurities such as spandex into smaller molecules that dissolve in ethylene glycol. Simultaneously, high-molecular-weight PET partially depolymerizes, reducing its molecular weight. Hot filtration removes solid impurities such as potassium carbonate. Upon cooling, the pre-depolymerized PET precipitates, while the impurities already decomposed into smaller molecules do not precipitate. Filtration removes other high-molecular-weight impurities from waste polyester textiles. A second alcoholysis, also using potassium carbonate as a catalyst, is performed at 230-260℃ with ethylene glycol. PET is completely decomposed into BHET, which dissolves in ethylene glycol. Hot filtration removes catalyst and other impurities. Cooling of the filtrate allows BHET crystals to precipitate. The purity of the obtained BHET crystals was determined, and its HPLC chromatogram is shown below. Figure 2 As shown, the purity of the obtained BHET crystal is 98.8% after testing and calculation.

[0061] Regenerated polyester staple fiber was prepared by polycondensation reaction of BHET crystals.

[0062] Tests showed that the recycled polyester staple fiber had a length of 56 mm, a linear density of 1.56 dtex, and a breaking strength of 4.85 cN / dtex.

[0063] S2.

[0064] Recycled polyester staple fibers are mixed, opened, and carded into a web, and then combined with wet-laid wood pulp fibers (2 mm in length) (the weight ratio of wood pulp fibers to recycled polyester staple fibers is 1:1). The web is then pre-hydroentangled under 1.5 MPa pressure, flat web hydroentangled under 2.5 MPa pressure, and drum hydroentangled under 4 MPa pressure. After dehydration and drying, a composite nonwoven fabric is formed.

[0065] S3.

[0066] The forming paper on the surface of the waste cellulose diacetate filter rod is peeled off, and the product is washed in water at 70°C for 40 minutes and dehydrated for 1 minute. The product is then rinsed in water at 60°C for 8 minutes and dehydrated for 1 minute. The product is then rinsed in water at 60°C for 10 minutes and dehydrated for 1 minute. The product is then dehydrated at high speed for 4 minutes and dried at 90°C for 40 minutes to obtain cellulose diacetate fiber.

[0067] Using a composite nonwoven fabric as the receiving substrate, cellulose acetate nanofiber membranes (with an average porosity of 3 μm and a microstructure as shown) were prepared by electrospinning of cellulose diacetate fibers. Figure 3 As shown, the composite nonwoven fabric and cellulose acetate nanofiber membrane are embedded and deposited on the composite nonwoven fabric. The weight ratio of the composite nonwoven fabric to the cellulose acetate nanofiber membrane is 8:1, thus obtaining the culture medium carrier.

[0068] The electrospinning process parameters are as follows: temperature 20℃, relative humidity 35%, voltage 25kV, injection rate 0.003mm / s, and receiving distance 10cm.

[0069] Testing revealed that the liquid absorption capacity of this culture medium carrier was 400%, and its weight was 40 g / m³. 2 .

[0070] Example 3: A method for preparing a culture medium carrier

[0071] This embodiment discloses a method for preparing a culture medium carrier, comprising the following steps performed sequentially:

[0072] S1.

[0073] 2.5 kg of colored waste polyester textiles containing PET (95 wt% PET, 4 wt% cotton, and 1 wt% dye) were uniformly mixed with 125 g of powdered polyethylene glycol-silica composite phase change material (5% of the PET weight in the waste polyester textiles) to obtain waste polyester textiles to be decolored; the waste polyester textiles to be decolored were placed in a metal mesh for steam decolorization treatment, and steam decolorization was carried out using 60 L of dimethyl sulfoxide as the decolorizing agent;

[0074] The specific steps of steam decolorization are as follows: stir and heat the decolorizing agent to the boiling point of the decolorizing agent 189°C, maintain this temperature for 2 hours to ensure that the decolorizing agent vapor comes into contact with the waste polyester textiles to be decolorized, stop heating, and wait for the decolorizing agent solution to cool to room temperature to complete the steam decolorization of waste polyester textiles.

[0075] The decolorization rate of waste polyester textiles before and after treatment was tested, and the calculated decolorization rate was 98.9%.

[0076] Add 75g of potassium carbonate and 15kg of ethylene glycol (6 times the weight of PET) to the decolorized waste polyester textiles, react at 195℃ for 15min, filter while hot, cool the filtrate to 8℃, and filter to obtain pre-depolymerized PET solid; add 75g of potassium carbonate and 10kg of ethylene glycol (4 times the weight of PET) to the pre-depolymerized PET solid, react at 260℃ for 2h, filter while hot, cool the filtrate to 12℃, and crystallize to obtain BHET;

[0077] The purity of the obtained BHET crystals was determined, and the purity of the obtained BHET crystals was found to be 99.3% after testing and calculation.

[0078] Regenerated polyester staple fiber was prepared by polycondensation reaction of BHET crystals.

[0079] Tests showed that the recycled polyester staple fiber had a length of 78 mm, a linear density of 2.22 dtex, and a breaking strength of 4.90 cN / dtex.

[0080] S2.

[0081] Recycled polyester staple fibers are mixed, opened, and carded into a web, and then combined with wet-laid wood pulp fibers (3 mm in length) (the weight ratio of wood pulp fibers to recycled polyester staple fibers is 1.5:1). The web is then pre-hydroentangled under 2.0 MPa pressure, flat web hydroentangled under 3.5 MPa pressure, and drum hydroentangled under 5 MPa pressure. After dehydration and drying, a composite nonwoven fabric is formed.

[0082] S3.

[0083] The forming paper on the surface of the waste cellulose diacetate filter rod is peeled off, and the product is washed in water at 90°C for 60 minutes and dehydrated for 1 minute. The product is then rinsed in water at 70°C for 10 minutes and dehydrated for 1 minute. The product is then rinsed in water at 70°C for 8 minutes and dehydrated for 1 minute. The product is then dehydrated at high speed for 4 minutes and dried at 100°C for 60 minutes to obtain cellulose diacetate fiber.

[0084] Using a composite nonwoven fabric as the receiving substrate, cellulose acetate nanofiber membranes (with an average porosity of 5 μm) were prepared by electrospinning cellulose diacetate fibers and embedded and deposited on the composite nonwoven fabric. The weight ratio of the composite nonwoven fabric to the cellulose acetate nanofiber membrane was 9:1, thus obtaining the culture medium carrier.

[0085] The electrospinning process parameters are as follows: temperature 30℃, relative humidity 48%, voltage 28kV, injection rate 0.003mm / s, and receiving distance 12cm.

[0086] Testing revealed that the liquid absorption capacity of this culture medium carrier was 500%, and its weight was 60 g / m³. 2 .

[0087] Example 4: A method for preparing a culture medium carrier

[0088] This embodiment discloses a method for preparing a culture medium carrier, comprising the following steps performed sequentially:

[0089] S1.

[0090] Colored waste polyester textiles containing 2.5 kg of PET (80 wt% PET, 18 wt% cotton, and 2 wt% dye) were uniformly mixed with 75 g of powdered polyethylene glycol-silica composite phase change material (3% of the PET weight in the waste polyester textiles) to obtain waste polyester textiles to be decolored; the waste polyester textiles to be decolored were placed in a metal mesh for steam decolorization treatment, and steam decolorization was carried out using 60 L of dimethyl sulfoxide as the decolorizing agent;

[0091] The specific steps of steam decolorization are as follows: stir and heat the decolorizing agent to the boiling point of the decolorizing agent 189°C, maintain this temperature for 2 hours to ensure that the decolorizing agent vapor comes into contact with the waste polyester textiles to be decolorized, stop heating, and wait for the decolorizing agent solution to cool to room temperature to complete the steam decolorization of waste polyester textiles.

[0092] The decolorization rate of waste polyester textiles before and after treatment was tested, and the calculated decolorization rate was 98.7%.

[0093] Add 75g of potassium carbonate and 12.5kg of ethylene glycol (5 times the weight of PET) to decolorized waste polyester textiles, react at 190℃ for 12min, filter while hot, cool the filtrate to 10℃, and filter to obtain pre-depolymerized PET solid; add 75g of potassium carbonate and 12.5kg of ethylene glycol (5 times the weight of PET) to the pre-depolymerized PET solid, react at 240℃ for 1.5h, filter while hot, cool the filtrate to 9℃, and crystallize to obtain BHET;

[0094] The purity of the obtained BHET crystals was determined, and the purity of the obtained BHET crystals was 98.9% after testing and calculation.

[0095] Regenerated polyester staple fiber was prepared by polycondensation reaction of BHET crystals.

[0096] Tests showed that the recycled polyester staple fiber had a length of 70 mm, a linear density of 1.63 dtex, and a breaking strength of 4.93 cN / dtex.

[0097] S2.

[0098] Recycled polyester staple fibers are mixed, opened, and carded into a web, and then combined with wet-laid wood pulp fibers (2.5 mm in length) (the weight ratio of wood pulp fibers to recycled polyester staple fibers is 1.3:1). The web is then pre-hydroentangled at 1.7 MPa, flat web hydroentangled at 3.0 MPa, and drum hydroentangled at 4.5 MPa. After dehydration and drying, a composite nonwoven fabric is formed.

[0099] S3.

[0100] The forming paper on the surface of the waste cellulose diacetate filter rod is peeled off, and the product is washed in water at 85°C for 50 minutes and dehydrated for 1 minute. The product is then rinsed in water at 65°C for 9 minutes and dehydrated for 1 minute. The product is then rinsed in water at 63°C for 9 minutes and dehydrated for 1 minute. The product is then dehydrated at high speed for 4 minutes and dried at 95°C for 50 minutes to obtain cellulose diacetate fiber.

[0101] Using a composite nonwoven fabric as the receiving substrate, cellulose acetate nanofiber membranes (with an average porosity of 0.5 μm) were prepared by electrospinning cellulose diacetate fibers and embedded and deposited on the composite nonwoven fabric. The weight ratio of the composite nonwoven fabric to the cellulose acetate nanofiber membrane was 10:1, thus obtaining the culture medium carrier.

[0102] The electrospinning process parameters are as follows: temperature 25℃, relative humidity 40%, voltage 27kV, injection rate 0.003mm / s, and receiving distance 11cm.

[0103] Testing revealed that the liquid absorption capacity of this culture medium carrier was 450%, and its weight was 50 g / m³. 2 .

[0104] Example 5: Application of a Culture Medium Carrier

[0105] The culture medium carrier prepared in Example 2 was cut into appropriate sizes and assembled in the order of film, culture medium carrier, and cover film. A mixture of yeast powder, tryptone, glucose, agar powder, Tween, and distilled water was selected as the culture medium, and indole indicator was used as the colorimetric reagent. Nine microbial detection slides were prepared and divided into three groups to detect Escherichia coli, Staphylococcus aureus, and Salmonella, respectively. The detection results were compared with those of the agar plate counting method. The results are shown in Table 1.

[0106] Table 1 Microbial detection results

[0107]

[0108] As shown in Table 1, the culture medium carrier provided by the present invention can be used to prepare microbial detection strips. The prepared microbial detection strips can achieve efficient detection of microorganisms such as Escherichia coli, Staphylococcus aureus, and Salmonella, with an average detection rate of over 96%.

Claims

1. A method for preparing a culture medium carrier, characterized in that, This includes the following steps performed sequentially: S1. Waste polyester textiles are decolorized and alcoholized to obtain BHET crystals, and the BHET crystals are polycondensation reaction to prepare recycled polyester staple fibers. S2. Recycled polyester staple fiber is carded into a web, combined with wet-laid wood pulp fiber, and then hydroentangled to form a composite nonwoven fabric; S3. After removing impurities from waste cellulose diacetate filter rods, cellulose diacetate fibers are obtained. Using composite nonwoven fabric as the receiving base fabric of the electrospinning device, cellulose diacetate fibers are used to prepare cellulose acetate nanofiber membranes by electrospinning and then embedded and deposited on the membrane to obtain the culture medium carrier. The decolorization process in step S1 specifically includes: adding 1%-5% by weight of polyethylene glycol-silica composite phase change material to waste polyester textiles, mixing them evenly, and then performing steam decolorization using dimethyl sulfoxide for 2 hours.

2. The method for preparing a culture medium carrier according to claim 1, characterized in that, The alcoholysis in step S1 specifically includes: adding potassium carbonate and 4-6 times the weight of PET in ethylene glycol to the decolorized waste polyester textiles, reacting at 185-195℃ for 10-15 minutes, filtering while hot, cooling the filtrate to 8-12℃, and filtering to obtain pre-depolymerized PET solid; adding potassium carbonate and 4-6 times the weight of PET in ethylene glycol to the pre-depolymerized PET solid, reacting at 230-260℃ for 1-2 hours, filtering while hot, cooling the filtrate to 8-12℃, and crystallizing to obtain purified BHET crystals.

3. A method for preparing a culture medium carrier according to claim 1 or 2, characterized in that, In step S3, the waste cellulose diacetate filter rods are cleaned of impurities to obtain cellulose diacetate fibers. Specifically, this includes: peeling off the forming paper from the surface of the waste cellulose diacetate filter rods, immersing them in water at a temperature of 70-90℃ for 40-60 minutes, and dehydrating them for 1 minute; immersing the product in water at a temperature of 60-70℃ for a first rinse for 8-10 minutes and dehydrating them for 1 minute; immersing the product in water at a temperature of 60-70℃ for a second rinse for 8-10 minutes and dehydrating them for 1 minute; and dehydrating the product at a high speed of 1500-2000 rpm for 4 minutes and drying it at 90-100℃ for 40-60 minutes to obtain cellulose diacetate fibers.

4. A method for preparing a culture medium carrier according to claim 1 or 2, characterized in that, In step S2, the hydroentangling process includes pre-hydroentangling, flat-net hydroentangling, and rotary drum hydroentangling; The pressure for pre-hydraulic spraying is 1.5-2.0 MPa, the pressure for flat-net hydraulic spraying is 2.5-3.5 MPa, and the pressure for rotary drum hydraulic spraying is 4-5 MPa. In step S3, the electrospinning process parameters are: temperature 20-30℃, relative humidity 35-48%, voltage 25-28kV, injection rate 0.003mm / s, and receiving distance 10-12cm.

5. A culture medium carrier, prepared by the method for preparing the culture medium carrier according to claim 1, characterized in that, It includes a bilayer structure consisting of a composite nonwoven fabric layer and a cellulose acetate nanofiber membrane layer fixed together; The weight ratio of the composite nonwoven fabric to the cellulose acetate nanofiber membrane is 8-10:

1. The raw materials for the composite nonwoven fabric are wood pulp fibers with a weight ratio of 1-1.5:1 and recycled polyester staple fibers prepared from waste polyester textiles with a PET weight content of 65%-95%. The cellulose acetate nanofiber membrane is made by removing impurities from waste cellulose diacetate filter rods and then electrospinning the resulting cellulose diacetate fibers.

6. A culture medium carrier according to claim 5, characterized in that, The recycled polyester staple fiber has a length of 56-78 mm, a linear density of 1.56-2.22 dtex, and a breaking strength ≥4.85 cN / dtex.

7. A culture medium carrier according to claim 5 or 6, characterized in that, The wood pulp fibers are 2-3 mm in length; the cellulose acetate nanofiber membrane has a porosity of 0.5-5 μm.

8. A culture medium carrier according to claim 5 or 6, characterized in that, Its liquid absorption capacity is ≥400%, and its weight is 40-60 g / m³. 2 .

9. The application of the culture medium carrier according to claim 5, characterized in that, The culture medium carrier is used to prepare microbial detection slides.

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