Electric field-pressure field coupling driving membrane separation method for accurately separating dye from salt and separation device of electric field-pressure field coupling driving membrane separation method

Abstract

The invention discloses an electric field-pressure field coupling driving membrane separation method for accurate separation of dye and salt and a separation device of the electric field-pressure field coupling driving membrane separation method, and belongs to the technical field of dye / salt membrane separation. The conductive substance polypyrrole endows the membrane with certain conductivity, and the selective separation performance of the composite membrane on small molecular organic matters / salts is improved by applying a constant electric field external force to assist in the membrane operation process. Meanwhile, after the membrane is electrified, due to repulsion of same electric properties, accumulation of dye pollutants on the surface of the membrane can be slowed down, the membrane pollution problem is relieved, and the membrane still keeps high water flux after long-time operation.

Description

Technical Field

[0001] The present invention relates to the technical field of dye / salt membrane separation, and in particular to an electric field-pressure field coupling driven membrane separation method and a separation device thereof for precise separation of dye and salt. Background Art

[0002] With the rapid development of industry, dyes are widely used in textile, papermaking, cosmetics and other industries. In the process of dye production, inorganic salts are often added to purify dye products or improve the dyeing properties of textiles. The dye wastewater produced poses a serious threat to human health and the ecological environment. The treatment of dye wastewater has always been a very challenging problem, because the high salinity, high durability and high solubility of dyes often make the biological, physical or chemical processes in conventional wastewater treatment methods ineffective. Therefore, how to recycle the useful components in wastewater; how to effectively separate small molecule organic matter / salt wastewater has become the focus of social attention.

[0003] Membrane technology has the advantages of simple operation, high efficiency and energy saving, high retention rate and low maintenance cost, making it widely used in the field of separating small molecule organic matter / salt. Li et al. (Li, Desalination, 2020, 479, 114343) used piperazine (PP) and tannic acid (TA) two monomers to prepare loose nanofiltration membranes by interfacial polymerization. The results showed that the retention rate of the membrane for various dyes reached 99.4%, and the permeability to salt was greater than 90%. Tohid et al. (Tohid, Chemical Engineering Journal, 2020, 385) prepared polyethersulfone (PES) loose nanofiltration nanocomposite membranes by incorporating cerium oxide (CeO2) through non-solvent induced phase separation technology. The results showed that the salt pass rate was greater than 96%. However, during the long-term operation of the membrane, due to the adsorption and deposition of organic and inorganic dirt rich in wastewater on the membrane surface, the membrane flux and retention capacity decreased, limiting the development and application of membrane technology. Conventional chemical cleaning is used to alleviate membrane fouling and restore membrane flux, but chemical cleaning has the problems of large chemical dosage, chemical pollution and damage to membrane structure. Therefore, it is very important to develop simple, efficient, green and energy-saving membrane fouling control methods. However, the current commercial membranes and membrane materials reported in the literature still have problems such as low water flux, poor separation accuracy and organic fouling of the membrane during the dye / salt separation process, which cannot achieve high-precision separation of dyes and salts, affecting the development and application of membrane technology in the field of dye / salt separation. Summary of the invention

[0004] The main purpose of the present invention is to propose an electric field-pressure field coupling driven membrane material for precise separation of dyes and salts and a preparation method thereof, as well as an electric field-pressure field coupling driven membrane separation device for precise separation of dyes and salts, aiming to improve the selective separation of small molecule organic matter / salts, while effectively reducing membrane pollution, restoring membrane flux and increasing the service life of the membrane.

[0005] To achieve the above object, the technical solution of the present invention is implemented as follows:

[0006] In the first aspect, the present invention provides a method for preparing an electric field-pressure field coupling driven membrane material for precise separation of dyes and salts, wherein bacterial cellulose (PPy@BC) is wrapped with highly conductive polypyrrole and mixed with high-toughness PVA, and then a loose nanofiltration membrane is prepared by surface modification with glutaraldehyde, specifically comprising the following steps:

[0007] S1, mixing polypyrrole and bacterial cellulose, and generating a stably dispersed PBC solution under the action of concentrated hydrochloric acid, FeCl3·6H2O and sodium dodecylbenzene sulfonate;

[0008] S2, placing polyvinyl alcohol in the PBC solution prepared in step S1, mixing the PBC solution and polyvinyl alcohol uniformly by magnetic stirring and ultrasonic treatment, draining into a glass funnel and letting it stand, and filtering to obtain a PBC / PVA film;

[0009] S3. Add glutaraldehyde (GA) aqueous solution to the membrane surface, then put it into an oven for heating and modification, then wash the excess glutaraldehyde on the membrane surface with deionized water, and filter to obtain PBC / PVA / GA membrane, which is the electric field-pressure field coupled driven membrane material for precise separation of dyes and salts.

[0010] Preferably, the specific process of step S1 is: placing bacterial cellulose in deionized water for ultrasonic dispersion; then dropping an ethanol solution containing pyrrole and a concentrated hydrochloric acid solution containing FeCl3·6H2O, stirring, so that the pyrrole is fully polymerized and coated on the surface of the bacterial cellulose; and adding sodium dodecylbenzene sulfonate and water for stirring to obtain a stably dispersed PBC solution.

[0011] Further preferably, in step S1, the usage ratio of bacterial cellulose, pyrrole and FeCl3·6H2O is 120-180 mg: 3-8 mL: 1-2 g.

[0012] Preferably, in step S2, the mass ratio of PBC to PVA is 1-3:1-3; further preferably, the mass ratio of PBC to PVA is 1:1.

[0013] Preferably, the concentration of the glutaraldehyde aqueous solution in step S3 is 0.5-1.5 wt %; further preferably, the concentration of the glutaraldehyde aqueous solution is 1.5 wt %.

[0014] Preferably, in the step S3, the heating modification temperature is 50-70° C., and the heating time is 5-15 min.

[0015] In a second aspect, the present invention further discloses an electric field-pressure field coupled driven membrane material obtained by the above-mentioned method for preparing an electric field-pressure field coupled driven membrane material for precise separation of dyes and salts.

[0016] In a third aspect, the present invention also discloses the application of the above-mentioned electric field-pressure field coupling driven membrane material, which is suitable for the separation of small molecule organic matter and salt under the condition of applying a constant electric field external force.

[0017] In a fourth aspect, the present invention further discloses an electric field-pressure field coupling driven membrane separation device for accurately separating dye and salt using the above-mentioned electric field-pressure field coupling driven membrane material, comprising a raw liquid pool, a water inlet, an electrically assisted cross-flow flow device, and a water outlet which are sequentially connected through pipelines; the raw liquid pool is used to store dye / brine solution; the electrically assisted cross-flow flow device is internally provided with a PBC / PVA / GA membrane, the dye / brine solution flows into the electrically assisted cross-flow flow device through the water inlet and flows on the surface of the PBC / PVA / GA membrane to separate the dye and salt, the salt-containing clean water can pass through the PBC / PVA / GA membrane and be collected in a clean water pool externally connected to the electrically assisted cross-flow flow device, and the separated dye flows back to the raw liquid through the water outlet through the pipeline for biodegradation or resource recycling and other treatments.

[0018] Preferably, the electrically assisted cross-flow flow device comprises an acrylic plate, a first pure titanium plate, a silicone sealing gasket, an acrylic flow plate, a silicone sealing gasket, a second pure titanium plate and an acrylic plate, which are arranged in sequence from top to bottom; the acrylic plate, the first pure titanium plate, the silicone sealing gasket, the acrylic flow plate, the silicone sealing gasket, the second pure titanium plate and the four corners of the acrylic plate are provided with screw holes of corresponding positions and sizes, and screws are inserted into the screw holes to fix the four sides of the electrically assisted cross-flow flow device; the acrylic plate is used to fix the device; the first pure titanium plate and the second pure titanium plate are used for conducting electricity, and the second pure titanium plate is hollow and used to place PBC / PV A / GA membrane; the silicone sealing gasket is used for sealing to prevent the solution from overflowing; there are channels on both sides of the surface of the acrylic flow plate for connecting with the water inlet and the water outlet; the silicone sealing gasket, acrylic flow plate, silicone sealing gasket, the second pure titanium plate and the acrylic plate are hollow for water to flow through; the dye / salt water solution enters the electrically assisted cross-flow flow device through the water inlet and the surface channel of the acrylic flow plate, flows into the clean water tank through the acrylic flow plate, the silicone sealing gasket, the second pure titanium plate (the PBC / PVA / GA membrane filters the dye / salt water solution) and the center of the acrylic plate, and the separated dye flows out through the water outlet.

[0019] Preferably, the first pure titanium plate and the second pure titanium plate are externally connected to an electrochemical workstation, which can provide a correct voltage to assist in rejecting pollutants and slow down the decline of water flux, thereby effectively slowing down membrane pollution.

[0020] In a fifth aspect, the present invention further discloses a method for using the above-mentioned electric field-pressure field coupling driven membrane separation device, comprising the following steps:

[0021] The dye / brine solution is placed in a stock solution pool, an electrochemical workstation is connected to the pure titanium plate of the electrically assisted cross-flow flow device to provide voltage, the valve on the pipeline between the stock solution pool and the electrically assisted cross-flow flow device and the valve on the downstream pipeline of the electrically assisted cross-flow flow device are opened, and the dye / brine solution is pumped into the electrically assisted cross-flow flow device by a vacuum pump. The dye / brine solution is separated from the dye and salt in the electrically assisted cross-flow flow device, and the dye / brine solution flows on the surface of the PBC / PVA / GA membrane. The salt-containing purified water can pass through the PBC / PVA / GA membrane into the purified water pool to intercept the dye, and the separated dye flows back to the stock solution pool through the outlet through the pipeline for biodegradation or resource reuse.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention uses polypyrrole with excellent conductivity and good stability to wrap bacterial cellulose with ultrafine network structure and high porosity. Polypyrrole grows in situ on the surface of bacterial cellulose to form a regular surface morphology. The resulting composite material has good electrical and mechanical properties. The PBC composite material is mixed with high-toughness, hydrophilic material PVA and filtered to form a membrane, and then the membrane surface is modified with glutaraldehyde to improve the water flux of the membrane by improving the hydrophilicity of the membrane;

[0024] 2. The self-made electrically assisted cross-flow device of the present invention can enhance the performance of the membrane by applying a constant electric field external force. The conductive material polypyrrole gives the membrane a certain conductivity. During the operation of the membrane, a constant electric field external force is applied to assist, and the selective separation performance of the composite membrane for small molecule organic matter / salt is improved; at the same time, after the membrane is energized, the accumulation of dye pollutants on the membrane surface can be slowed down to alleviate the membrane pollution problem because of the repulsion of like charges. The membrane can still maintain a high water flux after long-term operation;

[0025] 3. The composite membrane prepared by the method of the present invention has good separation performance and high water flux; the electrically assisted cross-flow device is simple to operate and small in size, and is suitable for use in small test environments such as laboratories. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a schematic plan view of an electric field-pressure field coupling driven membrane separation device for precise separation of dyes and salts according to the present invention;

[0028] Among them, 1. raw liquid tank; 2. water inlet; 3. electrically assisted cross-flow device; 4. water outlet; 5. electrochemical workstation; 6. water purification tank.

[0029] Figure 2 It is a plan view of the electrically assisted cross-flow device in the driven membrane separation device of the present invention;

[0030] Among them, 31, acrylic plate; 32, first pure titanium plate; 33, silicone sealing gasket; 34, acrylic flow plate; 35, silicone sealing gasket; 36, second pure titanium plate; 37, acrylic plate.

[0031] Figure 3 It is a schematic diagram of the internal structure of the PBC / PVA / GA membrane material of the present invention. DETAILED DESCRIPTION

[0032] To avoid redundancy, the items used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0033] Example 1

[0034] A method for preparing an electric field-pressure field coupling driven membrane material for precise separation of dyes and salts comprises the following steps:

[0035] S1. Mix 150 mg of bacterial cellulose and 100 mL of deionized water, stir and ultrasonically disperse for 30 min each to obtain a bacterial cellulose solution, then add 4.2 mL of pyrrole and 12 mL of anhydrous ethanol, stir for 1 h in a dark and ice bath to obtain a mixed solution of pyrrole and bacterial cellulose, drop 100 mL of pure water, 20 mL of concentrated hydrochloric acid, and 1.68 g of FeCl3·6H2O into the mixed solution of pyrrole and bacterial cellulose, stir for 10 h in a dark and ice bath, filter, add deionized water to the filtrate to obtain 250 mL of solution, add 250 mg of sodium dodecylbenzene sulfonate, stir for 1 h in a dark and ice bath, and generate PBC solution in situ after ultrasonic dispersion for 1 h;

[0036] S2, taking 3g of polyvinyl alcohol (PVA-124) and dissolving it in 97g of deionized water at 90°C to obtain a PVA aqueous solution; mixing the PBC solution obtained in step S1 with the PVA solution and stirring for 30min; after ultrasonic dispersion for 35min, draining into a glass funnel and standing for 10min, filtering to obtain a PBC / PVA film;

[0037] S3. Take 10 ml of 1.0 wt% glutaraldehyde aqueous solution and drain it onto the PBC / PVA membrane through a glass rod. Put it into an oven at 60°C for reaction for 5 min. Pour out the remaining glutaraldehyde, wash the membrane material with deionized water, and vacuum filter to obtain the PBC / PVA / GA membrane.

[0038] Example 2

[0039] A method for preparing an electric field-pressure field coupling driven membrane material for precise separation of dyes and salts comprises the following steps:

[0040] S1. Mix 150 mg of bacterial cellulose and 100 mL of deionized water, stir and ultrasonically disperse for 30 min each to obtain a bacterial cellulose solution, then add 4.2 mL of pyrrole and 12 mL of anhydrous ethanol, stir for 1 h in a dark and ice bath to obtain a mixed solution of pyrrole and bacterial cellulose, dropwise add a mixed solution of 100 mL of deionized water, 20 mL of concentrated hydrochloric acid and 1.68 g of FeCl3·6H2O to the mixed solution of pyrrole and bacterial cellulose, stir for 10 h in a dark and ice bath, filter, add deionized water to the filtrate to obtain 250 mL of a solution, add 250 mg of sodium dodecylbenzene sulfonate, stir for 1 h in a dark and ice bath, and generate a PBC solution in situ after ultrasonic dispersion for 1 h;

[0041] S2, taking 3g of polyvinyl alcohol (PVA-124) and dissolving it in 97g of deionized water at 90°C to obtain a PVA aqueous solution; mixing the PBC solution obtained in step S1 with the PVA solution and magnetically stirring for 30min; after ultrasonic dispersion for 35min, draining into a glass funnel and letting it stand for 10min, filtering to obtain a PBC / PVA film;

[0042] S3. Take 10 ml of 1.0 wt% glutaraldehyde aqueous solution and drain it onto the PBC / PVA membrane through a glass rod. Put it into an oven at 60°C for reaction for 10 min. Pour out the remaining glutaraldehyde, wash the membrane material with deionized water, and vacuum filter to obtain the PBC / PVA / GA membrane.

[0043] Example 3

[0044] A method for preparing an electric field-pressure field coupling driven membrane material for precise separation of dyes and salts comprises the following steps:

[0045] S1. Mix 150 mg of bacterial cellulose and 100 mL of deionized water, stir and ultrasonically disperse for 30 min each to obtain a bacterial cellulose solution, then add 4.2 mL of pyrrole and 12 mL of anhydrous ethanol, stir for 1 h in a dark and ice bath to obtain a mixed solution of pyrrole and bacterial cellulose, dropwise add a mixed solution of 100 mL of deionized water, 20 mL of concentrated hydrochloric acid and 1.68 g of FeCl3·6H2O to the mixed solution of pyrrole and bacterial cellulose, stir for 10 h in a dark and ice bath, filter, add deionized water to the filtrate to obtain 250 mL of a solution, add 250 mg of sodium dodecylbenzene sulfonate, stir for 1 h in a dark and ice bath, and generate a PBC solution in situ after ultrasonic dispersion for 1 h;

[0046] S2, taking 3g of polyvinyl alcohol (PVA-124) and dissolving it in 97g of deionized water at 90°C to obtain a PVA aqueous solution; mixing the PBC solution obtained in step S1 with the PVA solution and magnetically stirring for 30min; after ultrasonic dispersion for 35min, draining into a glass funnel and letting it stand for 10min, filtering to obtain a PBC / PVA film;

[0047] S3. Take 10 ml of 1.5 wt% glutaraldehyde aqueous solution and drain it onto the PBC / PVA membrane through a glass rod. Put it into an oven at 50°C for reaction for 15 min. Pour out the remaining glutaraldehyde, wash the membrane material with deionized water, and vacuum filter to obtain the PBC / PVA / GA membrane.

[0048] Example 4

[0049] A method for preparing an electric field-pressure field coupling driven membrane material for precise separation of dyes and salts comprises the following steps:

[0050] S1. Mix 150 mg of bacterial cellulose and 100 mL of deionized water, stir and ultrasonically disperse for 30 min each to obtain a bacterial cellulose solution, then add 4.2 mL of pyrrole and 12 mL of anhydrous ethanol, stir for 1 h in a dark and ice bath to obtain a mixed solution of pyrrole and bacterial cellulose, dropwise add a mixed solution of 100 mL of deionized water, 20 mL of concentrated hydrochloric acid and 1.68 g of FeCl3·6H2O to the mixed solution of pyrrole and bacterial cellulose, stir for 10 h in a dark and ice bath, filter, add deionized water to the filtrate to obtain 250 mL of a solution, add 250 mg of sodium dodecylbenzene sulfonate, stir for 1 h in a dark and ice bath, and generate a PBC solution in situ after ultrasonic dispersion for 1 h;

[0051] S2, taking 3g of polyvinyl alcohol (PVA-124) and dissolving it in 97g of deionized water at 90°C to obtain a PVA aqueous solution; mixing the PBC solution obtained in step S1 with the PVA solution and magnetically stirring for 30min; ultrasonically dispersing for 35min; ultrasonicating for 15min; draining into a glass funnel and letting it stand for 10min, and vacuum filtering to obtain a PBC / PVA film;

[0052] S3. Take 10 ml of 1.5 wt% glutaraldehyde aqueous solution and drain it onto the PBC / PVA membrane through a glass rod. Put it into an oven at 70°C for reaction for 10 min. Pour out the remaining glutaraldehyde, wash the membrane material with deionized water, and vacuum filter to obtain the PBC / PVA / GA membrane.

[0053] Example 5

[0054] A method for preparing an electric field-pressure field coupling driven membrane material for precise separation of dyes and salts comprises the following steps:

[0055] S1. Mix 150 mg of bacterial cellulose and 100 mL of deionized water, stir and ultrasonically disperse for 30 min each to obtain a bacterial cellulose solution, then add 4.2 mL of pyrrole and 12 mL of anhydrous ethanol, stir for 1 h in a dark and ice bath to obtain a mixed solution of pyrrole and bacterial cellulose, dropwise add a mixed solution of 100 mL of deionized water, 20 mL of concentrated hydrochloric acid and 1.68 g of FeCl3·6H2O to the mixed solution of pyrrole and bacterial cellulose, stir for 10 h in a dark and ice bath, filter, add deionized water to the filtrate to obtain 250 mL of a solution, add 250 mg of sodium dodecylbenzene sulfonate, stir for 1 h in a dark and ice bath, and generate a PBC solution in situ after ultrasonic dispersion for 1 h;

[0056] S2, taking 3g of polyvinyl alcohol (PVA-124) and dissolving it in 97g of deionized water at 90°C to obtain a PVA aqueous solution; mixing the PBC solution obtained in step S1 with the PVA solution and magnetically stirring for 30min; after ultrasonic dispersion for 35min, draining into a glass funnel and letting it stand for 10min, filtering to obtain a PBC / PVA film;

[0057] S3. Take 10 ml of 1.5 wt% glutaraldehyde aqueous solution and drain it onto the PBC / PVA membrane through a glass rod. Put it into an oven at 60°C for reaction for 10 min. Pour out the remaining glutaraldehyde, wash the membrane material with deionized water, and vacuum filter to obtain the PBC / PVA / GA membrane.

[0058] Example 6

[0059] An electric field-pressure field coupling driven membrane separation device for precise separation of dyes and salts, such as Figure 1As shown, it comprises a raw liquid pool (1), a water inlet (2), an electrically assisted cross-flow device (3), and a water outlet (4) which are sequentially connected through pipelines; the raw liquid pool (1) is used to store dye / salt water solution; the electrically assisted cross-flow device (3) is internally provided with a PBC / PVA / GA membrane; the dye / salt water solution flows into the electrically assisted cross-flow device (3) through the water inlet (2) and flows on the surface of the electric field-pressure field coupling driven membrane (31) to separate the dye and salt; the salt-containing purified water can pass through the electric field-pressure field coupling driven membrane (31) and be collected in a purified water pool (6) externally connected to the electrically assisted cross-flow device (3); the separated dye flows back to the raw liquid pool (1) through the water outlet (4) and the pipeline for biodegradation or resource recycling.

[0060] As a preferred implementation of this embodiment, the electrically assisted cross-flow flow device (3) comprises an acrylic plate (31), a first pure titanium plate (32), a silicone sealing gasket (33), an acrylic flow plate (34), a silicone sealing gasket (35), a second pure titanium plate (36) and an acrylic plate (37) which are arranged in sequence from top to bottom; the acrylic plate (31), the first pure titanium plate (32), the silicone sealing gasket (33), the acrylic flow plate (34), the silicone sealing gasket (35), the second pure titanium plate (36) and the acrylic plate (37) are provided with screw holes of corresponding positions and sizes at four corners, and screws are inserted into the screw holes to fix the electrically assisted cross-flow flow device (3) around; the acrylic plates (31) 31 and the acrylic plates (37) are used for fixing the device; the first pure titanium plate (32) and the second pure titanium plate (36) are used for conducting electricity, and the second pure titanium plate (36) ) is hollow and is used to place the PBC / PVA / GA membrane; the silicone sealing gasket (33) and the silicone sealing gasket (35) are used to seal and prevent the solution from overflowing; the acrylic flow plate (34) has channels on both sides of the surface for connecting with the water inlet (2) and the water outlet (4); the silicone sealing gasket (33), the acrylic flow plate (34), the silicone sealing gasket (35), the second pure titanium plate (36) and the acrylic plate (37) are hollow and are used for water to flow through; the dye / salt water solution enters the electrically assisted cross-flow flow device (3) through the surface channels of the water inlet (2) and the acrylic flow plate (34), flows into the clean water pool through the acrylic flow plate (34), the silicone sealing gasket (35), the second pure titanium plate (36) (the PBC / PVA / GA membrane filters the dye / salt water solution) and the center of the acrylic plate (37), and the separated dye flows out through the water outlet.

[0061] Preferably, the first pure titanium plate (32) and the second pure titanium plate (36) are externally connected to an electrochemical workstation, and the electrochemical workstation (5) can provide a correct voltage to assist in rejecting pollutants and slow down the decline in water flux, thereby effectively slowing down membrane pollution.

[0062] This example also provides a method for using the above-mentioned electric field-pressure field coupling driven membrane separation device for precise separation of dye and salt, comprising the following steps:

[0063] A dye (RhB) / salt (NaCl) aqueous solution with a concentration of 1 wt% is placed in a stock solution pool (1), an electrochemical workstation is connected to the pure titanium plate of the electrically assisted cross-flow flow device to provide voltage, a valve on the pipeline between the stock solution pool (1) and the electrically assisted cross-flow flow device (3) and a valve on the downstream pipeline of the electrically assisted cross-flow flow device are opened, and the dye / salt solution is pumped into the electrically assisted cross-flow flow device (3) by a vacuum pump. The electrically assisted cross-flow flow device (3) is provided with a PBC / PVA / GA membrane, and the dye / salt solution is The solution flows into the electrically assisted cross-flow device (3) through the water inlet (2) and flows on the surface of the PBC / PVA / GA membrane to separate the dye and the salt. The salt-containing clean water can pass through the PBC / PVA / GA membrane and be collected in the clean water tank (6) externally connected to the electrically assisted cross-flow device (3). The separated dye flows back to the original solution tank (1) through the water outlet (4) through the pipeline. The amount of clean water in the clean water tank (6) within 1 hour and the concentrations of the dye and salt ions in the clean water are measured, and the water flux of the membrane and the retention rate of the membrane for the dye and salt ions can be calculated:

[0064] The water flux calculation formula of the membrane is:

[0065] The calculation formula of the dye retention rate R (%) of the membrane is:

[0066] The calculation formula of the salt ion passing rate Q (%) of the membrane is:

[0067] Where V is the volume of the filtrate, L; A is the effective test membrane area, m 2 ; t is the time used to collect the filtrate, h; P is the operating pressure, bar; Cstock solution and Cfiltrate are the mass concentrations of the solute in the stock solution and filtrate respectively, g / L.

[0068] When -1.7V and 1.7V voltages were applied under power-on conditions, the long-term cycle performance of the membrane for separation of small molecule organic matter RhB and NaCl changed differently. When -1.7V was applied, the water flux decayed the slowest (decayed to 80% of the original), while when +1.7V was applied, the water flux decayed the most (decayed to 40% of the original).

[0069] Comparative Example 1 (Comparison of data from other papers)

[0070] In the document Journal of Membrane Science, 2022, 643, 120035, Paramita Manna et al. prepared a polyamide membrane on a polyacrylonitrile (PAN) carrier by a layer-by-layer self-assembly method. The electrostatic repulsion between the negatively charged dye and the membrane surface resulted in a higher dye retention rate for the negatively charged dye. The dye desalination separation performance data of the membrane was used as Comparative Example 1, and the data are listed in Table 1.

[0071] Comparative Example 2 (Comparison of Data from Others’ Papers)

[0072] In the document Science of The Total Environment, 2021, 754, 141848, Dawei Ji et al. successfully prepared a polyvinylidene fluoride (PVDF) loose nanofiltration (NF) hollow fiber membrane with a multilayer structure based on a solvent-free process. The prepared membrane has a high dye retention performance for negatively charged dyes. The dye desalination separation performance data of the membrane is used as Comparative Example 2, and the data are listed in Table 1.

[0073] Comparative Example 3 (Comparison of other people's patent data)

[0074] Patent "A polyamide membrane that can be used for separating dyes and salts and its preparation method" (application number 202010799117.6) Zhang Yatao et al. used 3,5-diamino-1,2,4-triazole as the aqueous phase monomer and adopted interfacial polymerization to obtain a polyamide membrane. The test performance data of the membrane was used as comparative example 3, and the data are listed in Table 1.

[0075] Comparative Example 4 (Comparison of other people's patent data)

[0076] Patent "Method for preparing dye / salt separation membrane based on co-deposition of dopamine and polymer framework materials" (application number 2023 10824863.X) Wang Zhi et al. obtained a dye / salt separation membrane by co-deposition of dopamine and polymer framework, and used the test performance data of the membrane as comparative example 4, and the data are listed in Table 1.

[0077] Comparative Example 5 (using the materials of Example 5 and testing without electricity)

[0078] PPG-2 membrane flux is 800L / m 2 h·bar, the dye (RhB) rejection rate was 100%, and the salt rejection rate was kept below 5%. After 8 hours of cyclic operation, the PPG-2 membrane separated small molecule organic matter / salt. As time went by, the organic matter contaminated the membrane, causing the PPG-2 membrane flux to drop significantly until it stabilized at about 65% of the original. After 4 hours of operation, the dye rejection rate was 100%, but then it dropped rapidly and stabilized to 72%. During this stage, the membrane flux was only restored to about 85% after 2 hours of pure water backwashing without power supply.

[0079] The performance test results of the membrane materials obtained in Examples 1-5 and Comparative Examples 1-5 are shown in Table 1:

[0080] Table 1 Performance test results of PBC / PVA / GA membranes prepared in Examples 1-5 and comparative membrane materials

[0081]

[0082]

[0083] It can be seen from the experimental results in Table 1 that the PBC / PVA / GA membranes prepared in Examples 1-5 of the present invention have significantly better separation effects on dye / salt wastewater than the comparative examples.

[0084] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A method for preparing an electric field-pressure field coupled driven membrane for precise separation of dyes and salts, characterized in that: The following steps are involved: S1, mixing polypyrrole and bacterial cellulose, and generating a stably dispersed PBC solution under the action of concentrated hydrochloric acid, FeCl3·6H2O and sodium dodecylbenzene sulfonate; S2, placing polyvinyl alcohol in the PBC solution prepared in step S1, mixing the PBC solution and polyvinyl alcohol uniformly by magnetic stirring and ultrasonic treatment, draining into a glass funnel and letting it stand, and filtering to obtain a PBC / PVA film; S3. Add glutaraldehyde aqueous solution to the membrane surface, then put it into an oven for heating and modification, then wash the excess glutaraldehyde on the membrane surface with deionized water, and filter to obtain the PBC / PVA / GA membrane, which is the electric field-pressure field coupled driven membrane material for precise separation of dyes and salts.

2. The preparation method according to claim 1, characterized in that: The step S1 specifically comprises: dispersing bacterial cellulose in deionized water; then dropping an ethanol solution containing pyrrole and a concentrated hydrochloric acid solution containing FeCl3·6H2O, stirring, so that the pyrrole is fully polymerized and coated on the surface of the bacterial cellulose; and adding sodium dodecylbenzene sulfonate and water, stirring, to obtain a stably dispersed PBC solution.

3. The preparation method according to claim 1, characterized in that: In the step S1, the usage ratio of bacterial cellulose, pyrrole and FeCl3·6H2O is 120-180 mg: 3-8 mL: 1-2 g.

4. The preparation method according to claim 1, characterized in that: In the step S2, the mass ratio of PBC to PVA is 1-3:1-3.

5. The preparation method according to claim 1, characterized in that: In the step S3, the heating modification temperature is 50-70° C., and the heating time is 5-15 min.

6. An electric field-pressure field coupled driven membrane for precise separation of dye and salt, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 5.

7. An application of the electric field-pressure field coupled driven membrane for precise separation of dyes and salts as claimed in claim 6, characterized in that: The driving membrane is suitable for separating small molecule organic matter from salt under the auxiliary condition of applying a constant electric field external force.

8. An electric field-pressure field coupled driven membrane separation device for accurately separating dyes and salts using the driven membrane according to claim 6, characterized in that: The invention comprises a raw liquid pool 1, a water inlet 2, an electrically assisted cross-flow flow device 3 and a water outlet 4 which are sequentially connected by pipelines; the raw liquid pool 1 is used to store dye / brine solution; the electrically assisted cross-flow flow device 3 is internally provided with a PBC / PVA / GA membrane, the dye / brine solution flows into the electrically assisted cross-flow flow device 3 through the water inlet 2 and flows on the surface of the PBC / PVA / GA membrane to separate the dye and salt, the salt-containing purified water can pass through the PBC / PVA / GA membrane and be collected in a purified water pool 6 externally connected to the electrically assisted cross-flow flow device 3, and the separated dye flows back to the raw liquid through the water outlet 4 through the pipeline for biodegradation or resource recycling and other treatments.

9. The separation device according to claim 8, characterized in that: The electrically assisted cross-flow device 3 comprises an acrylic plate 31, a first pure titanium plate 32, a silicone sealing gasket 33, an acrylic flow plate 34, a silicone sealing gasket 35, a second pure titanium plate 36 and an acrylic plate 37 which are arranged in sequence from top to bottom; the acrylic plate 31, the first pure titanium plate 32, the silicone sealing gasket 33, the acrylic flow plate 34, the silicone sealing gasket 35, the second pure titanium plate 36 and the acrylic plate 37 are provided with screw holes of corresponding positions and sizes at four corners, and screws are inserted into the screw holes to fix the electrically assisted cross-flow device 3 around; the acrylic plate 31 and the acrylic plate 37 are used for fixing the device; the first pure titanium plate 32 and the second pure titanium plate 36 are used for conducting electricity, and the second pure titanium plate 3 6 is hollow and is used to place the PBC / PVA / GA membrane; the silicone sealing gasket 33 and the silicone sealing gasket 35 are used to seal and prevent the solution from overflowing; there are channels on both sides of the surface of the acrylic flow plate 34 for connecting with the water inlet 2 and the water outlet 4; the silicone sealing gasket 33, the acrylic flow plate 34, the silicone sealing gasket 35, the second pure titanium plate 36 and the acrylic plate 37 are hollow for water to flow through; the dye / salt water solution enters the electrically assisted cross-flow flow device 3 through the surface channels of the water inlet 2 and the acrylic flow plate 34, flows into the clean water tank through the center of the acrylic flow plate 34, the silicone sealing gasket 35, the second pure titanium plate 36 and the acrylic plate 37, and the separated dye flows out through the water outlet.

10. The separation device according to claim 9, characterized in that: The first pure titanium plate 32 and the second pure titanium plate 36 are externally connected to an electrochemical workstation, which can provide a correct voltage to assist in rejecting pollutants and slow down the decline of water flux, thereby effectively slowing down membrane pollution.

Images