Method for recycling paper yarn fabric

Abstract

The present application belongs to the technical field of paper yarn textile recycling, and provides a paper yarn fabric recycling method. The paper yarn fabric is mixed with water, a non-ionic surfactant is added, and the mixture is defibrated to obtain a defibration system; an oxidizing agent and a metal ion activator are sequentially added to the defibration system to perform an activation reaction, and a redispersed paper yarn fiber is obtained; the non-ionic surfactant is a PEG series or a Tween series; the oxidizing agent is a persulfate; and the metal ion activator includes oleic acid modified nano zero-valent iron and a divalent copper salt. The length of the redispersed paper yarn fiber obtained by the present application is between 1.5 and 2.1 mm, the length retention rate is between 63 and 88%, and the yield is between 80 and 98%.

Description

Technical Field

[0001] This invention relates to the field of paper yarn textile recycling technology, and more particularly to a method for recycling paper yarn fabric. Background Technology

[0002] The global textile and apparel industry currently faces severe resource and environmental challenges. At present, synthetic fiber fabrics, primarily made of polyester, dominate the market, but their recycling faces significant bottlenecks. Of the more than 92 million tons of waste textiles globally each year, approximately 73% ends up in landfills or incinerators, releasing large amounts of microplastics and greenhouse gases. Chemical recycling processes require large quantities of organic solvents, resulting in high costs and potential secondary pollution. Paper yarn fabrics, made from natural plant fibers (wood pulp, bamboo pulp, or redispersed pulp) through wet forming, slitting, twisting, and weaving processes, possess advantages such as natural redispersibility, biodegradability, antibacterial properties, deodorization, and breathability, demonstrating significant potential for sustainable development.

[0003] Despite the significant environmental advantages of paper yarn fabrics, their recycling still faces multiple technical challenges. During the production of paper yarn base paper, wet strength agents such as polyamide epichlorohydrin (PAE) and melamine-formaldehyde resin (MF) are often added, forming a CN / CO covalent cross-linked network with the paper yarn fibers. Furthermore, the physical entanglement and hydrogen bonding between fibers also create a stable three-dimensional network structure.

[0004] Conventional recycling methods for paper yarn fabrics, such as mechanical descaling (hydraulic pulping), are insufficient to break down the chemical cross-linking network between fibers and PAEs and the physical entanglement network between fibers. High-temperature chemical treatment reduces the degree of polymerization of fibers, resulting in shorter fiber lengths, which cannot meet the requirements of high-value-added applications. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for recycling paper yarn fabrics. The recycling method provided by this invention utilizes a sulfate-based synergistic activation system to achieve directional breaking of the wet-strength agent crosslinking structure and efficient unwinding of the three-dimensional fiber entanglement structure, providing a key technology for the resource utilization of waste paper yarn fabrics. The redispersed paper yarn fibers obtained by the recycling method of this invention have a high length retention rate.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for recycling paper yarn fabric, comprising the following steps:

[0008] The paper yarn fabric is mixed with water, and a nonionic surfactant is added to dissolve it, thus obtaining a dissolving system.

[0009] An oxidant and a metal ion activator are added sequentially to the disintegration system to carry out an activation reaction, thereby obtaining redispersed paper yarn fibers.

[0010] The nonionic surfactant is either PEG series or Tween series;

[0011] The oxidant is persulfate;

[0012] The metal ion activator includes oleic acid-modified nano-zero-valent iron and divalent copper salts.

[0013] Preferably, the size of the paper yarn fabric is 1-16cm. 2 The solid-liquid ratio of the paper yarn fabric and water is 1g:10-50mL.

[0014] Preferably, the mass of the nonionic surfactant is 0.1 to 10% of the mass of the paper yarn fabric.

[0015] Preferably, the temperature for dissolving is 50–70°C, the time is 10–40 min, the dissolving is carried out under stirring conditions, and the stirring speed is 100–500 rpm.

[0016] Preferably, the persulfate includes potassium persulfate and / or sodium persulfate, and the mass of the persulfate is 0.5% to 30% of the mass of the paper yarn fabric.

[0017] Preferably, the oleic acid-modified nano-zero-valent iron comprises 10-80% of the mass of persulfate; the oleic acid-modified nano-zero-valent iron has a particle size of 50-100 nm and a specific surface area ≥20 m². 2 / g.

[0018] Preferably, the mass of the divalent copper salt is 10-80% of the mass of the persulfate.

[0019] Preferably, the activation reaction is carried out at a temperature of 70–140°C for 0.5–4 hours, and the activation reaction is carried out under stirring conditions at a speed of 200–400 rpm.

[0020] Preferably, after the activation reaction, the process further includes: washing and screening the obtained suspension to obtain the redispersed paper yarn fibers; the sieve plate of the washing and screening process has a pore size of 0.15 to 0.5 mm.

[0021] Preferably, the length of the redispersed paper yarn fibers is 1.5–2.1 mm, the length retention rate is 63–88%, and the yield is 90–98%.

[0022] This invention provides a method for recycling paper yarn fabric.

[0023] The recycling method provided by this invention applies a ternary system of "nonionic surfactant-persulfate-metal ion activator" to the recycling of paper yarn fibers in paper yarn fabrics. The ternary system targets and disrupts wet-strength cross-linked covalent bonds.

[0024] Nonionic surfactant penetration: Nonionic surfactants reduce the surface tension of water, promote the penetration of reagents into the fabric fibers, and simultaneously loosen the physical entanglement between paper yarn fibers;

[0025] Persulfate oxidation: The sulfate radical (SO4·4·4) formed by the decomposition of persulfate is a highly oxidizing free radical. - It selectively attacks the primary amines and epoxy groups in the fiber-wet strength agent crosslinking network, severing their crosslinking sites with cellulose hydroxyl groups;

[0026] Metal ion activator catalysis: Oleic acid modified nano-zero valent iron and copper ions (Cu) 2+ As a metal ion activator, it accelerates the decomposition of persulfate through a synergistic mechanism of chain redox reactions and catalytic cycle reactions, generating sulfate free radicals (SO4·4·4) with strong oxidizing power. - Oleic acid-modified nano-zero-valent iron is used as a reducing agent to directly reduce persulfate through electron transfer, generating sulfate radicals (SO4·4·4). - ) and ferrous ions (Fe 2+ ), the generated Fe 2+ Further reaction with persulfate initiates a free radical chain reaction; Cu 2+ It accepts electrons and is reduced to cuprous ions (Cu). + Cu + It reacts with persulfate to produce Cu 2+ Cu 2+ The decomposition of persulfate through valence state cycling catalyzes the formation of sulfate radicals, thus creating a redox cycle, Fe 0 As an electron donor, and also for Cu 2+ Reduction and persulfate activation provide electrons to form "Fe 0 →Cu 2+ / Fe 2+ →S2O8 2- "A highly efficient electronic transport chain."

[0027] This invention utilizes nonionic surfactants, synergistic oxidants (persulfate) and metal ion activators to disrupt the wet strength crosslinking structure of paper yarn fabrics and dissociate the physical entanglement network of paper yarn fibers, thereby achieving efficient dissociation and dispersion of individual fibers and realizing green and efficient recycling of waste paper yarn fabrics and high-value utilization of fibers. Attached Figure Description

[0028] Figure 1 A schematic flowchart illustrating the paper yarn fabric recycling method provided by the present invention;

[0029] Figure 2 The microscopic morphology of a portion of the paper yarn fabric in Example 3 is magnified (4x).

[0030] Figure 3 The fiber length distribution of the paper yarn fibers recovered in Example 3;

[0031] Figure 4 Microscopic morphology (10x) of the paper yarn fibers recovered in Example 3. Detailed Implementation

[0032] Figure 1 This is a flowchart illustrating the paper yarn fabric recycling method provided by the present invention, which is described below in conjunction with... Figure 1 The recycling method provided by this invention will be described in detail.

[0033] This invention provides a method for recycling paper yarn fabric, comprising the following steps:

[0034] After mixing paper yarn fabric with water, a nonionic surfactant is added to dissolve the fabric, resulting in a dissolving system.

[0035] An oxidant and a metal ion activator are added sequentially to the disintegration system to carry out an activation reaction, thereby obtaining redispersed paper yarn fibers.

[0036] The nonionic surfactant is either PEG series or Tween series;

[0037] The oxidant is persulfate;

[0038] The metal ion activator includes oleic acid-modified nano-zero-valent iron and divalent copper salts.

[0039] Unless otherwise specified, the raw materials used in this invention are preferably commercially available products.

[0040] This invention involves mixing paper yarn fabric with water, adding a nonionic surfactant, and then performing a disintegration process to obtain a disintegration system.

[0041] In this invention, the paper yarn fabric is preferably pretreated before being mixed with water; the pretreatment preferably includes sequentially screening to remove non-fibrous materials, cutting, and washing. In this invention, the non-fibrous materials preferably include metal and plastic fittings. This invention does not specifically limit the cutting parameters, as long as a size of 1–16 cm can be obtained. 2 Block-shaped materials are acceptable. In this invention, the preferred size of the paper yarn fabric is 1-16 cm. 2 The dimensions are preferably 2cm × 2cm or 3cm × 3cm. In this invention, the cleaning reagent is preferably water; this invention does not specifically limit the number of cleaning cycles or the amount of reagent used.

[0042] In this invention, the solid-liquid ratio of the paper yarn fabric and water is preferably 1g:10-50mL, more preferably 1g:20-30mL, and specifically preferably 1g:10mL, 1g:15mL, 1g:20mL, 1g:25mL, 1g:30mL, 1g:35mL, 1g:40mL, 1g:45mL, or 1g:50mL. This invention controls the size of the paper yarn fabric to be 1-16cm. 2 A solid-liquid ratio of 1g:10-50mL can balance the reaction rate and reduce the risk of yarn entanglement.

[0043] In this invention, the nonionic surfactant is a PEG series or a Tween series surfactant. Specifically, the PEG series preferably includes one or more of PEG-300, PEG-400, PEG-600, and PEG-800, and more preferably PEG-600. Specifically, the Tween series preferably includes one or more of Tween-20, Tween-40, Tween-60, and Tween-80, and more preferably Tween-80.

[0044] In this invention, nonionic surfactants reduce the liquid-solid interfacial tension, promoting the penetration of reagents into the interior of paper yarn fibers; simultaneously, they loosen the physical entanglement between paper yarn fibers, further promoting the subsequent penetration of reagents into the interwoven structure of the paper yarn fibers.

[0045] In this invention, the mass of the nonionic surfactant is preferably 0.1-10% of the mass of the paper yarn fabric, more preferably 0.5-3%, and specifically preferably 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%.

[0046] In this invention, the temperature for the dissolution is preferably 50–70°C, specifically 50°C, 55°C, 60°C, 65°C, or 70°C; the time is preferably 10–40 min, specifically 10 min, 20 min, 30 min, or 40 min; the dissolution is preferably carried out under stirring conditions, and the stirring speed is preferably 100–500 rpm, specifically 100 rpm, 200 rpm, 300 rpm, 400 rpm, or 500 rpm.

[0047] After the slack-out process, the present invention preferably proceeds directly to subsequent operations without any post-processing.

[0048] In this invention, the loosening process can serve as a pre-loosening of the paper yarn fabric; at the same time, the nonionic surfactant penetrates into the fiber gaps to promote subsequent reactions.

[0049] After obtaining the dispersing system, the present invention sequentially adds an oxidant and a metal ion activator to the dispersing system to carry out an activation reaction, thereby obtaining redispersed paper yarn fibers.

[0050] In this invention, the oxidant is a persulfate, preferably including potassium persulfate (K₂S₂O₈) and / or sodium persulfate (Na₂S₂O₈). In this invention, the mass of the persulfate is preferably 0.5% to 30% of the mass of the paper yarn fabric, more preferably 3% to 20%, and specifically preferably 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, 7.5%, 8%, 10%, 12.5%, 15%, 17.5%, 20%, 22.5%, 25%, 27.5%, or 30%.

[0051] In this invention, the oleic acid-modified nano-zero valent iron preferably has a particle size of 50–100 nm and a specific surface area preferably ≥20 m². 2 / g, more preferably 20-100m 2 / g, preferably 30m 2 / g. In this invention, the mass of the oleic acid-modified nano-zero-valent iron is preferably 10-80% of the mass of persulfate, more preferably 20-60%, and specifically preferably 10%, 20%, 30%, 40%, 50%, 60%, 70%, or 80%. In a specific embodiment of this invention, the preparation method of the oleic acid-modified nano-zero-valent iron preferably includes the following steps: dispersing nano-zero-valent iron in anhydrous ethanol, then adding oleic acid to carry out a modification reaction to obtain the oleic acid-modified nano-zero-valent iron. In this invention, the mass of the oleic acid is preferably 5-30% of the mass of the nano-zero-valent iron, and specifically preferably 5%, 10%, 15%, 20%, 25%, or 30%. In this invention, the modification reaction is preferably carried out under ultrasonic vibration, and the modification reaction time is preferably 30 min. After the modification reaction, this invention preferably further includes: sequentially performing solid-liquid separation on the obtained reaction solution, collecting the solid and sequentially washing with alcohol, drying, and grinding to obtain the oleic acid-modified nano-zero-valent iron. In this invention, the solid-liquid separation method is preferably magnetic separation or centrifugation. In this invention, the alcohol washing reagent is preferably anhydrous ethanol, and the number of alcohol washings is preferably 3 times. In this invention, the drying temperature is preferably 40–60°C, more preferably 50°C; the vacuum degree is preferably 0.05–0.1 bar, specifically preferably 0.05 bar, 0.06 bar, 0.07 bar, 0.08 bar, 0.09 bar, or 0.1 bar; the time is preferably 0.5–6 h, specifically preferably 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, or 6 h; the drying is preferably carried out under a nitrogen atmosphere, and preferably in a vacuum drying oven. This invention does not specifically limit the grinding speed and time, as long as the particle size of the oleic acid-modified nano-zero-valent iron is 50–100 nm. In this invention, the particle size of oleic acid-modified nano-zero-valent iron is controlled to be 50–100 nm, and the specific surface area is ≥20 m². 2 / g, which can further synergize with copper ions (Cu 2+ Highly efficient generation of active sulfate free radicals (SO4·) - ), and ensure sulfate free radicals (SO4· - Effective concentration.

[0052] In this invention, the mass of the divalent copper salt is preferably 10-80% of the mass of the persulfate, more preferably 20-50%, and specifically preferably 10%, 20%, 30%, 40%, 50%, 60%, 70%, or 80%. In this invention, the divalent copper salt preferably comprises copper sulfate and / or copper chloride, and the copper sulfate preferably comprises CuSO4·5H2O.

[0053] The present invention does not impose specific limitations on the method of adding the oleic acid modified nano-zero valent iron and divalent copper salts; they can be added together after mixing or added sequentially.

[0054] By selecting the amounts of the nonionic surfactant, oxidant, and metal ion activator within the above-mentioned range, the present invention can better control the degree of oxidation, ensure the length of paper yarn fibers, and improve the yield of paper yarn fibers.

[0055] In this invention, the activation reaction temperature is preferably 70–140°C, specifically 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, or 140°C; the activation time is preferably 0.5–4 hours, specifically 0.5 hours, 1 hour, 2 hours, 3 hours, or 4 hours; the activation reaction is preferably carried out under stirring conditions, and the stirring speed is preferably 200–400 rpm, specifically 200 rpm, 300 rpm, or 400 rpm. In this invention, the activation reaction is preferably carried out under sealed conditions. By selecting the activation reaction conditions within the above range, this invention can better ensure the efficient depolymerization of the wet-strength crosslinking structure of the paper yarn fabric and the dissociation of the three-dimensional entanglement structure of the paper yarn fibers under mild reaction conditions, while protecting fiber length and improving fiber yield.

[0056] Following the activation reaction, the present invention preferably further includes: washing and screening the obtained suspension to obtain the redispersed paper yarn fibers. In this invention, the pore size of the sieve plate used for washing and screening is preferably 0.15–0.5 mm, specifically preferably 0.15 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, or 0.5 mm. In this invention, the washing and screening is preferably performed on a vibrating screen or a square screen.

[0057] In this invention, the length of the redispersed paper yarn fibers is preferably 1.5 to 2.1 mm, the length retention rate is preferably 63 to 88%, and the yield is preferably 90 to 98%.

[0058] This invention applies a ternary system of "nonionic surfactant-persulfate-metal ion activator" to the recycling of paper yarn fabric fibers. Persulfate is used in the modification of oleic acid with nano-zero valent iron and Cu. 2+ Highly reactive sulfate radicals (SO4·) are generated under catalysis. - The high specific surface area of ​​oleic acid-modified nano-zero-valent iron and the valence state cycling of copper ions accelerate the decomposition of persulfate. 2+ Accelerate S2O8 2- Decomposition, Cu 2+ Through Cu + / Cu2+ Valence cycle prolongs reaction duration. Nonionic surfactants can reduce liquid-solid interfacial tension, loosen the physical entanglement network of paper yarn fibers, and promote the growth of sulfate free radicals (SO4·). - It penetrates into the interwoven structure of the paper yarn fabric and selectively attacks the cross-linking sites of the wet strength agent and the fiber hydroxyl groups. This invention, through a ternary system, overcomes the limitations of traditional single chemical reaction systems or mechanical methods. The length of the redispersed paper yarn fibers obtained is between 1.5 and 2.1 mm, the length retention rate is between 63% and 88%, and the yield is between 80% and 98%.

[0059] The following detailed description of the paper yarn fabric recycling method provided by the present invention, in conjunction with embodiments, should not be construed as limiting the scope of protection of the present invention.

[0060] Example 1

[0061] (1) Paper yarn fabric is pre-screened to remove non-fibrous materials such as metal and plastic parts, then cut into 3×3cm blocks, washed and put into a closed reaction device with stirring function along with water at a solid-liquid ratio of 1g:20mL.

[0062] (2) Add 1% of the nonionic surfactant PEG-600 by weight of the paper yarn fabric into the closed reaction device, and decompose the resulting reaction system at 50℃ and 200rpm for 30min.

[0063] (3) After dispersing for 30 minutes, add sodium persulfate of 5% by weight of paper yarn fabric, oleic acid modified nano zero-valent iron of 20% by weight of sodium persulfate, and CuSO4·5H2O of 10% by weight of sodium persulfate in sequence. Activate the reaction for 2 hours at 95℃ and 300 rpm to obtain a suspension containing redispersed paper yarn fibers.

[0064] (4) Using a screening device with a sieve plate aperture of 0.25mm, the paper yarn fiber suspension mixture in step (3) is washed and screened to finally obtain pure redispersed paper yarn fibers.

[0065] The preparation method of oleic acid modified nano-zero valent iron includes the following steps: dispersing nano-zero valent iron in anhydrous ethanol, then adding oleic acid at 20% of the mass of the nano-zero valent iron, and ultrasonically vibrating for 30 min to ensure uniform coating with oleic acid; collecting the resulting reaction solution by centrifugation, washing the resulting solid three times with anhydrous ethanol, vacuum drying at 0.08 bar and 50℃ for 4 h under a nitrogen atmosphere, and grinding to obtain oleic acid modified nano-zero valent iron with a particle size of 80±20 nm and a specific surface area of ​​30 m². 2 / g.

[0066] Example 2

[0067] (1) Paper yarn fabric is pre-screened to remove non-fibrous materials such as metal and plastic parts, then cut into 3×3cm blocks, washed and put into a closed reaction device with stirring function along with water at a solid-liquid ratio of 1g:20mL.

[0068] (2) Add 1.0% of the nonionic surfactant Tween-80 by weight of the paper yarn fabric into the closed reaction device, and decompose the resulting reaction system at 50℃ and 200rpm for 30min.

[0069] (3) After dispersing for 30 minutes, add sodium persulfate of 10% by weight of paper yarn fabric, oleic acid modified nano zero-valent iron of 20% by weight of sodium persulfate, and CuSO4·5H2O of 10% by weight of sodium persulfate in sequence. Activate the reaction for 3 hours at 90℃ and 300 rpm to obtain a suspension containing redispersed paper yarn fibers.

[0070] (4) Using a screening device with a sieve plate aperture of 0.25mm, the paper yarn fiber suspension mixture in step (3) is washed and screened to finally obtain pure redispersed paper yarn fibers.

[0071] The preparation method of oleic acid modified nano-zero valent iron is the same as in Example 1.

[0072] Example 3

[0073] (1) Paper yarn fabric is pre-screened to remove non-fibrous materials such as metal and plastic parts, then cut into 2×2cm blocks, washed and put into a closed reaction device with stirring function along with water at a solid-liquid ratio of 1g:15mL.

[0074] (2) Add 1.5% of the nonionic surfactant PEG-600 by weight of the paper yarn fabric into the closed reaction device, and decompose the resulting reaction system at 50℃ and 200rpm for 30min.

[0075] (3) After dispersing for 30 minutes, add sodium persulfate of 20% by weight of paper yarn fabric, oleic acid modified nano zero-valent iron of 40% by weight of sodium persulfate, and CuSO4·5H2O of 20% by weight of sodium persulfate in sequence. Activate the reaction at 105℃ and 300rpm for 2 hours to obtain a suspension containing redispersed paper yarn fibers.

[0076] (4) Using a screening device with a sieve plate aperture of 0.25mm, the paper yarn fiber suspension mixture in step (3) is washed and screened to finally obtain pure redispersed paper yarn fibers.

[0077] The preparation method of oleic acid modified nano-zero valent iron is the same as in Example 1.

[0078] Example 4

[0079] (1) Paper yarn fabric is pre-screened to remove non-fibrous materials such as metal and plastic parts, then cut into 2×2cm blocks, washed and put into a closed reaction device with stirring function along with water at a solid-liquid ratio of 1g:15mL.

[0080] (2) Add 1.5% of the nonionic surfactant PEG-600 by weight of the paper yarn fabric into the closed reaction device, and decompose the resulting reaction system at 50℃ and 200rpm for 30min.

[0081] (3) After dispersing for 30 minutes, sodium persulfate of 25% by weight of paper yarn fabric, oleic acid-modified nano-zero valent iron of 50% by weight of sodium persulfate, and CuSO4·5H2O of 30% by weight of sodium persulfate were added in sequence. The reaction was activated at 105℃ and 300rpm for 3 hours to obtain a suspension containing redispersed paper yarn fibers.

[0082] (4) Using a screening device with a sieve plate aperture of 0.25mm, the paper yarn fiber suspension mixture in step (3) is washed and screened to finally obtain pure redispersed paper yarn fibers.

[0083] The preparation method of oleic acid modified nano-zero valent iron is the same as in Example 1.

[0084] Example 5

[0085] (1) Paper yarn fabric is pre-screened to remove non-fibrous materials such as metal and plastic parts, then cut into 3×3cm blocks, washed and put into a closed reaction device with stirring function along with water at a solid-liquid ratio of 1g:25mL.

[0086] (2) Add 0.5% of the nonionic surfactant Tween-80 by weight of the paper yarn fabric into the closed reaction device, and decompose the resulting reaction system at 50℃ and 200rpm for 30min.

[0087] (3) After dispersing for 30 minutes, add sodium persulfate of 10% by weight of paper yarn fabric, oleic acid modified nano zero-valent iron of 40% by weight of sodium persulfate, and CuSO4·5H2O of 20% by weight of sodium persulfate in sequence. Activate the reaction for 2 hours at 95℃ and 300 rpm to obtain a suspension containing redispersed paper yarn fibers.

[0088] (4) Using a screening device with a sieve plate aperture of 0.25mm, the paper yarn fiber suspension mixture in step (3) is washed and screened to finally obtain pure redispersed paper yarn fibers.

[0089] The preparation method of oleic acid modified nano-zero valent iron is the same as in Example 1.

[0090] Example 6

[0091] (1) Paper yarn fabric is pre-screened to remove non-fibrous materials such as metal and plastic parts, then cut into 2×2cm blocks, washed and put into a closed reaction device with stirring function according to the solid-liquid ratio of 1g:15mL and water.

[0092] (2) Add 0.5% of the nonionic surfactant Tween-80 by weight of the paper yarn fabric into the closed reaction device, and decompose the resulting reaction system at 50℃ and 200rpm for 30min.

[0093] (3) After dispersing for 30 minutes, add sodium persulfate of 20% by weight of paper yarn fabric, oleic acid modified nano zero-valent iron of 20% by weight of sodium persulfate, and CuSO4·5H2O of 40% by weight of sodium persulfate in sequence. Activate the reaction at 90℃ and 300rpm for 4 hours to obtain a suspension containing redispersed paper yarn fibers.

[0094] (4) Using a screening device with a sieve plate aperture of 0.25mm, the paper yarn fiber suspension mixture in step (3) is washed and screened to finally obtain pure redispersed paper yarn fibers.

[0095] The preparation method of oleic acid modified nano-zero valent iron is the same as in Example 1.

[0096] Comparative Example 1

[0097] The paper yarn fabric is treated using a chlorination process, specifically through a steam cooking method.

[0098] (1) Paper yarn fabric is pre-screened to remove non-fibrous materials such as metal and plastic parts, then cut into 3×3cm blocks, washed and put into a closed reaction device with stirring function along with water at a solid-liquid ratio of 1g:15mL.

[0099] (2) Add 15% sodium chlorite by weight of paper yarn fabric to a closed reaction device and react for 2 hours at 105°C and 300 rpm to obtain a suspension containing redispersed paper yarn fibers.

[0100] (3) Using a screening device with a sieve plate aperture of 0.25mm, the paper yarn fiber suspension mixture in step (2) is washed and screened to finally obtain redispersed paper yarn fibers.

[0101] Comparative Example 2

[0102] The difference from Example 3 is that the nonionic surfactant PEG-600 is replaced with sodium dodecylbenzenesulfonate, otherwise it is the same as Example 3.

[0103] Comparative Example 3

[0104] The difference from Example 3 is that the nonionic surfactant PEG-600 is not added; otherwise, it is the same as Example 3.

[0105] Comparative Example 4

[0106] The difference from Example 3 is that oleic acid-modified nano-zero valent iron is not added; otherwise, it is the same as Example 3.

[0107] Comparative Example 5

[0108] The difference from Example 3 is that CuSO4·5H2O is not added; otherwise, it is the same as Example 3.

[0109] Comparative Example 6

[0110] The difference from Example 3 is that oleic acid-modified nano-zero-valent iron and CuSO4·5H2O are not added; otherwise, they are the same as in Example 3.

[0111] The average fiber length and fine fiber content of the redispersed paper yarn fibers obtained in Examples 1-6 and Comparative Examples 1-6 were analyzed using an L&W fiber analyzer, and the fiber length retention rate and fiber yield were calculated. The results are shown in Table 1.

[0112] Meanwhile, taking paper yarn base paper fiber as a comparative reference, the paper yarn base paper fiber is bleached softwood sulfate pulp, which is pulped before paper yarn base paper is made, with a beating degree of 45°SR and a fine fiber content of 4.8%.

[0113] Table 1. Comparison of the redispersed paper yarn fiber data and paper yarn fibrils obtained in Examples 1-6 and Comparative Examples 1-6.

[0114]

[0115] As shown in Table 1, by changing the amounts of surfactant, persulfate, and metal ion catalyst, as well as the reaction conditions, pure redispersed paper yarn fibers can be recovered. Compared to redispersed paper yarn fibers obtained by chlorination, these fibers are longer, have a higher fiber length retention rate, and the reaction is milder and more environmentally friendly.

[0116] Figure 2 The image shows a magnified (4x) microstructure of a portion of the paper yarn fabric in Example 3; from Figure 2 It can be seen that the fibers of the paper yarn fabric are tightly interwoven, while individual fibers are exposed in the yarn.

[0117] Figure 3 The fiber length distribution of the paper yarn fibers recovered in Example 3; from Figure 3 It can be seen that the average length of the recycled fibers is 2.07 mm, and the content of fine fibers is 5.2%.

[0118] Figure 4The microstructure (10x magnification) of the paper yarn fibers recovered in Example 3 is shown below. Figure 4 It can be seen that the recycled fibers are in good condition with almost no damage and can be reused.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recycling paper yarn fabric, characterized in that, Includes the following steps: After mixing paper yarn fabric with water, a nonionic surfactant is added to dissolve the fabric, resulting in a dissolving system. An oxidant and a metal ion activator are added sequentially to the disintegration system to carry out an activation reaction, thereby obtaining redispersed paper yarn fibers. The nonionic surfactant is PEG-600 or Tween-80; the mass of the nonionic surfactant is 0.5-10% of the mass of the paper yarn fabric. The oxidant is persulfate; the mass of the persulfate is 0.5-30% of the mass of the paper yarn fabric. The metal ion activator includes oleic acid-modified nano-zero-valent iron and divalent copper salt; The mass of the oleic acid-modified nano-zero-valent iron is 10-80% of the mass of the persulfate; the mass of the divalent copper salt is 10-80% of the mass of the persulfate.

2. The recycling method according to claim 1, characterized in that, The size of the paper yarn fabric is 1~16cm. 2 The solid-liquid ratio of the paper yarn fabric and water is 1g:10~50mL.

3. The recycling method according to claim 1 or 2, characterized in that, The dissolution temperature is 50~70℃, the time is 10~40min, the dissolution is carried out under stirring conditions, and the stirring speed is 100~500rpm.

4. The recycling method according to claim 1, characterized in that, The persulfate includes potassium persulfate and / or sodium persulfate.

5. The recycling method according to claim 1, characterized in that, The oleic acid-modified nano-zero valent iron has a particle size of 50~100nm and a specific surface area ≥20m². 2 / g.

6. The recycling method according to claim 1, characterized in that, The activation reaction is carried out at a temperature of 70~140℃ for a time of 0.5~4h, and is conducted under stirring conditions at a speed of 200~400rpm.

7. The recycling method according to claim 1 or 6, characterized in that, After the activation reaction, the process further includes: washing and screening the obtained suspension to obtain the redispersed paper yarn fibers; the sieve plate of the washing and screening process has a pore size of 0.15~0.5mm.

8. The recycling method according to claim 1, characterized in that, The length of the redispersed paper yarn fibers is 1.5~2.1mm, the length retention rate is 63~88%, and the yield is 90~98%.

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