A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater

Abstract

The present invention relates to a method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater. The method comprises mixing an aqueous phase with an oil phase, followed by freeze-drying to obtain a composite material, which is then added to the polyester fabric printing and dyeing wastewater to remove microplastics and disperse dyes from the polyester fabric printing and dyeing wastewater. The aqueous phase is obtained by dissolving water-soluble pectin, polyacrylamide, and polyvinyl alcohol in deionized water, and the oil phase is a mixture of liquid polyisoprene and benzyl alcohol. The present invention combines water-soluble pectin with liquid polyisoprene and simultaneously compounds polyacrylamide to obtain a composite material with flocculation and adhesion effects. The composite material can effectively remove disperse dyes and microplastics simultaneously, thereby solving the pollution problem of polyester printing and dyeing wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of printing and dyeing wastewater treatment, and relates to a method for removing microplastics and disperse dyes in polyester fabric printing and dyeing wastewater. Background Art

[0002] Polyethylene terephthalate, also known as polyester, is produced by the polycondensation of terephthalic acid or dimethyl terephthalate with ethylene glycol. Also known as polyester in the textile industry, it is the largest category of synthetic fibers, leading in both production and usage among all chemical fibers. Polyester fibers possess excellent breaking strength, heat-setting properties, and high heat resistance. The development of polyester fibers has also spawned various similar fibers, such as polybutylene terephthalate, polypropylene terephthalate, and polycyclohexyl-1,4-dimethyl terephthalate. The pretreatment and dyeing processes for polyester consume significant resources, and improper handling can cause significant pollution. With the development of the textile industry and increased environmental awareness, the environmental impacts of polyester production have gradually come into the public's attention. In addition to the typical discharge of dyes into wastewater, other pollutants are also being continuously studied, with microplastics being a particularly prominent concern.

[0003] The concept of microplastics was first proposed in 2004. Microplastics are tiny plastic particles with a diameter of less than 5mm, formed by the breakdown of fine plastics or discarded plastics in daily life and production due to ultraviolet radiation, mechanical forces, and biological activity. There are many types of microplastics, including polyester, polyamide, and polystyrene. They can be released into the environment through washing, tea brewing, cooking, and other daily activities. Textile fibers have become the largest type of microplastic, so the microplastics generated during dyeing processes cannot be ignored.

[0004] Because polyester fibers have few reactive groups, they are difficult to effectively dye using chemically bonded dyes. Disperse dyes are weakly polar, poorly soluble dyes with good compatibility with polyester fibers, making them the most commonly used dyes for unmodified polyester fibers. Polyester fiber dyeing methods include carrier dyeing, high-temperature and high-pressure dyeing, hot-melt dyeing, and supercritical CO2 dyeing. Supercritical CO2 dyeing is relatively expensive and has not yet been widely used in industrial production. The residual liquid left after polyester fiber dyeing can cause serious pollution if not effectively treated. Disperse dyes exist in wastewater as dispersions and can be effectively treated using flocculation. Flocculants for disperse dyes are divided into two categories: organic and inorganic. Inorganic flocculants primarily use polyaluminum chloride and polyferric sulfate, while organic flocculants are primarily polyacrylamide. Polyacrylamide can be regulated to form four types of ions: anionic, cationic, nonionic, and zwitterionic.

[0005] The literature (Wan Tao, Feng Ling, Du Shiyong, et al. Research on the decolorization of printing and dyeing wastewater by amphoteric polyacrylamide [J]. Water Treatment Technology, 2005, 31(9): 39-41.) uses amphoteric polyelectrolyte polyacrylamide to decolorize alkaline, acidic and disperse dyes, but polyacrylamide can only treat disperse dyes and cannot treat disperse dyes and microplastics at the same time.

[0006] Patent CN117143389A provides a method for preparing a microcrystalline cellulose / chitosan composite aerogel from bamboo shoot shells and its application in microplastic adsorption, which utilizes electrostatic and hydrogen bonding to adsorb microplastics in wastewater, solving the shortcoming that powder materials are not easily recovered in water. However, the highly porous aerogel in this solution can only process microplastics, and since disperse dyes do not contain ionizable water-soluble groups, disperse dyes cannot be bound to aerogels by electrostatic action, and aerogels cannot remove disperse dyes by relying solely on hydrogen bonding. Therefore, aerogels cannot play a role in disperse dyes, and can only flocculate disperse dyes with nanometer particle sizes to suspend and aggregate in water to form flocs, thereby accelerating the coagulation of particles and achieving the purpose of solid-liquid separation and removal. In addition, aerogel materials are solid materials with fixed shapes and good stability in air and water. They are difficult to combine with flocculants and cannot form composite materials with the ability to process disperse dyes and microplastics.

[0007] Patent CN113952899A provides a magnetic chitosan / polydopamine aerogel, its preparation method and application. It adsorbs microplastics in water through electrostatic and physical adsorption, and introduces magnetic substances to easily separate the aerogel from wastewater. Polydopamine can exhibit good adhesion through the phenolic hydroxyl groups in its structure and has good adsorption performance for microplastics. At the same time, the introduction of magnetic substances makes the aerogel easy to separate. However, the aerogel also cannot have a flocculation effect on disperse dyes. In addition, the aerogel is a solid solid with good stability in air and water. It is difficult to combine with flocculants and cannot form a composite material capable of treating disperse dyes and microplastics.

[0008] Patent CN115448435B provides a method and application for preparing a coagulant using jackfruit peel. Polysaccharides are extracted from the jackfruit peel as a coagulant, which can be used in combination with inorganic flocculants and has good biosafety and degradability. Although polysaccharides have good adhesion, they are also insoluble in water. The particle size range tested in this patent is within the range of 83nm to 2.383μm, indicating that the extracted substance contains a large amount of insoluble polysaccharides with a large molecular weight and a large number of carboxylic acid groups, hydroxyl groups and other groups. These groups can play an electrical neutralization, bridging and netting role in the coagulation process, thereby improving the flocculation efficiency. No hydrogen bonds and electrostatic effects will occur to adsorb microplastics, and it can only process disperse dyes.

[0009] Therefore, it is of great significance to study a method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater so as to simultaneously and efficiently treat disperse dyes and microplastics in printing and dyeing wastewater. Summary of the Invention

[0010] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for removing microplastics and disperse dyes in polyester fabric printing and dyeing wastewater.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, comprising mixing an aqueous phase with an oil phase and freeze-drying the mixture to obtain a composite material, which is then added to the polyester fabric printing and dyeing wastewater to remove microplastics and disperse dyes from the polyester fabric printing and dyeing wastewater;

[0013] The aqueous phase is obtained by dissolving water-soluble pectin, polyacrylamide and polyvinyl alcohol in deionized water, and the oil phase is a mixture of polyisoprene and benzyl alcohol;

[0014] The organic flocculant for disperse dyes is polyacrylamide, which has good water solubility, so the aqueous phase uses water as the main body of material dissolution. During the peeling process of jackfruit, a white substance with good adhesion is present, which can adhere to the skin and cutting tools, and its adhesion is not weakened even under the condition of water rinsing. Studies have confirmed that the white adhesive substance includes polysaccharides and polyisoprene, and jackfruit can combine the two during growth. To imitate this type of structure, the present invention transfers water-soluble substances from the aqueous phase to the oil phase, transferring water-soluble pectin and polyacrylamide to polyisoprene. The aqueous phase also contains polyvinyl alcohol. The polyvinyl alcohol is selected so that when the aqueous phase transfers the oil phase, the polyvinyl alcohol can combine with the oil phase substance to play a role similar to that of an emulsifier, and can aggregate the molecular chains of polyacrylamide and pectin in the aqueous phase, thereby transferring them together to the oil phase.

[0015] Polyisoprene only exists in two isomers in nature, namely cis-1,4-polyisoprene (natural rubber, hevea gum) and trans-1,4-polyisoprene (eucommia gum, gutta-percha). Cis-polyisoprene is mainly used in industry. Under normal conditions, polyisoprene is an elastic solid with good heat resistance and chemical corrosion resistance. Usually, other monomers are introduced during the polymerization stage to obtain polyisoprene with different functions. Mixing water-soluble pectin with solid polyisoprene based on the structure of jackfruit gum will prevent the combination due to the relatively stable nature of polyisoprene itself, so liquid polyisoprene is used to compound with water-soluble pectin. Liquid polyisoprene It is a colorless and odorless viscous liquid. Its molecular chain units are similar to those of natural rubber and it has good compatibility with natural rubber. It is liquid at room temperature, so there is no crystalline region. The molecular chain easily expands under the action of a suitable solvent. The Hansen solubility parameter of liquid polyisoprene is 18.5, and the Hansen solubility parameter of benzyl alcohol is 23.8. The solubility parameters of the two are close, indicating good compatibility. Liquid polyisoprene is a non-crystalline polymer. Benzyl alcohol and liquid polyisoprene do not require the process of solvent dissolution of semi-crystalline polymers, which involves the dissociation of crystalline regions. Instead, solvent penetration can occur to expand the liquid polyisoprene. The pores of the molecular chains of polyolefins become larger, providing channels for the entry and exit of substances; benzyl alcohol is used because its Hansen solubility parameter is close to that of liquid polyisoprene, and on the other hand, it can serve as a carrier for transferring substances in the aqueous phase to liquid polyisoprene in the oil phase; benzyl alcohol has extremely weak force on polyvinyl alcohol in a solid state and cannot dissolve it or perform de-crystallization and expansion on the crystalline region, while polyvinyl alcohol is in a free molecular chain state in aqueous solution. At this time, polyvinyl alcohol forms a relatively strong hydrogen bond with water. However, when benzyl alcohol is dispersed in the polyvinyl alcohol aqueous solution under the action of mechanical force, the ability of the hydroxyl groups of benzyl alcohol to form hydrogen bonds with the hydroxyl groups of polyvinyl alcohol is the same as that of water with Polyvinyl alcohol has a relatively weak ability to form hydrogen bonds. The benzene ring of benzyl alcohol can combine with the vinyl group of polyvinyl alcohol through van der Waals forces. The hydrophilicity and hydrophobicity of the polyvinyl alcohol after combining with benzyl alcohol are changed, allowing the polyvinyl alcohol to act as an emulsifier. During the process of mixing the aqueous phase and the oil phase, the aqueous phase containing water-soluble substances can be dispersed in the oil phase in the form of droplets. Due to its good compatibility with liquid polyprene, the benzyl alcohol in the oil phase can carry the water-soluble substances to the liquid polyprene to a certain extent, and then form a crystalline solid through rapid freezing, embedding the water-soluble substances into the liquid polyprene, and obtaining a composite material after freeze-drying.

[0016] As the preferred technical solution:

[0017] The composite material has a decolorization rate of 66-68% for disperse dyes in polyester fabric printing and dyeing wastewater and a removal rate of 87-89% for microplastics in polyester fabric printing and dyeing wastewater.

[0018] In the method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater as described above, the dosage of the composite material is 800 to 1000 mg / L, based on the polyester fabric printing and dyeing wastewater.

[0019] In the method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater as described above, the mass ratio of water-soluble pectin, polyacrylamide and polyvinyl alcohol is 3:3.5~5:3.5~5.

[0020] As described above, a method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, the specific process of preparing the aqueous phase is: after mixing water-soluble pectin, polyacrylamide and polyvinyl alcohol, dissolving them in deionized water at 85-90°C for 20-30 minutes; polyvinyl alcohol, water-soluble pectin and polyacrylamide are all high molecular weight compounds, and increasing the temperature helps to dissolve the polymer. If the temperature is too low, the dissolution time of the polymer is longer and the degree of freedom of the molecular chain in the solution is also lower. The polymer is dissolved at an appropriate temperature and has been well dissolved, and the impact caused by continuing to increase the temperature is relatively small.

[0021] In the above-mentioned method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, the mass ratio of the total amount of water-soluble pectin, polyacrylamide and polyvinyl alcohol to deionized water is 1 to 4 to 4.5.

[0022] In the method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater as described above, the mass ratio of benzyl alcohol to liquid polyisoprene is 4 to 5:1.

[0023] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater as described above, wherein the mass ratio of the aqueous phase to the oil phase is 5 to 5.5:4;

[0024] The mixing temperature of the water phase and the oil phase is 90-95°C, and the mixing time is 30-40 minutes.

[0025] As described above, a method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater comprises the following freeze-drying process: first freezing at a temperature of -70°C, and then freeze-drying at a vacuum degree of 2 Pa for 48 to 50 hours.

[0026] Principle of the invention:

[0027] Existing technologies target one pollutant (microplastics or disperse dyes) and have limited treatment capabilities for the other. Combining microplastic and disperse dye treatments can lead to competition between the two due to similar mechanisms, reducing treatment effectiveness. The present invention combines water-soluble pectin with liquid polyisoprene and polyacrylamide to create a composite material with flocculation and adhesion properties, capable of treating both microplastics and disperse dyes. The preparation principle is as follows: benzyl alcohol is used to open the molecular chains of liquid polyisoprene. Then, through the mixing of the oil phase and the water phase, the polyvinyl alcohol in the water phase can combine with the benzyl alcohol, making it have an emulsifier-like effect. Under the action of stirring, some water-soluble substances in the water phase (water-soluble pectin and polyacrylamide) can be dispersed in the oil phase substance. At this time, the solubility of the water phase in the droplets for the solute is limited, and the water-soluble substances will also precipitate to a certain extent. At this time, benzyl alcohol has good compatibility with the liquid polyisoprene and easily diffuses into the interior of the liquid polyisoprene, making the movement of the amorphous liquid polyisoprene molecular chains easier, and the structure becomes more relaxed, which is conducive to the diffusion of the water phase droplets into the liquid polyisoprene. The polyvinyl alcohol combined with the benzyl alcohol gathers around the droplets, which also helps the water phase droplets diffuse into the liquid polyisoprene. Through freeze-setting, the water phase substances are embedded in the liquid polyisoprene, forming a composite material with flocculation and adhesion capabilities.

[0028] Among them, the reason why the present invention can achieve a good adhesion effect on microplastics through the composite of water-soluble pectin and liquid polyisoprene is that when the liquid polyisoprene is swollen in benzyl alcohol, the force between the molecular chains is reduced and the gaps between the molecular chains are increased. The water-soluble pectin can easily disrupt the molecular chain arrangement of the liquid polyisoprene, so that the water-soluble pectin and the liquid polyisoprene form a disordered polymer chain with a certain degree of activity. In contact with microplastics, the disordered polymer chains of the composite material are entangled with the surface of the microplastics, forming an adhesion effect.

[0029] In addition, the water-soluble pectin of the present invention is easily diffused into the entire wastewater environment during use. Even though pectin is a natural product, it can affect water quality treatment. However, the present invention combines the water-soluble pectin with liquid polyisoprene, imitating the structure of jackfruit gum, so that the composite material has good adhesion in water. In addition, the liquid polyisoprene is insoluble in water. After the combination, the water-soluble pectin can be prevented from diffusing into the wastewater, thereby having good stability.

[0030] The main differences between the present invention and the prior art mentioned in the background art are as follows:

[0031] The literature (Wan Tao, Feng Ling, Du Shiyong, et al. Study on the decolorization of printing and dyeing wastewater by amphoteric polyacrylamide [J]. Water Treatment Technology, 2005, 31(9): 39-41.) cannot handle the adsorption of microplastics, while the composite material of the present invention has a stable physical adhesion effect that can not only adsorb microplastics, but also flocculate with disperse dyes to form independent treatment methods.

[0032] Compared with CN117143389A and CN113952899A, the microplastic adsorption mechanism in CN117143389A and CN113952899A is hydrogen bonding and electrostatic action, while disperse dyes cannot combine with adsorption materials through electrostatic action, the hydrogen bonding effect is also extremely small, and they cannot combine with flocculants. The present invention can combine flocculants with microplastic removal materials to obtain a composite material that removes both pollutants.

[0033] Compared with CN115448435B, the insoluble pectin in CN115448435B only plays an effect of promoting the functioning of the flocculant and has no other effects. However, the composite material of the present invention imitates the structure of jackfruit gum to ensure that the composite material has good adhesion in water, and the liquid polyisoprene is insoluble in water. After the composite material is combined with the liquid polyisoprene, the pectin can be prevented from diffusing into the wastewater, the composite material has good stability, and can be better separated after the wastewater is treated.

[0034] Beneficial effects:

[0035] (1) A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater of the present invention combines water-soluble pectin with polyisoprene and simultaneously compounds polyacrylamide to obtain a composite material with flocculation and adhesion effects, which can effectively remove disperse dyes and microplastics at the same time;

[0036] (2) The method of the present invention for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater can solve the pollution problem of polyester printing and dyeing wastewater by using composite materials, which is beneficial to environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the infrared spectrum of the composite material of Example 1. DETAILED DESCRIPTION

[0038] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0039] The testing methods for the relevant performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0040] Preparation of simulated printing and dyeing wastewater: 0.5 g of Disperse Yellow 54 dye (manufacturer: Zhejiang Boao New Materials Co., Ltd., CAS: 1223-85-7) was weighed and dissolved in distilled water and transferred to a 250 mL volumetric flask. The volume was adjusted to 2 g·L. -1 Simulated dye wastewater: Before the decolorization experiment, the simulated dye wastewater was shaken vigorously and diluted to 100 mg·L -1 Set aside, then add 0.05 g of 60 μm polyester powder to prepare simulated printing and dyeing wastewater with a microplastic abundance of 520 pieces / L, that is, the polyester fabric printing and dyeing wastewater in the embodiment and comparative example.

[0041] Removal rate of microplastics: Accurately measure two 250mL simulated printing and dyeing wastewater samples in a stoppered conical flask. After thorough stirring, add the composite material to one of them. After the two simulated printing and dyeing wastewater samples are sealed and oscillated at a constant temperature for 1h, the simulated printing and dyeing wastewater samples are filtered 5 times using a cellulose filter membrane (pore size 0.45μm, diameter 50mm). After filtration, the substances collected on the filter membrane are rinsed into a beaker with 100mL of deionized water, and the rinse liquid is transferred to a conical flask, stirred again, and 100mL of 30wt% hydrogen peroxide solution is added. Oscillate at 60℃ for 8h in a low-noise oscillating dyeing machine; after the simulated printing and dyeing wastewater is cooled to 25℃, filter it with a 10mL disposable syringe and a 13mm filter, place the filter membrane in the 13mm filter in a glass culture dish that has been thoroughly rinsed with deionized water and dried, cover it with aluminum foil, and allow the filter membrane to dry naturally. After drying, the microplastics on the filter membrane in the 13mm filter were quantitatively analyzed using a high-resolution field emission scanning electron microscope Regulus 8100 to calculate the removal rate of microplastics by the composite material. The calculation formula is as follows: Removal rate = (microplastic abundance before simulated printing and dyeing wastewater treatment - microplastic abundance after simulated printing and dyeing wastewater treatment) / microplastic abundance before simulated printing and dyeing wastewater treatment × 100%.

[0042] Determination of Dye Decolorization Rate: Accurately measure 250 mL of simulated printing and dyeing wastewater into a stoppered conical flask, add the composite material, seal the flask, and shake at a constant temperature for 1 hour. After high-speed centrifugation for 15 minutes, measure the absorbance of the supernatant 30 mm above the liquid surface at the dye's maximum absorption wavelength, λ = 440 nm, to characterize the residual dye content. The decolorization rate of the disperse dye by the composite material is calculated using the following formula: Decolorization Rate = (Absorbance of Simulated Printing and Dyeing Wastewater Before Treatment - Absorbance of Simulated Printing and Dyeing Wastewater After Treatment) / Absorbance of Simulated Printing and Dyeing Wastewater Before Treatment × 100%.

[0043] Example 1

[0044] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, comprising the following steps:

[0045] (1) Preparation of raw materials:

[0046] Water-soluble pectin: Manufacturer: Jiangsu Caiwei Biotechnology Co., Ltd., CAS: 9020-65-9;

[0047] Polyacrylamide: Manufacturer: Zhengjie Environmental Protection Materials Co., Ltd., 30% cationic ionization, number average molecular weight 10 million;

[0048] Polyvinyl alcohol: Manufacturer: Aladdin Reagent (Shanghai) Co., Ltd., CAS: 9002-89-5;

[0049] benzyl alcohol;

[0050] Polyisoprene: Manufacturer: Jinan Xiangfa Chemical Technology Co., Ltd., model IR-30, number average molecular weight 30,000;

[0051] (2) mixing water-soluble pectin, polyacrylamide, and polyvinyl alcohol in a mass ratio of 3:5:5, and dissolving the mixture in deionized water at 85°C for 20 minutes to obtain an aqueous phase;

[0052] The mass ratio of the total amount of water-soluble pectin, polyacrylamide and polyvinyl alcohol to deionized water is 1:4;

[0053] (3) benzyl alcohol and liquid polyisoprene were mixed at a mass ratio of 4:1 at 25°C for 40 min to obtain an oil phase;

[0054] (4) The aqueous phase and the oil phase with a mass ratio of 5:4 were mixed at 90°C for 30 min, then frozen at -70°C, and then freeze-dried at a vacuum degree of 2 Pa for 48 h to obtain a composite material;

[0055] (5) adding the composite material into polyester fabric printing and dyeing wastewater to remove microplastics and disperse dyes in the polyester fabric printing and dyeing wastewater;

[0056] Taking polyester fabric printing and dyeing wastewater as the benchmark, the dosage of the composite material is 1000 mg / L.

[0057] The composite material has a decolorization rate of 68% for disperse dyes in polyester fabric printing and dyeing wastewater, and a removal rate of 87.6% for microplastics in polyester fabric printing and dyeing wastewater.

[0058] like Figure 1 As shown, 3413cm -1 The absorption peak at 1650cm is the characteristic absorption peak of -NH2. -1 The absorption peak belongs to the amide I band, indicating the successful introduction of cationic polyacrylamide, 885cm -1The absorption peak at 3131 cm is caused by CH2=CH2 in polyisoprene, indicating the successful introduction of polyisoprene. -1 The absorption peak at 2987 cm is caused by -OH in polyvinyl alcohol. -1 It is the symmetrical stretching vibration of CH2, which may be caused by any of the substances contained. -1 、1211cm -1 、1128cm -1 、1087cm -1 The absorption peaks appearing at are caused by the stretching vibrations of CO, CCH, CC and O-CH of carbohydrates, indicating that the composite material was successfully prepared.

[0059] Comparative Example 1

[0060] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater is basically the same as Example 1, except that liquid polyisoprene is omitted from the oil phase.

[0061] The composite material has a decolorization rate of 68% for disperse dyes in polyester fabric printing and dyeing wastewater and a removal rate of 0% for microplastics in polyester fabric printing and dyeing wastewater.

[0062] Comparing Comparative Example 1 with Example 1, it can be found that Comparative Example 1 does not use liquid polyisoprene, polyacrylamide, water-soluble pectin, and polyvinyl alcohol, and has no effect on removing microplastics. This is because liquid polyisoprene can only have a messy polymer chain that can be entangled with microplastics after combining with water-soluble pectin. Single liquid polyisoprene or water-soluble pectin cannot remove microplastics.

[0063] Comparative Example 2

[0064] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater is basically the same as Example 1, except that the liquid polyisoprene is replaced with polypropylene (manufacturer: Suzhou Jishao Engineering Plastics Co., Ltd., CAS: 9003-07-0, model Total HJ730).

[0065] The composite material has a decolorization rate of 68% for disperse dyes in polyester fabric printing and dyeing wastewater and a removal rate of 0% for microplastics in polyester fabric printing and dyeing wastewater.

[0066] Comparing Comparative Example 2 with Example 1, it can be found that the polypropylene used in Comparative Example 2 failed to combine with polyacrylamide and was unable to remove microplastics. This is because polypropylene is in a solid state and it is difficult for benzyl alcohol to swell it. In addition, the intermolecular force is extremely strong and cannot be affected by water-soluble pectin to form a messy polymer chain that can entangle with other substances.

[0067] Comparative Example 3

[0068] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater is basically the same as Example 1, except that water-soluble pectin is omitted from the aqueous phase.

[0069] The composite material has a decolorization rate of 68% for disperse dyes in polyester fabric printing and dyeing wastewater and a removal rate of 0% for microplastics in polyester fabric printing and dyeing wastewater.

[0070] Comparing Comparative Example 3 with Example 1, it can be found that Comparative Example 3 cannot remove microplastics in polyester fabric printing and dyeing wastewater. This is because a single liquid polyisoprene needs to combine with water-soluble pectin to form a messy polymer chain entangled with other substances. Without using water-soluble pectin, the intermolecular force of liquid polyisoprene still hinders the movement of its molecular chain.

[0071] Comparative Example 4

[0072] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater is basically the same as Example 1, except that the water-soluble pectin is replaced with polydopamine.

[0073] The composite material has a decolorization rate of 68% for disperse dyes in polyester fabric printing and dyeing wastewater and a removal rate of 0% for microplastics in polyester fabric printing and dyeing wastewater.

[0074] Comparing Comparative Example 4 with Example 1, it can be found that Comparative Example 4 cannot remove microplastics in polyester fabric printing and dyeing wastewater. This is because polydopamine is a solid particle and is not water-soluble. During the preparation process, it cannot affect the molecular chain force and molecular chain state of liquid polyisoprene, thereby failing to enable liquid polyisoprene to adhere to microplastics.

[0075] Comparative Example 5

[0076] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater is basically the same as Example 1, except that benzyl alcohol is replaced with cyclohexane.

[0077] The composite material has a decolorization rate of 68% for disperse dyes in polyester fabric printing and dyeing wastewater and a removal rate of 0% for microplastics in polyester fabric printing and dyeing wastewater.

[0078] Comparing Comparative Example 5 with Example 1, it can be found that Comparative Example 5 is unable to remove microplastics in polyester fabric printing and dyeing wastewater. This is because the aqueous phase containing polyvinyl alcohol can be restored to two distinct phases in a relatively fast time during the mixing process with the oil phase containing cyclohexane. As a result, polyvinyl alcohol cannot carry polyacrylamide and water-soluble pectin into the swollen liquid polyisoprene, making it impossible for the liquid polyisoprene to adhere to microplastics.

[0079] Example 2

[0080] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, comprising the following steps:

[0081] (1) Preparation of raw materials:

[0082] Water-soluble pectin: Manufacturer: Jiangsu Caiwei Biotechnology Co., Ltd., CAS: 9020-65-9;

[0083] Polyacrylamide: Manufacturer: Zhengjie Environmental Protection Materials Co., Ltd., 30% cationic ionization, number average molecular weight 10 million;

[0084] Polyvinyl alcohol: Manufacturer: Aladdin Reagent (Shanghai) Co., Ltd., CAS: 9002-89-5;

[0085] benzyl alcohol;

[0086] Polyisoprene: Manufacturer: Jinan Xiangfa Chemical Technology Co., Ltd., model IR-30, number average molecular weight 30,000;

[0087] (2) mixing water-soluble pectin, polyacrylamide, and polyvinyl alcohol in a mass ratio of 3:3.5:3.5, and dissolving the mixture in deionized water at 85°C for 30 minutes to obtain an aqueous phase;

[0088] The mass ratio of the total amount of water-soluble pectin, polyacrylamide and polyvinyl alcohol to deionized water is 1:4.5;

[0089] (3) benzyl alcohol and liquid polyisoprene were mixed at a mass ratio of 4:1 at 25°C for 30 min to obtain an oil phase;

[0090] (4) The aqueous phase and the oil phase with a mass ratio of 5:4 were mixed at 95°C for 40 min, then frozen at -70°C, and then freeze-dried at a vacuum degree of 2 Pa for 48 h to obtain a composite material;

[0091] (5) adding the composite material into polyester fabric printing and dyeing wastewater to remove microplastics and disperse dyes in the polyester fabric printing and dyeing wastewater;

[0092] Taking polyester fabric printing and dyeing wastewater as the benchmark, the dosage of the composite material is 1000 mg / L.

[0093] The composite material has a decolorization rate of 66.8% for disperse dyes in polyester fabric printing and dyeing wastewater, and a removal rate of 87.8% for microplastics in polyester fabric printing and dyeing wastewater.

[0094] Example 3

[0095] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, comprising the following steps:

[0096] (1) Preparation of raw materials:

[0097] Water-soluble pectin: Manufacturer: Jiangsu Caiwei Biotechnology Co., Ltd., CAS: 9020-65-9;

[0098] Polyacrylamide: Manufacturer: Zhengjie Environmental Protection Materials Co., Ltd., 30% cationic ionization, number average molecular weight 10 million;

[0099] Polyvinyl alcohol: Manufacturer: Shanghai MacLean Biochemical Technology Co., Ltd., CAS: 9002-89-5;

[0100] benzyl alcohol;

[0101] Polyisoprene: Manufacturer: Jinan Xiangfa Chemical Technology Co., Ltd., model IR-30, number average molecular weight 30,000;

[0102] (2) mixing water-soluble pectin, polyacrylamide, and polyvinyl alcohol in a mass ratio of 3:4.5:4.5 and dissolving them in deionized water at 86°C for 27 minutes to obtain an aqueous phase;

[0103] The mass ratio of the total amount of water-soluble pectin, polyacrylamide and polyvinyl alcohol to deionized water is 1:4.25;

[0104] (3) benzyl alcohol and liquid polyisoprene were mixed at a mass ratio of 4:1 at 25°C for 35 minutes to obtain an oil phase;

[0105] (4) The aqueous phase and the oil phase with a mass ratio of 5.5:4 were mixed at 92°C for 38 min, then frozen at -70°C, and then freeze-dried at a vacuum degree of 2 Pa for 49 h to obtain a composite material;

[0106] (5) adding the composite material into polyester fabric printing and dyeing wastewater to remove microplastics and disperse dyes in the polyester fabric printing and dyeing wastewater;

[0107] Taking polyester fabric printing and dyeing wastewater as the benchmark, the dosage of the composite material is 1000 mg / L.

[0108] The composite material has a decolorization rate of 67.2% for disperse dyes in polyester fabric printing and dyeing wastewater, and a removal rate of 88% for microplastics in polyester fabric printing and dyeing wastewater.

[0109] Example 4

[0110] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, comprising the following steps:

[0111] (1) Preparation of raw materials:

[0112] Water-soluble pectin: Manufacturer: Jiangsu Caiwei Biotechnology Co., Ltd., CAS: 9020-65-9;

[0113] Polyacrylamide: Manufacturer: Zhengjie Environmental Protection Materials Co., Ltd., 30% cationic ionization, number average molecular weight 10 million;

[0114] Polyvinyl alcohol: Manufacturer: Shanghai MacLean Biochemical Technology Co., Ltd., CAS: 9002-89-5;

[0115] benzyl alcohol;

[0116] Polyisoprene: Manufacturer: Jinan Xiangfa Chemical Technology Co., Ltd., model IR-30, number average molecular weight 30,000;

[0117] (2) mixing water-soluble pectin, polyacrylamide, and polyvinyl alcohol in a mass ratio of 3:5.5 and dissolving them in deionized water at 88°C for 24 minutes to obtain an aqueous phase;

[0118] The mass ratio of the total amount of water-soluble pectin, polyacrylamide and polyvinyl alcohol to deionized water is 1:4;

[0119] (3) benzyl alcohol and liquid polyisoprene were mixed at a mass ratio of 5:1 at 25°C for 40 min to obtain an oil phase;

[0120] (4) The aqueous phase and the oil phase with a mass ratio of 5:4 were mixed at 94°C for 35 min, then frozen at -70°C, and then freeze-dried at a vacuum degree of 2 Pa for 49 h to obtain a composite material;

[0121] (5) adding the composite material into polyester fabric printing and dyeing wastewater to remove microplastics and disperse dyes in the polyester fabric printing and dyeing wastewater;

[0122] Taking polyester fabric printing and dyeing wastewater as the benchmark, the dosage of the composite material is 800 mg / L.

[0123] The composite material has a decolorization rate of 66% for disperse dyes in polyester fabric printing and dyeing wastewater, and a removal rate of 87% for microplastics in polyester fabric printing and dyeing wastewater.

[0124] Example 5

[0125] A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, comprising the following steps:

[0126] (1) Preparation of raw materials:

[0127] Water-soluble pectin: Manufacturer: Jiangsu Caiwei Biotechnology Co., Ltd., CAS: 9020-65-9;

[0128] Polyacrylamide: Manufacturer: Zhengjie Environmental Protection Materials Co., Ltd., 30% cationic ionization, number average molecular weight 10 million;

[0129] Polyvinyl alcohol: Manufacturer: Aladdin Reagent (Shanghai) Co., Ltd., CAS: 9002-89-5;

[0130] benzyl alcohol;

[0131] Polyisoprene: Manufacturer: Jinan Xiangfa Chemical Technology Co., Ltd., model IR-30, number average molecular weight 30,000;

[0132] (2) mixing water-soluble pectin, polyacrylamide, and polyvinyl alcohol in a mass ratio of 3:5.5, and dissolving the mixture in deionized water at 90°C for 20 minutes to obtain an aqueous phase;

[0133] The mass ratio of the total amount of water-soluble pectin, polyacrylamide and polyvinyl alcohol to deionized water is 1:4;

[0134] (3) benzyl alcohol and liquid polyisoprene were mixed at a mass ratio of 4.5:1 at 25°C for 30 minutes to obtain an oil phase;

[0135] (4) The aqueous phase and the oil phase with a mass ratio of 5.25:4 were mixed at 95°C for 30 min, then frozen at -70°C, and then freeze-dried at a vacuum degree of 2 Pa for 50 h to obtain a composite material;

[0136] (5) adding the composite material into polyester fabric printing and dyeing wastewater to remove microplastics and disperse dyes in the polyester fabric printing and dyeing wastewater;

[0137] Taking polyester fabric printing and dyeing wastewater as the benchmark, the dosage of the composite material is 900 mg / L.

[0138] The composite material has a decolorization rate of 67.3% for disperse dyes in polyester fabric printing and dyeing wastewater, and a removal rate of 87.9% for microplastics in polyester fabric printing and dyeing wastewater.

Claims

1. A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater, characterized by: The aqueous phase and the oil phase are mixed and freeze-dried to obtain a composite material, which is then added to polyester fabric printing and dyeing wastewater to remove microplastics and disperse dyes from the polyester fabric printing and dyeing wastewater; The aqueous phase is obtained by dissolving water-soluble pectin, polyacrylamide and polyvinyl alcohol in deionized water, and the oil phase is a mixture of liquid polyisoprene and benzyl alcohol; The preparation process of the aqueous phase is as follows: water-soluble pectin, polyacrylamide and polyvinyl alcohol are mixed and dissolved in deionized water at 85-90°C for 20-30 minutes; The freeze-drying process is as follows: first, freeze at -70 °C, and then freeze-dry at a vacuum degree of 2 Pa for 48 to 50 h.

2. A method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater according to claim 1, characterized in that: The composite material has a decolorization rate of 66~68% for disperse dyes in polyester fabric printing and dyeing wastewater, and a removal rate of 87~89% for microplastics in polyester fabric printing and dyeing wastewater.

3. The method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater according to claim 1, wherein: Taking polyester fabric printing and dyeing wastewater as the benchmark, the dosage of the composite material is 800~1000 mg / L.

4. The method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater according to claim 1, characterized in that: The mass ratio of water-soluble pectin, polyacrylamide and polyvinyl alcohol is 3:3.5~5:3.5~5.

5. The method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater according to claim 1, characterized in that: The mass ratio of the total amount of water-soluble pectin, polyacrylamide and polyvinyl alcohol to deionized water is 1:4~4.

5.

6. The method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater according to claim 1, characterized in that: The mass ratio of benzyl alcohol to liquid polyisoprene is 4-5:

1.

7. The method for removing microplastics and disperse dyes from polyester fabric printing and dyeing wastewater according to claim 1, characterized in that: The mass ratio of water phase to oil phase is 5~5.5:4; The mixing temperature of the water phase and the oil phase is 90~95℃, and the mixing time is 30~40 min.

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