Tail water fiber micro-plastic removal method based on magnetic separation

Abstract

The invention relates to the technical field of microplastic removal, in particular to a tail water fiber microplastic removal method based on magnetic separation, which comprises the following steps: S1, mixing ferrous chloride tetrahydrate with ferric chloride hexahydrate to prepare a mixture A; s2, mixing the mixture A with deionized water to prepare a mixture B; s3, charcoal is added into the mixture B for mixing, and a mixture C is prepared; s4, adjusting the pH value of the mixture C; s5, preparing a solid substance D; s6, preparing a solid substance F; and S7, obtaining the magnetic iron-based biochar composite material. According to the tail water fiber micro-plastic removal method based on magnetic separation, the process for removing the fiber micro-plastic in the tail water is easy to operate and high in efficiency, the tail water can be treated on a large scale, the market advantage of tail water treatment is improved by reducing the production cost, and a practical and effective solution is provided for solving the micro-plastic pollution problem in the tail water.

Description

Technical Field

[0001] The present invention relates to the technical field of microplastic removal, and in particular to a method for removing microplastics from tail water fibers based on magnetic separation. Background Art

[0002] Fibrous microplastics are one of the most common pollutants in the global water environment. Their sources are diverse, extensive and continuous, including synthetic textiles, industrial emissions, atmospheric sediments and environmental degradation of plastic products, posing a serious threat to the ecosystem. Fibrous microplastics are small in size, irregular in shape, highly flexible and have a strong adsorption capacity for other chemicals in the water environment. Due to their form, they are more easily ingested by aquatic organisms and can threaten human health through the food chain. Traditional sewage treatment methods are difficult to completely remove them.

[0003] Common treatment methods for fibrous microplastics in tail water include advanced oxidation, membrane separation, coagulation, adsorption, etc., but the reaction condition control, intermediate product toxicity, catalyst recovery and other issues of advanced oxidation technology still need to be studied. Its cost is relatively high, and it lacks economic advantages in the large-scale treatment of large amounts of tail water containing fibrous microplastics; membrane separation technology has problems such as membrane pollution, expensive membrane technology, and low treatment capacity; coagulation may cause secondary pollution due to coagulant residues, and microplastics in the settled sludge need further disposal; adsorption method has the advantages of wide applicability and significant effect in treating microplastics in tail water, but commonly used adsorbents such as carbon nanotubes are expensive, have residues, and have poor adsorption effects.

[0004] In summary, although various methods have certain effects on the removal of fibrous microplastics, there are still problems such as low removal efficiency, high cost, and secondary pollution that need to be overcome. It is urgent to develop an adsorbent with high magnetic separation performance and high-efficiency fiber microplastic adsorption capacity to solve the existing problems of high cost and low removal efficiency in the treatment of fibrous microplastics. Therefore, a method for removing fiber microplastics from tail water based on magnetic separation is urgently needed to improve the above problems. Summary of the Invention

[0005] The object of the present invention is to solve at least one of the technical drawbacks.

[0006] To this end, one purpose of the present invention is to propose a method for removing tailwater fiber microplastics based on magnetic separation to solve the problems mentioned in the background technology and overcome the shortcomings of the existing technology.

[0007] In order to achieve the above objectives, an embodiment of one aspect of the present invention provides a method for removing microplastics from tailwater fibers based on magnetic separation, comprising the following steps:

[0008] S1: Mixing ferrous chloride tetrahydrate and ferric chloride hexahydrate to prepare a mixture A;

[0009] S2: Mixing the mixture A with deionized water to prepare a mixture B;

[0010] S3: adding biochar to the mixture B and mixing to prepare a mixture C;

[0011] S4: adjusting the pH value of the mixture C;

[0012] S5: preparing solid material D;

[0013] S6: preparing a solid substance F;

[0014] S7: Obtaining magnetic iron-based biochar composites;

[0015] S8: adding the obtained magnetic iron-based biochar composite material to the tail water to be treated.

[0016] The present invention is further configured as follows: the mass percentage ratio of ferrous chloride tetrahydrate to ferric chloride hexahydrate in step S1 is: ferrous chloride tetrahydrate: ferric chloride hexahydrate = (4-6): (3-4).

[0017] By adopting the above technical solution, mixture A can be obtained.

[0018] The present invention is further configured as follows: in step S2, the mass percentage of the mixture A and deionized water is a ratio of mixture A: water = 1: (15-25%), and the mixture A and deionized water are stirred under a magnetic stirrer for 30 minutes (450-500 r / min).

[0019] By adopting the above technical solution, mixture B can be obtained.

[0020] The present invention is further configured as follows: in step S3, the ratio of the biochar added to the mixture B is ferrous chloride tetrahydrate: ferric chloride hexahydrate: biochar = (4 to 6): (3 to 4): (2 to 4), and stirred under a magnetic stirrer for 30 minutes (450 to 500 r / min), and allowed to stand and foam for 24 hours.

[0021] By adopting the above technical solution, mixture C can be obtained.

[0022] The present invention is further configured as follows: in step S4, an appropriate amount of NaOH is weighed and added to deionized water, and the mixed deionized water is added into the mixture C to make the pH of the mixture C between (10 and 11).

[0023] By adopting the above technical solution, the pH value of the mixture C can be adjusted.

[0024] The present invention is further configured as follows: in step S5, the adjusted mixture C is sealed with a sealing film, and is allowed to stand for 24 hours before being filtered.

[0025] By adopting the above technical solution, solid material D can be obtained.

[0026] The present invention is further configured as follows: in step S6, the solid material D is dried at a temperature of (70-90° C.).

[0027] By adopting the above technical solution, solid material F can be obtained.

[0028] The present invention is further configured as follows: in step S7, a tubular muffle furnace is used to set pyrolysis parameters in a N2 atmosphere, and the flow rate of N2 is maintained at (0.5-2m 3 / h), and the temperature is increased at a rate of (5-15°C) per minute, so that the solid material F is calcined (1.5-2.5h) at a temperature of (375-425°C), and the solid obtained after cooling is the magnetic iron-based biochar composite material prepared by the present invention.

[0029] By adopting the above technical solution, a magnetic iron-based biochar composite material can be obtained.

[0030] In summary, the beneficial technical effects of the present invention are:

[0031] 1. This method for removing microplastics from tailwater fibers based on magnetic separation uses waste straw, ferrous chloride tetrahydrate, and ferric chloride hexahydrate as raw materials. Compared with commonly used adsorbents such as carbon nanotubes, the raw materials used in this invention are inexpensive and readily available, are environmentally friendly, and have low production costs and a simple production process, without causing any pollution to the environment.

[0032] 2. This method for removing fiber microplastics from tailwater based on magnetic separation uses an adsorbent, namely magnetic biochar, which has high magnetic separation performance and can be adsorbed by strong magnets, making it easy to separate;

[0033] 3. The magnetic separation-based tailwater fibrous microplastic removal method uses an adsorbent, namely magnetic biochar, which has a high efficiency in adsorbing fibrous microplastics. On the one hand, the surface of fibrous microplastics is usually hydrophobic, and magnetic biochar can bind to fibrous microplastics through hydrophobic interactions to achieve adsorption. On the other hand, the surface functionalization of magnetic biochar can enhance its adsorption capacity for fibrous microplastics. Through chemical modification, specific functional groups (such as carboxyl groups, hydroxyl groups, etc.) can be introduced into the surface of magnetic biochar. These functional groups can interact with the chemical groups on the surface of fibrous microplastics, thereby improving the adsorption efficiency. In addition, the charge characteristics of the surfaces of fibrous microplastics and magnetic biochar will also affect the adsorption effect, and electrostatic interactions will promote the adsorption process. At the same time, fibrous microplastics are easy to aggregate in water, and magnetic biochar can improve the adsorption efficiency by promoting the aggregation of fibrous microplastics. The addition of magnetic materials can change the dispersion state of fibrous microplastics, making them easier to be adsorbed and separated. After a certain adsorption effect, the magnetic biochar contains iron metal and its oxides. These materials can bind to fibrous microplastics under the action of a magnetic field and be quickly separated, achieving efficient adsorption of fibrous microplastics by magnetic biochar.

[0034] 4. This method for removing fibrous microplastics from tail water based on magnetic separation is easy to operate and highly efficient. It can treat tail water on a large scale, improves the market advantage of tail water treatment by reducing production costs, and provides a practical and effective solution to the problem of microplastic pollution in tail water.

[0035] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] The present invention discloses a method for removing microplastics from tail water fibers based on magnetic separation, comprising the following steps:

[0039] S1: Mixing ferrous chloride tetrahydrate and ferric chloride hexahydrate to prepare a mixture A;

[0040] S2: Mixing the mixture A with deionized water to prepare a mixture B;

[0041] S3: adding biochar to the mixture B and mixing to prepare a mixture C;

[0042] S4: adjusting the pH value of the mixture C;

[0043] S5: preparing solid material D;

[0044] S6: preparing a solid substance F;

[0045] S7: Obtaining magnetic iron-based biochar composites;

[0046] S8: adding the obtained magnetic iron-based biochar composite material to the tail water to be treated.

[0047] The present invention is further configured as follows: the mass percentage ratio of ferrous chloride tetrahydrate to ferric chloride hexahydrate in step S1 is: ferrous chloride tetrahydrate: ferric chloride hexahydrate = (4-6): (3-4), and mixture A can be obtained.

[0048] The present invention is further configured as follows: in step S2, the mass percentage of the mixture A and the deionized water is a ratio of mixture A: water = 1: (15-25%), and the mixture A and the deionized water are stirred under a magnetic stirrer for 30 minutes (450-500 r / min), and the mass percentage of the mixture A and the deionized water is preferably a ratio of mixture A: water = 1: (15-25%), so that a mixture B can be obtained.

[0049] The present invention is further configured as follows: the ratio of the biochar added to the mixture B in step S3 is ferrous chloride tetrahydrate: ferric chloride hexahydrate: biochar = (4 to 6): (3 to 4): (2 to 4), and the mixture is stirred under a magnetic stirrer for 30 minutes (450 to 500 r / min) and allowed to stand for foaming for 24 hours to obtain a mixture C.

[0050] The present invention is further configured as follows: in step S4, an appropriate amount of NaOH is weighed and added to deionized water, and the evenly mixed deionized water is added to the interior of the mixture C so that the pH of the mixture C is (10-11), and the pH value of the mixture C can be adjusted.

[0051] The present invention is further configured as follows: in step S5, the adjusted mixture C is sealed with a sealing film, and is allowed to stand for 24 hours before being filtered to obtain a solid substance D.

[0052] The present invention is further configured as follows: in step S6, the solid material D is dried at a temperature of (70-90° C.) to obtain a solid material F.

[0053] The present invention is further configured as follows: in step S7, a tubular muffle furnace is used to set pyrolysis parameters in a N2 atmosphere, and the flow rate of N2 is maintained at (0.5-2m 3 / h), and the temperature is increased at a rate of (5 to 15°C) per minute, so that the solid substance F is calcined (1.5 to 2.5h) at a temperature of (375 to 425°C), and the solid obtained after cooling is the magnetic iron-based biochar composite material prepared by the present invention. The magnetic iron-based biochar composite material can be obtained, and the solid obtained after cooling is the magnetic iron-based biochar composite material prepared by the present invention, which has rapid adsorption capacity and can be quickly separated, recovered and recycled under the attraction of an external magnetic field.

[0054] Example 2

[0055] The present invention discloses a method for removing fiber microplastics from tail water based on magnetic separation. The adsorbent manufactured by the present invention is used to adsorb PET in water. 0.2 g of PET is added to 80 mL of water and stirred evenly to prepare a 1 g / L PET solution to simulate the tail water to be treated. Magnetic biochar is added in different dosages of 0.1 g / L, 0.5 g / L, 1 g / L, 3 g / L, and 5 g / L, respectively. After shaking on a shaker for 24 hours, the magnetic biochar and the PET adsorbed by the magnetic biochar in the solution are sucked out with a strong magnet. After filtration, the solution is placed in an 85°C oven for 24 hours. After drying, the mass of the remaining PET is weighed, and the adsorption amount of the magnetic biochar on PET is calculated by the mass difference method.

[0056] The experiment showed that when the dosage of magnetic biochar was 3 g / L, the adsorption capacity of PET was the largest, and the adsorption rates in the three parallel experiments were 97.33%, 99.33%, and 96.00%, respectively. It can be seen from this embodiment that the method for removing fiber microplastics in tail water based on magnetic separation provided by the present invention can efficiently remove fiber microplastics PET in tail water, and the optimal dosage of magnetic biochar is 3 g / L.

[0057] Example 3

[0058] The present invention discloses a method for removing fiber microplastics from tail water based on magnetic separation. The adsorbent produced by the present invention is used to adsorb PET in water. A 1 g / L PET solution is prepared. The pH value of the PET solution is adjusted to 4, 5, 6, 7, 8, and 9 with a 1 mol / L NaOH solution and a 1 mol / L HCl solution, respectively. The amount of magnetic biochar added is 3 g / L. After shaking on a shaker for 24 hours, the magnetic biochar in the solution and the PET adsorbed by the magnetic biochar are sucked out with a strong magnet. After filtration, the solution is placed in an 85°C oven for 24 hours. After drying, the mass of the remaining PET is weighed, and the adsorption amount of the magnetic biochar on PET is calculated using a mass difference method.

[0059] The experiment showed that the adsorption amount of PET by magnetic biochar has no obvious dependence on pH, and there is no large difference in the adsorption amount within the pH gradient of 4 to 9. The adsorption amount is the largest at pH 8, which is 95.05%, 93.19% and 94.26% in three sets of parallel experiments respectively. It can be seen from this embodiment that the method for removing fiber microplastics in tail water based on magnetic separation provided by the present invention can efficiently remove fiber microplastics PET in tail water, and the optimal pH for adsorption is 8.

[0060] By adopting the above technical solution, a magnetic iron-based biochar composite material can be obtained. The implementation principle of this embodiment is:

[0061] The method for removing fiber microplastics from tail water based on magnetic separation is as follows: first, the staff mixes ferrous chloride tetrahydrate: ferric chloride hexahydrate in a mass percentage of (4-6): (3-4) to obtain a mixture A, then mixes the obtained mixture A with deionized water, and stirs it under a magnetic stirrer for 30 minutes (450-500r / min) to make a mixture B, then adds biochar in a ratio of ferrous chloride tetrahydrate: ferric chloride hexahydrate: biochar = (4-6): (3-4): (2-4) to the mixture B, mixes them evenly, and stirs them under a magnetic stirrer for 30 minutes (450-500r / min) to make a mixture C, at this time, the staff weighs an appropriate amount of NaOH, pours it into deionized water, and stirs it properly to dissolve it quickly, then adds the NaOH solution to the mixture C, and then adjusts the pH value of the mixture C to (10-11), then the staff uses a sealing film The adjusted mixture C is sealed and allowed to stand for 24 hours before being filtered to obtain solid substance D. The solid substance D is placed in a drying oven and dried at a temperature of (70-90°C). After the solid substance D is completely dried, solid substance F is obtained. Subsequently, the staff uses a tubular muffle furnace to set the pyrolysis parameters under a N2 atmosphere to maintain its flow rate at (0.5-2m3 / h) and the temperature is increased at (5-15°C) per minute. The solid substance F is calcined at (375-425°C) for 1.5-2.5h. The solid obtained after cooling is the magnetic iron-based biochar composite material prepared by the present invention with rapid adsorption capacity, and can be rapidly separated, recovered and recycled under the attraction of an external magnetic field. When the tail water needs to be treated, the staff adds magnetic biochar at a ratio of 3g / L and makes the pH of the tail water 8. At this time, the maximum adsorption capacity of the magnetic biochar can be reached, and it is ready for adsorption of the fiber microplastics in the tail water.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] 1. This method for removing microplastics from tailwater fibers based on magnetic separation uses waste straw, ferrous chloride tetrahydrate, and ferric chloride hexahydrate as raw materials. Compared with commonly used adsorbents such as carbon nanotubes, the raw materials used in this invention are inexpensive and readily available, are environmentally friendly, and have low production costs and a simple production process, without causing any pollution to the environment.

[0064] 2. This method for removing fiber microplastics from tailwater based on magnetic separation uses an adsorbent, namely magnetic biochar, which has high magnetic separation performance and can be adsorbed by strong magnets, making it easy to separate;

[0065] 3. The magnetic separation-based tailwater fibrous microplastic removal method uses an adsorbent, namely magnetic biochar, which has a high efficiency in adsorbing fibrous microplastics. On the one hand, the surface of fibrous microplastics is usually hydrophobic, and magnetic biochar can bind to fibrous microplastics through hydrophobic interactions to achieve adsorption. On the other hand, the surface functionalization of magnetic biochar can enhance its adsorption capacity for fibrous microplastics. Through chemical modification, specific functional groups (such as carboxyl groups, hydroxyl groups, etc.) can be introduced into the surface of magnetic biochar. These functional groups can interact with the chemical groups on the surface of fibrous microplastics, thereby improving the adsorption efficiency. In addition, the charge characteristics of the surfaces of fibrous microplastics and magnetic biochar will also affect the adsorption effect, and electrostatic interactions will promote the adsorption process. At the same time, fibrous microplastics are easy to aggregate in water, and magnetic biochar can improve the adsorption efficiency by promoting the aggregation of fibrous microplastics. The addition of magnetic materials can change the dispersion state of fibrous microplastics, making them easier to be adsorbed and separated. After a certain adsorption effect, the magnetic biochar contains iron metal and its oxides. These materials can bind to fibrous microplastics under the action of a magnetic field and be quickly separated, achieving efficient adsorption of fibrous microplastics by magnetic biochar.

[0066] 4. This method for removing fibrous microplastics from tail water based on magnetic separation is easy to operate and highly efficient. It can treat tail water on a large scale, improves the market advantage of tail water treatment by reducing production costs, and provides a practical and effective solution to the problem of microplastic pollution in tail water.

[0067] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for removing microplastics from tailwater fibers based on magnetic separation, characterized by: The steps include: S1: Mixing ferrous chloride tetrahydrate and ferric chloride hexahydrate to prepare a mixture A; S2: Mixing the mixture A with deionized water to prepare a mixture B; S3: adding biochar to the mixture B and mixing to prepare a mixture C; S4: adjusting the pH value of the mixture C; S5: preparing solid material D; S6: preparing a solid substance F; S7: Obtaining magnetic iron-based biochar composites; S8: adding the obtained magnetic iron-based biochar composite material to the tail water to be treated.

2. The method for removing microplastics from tailwater fibers based on magnetic separation according to claim 1, wherein: The mass percentage ratio of ferrous chloride tetrahydrate to ferric chloride hexahydrate in step S1 is: ferrous chloride tetrahydrate: ferric chloride hexahydrate = (4-6): (3-4).

3. The method for removing microplastics from tailwater fibers based on magnetic separation according to claim 1, wherein: In step S2, the mass percentage of the mixture A and deionized water is mixture A: water = 1: (15-25%), and the mixture A and deionized water are stirred under a magnetic stirrer for 30 minutes (450-500 r / min).

4. The method for removing microplastics from tailwater fibers based on magnetic separation according to claim 1, wherein: In step S3, the ratio of biochar added to mixture B is ferrous chloride tetrahydrate: ferric chloride hexahydrate: biochar = (4-6): (3-4): (2-4), and stirred under a magnetic stirrer for 30 minutes (450-500 r / min), and allowed to stand for foaming for 24 hours.

5. The method for removing microplastics from tailwater fibers based on magnetic separation according to claim 1, wherein: In step S4, an appropriate amount of NaOH is weighed and added to deionized water, and the mixed deionized water is added into the mixture C to make the pH of the mixture C be (10-11).

6. The method for removing microplastics from tailwater fibers based on magnetic separation according to claim 1, characterized in that: In step S5, the adjusted mixture C is sealed with a sealing film, and allowed to stand for 24 hours before being filtered.

7. The method for removing tailwater fiber microplastics based on magnetic separation according to claim 1, characterized in that: In step S6, the solid material D is dried at a temperature of (70-90° C.).

8. The method for removing microplastics from tailwater fibers based on magnetic separation according to claim 1, characterized in that: In step S7, a tubular muffle furnace is used to set the pyrolysis parameters under N2 atmosphere, and the flow rate of N2 is maintained at (0.5~2m 3 / h), and the temperature is increased at a rate of (5-15°C) per minute, so that the solid material F is calcined (1.5-2.5h) at a temperature of (375-425°C), and the solid obtained after cooling is the magnetic iron-based biochar composite material prepared by the present invention.