A method and device for enhanced ultrafiltration treatment of heavy metal ion-containing wastewater by micellar complexation

Abstract

The present invention discloses a method and device for enhanced ultrafiltration treatment of heavy metal ion-containing wastewater by micellar complexation. The method includes the steps of: S1. Self-assembling poloxamer and tannic acid in an aqueous solution, and combining them through multiple hydrogen bond interactions between the phenolic hydroxyl groups of tannic acid and the ether bonds of poloxamer to form a poloxamer-tannic acid micelle mixture; S2. Mixing the poloxamer-tannic acid micelle mixture with the heavy metal ion-containing wastewater so that the poloxamer-tannic acid micelles capture the heavy metal ions in the wastewater; S3. Filtering the liquid after the poloxamer-tannic acid micelles capture the heavy metal ions with an ultrafiltration membrane, and the obtained filtrate is the wastewater from which the heavy metal ions have been removed. This method is simple. Poloxamer and tannic acid self-assemble in an aqueous solution to form poloxamer-tannic acid micelles with a specific structure, which have both the characteristics of poloxamer micelles and the heavy metal complexation characteristics of tannic acid, improving the interception and adsorption of various heavy metals; there is no need to add a large amount of surfactants and complexing agents, which is more environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the field of water treatment in environmental engineering, and more specifically, relates to a method and device for enhanced ultrafiltration treatment of heavy metal ion-containing wastewater by micellar complexation Background Technique

[0002] Heavy metal pollution has become one of the most serious environmental problems endangering human health, which has made the treatment of heavy metal wastewater a research hotspot at the forefront of world science and technology in recent years. There are many treatment technologies for heavy metal wastewater, including precipitation, coagulation-flocculation, ion exchange, adsorption, membrane separation, ultrafiltration, etc. Each technology has its advantages and limitations. Ultrafiltration membrane separation technology is a commonly used technology for heavy metal treatment. Since the size of heavy metal ions or their hydrated ions is extremely small (0.1 - 1 nm), which is much smaller than the size of conventional ultrafiltration membranes (micrometer level), when choosing ultrafiltration membrane separation technology for the treatment of heavy metal wastewater, some auxiliary enhancement measures are required. Mainly micellar-enhanced ultrafiltration (MEUF) and complexation-enhanced ultrafiltration (CEUF). These two methods can both be used to enhance the ultrafiltration of heavy metal wastewater

[0003] MEUF forms large micelles by using surfactants to combine with small molecules including heavy metal ions in water; CEUF forms large complexes by combining specific structural groups with specific types of heavy metal ions. The purpose of both technologies is to make the heavy metal ion particles grow larger than the pore size of the ultrafiltration membrane, and then be intercepted by the ultrafiltration membrane. However, both of the above two technologies have certain problems. MEUF has no selectivity for heavy metal ions. For example, the Chinese invention patent with the publication number CN101293715A discloses a method and device for deep purification of water by micellar-enhanced ultrafiltration. It mainly adsorbs or dissolves small molecules in water (such as environmental hormones, halogenated hydrocarbon disinfection by-products, and metal ions such as lead and manganese) through the hydrophobic group of the surfactant, and then removes them by ultrafiltration. Therefore, it is easily affected by some competing ions present in water, such as K + , Na +etc., which leads to the need to add a larger amount of surfactant for forming micelles with substances in water; CEUF treatment of heavy metals must rely on complexes containing heavy metal complexing groups. Different complexing groups bind to different heavy metal ions, and generally, multiple polymers containing different groups are required to achieve the removal of heavy metals. Although the complexing agent tannic acid can complex with multiple heavy metals, after its complexation with heavy metal ions, due to the small particle size of the complexation product, the removal rate of heavy metals is low. In order to increase the size of the combination of heavy metals and the complexing agent and improve the removal rate of heavy metal ions, a large amount of multiple complexing agents also need to be added, resulting in a waste of resources.

[0004] Therefore, there is an urgent need to develop an enhanced ultrafiltration method that combines micelles and complexation, has a high removal rate for multiple heavy metal ions, and is more resource-saving. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a micellar complexation enhanced ultrafiltration treatment method for wastewater containing heavy metal ions. This micellar complexation enhanced ultrafiltration treatment method combines micelles and complexation to endow it with the characteristic of efficiently adsorbing and intercepting heavy metal ions. Another object of the present invention is to provide the application of the micellar complexation enhanced ultrafiltration treatment method in the filtration of heavy metal wastewater; still another object of the present invention is to provide a micellar complexation enhanced ultrafiltration device for wastewater containing heavy metal ions.

[0006] In order to achieve the above objects, the present invention adopts the following technical solutions:

[0007] A micellar complexation enhanced ultrafiltration treatment method for wastewater containing heavy metal ions includes the following steps:

[0008] S1. Self-assemble poloxamer and tannic acid in an aqueous solution so that the phenolic hydroxyl group of tannic acid and the ether bond of poloxamer are combined through multiple hydrogen bond interactions to form a poloxamer-tannic acid micelle mixture;

[0009] S2. Mix the poloxamer-tannic acid micelle mixture with the wastewater containing heavy metal ions so that the poloxamer-tannic acid micelles capture the heavy metal ions in the wastewater;

[0010] S3. Filter the liquid captured by the poloxamer-tannic acid micelles with an ultrafiltration membrane, and the obtained filtrate is the wastewater from which heavy metal ions have been removed.

[0011] This micellar complexation enhanced ultrafiltration treatment method forms a new micelle-complexation enhanced ultrafiltration system through multiple hydrogen bond interactions between the phenolic hydroxyl group of tannic acid and the ether bond of poloxamer, integrating the micelle characteristics of poloxamer and the heavy metal complexation characteristics of tannic acid, and greatly improving the interception and adsorption of multiple heavy metals.

[0012] Furthermore, the tannic acid and poloxamer self-assemble in an aqueous solution, and the self-assembled structure is as follows:

[0013] (I)

[0014] Among them, in structure (I), the sum of x and z is 2 to 130, and y is 15 to 67.

[0015] For the specific model of the above-mentioned poloxamer structure, x, y, and z will have specific values. x and z do not need to be equal. For example, in poloxamer 188 in the copolymer, the sum of x and z is 75 to 85, and y is 25 to 30.

[0016] Furthermore, the poloxamer and tannic acid in step S1 self-assemble in an aqueous solution, and the mass ratio of poloxamer to tannic acid in the aqueous solution is 4:6 - 6:4.

[0017] Preferably, the mass ratio of poloxamer to tannic acid in the aqueous solution is 5:5.

[0018] Furthermore, the poloxamer is one of poloxamer 188, poloxamer 338, and poloxamer 407.

[0019] Poloxamer is a non-ionic triblock copolymer composed of a middle hydrophobic polyoxypropylene chain (PPO) with two hydrophilic polyoxyethylene (PEO) segments connected on the sides.

[0020] Furthermore, the poloxamer and tannic acid in step S1 self-assemble in an aqueous solution, and the total concentration of poloxamer and tannic acid in the aqueous solution is not less than 0.01 mg / mL.

[0021] Furthermore, the poloxamer and tannic acid in step S1 self-assemble in an aqueous solution, and the total concentration of poloxamer and tannic acid in the aqueous solution is not less than 0.1 - 1 mg / mL.

[0022] Even further, the self-assembly of the poloxamer and tannic acid in step S1 in an aqueous solution is carried out under the following conditions: the temperature is 0 - 60°C; the pH value is 2 - 7.

[0023] Furthermore, for the self-assembly of the poloxamer and tannic acid in step S1 in an aqueous solution, stirring is also required for 1 min - 24 h.

[0024] Preferably, the stirring time is 1 - 2 h.

[0025] Furthermore, the ultrafiltration membrane in step S3 is one of an ultrafiltration membrane with a molecular weight cut-off of 1 - 500 kDa, a microporous membrane with a pore size of 0.1 - 1.2 μm, and a filter paper with a pore size of 2.5 μm.

[0026] Further, the ultrafiltration membrane material is polyethersulfone PES, mixed cellulose MCE, regenerated cellulose RC, polypropylene PP or polytetrafluoroethylene PTFE.

[0027] Further, the heavy metal ion-containing wastewater in step S2 is composed of one or any combination of the following ions: Co 2 + , Cu 2+ , Ni 2+ , Pb 2+ , Fe 3+ , Cd 2+ , Zn 2+ and Mn 2+ .

[0028] Further, the total concentration of the heavy metal ions is 0.01 mmol / L - 10 mol / L.

[0029] This application also provides the application of the above micellar complexation enhanced ultrafiltration treatment method in the filtration of heavy metal wastewater.

[0030] This application also provides a micellar complexation enhanced ultrafiltration device for heavy metal ion-containing wastewater, including a liquid inlet, a pressure supply device, a micellar complexation strengthening pool, an ultrafiltration membrane, and a liquid outlet. There is a self-assembled poloxamer and tannic acid aqueous solution in the micellar complexation strengthening pool. The upper part of the micellar complexation strengthening pool is respectively connected to the liquid inlet and the pressure supply device. An ultrafiltration membrane is provided at the lower part of the micellar complexation strengthening pool. The ultrafiltration membrane is connected to the outside through the liquid outlet, and the liquid passing through the ultrafiltration membrane is discharged from the liquid outlet. The self-assembled poloxamer and tannic acid aqueous solution is self-assembled by poloxamer and tannic acid in an aqueous solution. The total concentration of poloxamer and tannic acid in the aqueous solution is not less than 0.01 mg / mL, and the mass ratio of poloxamer to tannic acid in the aqueous solution is 4:6 - 6:4.

[0031] Further, a stirring rod for stirring is also provided in the micellar complexation strengthening pool.

[0032] Furthermore, the stirring rod is provided with rotatable magnetic blades, and the rotational speed of the magnetic blades of the stirring rod can be controlled by a magnetic stirrer provided outside the micellar complexation strengthening pool.

[0033] Further, the pressure supply device is also provided with a pressure gauge for monitoring the pressure provided by the pressure supply device.

[0034] Further, the pressure supply device is also connected to a pressure reducing valve communicating with the outside to adjust the actual air pressure entering the micellar complexation strengthening pool.

[0035] Further, the actual air pressure entering the micellar complexation strengthening pool is not higher than 2 MPa.

[0036] Further, the pressure supply device is a gas cylinder that provides transmembrane pressure for the liquid in the micellar complexation strengthening pool.

[0037] Preferably, the gas cylinder provides compressed air or nitrogen.

[0038] The beneficial effects of the present invention are as follows:

[0039] (1) A micellar complexation enhanced ultrafiltration treatment method for heavy metal ion-containing wastewater developed by the present invention can filter heavy metal ions and is used for the treatment of various heavy metal ion waste liquids. In this micellar complexation enhanced ultrafiltration treatment method, poloxamer and tannic acid self-assemble in an aqueous solution, and the multi-hydrogen bond interaction between the phenolic hydroxyl group of tannic acid and the ether bond of poloxamer combines to form a poloxamer-tannic acid micellar mixture, forming a new micelle-complexation enhanced ultrafiltration system. Combining the micellar characteristics of poloxamer and the heavy metal complexation characteristics of tannic acid greatly improves the interception and adsorption of various heavy metals, and the heavy metal removal rate is high.

[0040] (2) The process of this micellar complexation enhanced ultrafiltration treatment method is simple. After poloxamer and tannic acid self-assemble in an aqueous solution, poloxamer-tannic acid micelles with a specific structure are formed, which can directly filter various heavy metals with little influence from competing ions. There is no need to add a large amount of complexing agents or surfactants to the wastewater, which is more environmentally friendly. Description of the Drawings

[0041] Figure 1 It is a schematic diagram of the micellar complexation enhanced ultrafiltration treatment;

[0042] In the figure: 11 represents non-heavy metal ions; 12 represents water molecules; 13 represents heavy metal ions; 14 represents poloxamer-tannic acid micelles; 15 represents poloxamer-tannic acid micelles combined with heavy metals; 16 represents the ultrafiltration membrane; 17 represents the mixing of heavy metal ions and poloxamer-tannic acid micelles; 18 represents filtration through the ultrafiltration membrane.

[0043] Figure 2 It is the Fourier infrared spectrum diagram of the micelles in Example 1;

[0044] In the figure: a is tannic acid; b is poloxamer 188; c is the micelles formed by tannic acid and poloxamer.

[0045] Figure 3 It is the transmission electron microscopy characterization diagram of the micelles in Example 1.

[0046] Figure 4 It is the micellar complexation enhanced ultrafiltration device in Example 1;

[0047] Labels in the figure: 2 represents the liquid inlet; 3 represents the pressure supply device; 31 represents the pressure gauge; 32 represents the pressure reducing valve; 4 represents the micellar complexation strengthening tank; 41 represents the stirring rod; 411 represents the magnetic blade; 42 represents the magnetic stirrer; 5 represents the ultrafiltration membrane; 6 represents the liquid outlet, 7 represents the air inlet; 8 represents the liquid collection tank; 9 represents the balance. Detailed implementation mode

[0048] The present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

[0049] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0050] Example 1

[0051] A method for treating heavy metal ion-containing wastewater by micellar complexation enhanced ultrafiltration, comprising the following steps:

[0052] S1. Self-assemble poloxamer and tannic acid in an aqueous solution, and combine the multi-hydrogen bond interaction between the phenolic hydroxyl group of tannic acid and the ether bond of poloxamer to form a poloxamer-tannic acid micelle mixture. Among them, the poloxamer is poloxamer 188; the mass ratio of poloxamer and tannic acid in the aqueous solution for self-assembly is 5:5, and the total concentration of poloxamer and tannic acid in water is 0.1 mg / mL. The self-assembly of poloxamer and tannic acid in the aqueous solution is carried out under the following conditions: the temperature is 25°C; the pH value is 6; stirring is also required for 1 h during self-assembly.

[0053] S2. Mix the poloxamer-tannic acid micelle mixture with the heavy metal ion-containing wastewater to enable the poloxamer-tannic acid micelles to capture the heavy metal ions in the wastewater. Among them, the heavy metal ion solution is 10 mM CuSO 4 •5H 2 O wastewater 1L;

[0054] S3. Filter the liquid after the poloxamer-tannic acid micelles capture with a 30 kDa polyethersulfone membrane, and the obtained filtrate is the wastewater from which heavy metal ions have been removed.

[0055] The schematic diagram of this micellar complexation enhanced ultrafiltration treatment is as Figure 1, the heavy metal ion wastewater contains non-heavy metal ions 11, water molecules 12 and heavy metal ions 13; adding the heavy metal ion wastewater to the poloxamer-tannic acid micelle 14; the heavy metal ions are mixed with the poloxamer-tannic acid micelle 17. At this time, the poloxamer-tannic acid micelle 15 combined with the heavy metal is formed in the solution. At this time, the heavy metal ions change from the free state to the non-free state; filtering the mixed solution through the ultrafiltration membrane 16. After filtering 18 through the ultrafiltration membrane, the heavy metals in the wastewater are removed.

[0056] Among them, the above-mentioned poloxamer can also be poloxamer 338 or poloxamer 407, and self-assembly can be achieved by stirring at 0-60 °C for 1 min-24 hours; the ultrafiltration membrane can also be a commonly used 2.5 μm filter paper or a 0.1-1.2 μm microporous filter membrane. The ultrafiltration membrane material can also be other commonly used ultrafiltration membrane materials such as polyethersulfone PES, mixed cellulose MCE, regenerated cellulose RC, polypropylene PP or polytetrafluoroethylene PTFE; when the heavy metal ion solution is 0.01 mmol / L-10 mol / L, similar removal effects are obtained.

[0057] Example 2

[0058] Referring to the micelle complexation enhanced ultrafiltration treatment method of Example 1, the difference is only that the wastewater containing heavy metal ions is composed of the following ions with the same concentration: Na + , Co 2+ , Cu 2+ , Ni 2+ , Pb 2+ , Fe 3+ , Cd 2+ , Zn 2+ and Mn 2+ , where the concentrations of each ion are the same and the total ion concentration is 9 mM, and other steps remain unchanged.

[0059] Example 3

[0060] Referring to the micelle complexation enhanced ultrafiltration treatment method of Example 1, the difference is only that the mass ratio of poloxamer to tannic acid in the aqueous solution is 4:6, and other steps remain unchanged.

[0061] Example 4

[0062] Referring to the micelle complexation enhanced ultrafiltration treatment method of Example 1, the difference is only that the mass ratio of poloxamer to tannic acid in the aqueous solution is 6:4, and other steps remain unchanged.

[0063] Example 5

[0064] Referring to the micelle complexation enhanced ultrafiltration treatment method of Example 1, the difference is only that the total concentration of poloxamer and tannic acid in water is 0.5 mg / mL.

[0065] Example 6

[0066] Referring to the method for enhanced ultrafiltration by micellar complexation in Example 1, the only difference is that the total concentration of poloxamer and tannic acid in water is 1.0 mg / mL.

[0067] Example 7

[0068] Referring to the method for enhanced ultrafiltration by micellar complexation in Example 4, the only difference is that the total concentration of poloxamer and tannic acid in water is 0.5 mg / mL.

[0069] Example 8

[0070] Referring to the method for enhanced ultrafiltration by micellar complexation in Example 4, the only difference is that the total concentration of poloxamer and tannic acid in water is 1.0 mg / mL.

[0071] Example 9 Micellar Complexation Enhanced Ultrafiltration Device

[0072] This application also provides a micellar complexation enhanced ultrafiltration device for wastewater containing heavy metal ions, as Figure 4 shown, which includes a liquid inlet 2, a pressure supply device 3, a micellar complexation enhancement tank 4, an ultrafiltration membrane 5, and a liquid outlet 6. There is a self-assembled aqueous solution of poloxamer and tannic acid in the micellar complexation enhancement tank 4. The upper part of the micellar complexation enhancement tank 4 is respectively connected to the liquid inlet 2 and the pressure supply device 3 and is communicated through an air inlet 7. An ultrafiltration membrane 5 is provided at the lower part of the micellar complexation enhancement tank 4. The ultrafiltration membrane 5 is communicated with the outside through the liquid outlet 6, and the liquid passing through the ultrafiltration membrane 5 is discharged from the liquid outlet 6; A stirring rod 41 for stirring is also provided in the micellar complexation enhancement tank 4. The stirring rod 41 is provided with rotatable magnetic blades 411, and the rotational speed of the magnetic blades 411 of the stirring rod 41 can be controlled by a magnetic stirrer 42 provided outside the micellar complexation enhancement tank 4. The pressure supply device 3 is also provided with a pressure gauge 31 for monitoring the pressure provided by the pressure supply device 3. The pressure supply device 3 is also connected with a pressure reducing valve 32 communicated with the outside for adjusting the actual air pressure entering the micellar complexation enhancement tank 4. The actual air pressure entering the micellar complexation enhancement tank 4 is not higher than 2 MPa. Excessive pressure will cause the ultrafiltration membrane to deform or even be damaged. The pressure supply device 3 is a gas cylinder that provides transmembrane pressure for the liquid in the micellar complexation enhancement tank 4. The gas cylinder provides compressed air or nitrogen; The liquid outlet 6 is connected to a liquid collection tank 8, and the liquid collection tank 8 is used to hold the filtered liquid. Preferably, the liquid collection tank 8 is placed on a balance 9 to facilitate monitoring of the mass change of the liquid in the liquid collection tank 8. The self-assembled aqueous solution of poloxamer and tannic acid is self-assembled by poloxamer and tannic acid in an aqueous solution, and the total concentration of poloxamer and tannic acid in the aqueous solution is not less than 0.01 mg / mL, and the mass ratio of poloxamer to tannic acid in the aqueous solution is 4:6 - 6:4.

[0073] In the specific implementation process, there is a self-assembled poloxamer and tannic acid aqueous solution in the micellar complexation strengthening pool 4. The heavy metal ion wastewater enters the micellar complexation strengthening pool 4 from the liquid inlet 2. The stirring rod 41 is started, and the magnetic blades 411 of the stirring rod 41 rotate, and the rotation speed is controlled by a magnetic stirrer 42 arranged outside the micellar complexation strengthening pool 4. The self-assembled poloxamer and tannic acid in the micellar complexation strengthening pool 4 adsorb heavy metals. The pressure supply device 3 generates pressure on the liquid in the micellar complexation strengthening pool 4. The pressure reducing valve 32 is adjusted and the reading of the pressure gauge 31 is read not higher than 2 MPa. At this time, the liquid passing through the ultrafiltration membrane 5 is discharged from the liquid outlet 6 and enters the liquid collection pool 8. Since the liquid collection pool 8 is placed on the balance 9, the liquid production can be monitored in real time.

[0074] Comparative Example 1

[0075] Referring to the micellar complexation enhanced ultrafiltration treatment method of Example 1, the difference is only that there is only poloxamer with the same concentration in the aqueous solution, and other steps remain unchanged.

[0076] Comparative Example 2

[0077] Referring to the micellar complexation enhanced ultrafiltration treatment method of Example 2, the difference is only that there is only poloxamer with the same concentration in the aqueous solution, and other steps remain unchanged.

[0078] Comparative Example 3

[0079] Referring to the micellar complexation enhanced ultrafiltration treatment method of Example 2, the difference is only that there is only poloxamer with a concentration of 20 mg / mL in the aqueous solution, and other steps remain unchanged.

[0080] Comparative Example 4

[0081] Referring to the micellar complexation enhanced ultrafiltration treatment method of Example 1, the difference is only that there is only tannic acid with the same concentration in the aqueous solution, and other steps remain unchanged.

[0082] Comparative Example 5

[0083] Referring to the micellar complexation enhanced ultrafiltration treatment method of Example 2, the difference is only that there is only tannic acid with the same concentration in the aqueous solution, and other steps remain unchanged.

[0084] Comparative Example 6

[0085] Referring to the micellar complexation enhanced ultrafiltration treatment method of Example 2, the difference is only that there is only tannic acid with a concentration of 20 mol / L in the aqueous solution, and other steps remain unchanged.

[0086] Comparative Example 7

[0087] Referring to the micellar complexation enhanced ultrafiltration treatment method of Example 1, the difference is only that the mass ratio of poloxamer to tannic acid in the aqueous solution is 9:1, and other steps remain unchanged.

[0088] Comparative Example 8

[0089] Referring to the micellar complexation enhanced ultrafiltration treatment method of Example 1, the difference is only that the mass ratio of poloxamer to tannic acid in the aqueous solution is 1:9, and other steps remain unchanged.

[0090] Experimental Example 1 Characterization of Micellar Self-Assembly Structure

[0091] 1. Experimental Method

[0092] For the liquid after self-assembly of poloxamer and tannic acid in the aqueous solution of Example 1, Fourier transform infrared spectroscopy and ultraviolet-visible absorption spectroscopy were used to observe the formation of new absorption peaks, and a transmission electron microscope was used to evaluate the particle size and distribution uniformity of the micelles to verify its self-assembly structure.

[0093] 2. Experimental Results

[0094] The results are as Figure 2 shown in the Fourier transform infrared spectrum. It can be seen that the micelles formed by the self-assembly of poloxamer and tannic acid contain the characteristic absorption peaks of both. From the above experimental results, the structure formed by poloxamer and tannic acid after self-assembly is:

[0095]

[0096] In the above structure, the structure with a benzene ring is tannic acid, and the polymer hydrogen-bonded to the upper part of tannic acid is poloxamer 188. The sum of x and z in the copolymer of poloxamer 188 is 75-85, and y is 25-30. The morphology and size of the micelles are as Figure 3 characterized by transmission electron microscopy. It can be seen that a stable and uniform micellar system can be formed when the mass ratio of poloxamer P188 to tannic acid is 5:5, and the micelle size is about 100 nm at this time.

[0097] Experimental Example 2 Removal of Heavy Metal Ions in Heavy Metal Wastewater

[0098] 1. Experimental Method

[0099] The content of heavy metal ions in the wastewater after removing heavy metal ions in the above Examples 1-8 and Comparative Examples 1-8 was measured, the filtration time was recorded, and the concentration of heavy metal ions in the solution before and after filtration was measured by flame atomic absorption spectrometry; and the membrane flux and removal rate were calculated.

[0100] 2. Experimental Results

[0101] The experimental results are shown in Table 1. It can be seen that Example 1 can effectively remove Cu 2+ ions, and the removal efficiency is more than 98%. The membrane flux is 16 L·m -2 ·h -1 ·bar-1 Under the same conditions, as can be seen from Example 2, for a mixed solution of various different heavy metal ions, the removal rate exceeds 95%, and the membrane flux shows no obvious fluctuation. In Examples 3 and 4, on the premise of the optimal conditions, the ratio of poloxamer to tannic acid was changed. From the results, it can be seen that the removal rate decreased slightly compared to Example 1, both around 91%, and the membrane flux showed no obvious change. Examples 5 - 8 indicate that according to Examples 1 and 2, while maintaining the mass ratio of poloxamer to tannic acid (5:5), the total concentration of the micellar solution was changed and increased to 0.5 mg / mL and 1.0 mg / mL respectively. From the results in the table, when the concentration was increased to 0.5 mg / mL, the removal effects of Examples 5 and 7 on single metal (97.9%) and mixed metal ions (above 94%) decreased slightly compared to Examples 1 and 2 under the optimal conditions, and the membrane flux decreased slightly, to 15 L·m -2 ·h -1 ·bar -1 or so. When the concentration was further increased to 1.0 mg / mL, the removal effects of Examples 6 and 8 on single metal (97.3%) and mixed metal ions (above 89%) showed a downward trend compared to Examples 1 and 2 under the optimal conditions, and the membrane flux further decreased to 14 L·m -2 ·h -1 ·bar -1 . In addition, through the comparison of different heavy metal ions, it can be seen that tannic acid has a certain complexation selectivity for heavy metal ions, and the removal effect of Fe 3+ is the best, which is consistent with the stability of the complex of phenolic hydroxyl groups. Finally, the addition of non-complexing Na + ions does not affect the removal of heavy metal ions.

[0102] The efficiencies of Comparative Examples 1 and 2 are very low, with almost no heavy metal removal effect, but with a relatively large membrane flux (20 L·m -2 ·h -1 ·bar -1 ). This is because the poloxamer alone at the same concentration does not reach its critical micelle concentration and will not self-assemble to form micelles, so there is no micellar enhanced ultrafiltration effect during filtration. In Comparative Example 3, the concentration of poloxamer was increased beyond its critical micelle concentration, so micellar enhanced ultrafiltration could be achieved to remove heavy metal ions. However, due to its low concentration and the presence of Na +The influence of ions makes its removal effect poor (25.5%-46.7%). In Comparative Examples 4 and 5, the same concentration of tannic acid existing alone, although it has a complexing effect on heavy metal ions, the formed small molecules can still pass through the pore size of the filter membrane and cannot effectively remove heavy metal ions. In Comparative Example 6, the concentration of tannic acid was increased so that it could complex with metal ions in large amounts to form small particles and precipitate, that is, tannic acid played the role of a flocculant. Although a large amount of tannic acid was used, the removal effect was still not very ideal (55.6%-58.9%). The results of Comparative Examples 1-6 show that even if a large amount of poloxamer and tannic acid existing alone are used, their effects are far lower than those of the micelle complexation enhanced ultrafiltration method composed of poloxamer and tannic acid. When the mass ratio of poloxamer and tannic acid in the aqueous solution is too low (1:9) or too high (9:1), good heavy metal adsorption effects cannot be obtained (Comparative Examples 7-Comparative Example 8). This is because the ratio of this poloxamer and tannic acid affects the size and uniformity of the formed micelles (at a total concentration of 0.1 mg / mL, the mass ratio of poloxamer and tannic acid of 9:1 basically does not form effective micelles), and an ultrafiltration membrane with a suitable pore size needs to be matched.

[0103] Table 1 Membrane flux and heavy metal removal rate of examples and comparative examples

[0104]

[0105] Note: The unit of membrane flux is: L·m -2 ·h -1 ·bar -1 ; " / " indicates that there are no such metal ions.

[0106] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for enhanced ultrafiltration treatment of heavy metal ion-containing wastewater by micellar complexation, characterized in that, it comprises the following steps: S1. Self-assemble poloxamer and tannic acid in an aqueous solution, and combine them through multiple hydrogen bond interactions between the phenolic hydroxyl groups of tannic acid and the ether bonds of poloxamer to form a poloxamer-tannic acid micelle mixture; S2. Mix the poloxamer-tannic acid micelle mixture with the heavy metal ion-containing wastewater to enable the poloxamer-tannic acid micelles to capture heavy metal ions in the wastewater; S3. Filter the liquid after the poloxamer-tannic acid micelles capture heavy metal ions with an ultrafiltration membrane, and the obtained filtrate is the wastewater from which heavy metal ions have been removed.

2. The method for enhanced ultrafiltration treatment of micellar complexation according to claim 1, characterized in that, the self-assembly of the tannic acid and poloxamer in the aqueous solution has the following structure: （I） Among them, in structure (I), the sum of x and z is 2 to 130, and y is 15 to 67.

3. The method for enhanced ultrafiltration treatment of micellar complexation according to claim 1, characterized in that, in step S1, the self-assembly of the poloxamer and tannic acid in the aqueous solution is carried out with a mass ratio of poloxamer to tannic acid in the aqueous solution of 4:6 - 6:

4.

4. The method for enhanced ultrafiltration treatment of micellar complexation according to claim 1, characterized in that, in step S1, the self-assembly of the poloxamer and tannic acid in the aqueous solution is carried out with a total concentration of poloxamer and tannic acid in the aqueous solution of not less than 0.01 mg / mL.

5. The method for enhanced ultrafiltration treatment of micellar complexation according to claim 1, characterized in that, in step S1, the self-assembly of the poloxamer and tannic acid in the aqueous solution is carried out under the following conditions: the temperature is 25 - 60 °C; the pH value is 2 - 7.

6. The method for enhanced ultrafiltration treatment of micellar complexation according to claim 1, characterized in that, in step S1, when self-assembling the poloxamer and tannic acid in the aqueous solution, stirring is also required for 1 min - 24 h.

7. The method for enhanced ultrafiltration treatment of micellar complexation according to claim 1, characterized in that, the ultrafiltration membrane in step S3 is an ultrafiltration membrane sheet with a molecular weight cut-off of 1 - 500 kDa.

8. The method for enhanced ultrafiltration treatment of micellar complexation according to claim 1, characterized in that, the ultrafiltration membrane in step S3 can be replaced with a microporous filter membrane with a pore size of 0.1 - 1.2 μm or a filter paper with a pore size of 2.5 μm.

9. The method for enhanced ultrafiltration treatment of micellar complexation according to claim 1, characterized in that, The wastewater containing heavy metal ions described in step S2 consists of one or any combination of the following ions: Co 2+ , Cu 2+ , Ni 2+ , Pb 2+ , Fe 3+ , Cd 2+ , Zn 2+ and Mn 2+ .

10. Application of the method for enhanced ultrafiltration treatment of micellar complexation according to any one of claims 1 - 9 in the filtration of heavy metal wastewater.

11. A device for enhanced ultrafiltration treatment of heavy metal ion-containing wastewater by micellar complexation, characterized in that, It includes a liquid inlet (2), a pressure supply device (3), a micelle complexation strengthening tank (4), an ultrafiltration membrane (5), and a liquid outlet (6). There is a self-assembled poloxamer and tannic acid aqueous solution in the micelle complexation strengthening tank (4). The upper part of the micelle complexation strengthening tank (4) is respectively connected to the liquid inlet (2) and the pressure supply device (3). The lower part of the micelle complexation strengthening tank (4) is provided with an ultrafiltration membrane (5). The ultrafiltration membrane (5) is communicated with the outside through the liquid outlet (6). The liquid passing through the ultrafiltration membrane (5) is discharged from the liquid outlet (6). The self-assembled poloxamer and tannic acid aqueous solution is self-assembled by poloxamer and tannic acid in an aqueous solution. The total concentration of poloxamer and tannic acid in the aqueous solution is not less than 0.01 mg / mL, and the mass ratio of poloxamer to tannic acid in the aqueous solution is 4:6 - 6:4.

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