CN117225194A - Preparation method of high-flux scale-inhibiting anti-wetting composite distillation membrane - Google Patents
Preparation method of high-flux scale-inhibiting anti-wetting composite distillation membrane Download PDFInfo
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- 230000002401 inhibitory effect Effects 0.000 title claims abstract description 12
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
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- 239000000758 substrate Substances 0.000 claims description 23
- -1 polytetrafluoroethylene Polymers 0.000 claims description 15
- 239000002033 PVDF binder Substances 0.000 claims description 14
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 14
- 239000004743 Polypropylene Substances 0.000 claims description 9
- 239000007788 liquid Substances 0.000 claims description 9
- 229920001155 polypropylene Polymers 0.000 claims description 9
- MYRTYDVEIRVNKP-UHFFFAOYSA-N 1,2-Divinylbenzene Chemical compound C=CC1=CC=CC=C1C=C MYRTYDVEIRVNKP-UHFFFAOYSA-N 0.000 claims description 6
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 6
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 6
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 6
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 6
- IMNIMPAHZVJRPE-UHFFFAOYSA-N triethylenediamine Chemical compound C1CN2CCN1CC2 IMNIMPAHZVJRPE-UHFFFAOYSA-N 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 5
- 238000002791 soaking Methods 0.000 claims description 5
- PSBDWGZCVUAZQS-UHFFFAOYSA-N (dimethylsulfonio)acetate Chemical group C[S+](C)CC([O-])=O PSBDWGZCVUAZQS-UHFFFAOYSA-N 0.000 claims description 4
- BCAIDFOKQCVACE-UHFFFAOYSA-N 3-[dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azaniumyl]propane-1-sulfonate Chemical compound CC(=C)C(=O)OCC[N+](C)(C)CCCS([O-])(=O)=O BCAIDFOKQCVACE-UHFFFAOYSA-N 0.000 claims description 4
- 238000011010 flushing procedure Methods 0.000 claims description 4
- 229940117986 sulfobetaine Drugs 0.000 claims description 4
- 229920002818 (Hydroxyethyl)methacrylate Polymers 0.000 claims description 3
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 3
- WOBHKFSMXKNTIM-UHFFFAOYSA-N Hydroxyethyl methacrylate Chemical compound CC(=C)C(=O)OCCO WOBHKFSMXKNTIM-UHFFFAOYSA-N 0.000 claims description 3
- KWYHDKDOAIKMQN-UHFFFAOYSA-N N,N,N',N'-tetramethylethylenediamine Chemical compound CN(C)CCN(C)C KWYHDKDOAIKMQN-UHFFFAOYSA-N 0.000 claims description 3
- 229910001870 ammonium persulfate Inorganic materials 0.000 claims description 3
- ZIUHHBKFKCYYJD-UHFFFAOYSA-N n,n'-methylenebisacrylamide Chemical compound C=CC(=O)NCNC(=O)C=C ZIUHHBKFKCYYJD-UHFFFAOYSA-N 0.000 claims description 3
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 3
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 3
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 3
- 238000010041 electrostatic spinning Methods 0.000 claims description 2
- 238000000614 phase inversion technique Methods 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
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- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 26
- 230000001276 controlling effect Effects 0.000 description 17
- 230000004907 flux Effects 0.000 description 17
- 239000011780 sodium chloride Substances 0.000 description 13
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- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 2
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- Separation Using Semi-Permeable Membranes (AREA)
Abstract
A preparation method of a high-flux scale-inhibiting anti-wetting composite distillation membrane, belonging to the technical field of high-salt wastewater treatment. The method comprises the following steps: a zwitterionic monomer is adopted as a gel layer precursor to prepare an aqueous solution, and the aqueous solution is ultrasonically mixed; adding a cross-linking agent and carrying out ultrasonic mixing; adding an initiator and carrying out ultrasonic mixing; adding a catalyst and mixing by ultrasonic waves; coating gel layer precursor solution on the hydrophobic microporous membrane, and initiating radical polymerization reaction of the zwitterionic monomer and crosslinking reaction between polymers by heating; cleaning and drying. The invention adopts simple coating and thermal crosslinking technology to prepare the high-flux anti-scaling/wetting composite distillation membrane, has simple preparation method and low cost, and can realize industrial production. The polyion gel layer on the surface of the composite membrane can strengthen water mass transfer and interfacial evaporation, and meanwhile, the compact and nonporous surface structure morphology can prevent the diffusion and deposition of pollutants into the pores, and is easy to clean, so that good operation efficiency can be maintained in a high concentration state of wastewater.
Description
Technical Field
The invention belongs to the technical field of high-salt wastewater treatment, and particularly relates to a preparation method of a high-flux scale-inhibiting anti-wetting composite distillation membrane.
Background
High-salt wastewater is an important point and a difficult point in the current water treatment field. The membrane distillation has the advantages of high salt tolerance, available low-grade energy, simple device, good quality of produced water and the like, and can reach deep concentration and near zero emission of wastewater theoretically. However, in the process of deep concentration of wastewater, the problems of membrane scaling, membrane hole wetting and the like caused by high-concentration inorganic salt are particularly serious. Membrane scaling is caused by precipitation or deposition of inorganic salts in wastewater on the membrane surface, and growth of scale crystals into membrane pores can cause irreversible damage to the membrane pore structure, and finally, the membrane Kong Runshi and the membrane distillation process fail. Due to the hydrophobicity of the membrane, scale crystals deposited in the membrane pores are difficult to clean and membrane performance is difficult to recover. Therefore, control of membrane fouling and membrane wetting is critical to achieving long-term stability of membrane distillation treatment of high-salt wastewater.
The prior method for relieving the scale of the membrane mainly reduces the contact between the solution and the membrane and reduces the occurrence tendency of salt scale pollution by constructing a super-hydrophobic/super-smooth microporous membrane. However, since micropores exist on the surface of the membrane, it is difficult to avoid the invasion and growth of scale crystals into the membrane pores and to destroy the membrane pore structure. Reducing the pores on the surface of the membrane can ease the invasion and damage of scale crystals, but the conventional hydrophobic membrane is difficult to combine compactness and water permeability. In addition, when the wastewater is deeply concentrated, the salinity is increased, so that the flux of the membrane water is obviously reduced, and the operation efficiency of the membrane distillation is affected.
Disclosure of Invention
The invention aims to simultaneously overcome the problems of high water mass transfer resistance and scale formation type membrane pollution/wetting caused by a high-salt environment, and provides a preparation method of a high-flux scale-inhibiting anti-wetting composite distillation membrane, and the prepared composite distillation membrane can efficiently and stably realize deep concentration and recycling of high-salt wastewater.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a preparation method of a high-flux scale-inhibiting anti-wetting composite distillation membrane comprises the following steps:
step one: adopting a zwitterionic monomer as a gel layer precursor to prepare an aqueous solution with the mass concentration of 1-5%, and carrying out ultrasonic mixing for 5-30 min;
step two: adding a cross-linking agent into the solution prepared in the step one, and controlling the mass ratio of the cross-linking agent to the zwitterionic monomer to be 1: 20-100, and ultrasonic mixing for 2-10 min;
step three: adding an initiator into the solution obtained in the step two, controlling the mass concentration of the initiator to be 0.5-2 g/L, and carrying out ultrasonic mixing for 2-10 min;
step four: adding the catalyst into the solution obtained in the step three, controlling the volume concentration of the catalyst to be 0.1-0.5%, and carrying out ultrasonic mixing for 2-5 min;
step five: rapidly coating the gel layer precursor solution obtained in the step four on a hydrophobic microporous membrane substrate, controlling the thickness of the liquid layer to be 10-50 microns, placing the substrate in a 90 ℃ oven, and heating to initiate the radical polymerization reaction of the zwitterionic monomer and the crosslinking reaction between polymers, wherein the reaction time is 60-180 min; heating, crosslinking and drying, wherein the thickness of the surface coating is 2-4 microns;
step six: soaking the composite membrane prepared in the step five in pure water for 2-6 hours, then flushing the composite membrane with pure water for 3-5 times to remove unreacted impurities remained in the surface gel layer, and then placing the composite membrane in a baking oven at 40-60 ℃ for drying for 1-2 hours to obtain the polyion gel composite distillation membrane.
Further, in the first step, the zwitterionic monomer is sulfobetaine or [2- (methacryloyloxy) ethyl ] dimethyl- (3-sulfopropyl) ammonium hydroxide.
Further, in the second step, the cross-linking agent is one of N, N' -methylenebisacrylamide, divinylbenzene or hydroxyethyl methacrylate.
Further, in the third step, the initiator is one of ammonium persulfate, potassium persulfate or sodium persulfate.
Further, in the fourth step, the catalyst is one of N, N' -tetramethyl ethylenediamine, triethylene diamine or pyridine.
In the fifth step, the hydrophobic microporous membrane is prepared from polyvinylidene fluoride, polytetrafluoroethylene and polypropylene by a phase inversion method or an electrostatic spinning method.
Compared with the prior art, the invention has the beneficial effects that:
1. the polyion gel composite distillation membrane prepared by the invention not only can improve the water flux of the hydrophobic microporous membrane, but also can avoid the membrane scaling and scaling type membrane wetting problems in the membrane distillation process, thereby efficiently and stably realizing deep concentration (supersaturation and crystal precipitation can not influence the membrane operation effect) and high-quality water production (the water production and electric conductivity is less than 5 mu S/cm).
2. The invention adopts simple coating and thermal crosslinking technology to prepare the high-flux anti-scaling/wetting composite distillation membrane, has simple preparation method and low cost, and can realize industrial production.
3. The polyion gel layer on the surface of the polyion gel composite membrane prepared by the invention is of a compact nonporous morphology (figure 2), and the compact nonporous surface structure morphology can prevent the diffusion and deposition of pollutants into the pores and is easy to clean, so that good running efficiency can be maintained in a high concentration state of wastewater (figures 3 and 4).
Drawings
FIG. 1 is a scanning electron microscope image of the surface and cross section of a PVDF hydrophobic microporous film substrate in example 1 of the present invention;
FIG. 2 is a scanning electron microscope image of the surface and cross section of a polyion gel composite distillation membrane according to example 1 of the present invention;
FIG. 3 is a graph showing the results of water flux test of PVDF hydrophobic microporous membrane substrate and polyion gel composite membrane in the membrane distillation concentration process of 10wt% sodium chloride solution in example 1 of the present invention;
FIG. 4 is a graph showing the results of the conductivity test on the water-producing side of a PVDF hydrophobic microporous membrane substrate and polyionic gel composite membrane of example 1 of the present invention during concentration by membrane distillation of 10wt% sodium chloride solution;
FIG. 5 is a scanning electron microscope image of a cross-section of a PVDF hydrophobic microporous film substrate of example 1 of the present invention after concentration experiments on sodium chloride;
FIG. 6 is a graph of the X-ray spectrum of sodium element of the PVDF hydrophobic microporous film substrate of example 1 of the present invention after concentration experiments on sodium chloride;
FIG. 7 is a graph of X-ray spectra of chlorine element of the PVDF hydrophobic microporous film substrate of example 1 of the present invention after concentration experiments on sodium chloride;
FIG. 8 is a scanning electron microscope image of a cross-section of a polyion gel composite membrane according to example 1 of the present invention after concentration experiments on sodium chloride;
FIG. 9 is a graph of the X-ray spectrum of sodium element of the polyion gel composite membrane of example 1 after concentration experiment on sodium chloride;
FIG. 10 is a graph showing the X-ray spectrum of chlorine element of the polyion gel composite membrane of example 1 after concentration experiment on sodium chloride.
Detailed Description
The following description of the present invention is provided with reference to the accompanying drawings and examples, but is not limited to the following description, but is intended to cover all modifications and equivalents of the present invention without departing from the spirit and scope of the present invention.
The invention provides a preparation method of a composite distillation membrane, which can simultaneously avoid membrane scaling/wetting and ensure membrane water flux. According to the method, a layer of zwitterionic gel layer with compact structure is loaded on the surface of the hydrophobic microporous membrane, and the water chemical potential in the gel can be reduced by regulating and controlling the polyion capacity of the gel layer, so that the mass transfer of water molecules into the gel is promoted, meanwhile, the crystallization potential in the membrane can be controlled, and the membrane Kong Jiegou and wetting are prevented. The gel layer polyion behavior can also weaken the electrostatic attraction effect between polymer chain segments, so that a looser gel network is formed in a high-salt environment, the water molecule transmission space is increased, the water mass transfer rate is accelerated, meanwhile, the intermediate state water proportion is increased, and the evaporation rate of water molecules at a gel interface is improved. The electrostatic repulsive effect of the high ion density produced water in the gel and the salt interception effect under the high salt chemical potential can prevent the infiltration of excessive feed liquid ions, thereby ensuring the anti-scaling capability of the composite membrane. The polyion gel composite membrane prepared by the invention can stably and efficiently realize the deep concentration and recycling of the high-salt wastewater by membrane distillation.
The invention adopts the amphoteric ion monomer as the raw material, and initiates the radical polymerization reaction of the amphoteric ion monomer and the crosslinking reaction between polymers to form a surface gel layer by heating; (2) The polyion behavior of the gel layer can also weaken the electrostatic attraction between polymer chain segments, so that a more loose gel network (polyelectrolyte effect resistance) is formed in a high-salt environment, the water molecule transmission space is increased, and the water mass transfer rate is accelerated; (3) The electrostatic repulsion effect of the high ion density produced water in the gel and the salt interception effect under the high salt chemical potential can prevent the infiltration of excessive feed liquid ions, thereby avoiding the occurrence of salt crystallization; (4) In addition, the polyelectrolyte resistant effect of the zwitterionic gel layer can also increase the proportion of intermediate water, so that the evaporation rate of water molecules at the gel interface is improved; (5) The strong ionic solvation of the gel surface can enhance the effectiveness of the membrane against organic contamination. Therefore, the gel layer on the surface of the composite membrane designed by the invention not only can efficiently resist dirt and scale, but also can overcome high water mass transfer resistance caused by a high-salt environment, improves the water flux of the membrane, has smaller influence on the salinity of the feed liquid, and can not obviously cause the breakage of the water flux due to the increase of the salinity (figures 3-10).
Example 1:
step S1: preparing an aqueous solution with the mass concentration of 2.5% by using a [2- (methacryloyloxy) ethyl ] dimethyl- (3-sulfopropyl) ammonium hydroxide zwitterionic monomer as a gel layer precursor, and carrying out ultrasonic mixing for 5min;
step S2: adding a cross-linking agent N, N' -methylene bisacrylamide into the solution prepared in the step one, controlling the mass ratio of the cross-linking agent to the zwitterionic monomer to be 1:25, and carrying out ultrasonic mixing for 5min;
step S3: adding an initiator ammonium persulfate into the solution obtained in the step two, controlling the mass concentration of the initiator to be 1g/L, and carrying out ultrasonic mixing for 2min;
step S4: adding a catalyst N, N, N ', N' -tetramethyl ethylenediamine into the solution obtained in the step three, controlling the volume concentration of the catalyst to be 0.1%, and carrying out ultrasonic mixing for 2min;
step S5: coating the gel layer precursor solution obtained in the step four on the surface of a substrate PVDF hydrophobic microporous membrane (average pore diameter of 0.45 mu m) rapidly, controlling the thickness of the liquid layer to be 20 mu m, and placing the substrate into a 90 ℃ oven for thermal crosslinking reaction for 90min;
step S6: and (3) soaking the composite membrane prepared in the step (V) in pure water for 2 hours, then flushing the composite membrane with pure water for 3 times to remove unreacted impurities remained in the surface gel layer, and then drying the composite membrane in a 60 ℃ oven for 1 hour to obtain the polyion gel composite distillation membrane.
The surface and cross-section morphology of the PVDF hydrophobic microporous membrane and the prepared polyion gel composite distillation membrane in example 1 are characterized, and the results are shown in figures 1-2, and it can be found that the surface of the composite membrane prepared in the steps S1-S6 is provided with a compact gel layer of 3.08 mu m. The PVDF hydrophobic membrane and the composite membrane are subjected to a 10wt% sodium chloride concentration experiment under the following test conditions: the temperature of the high salt liquid side is controlled at 60 ℃, the condensed water is deionized water, the temperature of the condensed side is controlled at 20 ℃, and the solutions at the two sides of the membrane flow in a cross-flow way, and the flow speed is 0.1m/s. The results showed that the PVDF hydrophobic microporous membrane only concentrated the sodium chloride solution to 28.8wt% but a significant dip in water flux (from the initial 20.5 Lm) -2 h -1 Reduced to 2.0L m -2 h -1 FIG. 3) with an increase in produced water conductivity from 2. Mu.S/cm to 67.9. Mu.S/cm (FIG. 4), indicating that the PVDF membrane has suffered from membrane pore wetting during operation, resulting in a decrease in membrane rejection for ions; the composite membrane can still keep the constant water flux (18.8 Lm during the concentration to 70wt% -2 h -1 FIG. 3), while the water-producing side conductivity may beginThe final stability was below 5. Mu.S/cm (FIG. 4). Characterization of the morphology and element distribution of the membrane sections after the concentration experiment shows that the surface and the sections of the PVDF membrane are deposited with sodium chloride crystals (figures 5-7), and the surface and the sections of the composite membrane are not polluted (figures 8-10).
Example 2:
step S1: preparing an aqueous solution with the mass concentration of 4% by using a [2- (methacryloyloxy) ethyl ] dimethyl- (3-sulfopropyl) ammonium hydroxide zwitterionic monomer as a gel layer precursor, and carrying out ultrasonic mixing for 10min;
step S2: adding a cross-linking agent hydroxyethyl methacrylate into the solution prepared in the step one, controlling the mass ratio of the cross-linking agent to the zwitterionic monomer to be 1:100, and carrying out ultrasonic mixing for 10min;
step S3: adding an initiator sodium persulfate into the solution obtained in the step two, controlling the mass concentration of the initiator to be 2g/L, and carrying out ultrasonic mixing for 5min;
step S4: adding a catalyst pyridine into the solution obtained in the step three, controlling the volume concentration of the catalyst to be 0.5%, and carrying out ultrasonic mixing for 5min;
step S5: coating the gel layer precursor solution obtained in the step four on the surface of a substrate polypropylene hydrophobic microporous membrane (average pore diameter 1.0 mu m) rapidly, controlling the thickness of the liquid layer to be 30 mu m, and placing the substrate polypropylene hydrophobic microporous membrane in a 90 ℃ oven for thermal crosslinking reaction for 180min;
step S6: and (3) soaking the composite membrane prepared in the step (V) in pure water for 3 hours, then washing the composite membrane for 5 times by adopting pure water to remove unreacted impurities remained in the surface gel layer, and then drying the composite membrane in a drying oven at 40 ℃ for 2 hours to obtain the polyion gel composite distillation membrane.
In this example, a polypropylene hydrophobic microporous membrane (1 μm) was used as a substrate to prepare a composite membrane having a dense, nonporous structural morphology surface gel layer. The polypropylene hydrophobic microporous membrane substrate and the composite membrane are subjected to membrane distillation test under the following conditions: the high salt solution adopts 10wt% sodium chloride solution, the temperature is controlled at 60 ℃, the condensed water adopts deionized water, the temperature is controlled at 20 ℃, and the solutions at the two sides of the membrane flow in a cross-flow way, and the flow rate is 0.1m/s. The test result shows that the water flux of the composite membrane with the surface loaded with the ionic gel layer is30.5Lm -2 h -1 The water flux was higher than that of the polypropylene hydrophobic microporous membrane substrate (25.2L m -2 h -1 ) While the water flux of the composite membrane can be kept stable basically in the process of concentrating to salt crystallization (the salinity is 40 wt%), the water flux of the polypropylene hydrophobic microporous membrane substrate is suddenly reduced at the salinity of 27wt% (the water flux is reduced from 25 to L m in 30 min) -2 h -1 Reduced to 5L m -2 h -1 ) At the same time, the membrane wetting phenomenon occurs, the salt rejection rate of the membrane is reduced sharply, and the conductivity of the water producing side is increased sharply (from 2 mu S cm within 30 min) -1 Raised to 80 mu S cm -1 )。
Example 3:
step S1: preparing an aqueous solution with the mass concentration of 1% by adopting a sulfobetaine zwitterionic monomer as a gel layer precursor, and carrying out ultrasonic mixing for 30min;
step S2: adding a cross-linking agent divinylbenzene into the solution prepared in the step one, controlling the mass ratio of the cross-linking agent to the zwitterionic monomer to be 1:80, and carrying out ultrasonic mixing for 2min;
step S3: adding an initiator potassium persulfate into the solution obtained in the step two, controlling the mass concentration of the initiator to be 1g/L, and carrying out ultrasonic mixing for 10min;
step S4: adding catalyst triethylene diamine into the solution obtained in the step three, controlling the volume concentration of the catalyst to be 0.2%, and carrying out ultrasonic mixing for 5min;
step S5: coating the gel layer precursor solution obtained in the step four on the surface of a substrate polytetrafluoroethylene hydrophobic microporous membrane (average pore diameter of 0.1 mu m) rapidly, controlling the thickness of the liquid layer to be 20 mu m, and placing the substrate polytetrafluoroethylene hydrophobic microporous membrane in a 90 ℃ oven for thermal crosslinking reaction for 120min;
step S6: and (3) soaking the composite membrane prepared in the step (V) in pure water for 6 hours, then flushing the composite membrane with pure water for 3 times to remove unreacted impurities remained in the surface gel layer, and then drying the composite membrane in a drying oven at 50 ℃ for 2 hours to obtain the polyion gel composite distillation membrane.
In the embodiment, a polytetrafluoroethylene hydrophobic microporous membrane (0.1 mu m) is used as a substrate, and sulfobetaine is used as a zwitterionic monomer to prepare the composite membrane with a compact nonporous structural morphology surface gel layer. By means of the membrane distillation test,the test conditions were: the high salt solution adopts 10wt% sodium chloride solution, the temperature is controlled at 60 ℃, the condensed water adopts deionized water, the temperature is controlled at 20 ℃, and the solutions at the two sides of the membrane flow in a cross-flow way, and the flow rate is 0.1m/s. The result shows that the water flux of the composite membrane with the surface loaded with the ionic gel layer is 20.6Lm -2 h -1 Higher water flux than the polypropylene hydrophobic microporous membrane substrate (15.2 Lm -2 h -1 ) While the water flux of the composite membrane can be kept stable basically in the process of concentrating to salt crystallization (the salinity is 50 wt%), the water flux of the polytetrafluoroethylene hydrophobic microporous membrane substrate is suddenly reduced at the salinity of 28wt% (from 15L m in 60 min) -2 h -1 Reduced to 3L m -2 h -1 ) At the same time, the membrane wetting phenomenon occurs, the salt rejection rate of the membrane is reduced sharply, and the conductivity of the water producing side is increased sharply (from 2 mu S cm in 60 min) -1 Raised to 50 mu S cm -1 )。
Claims (6)
1. A preparation method of a high-flux scale-inhibiting anti-wetting composite distillation membrane is characterized by comprising the following steps: the method comprises the following steps:
step one: adopting a zwitterionic monomer as a gel layer precursor to prepare an aqueous solution with the mass concentration of 1-5%, and carrying out ultrasonic mixing for 5-30 min;
step two: adding a cross-linking agent into the solution prepared in the step one, and controlling the mass ratio of the cross-linking agent to the zwitterionic monomer to be 1: 20-100, and ultrasonic mixing for 2-10 min;
step three: adding an initiator into the solution obtained in the step two, controlling the mass concentration of the initiator to be 0.5-2 g/L, and carrying out ultrasonic mixing for 2-10 min;
step four: adding the catalyst into the solution obtained in the step three, controlling the volume concentration of the catalyst to be 0.1-0.5%, and carrying out ultrasonic mixing for 2-5 min;
step five: rapidly coating the gel layer precursor solution obtained in the step four on a hydrophobic microporous membrane substrate, controlling the thickness of the liquid layer to be 10-50 microns, placing the substrate in a 90 ℃ oven, and heating to initiate the radical polymerization reaction of the zwitterionic monomer and the crosslinking reaction between polymers, wherein the reaction time is 60-180 min;
step six: soaking the composite membrane prepared in the step five in pure water for 2-6 hours, then flushing the composite membrane with pure water for 3-5 times to remove unreacted impurities remained in the surface gel layer, and then placing the composite membrane in a baking oven at 40-60 ℃ for drying for 1-2 hours to obtain the polyion gel composite distillation membrane.
2. The method for preparing the high-flux scale-inhibiting anti-wetting composite distillation membrane according to claim 1, wherein the method comprises the following steps: in the first step, the zwitterionic monomer is sulfobetaine or [2- (methacryloyloxy) ethyl ] dimethyl- (3-sulfopropyl) ammonium hydroxide.
3. The method for preparing the high-flux scale-inhibiting anti-wetting composite distillation membrane according to claim 1, wherein the method comprises the following steps: in the second step, the cross-linking agent is one of N, N' -methylene bisacrylamide, divinylbenzene or hydroxyethyl methacrylate.
4. The method for preparing the high-flux scale-inhibiting anti-wetting composite distillation membrane according to claim 1, wherein the method comprises the following steps: in the third step, the initiator is one of ammonium persulfate, potassium persulfate or sodium persulfate.
5. The method for preparing the high-flux scale-inhibiting anti-wetting composite distillation membrane according to claim 1, wherein the method comprises the following steps: in the fourth step, the catalyst is one of N, N, N ', N' -tetramethyl ethylenediamine, triethylene diamine or pyridine.
6. The method for preparing the high-flux scale-inhibiting anti-wetting composite distillation membrane according to claim 1, wherein the method comprises the following steps: in the fifth step, the hydrophobic microporous membrane is prepared from polyvinylidene fluoride, polytetrafluoroethylene and polypropylene by a phase inversion method or an electrostatic spinning method.
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| CN117654287B (en) * | 2024-02-01 | 2024-05-14 | 蓝星（杭州）膜工业有限公司 | Composite membrane and preparation method and application thereof |
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