CN111744369A - Janus type distillation membrane with wetting resistance and oil stain resistance as well as preparation method and application thereof - Google Patents
Janus type distillation membrane with wetting resistance and oil stain resistance as well as preparation method and application thereof Download PDFInfo
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- CN111744369A CN111744369A CN202010430388.4A CN202010430388A CN111744369A CN 111744369 A CN111744369 A CN 111744369A CN 202010430388 A CN202010430388 A CN 202010430388A CN 111744369 A CN111744369 A CN 111744369A
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
- B01D61/364—Membrane distillation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/02—Hydrophilization
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D2323/00—Details relating to membrane preparation
- B01D2323/04—Hydrophobization
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D2325/00—Details relating to properties of membranes
- B01D2325/36—Hydrophilic membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/38—Hydrophobic membranes
Abstract
The invention relates to a Janus type distillation membrane with wetting resistance and oil stain resistance, and a preparation method and application thereof, wherein the distillation membrane comprises a base membrane, one side of the base membrane is a hydrophilic cortex, the other side of the base membrane is a fully-hydrophobic cortex, and the hydrophilic cortex is a polydopamine layer; the whole hydrophobic cortex layer is a PAL layer modified by dopamine. The Janus type distillation membrane has an asymmetric structure in the membrane thickness direction, one surface of the distillation membrane is hydrophilic, the other surface of the distillation membrane is super-hydrophobic, and the distillation membrane has good wetting resistance, pollution resistance and thermal stability. The membrane preparation method for membrane distillation is simple, low in cost and environment-friendly. The asymmetric all-hydrophobic membrane has good wetting resistance and pollution resistance, can treat high-salt oily sewage, has good stability, can basically achieve 100 percent of desalination, and keeps stable flux in long-time use.
Description
Technical Field
The invention relates to a Janus type distillation membrane with wetting resistance and oil stain resistance, and a preparation method and application thereof, and belongs to the technical field of bionic interface materials and membrane distillation.
Background
The membrane distillation technology is a thermally driven membrane separation process, and uses a microporous hydrophobic membrane as a separation medium and the steam pressure difference at two sides of the membrane as a mass transfer driving force to make steam molecules at a hot side pass through membrane pores and then condensed and enriched at a cold side, so that high-efficiency separation of water and pollutants is realized, and a high-quality separation product can be obtained. The membrane distillation process has the advantages of salt rejection rate close to 100%, lower operation temperature, utilization of low-grade heat energy such as waste energy and the like, lower requirement on the mechanical property of the membrane and the like. The method has good separation effect and huge market potential in the aspect of challenging feedwater treatment.
However, with the development of water industry and the demand of ecological protection, the membrane distillation technology faces more complicated treatment objects, such as industrial wastewater with complicated components, polluted seawater or brackish water, oily wastewater, dye wastewater and the like, and in the actual operation process, the durability of the membrane is greatly challenged, and the double constraints of membrane wetting and membrane pollution are borne. Affecting the application and popularization of the distillation membrane. The ideal distillation membrane should have the characteristics of wetting resistance, pollution resistance, high permeability, low heat conduction, high thermal stability and the like. The fully-hydrophobic membrane has better stability and better water and oil repellency in the air, but has underwater lipophilicity and can be polluted by oil-containing water supply; an air-hydrophilic composite membrane has a stain resistance but cannot effectively inhibit the wetting of the membrane by a low surface energy substance.
Chinese patent document CN107020017A discloses an anti-pollution composite distillation membrane and a preparation method and application thereof, the composite membrane takes a polytetrafluoroethylene microfiltration membrane as a base membrane, after the hot side surface of the polytetrafluoroethylene microfiltration membrane is cleaned or etched by a physicochemical method, hydrophilic modification is carried out on the hot side surface by interfacial polymerization, and the hydrophilic and hydrophobic composite distillation membrane with good anti-pollution capacity is prepared. Although the membrane has better anti-pollution capability, the performance of treating oily sewage and wastewater containing low-surface-energy substances (such as surfactant) is poor, and the membrane is not suitable for treating petroleum-polluted seawater, oily wastewater and industrial wastewater with complex components at present because the membrane is not resistant to oil wetting.
Chinese patent document CN108404685A relates to a preparation method of a distillation membrane for high-permeability, moisture-resistant and anti-pollution membrane distillation, which comprises the following steps: the first step is as follows: carrying out electrostatic spinning on the hydrophobic polymer spinning solution to obtain a hydrophobic porous fiber membrane; the second step is that: spraying the super-hydrophobic skin layer spinning solution on a hydrophobic base film by using electrostatic spraying to obtain a super-hydrophobic skin layer; the third step: spraying the super-hydrophilic cortex spinning solution on the super-hydrophobic cortex by using electrostatic spraying to obtain an asymmetric super-wetting composite nanofiber distillation membrane; the fourth step: and drying the asymmetric super-wetting composite nanofiber distillation membrane. Because the method adopts electrostatic spinning to prepare the base membrane, the problem of uneven membrane exists, the production efficiency of electrostatic spinning is low, the mass rapid production of the membrane cannot be realized, and the membrane popularization is limited.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a Janus type distillation membrane with wetting resistance and oil stain resistance, and a preparation method and application thereof. The modified membrane is modified on the basis of a commercial membrane, the rapid preparation of the membrane can be realized by a simple deposition and spraying method, the problems that the commercial membrane is easily wetted by oil-containing liquid and low-surface tension substances are solved, and the modified membrane is well suitable for a membrane distillation process and can be used for treating high-salinity wastewater containing oil.
In order to solve the problems, the invention is realized by the following technical scheme:
a Janus type distillation membrane with wetting resistance and oil stain resistance comprises a base membrane, wherein one side of the base membrane is a hydrophilic skin layer, the other side of the base membrane is a fully-hydrophobic skin layer, and the hydrophilic skin layer is a poly-dopamine layer; the all-hydrophobic skin layer is an all-hydrophobic material layer modified by dopamine.
A preparation method of a Janus type distillation membrane with wetting resistance and oil stain resistance comprises the following steps:
the first step is to prepare a hydrophilic skin layer:
placing the basement membrane into a dopamine buffer solution to vibrate so that polydopamine is uniformly attached to the surface of the membrane, and then washing with deionized water to obtain a hydrophilic cortex basement membrane;
step two, preparing a fully hydrophobic skin layer:
(1) adding the all-hydrophobic layer material into a Tirs-HCl buffer solution for ultrasonic treatment to obtain a suspension, adding dopamine into the suspension, stirring and reacting at room temperature for 1-4 hours, washing a product after reaction to be neutral, and drying to obtain a dopamine-modified all-hydrophobic layer material;
(2) adding absolute ethyl alcohol and ammonia water or single toluene into a dopamine-modified all-hydrophobic material, ultrasonically mixing uniformly, adding Tetraethoxysilane (TEOS) and a fluorinating agent, fluorinating at room temperature, and ultrasonically crushing to obtain a uniformly mixed all-hydrophobic material suspension;
step three, preparing Janus type distillation membrane
And spraying the uniformly mixed all-hydrophobic material suspension on the other side of the hydrophilic skin layer base membrane prepared in the first step, and drying to obtain the Janus type distillation membrane with wetting resistance and oil stain resistance.
Preferably, in the first step, the concentration of dopamine in the dopamine buffer solution is 0.125-0.5 g/L.
Preferably, in the first step, the dopamine buffer solution is a buffered solution of dopamine in Tirs-HCl at a concentration of 10mM and a pH of 8.5. The Tris-HCl buffer solution maintained the reaction at a constant pH.
Preferably, in the first step, the base membrane is a PTFE membrane, a PVDF membrane, or a PP membrane, and the size of the base membrane is 3 × 8 cm.
Further preferably, the base membrane is a PTFE membrane.
According to the invention, in the first step, the membrane is shaken in the dopamine buffer solution at the speed of 50-300r/min, the temperature of 20-30 ℃ and the shaking time of 3-6 hours.
Preferably, in the second step (1), the all-hydrophobic layer material is one of attapulgite PAL, Carbon Nanotube (CNT) or nano Cellulose (CNF).
Most preferably, in the second step (1), the all-hydrophobic layer material is attapulgite PAL.
Preferably, in the second step (1), when the all-sparse layer material is the attapulgite PAL, the attapulgite PAL is activated firstly, then the attapulgite PAL is added into the Tirs-HCl buffer solution, the attapulgite PAL is activated by adding the attapulgite PAL into the hydrochloric acid solution and stirring the solution, the activated attapulgite PAL is washed by deionized water until the pH value is 6, then the attapulgite PAL is dried in a vacuum oven to constant weight, and the dried attapulgite PAL is ground into powder.
When the material of the all-hydrophobic layer is the Carbon Nano Tube (CNT) or the nano Cellulose (CNF), the activation is not needed, and the all-hydrophobic layer is directly added into the Tirs-HCl buffer solution.
Further preferably, the concentration of the attapulgite PAL in the hydrochloric acid solution is 0.1 g/mL; the concentration of the hydrochloric acid solution is C HCl1 mol/L; the stirring speed is 650 rpm; the drying temperature was 105 ℃.
Preferably, according to the invention, in the second step (1), the concentration of the all-phobic layer material in the suspension is from 0.001 to 0.002 g/L.
Further preferably, the concentration of the all-phobic layer material in the suspension is 0.0017 g/L.
Preferably, in the second step (1), the dopamine is added to a concentration of 0.05-1.5g/L in the suspension.
Preferably, according to the invention, in the second step (1), the drying is carried out at 60 ℃ for 10 hours under vacuum.
Preferably, in the second step (2), the mass-to-volume ratio of the dopamine modified all-hydrophobic layer material to the absolute ethyl alcohol is as follows: (0.1-0.3) and (8-10), wherein the unit is g/mL, and the mass-volume ratio of the dopamine modified all-hydrophobic layer material to ammonia water is as follows: (0.1-0.3): (0.5-3), unit, g/mL.
Preferably, in the second step (2), the mass-to-volume ratio of the dopamine modified all-hydrophobic layer material to the absolute ethyl alcohol is as follows: (0.1-0.3): (40-60), unit, g/mL.
Preferably, in the second step (2), the mass-to-volume ratio of the dopamine modified all-hydrophobic layer material to Tetraethoxysilane (TEOS) is: (0.1-0.3): (5-15), unit, g/microliter.
Preferably, in the second step (2), the fluorinating agent is 1H,1H,2H, 2H-Perfluorodecyltriethoxysilane (PFDTES), and the volume ratio of 1H,1H,2H, 2H-Perfluorodecyltriethoxysilane (PFDTES) to absolute ethyl alcohol is: (0.1-0.3):(8-10).
Preferably, in the second step (2), the cell disruption is performed by using a cell disruptor with a power of 288W and a disruption time of 40 minutes.
Preferably, according to the invention, the amount of the all-phobic material suspension solution sprayed in the third step is 6 mL.
In the preparation method, taking the all-hydrophobic layer material as the attapulgite PAL as an example, the acidification PAL can disperse the nanorods, remove the impurity part and dissolve the inner layer, thereby facilitating the subsequent fluorination treatment. Milling can form mesopores and micropores, which can effectively modify the structure and properties of PAL. TEOS and PFDTES form a fluorinated polysiloxane coating to wrap PAL through hydrolytic condensation, and form a bulge and micropore structure on the PAL surface to form a reentrant structure, so that the coating formed after suspension spraying has super-hydrophobic and super-oleophobic characteristics. In the preparation process of PAL suspension, the modification of PAL with dopamine utilizes its adhesion to make PAL coating more firmly adhere to the membrane surface, and the modification of dopamine does not affect PAL properties, but it makes PAL aggregation affect dispersion effect; TEOS and PFDTES are hydrolyzed and condensed to form fluorinated polysiloxane, which can bridge and induce the aggregation of PAL nano-rods, so that PAL is uniformly dispersed by using a cell disruptor to form a more stable uniformly dispersed suspension.
Compared with the existing membrane distillation membrane, the Janus type distillation membrane with wetting resistance and oil stain resistance has the following beneficial effects:
1. the Janus type distillation membrane resistant to wetting and oil stain is characterized in that a hydrophilic skin layer is prepared by a method for depositing dopamine, and a bionic material dopamine is a biological adhesive inspired by mussel byssus and contains abundant hydroxyl and amino, and can form an ultrathin hydrophilic polydopamine layer by self-polymerization on the surface of any material. The formed hydrophilic layer does not influence the property of the base membrane, does not reduce the flux of the membrane, and is firmly adhered to the surface of the membrane. Due to the hydrophilic characteristic of the coating, the membrane can realize underwater oleophobic property and pollution resistance, and flux reduction and effluent quality reduction caused by blocking membrane pores by pollutants such as oil drops are prevented; and the hydrophilic skin layer is simple, quick, effective and environment-friendly to prepare.
2. The Janus type distillation membrane with wetting resistance and oil stain resistance is prepared by adopting the modified PAL to prepare the fully-hydrophobic layer, the PAL modified by dopamine has strong viscosity, and has a micro-nano structure suitable for constructing a bionic super-fully-hydrophobic coating, and the nano channel and the layered silicate micropore can easily form a reentrant structure. The PAL suspension after the all-hydrophobic modification is sprayed on the surface of a Polytetrafluoroethylene (PTFE) membrane by a spray gun, the spraying is uniform, a super-all-hydrophobic coating prepared by PAL after fluorination has better wetting resistance, is super-hydrophobic in air, and can prevent liquids with low surface tension, such as mineral oil, surfactants (such as sodium dodecyl sulfate and the like), n-tetradecane and the like from wetting. The coating is firmly attached to the surface of the membrane, is not easy to fall off, so that the membrane has good stability, and the material cost is low and easy to obtain, which is the first time of preparing the membrane for membrane distillation by using PAL.
3. The membrane preparation method for membrane distillation provided by the invention is simple, low in cost and environment-friendly. The asymmetric all-hydrophobic membrane has good wetting resistance and pollution resistance, can treat high-salt oily sewage, has good stability, can basically achieve 100 percent of desalination, and keeps stable flux in long-time use.
Drawings
FIG. 1 is a scanning electron microscope image of the super-hydrophobic surface of the Janus film prepared by the method of example 1.
FIG. 2 is a scanning electron microscope image of the hydrophilic surface of the Janus film prepared by the method of example 1.
Fig. 3 is a photograph of the water contact angle in air of the superhydrophobic surface of the Janus membrane prepared by the method of example 1.
Fig. 4 is a photograph of the underwater oil contact angle of the hydrophilic surface of the Janus membrane prepared by the method of example 1.
FIG. 5 is a graphical representation of flux and salt rejection results for testing the stability of the Janus membrane distillation process using the method of example 2.
FIG. 6 is a graphical representation of the flux and salt rejection results for testing the resistance of the Janus membrane distillation process to wetting using the method of example 2.
Fig. 7 is a graphical representation of the flux and salt rejection performance of the Janus membrane distillation process tested for oil resistance using the method of example 2.
Detailed Description
The invention will be better understood from the following description of a specific embodiment and the attached drawings, without limiting the scope of the invention thereto.
The raw materials involved in the present invention are the prior art unless otherwise specified.
Example 1
A preparation method of a Janus type distillation membrane with wetting resistance and oil stain resistance comprises the following steps:
(1) dopamine was added to a 10mM, pH 8.5, Tirs-HCl buffer solution to a dopamine solution concentration of 0.5 g/L. Placing a commercial PTFE membrane with the size of 3 x 8cm into a PDA solution to vibrate under the conditions of 100r/min and the temperature of 25 ℃, so that the PDA is uniformly attached to the surface of the membrane.
(2) Washing the surface of the membrane with deionized water for at least three times to obtain a hydrophilic skin layer base membrane;
(3) 5g PAL was added to 50mL of CHClThe solution was stirred for 2h in 1M hydrochloric acid at 650rpm for activation. The slurry was then washed with deionized water to pH 6 and then dried in a vacuum oven at 105 ℃ to constant weight, and the dried PAL was ground to a powder.
(4) Adding 0.1g of PALactivated in the step (3) into 60mL of Tirs-HCl buffer solution for ultrasonic treatment, then adding dopamine into the uniformly mixed suspension to enable the concentration to reach 0.05-1.5g/L, and stirring for 3 hours at room temperature; after the solutions were thoroughly mixed, they were washed to neutrality by centrifugation and dried under vacuum at 60 ℃ for 10 hours to obtain dopamine-modified PAL.
(5) And (3) taking 0.1g of dopamine-modified PAL in the step (4), adding 8.6mL of absolute ethyl alcohol and 1.4mL of ammonia water, carrying out ultrasonic treatment for 1 hour, then adding 10 mu L of Tetraethoxysilane (TEOS) and 0.12mL of 1H,1H,2H, 2H-perfluorodecyl triethoxysilane (PFDTES) into the mixed solution, stirring for 16 hours at room temperature, and then crushing for 40 minutes at 288W power by using an ultrasonic cell crusher to obtain a PAL suspension which is completely and uniformly mixed.
(6) At 0.2MPaN2Spraying 4mL of PAL suspension to the other side of the hydrophilic cortical basal membrane vertically placed by using a spray gun under the pressure, and drying in a vacuum oven at 80 ℃ for 6 hours to obtain the prepared Janus membrane.
The Janus film is shown on both sides in FIGS. 1 and 2, respectively. The hydrophilicity and hydrophobicity of the two surfaces of the membrane are tested, and the water contact angle of the hydrophobic surface is found to be above 160 degrees and is shown in figure 3; testing of hydrophilic surfaces with mineral oil the underwater oil contact angle of the hydrophilic surface is above 119 ° as shown in fig. 4, and the original film will be wetted by mineral oil under water.
Example 2
A preparation method of a Janus type distillation membrane with wetting resistance and oil stain resistance comprises the following steps:
(1) dopamine was added to a 10mM, pH 8.5, Tirs-HCl buffer solution to a dopamine solution concentration of 0.5 g/L. Placing a commercial PVDF membrane with the size of 3 x 8cm into a PDA solution to vibrate under the conditions of 100r/min and the temperature of 25 ℃, so that the PDA is uniformly attached to the surface of the membrane;
(2) washing the surface of the membrane with deionized water for at least three times to obtain a hydrophilic skin layer base membrane;
(3) and adding 0.1g of CNT into 50mL of Tirs-HCl buffer solution for ultrasonic treatment, then adding dopamine into the uniformly mixed suspension to enable the concentration to reach 0.05-1.5g/L, stirring for 3 hours at room temperature, after the solution is fully mixed, centrifuging and washing the solution to be neutral, and drying the solution in vacuum at 60 ℃ for 10 hours to obtain the dopamine modified CNT.
(4) 0.1g dopamine-modified CNT is taken and added into 50mL toluene for ultrasonic treatment for 30 minutes, then 10 μ L Tetraethoxysilane (TEOS), 0.12mL 1H,1H,2H, 2H-perfluorodecyl triethoxysilane (PFDTES) are added into the mixed solution, stirred for 15 hours at room temperature, and then crushed for 40 minutes under 288W power by an ultrasonic cell crusher to obtain a CNT suspension which is mixed completely and uniformly.
(5) At 0.2MPaN2And (3) spraying 4mL of CNT suspension liquid to the other side of the hydrophilic skin layer basement membrane which is vertically arranged by using a spray gun under the pressure, and then putting the CNT suspension liquid into a vacuum oven at the temperature of 80 ℃ for drying for 6 hours to obtain the prepared Janus membrane.
Example 3
A preparation method of a Janus type distillation membrane with wetting resistance and oil stain resistance comprises the following steps:
(1) dopamine was added to a 10mM, pH 8.5, Tirs-HCl buffer solution to a dopamine solution concentration of 0.5 g/L. Placing a commercial PP film with the size of 3 x 8cm into a PDA solution to vibrate under the conditions of 100r/min and the temperature of 25 ℃, so that the PDA is uniformly attached to the surface of the film.
(2) Washing the surface of the membrane with deionized water for at least three times to obtain a hydrophilic skin layer base membrane;
(3) adding 0.1g of CNF into 50mL of Tirs-HCl buffer solution for ultrasonic treatment, then adding dopamine into the uniformly mixed suspension until the concentration reaches 0.05-1.5g/L, and stirring at room temperature for 3 hours. After the solution was thoroughly mixed, it was washed to neutrality by centrifugation. And dried at 60 ℃ for 10 hours under vacuum to obtain dopamine-modified CNF.
(4) And adding 8.6mL of absolute ethyl alcohol and 1.4mL of ammonia water into the dopamine-modified CNF, and carrying out ultrasonic treatment for 1 hour. Next, 10. mu.L of Tetraethoxysilane (TEOS), 0.12mL of 1H,1H,2H, 2H-Perfluorodecyltriethoxysilane (PFDTES) was added to the mixture, stirred at room temperature for 20 hours, and then disrupted with an ultrasonic cell disruptor at 300W power for 40 minutes to give a CNF suspension which was well mixed.
(5) And (3) spraying 4mL of CNF suspension onto the other side of the hydrophilic cortical basal membrane which is vertically arranged by using a spray gun, and then putting the CNF suspension into a vacuum oven at 80 ℃ for drying for 6 hours to obtain the prepared Janus membrane.
Examples of the experiments
Membrane distillation experiments were performed using the Janus membranes prepared in example 1.
This example uses a direct contact membrane distillation procedure to evaluate the membrane. The hot side adopts 3.5 wt.% sodium chloride aqueous solution (simulating seawater salinity) at 65 ℃, the cold side is deionized water at 25 ℃, the flow rates of the two sides are controlled at 0.5L/min, and the effective membrane area is 24cm2. Normalized flux (Normalized flux) as J/J0Calculation was performed where J is the real-time flux LMH (L/m)2/h)，J0Is the flux LMH (L/m) when the initial membrane flux is stable2H). The results are shown in fig. 5, the membrane has good stability within 20 hours of operation, the salt rejection rate is close to 100%, and the pure water flux remains substantially stable.
Wetting resistance test of the film: deionized water with hot side of 65 deg.C and cold side of 25 deg.C, flow rate of both sides controlled at 0.5L/min, effective membrane area of 24cm2. Initially, 0.1mM SDS was added to a 3.5 wt% NaCl salt solution, and the system was run for 2h and then warmedSDS was added to the side so that the concentration of SDS in the solution was 0.2mM, and then SDS was added to the hot side every 2 hours of operation of the system so that the concentration of SDS in the solution was 0.3mM, 0.4 mM. The pure water flux and salt rejection of the original PTFE membrane and the prepared Janus membrane were tested in the same manner. The results of the two film tests are shown in figure 6. Both membranes had near 100% salt rejection over 8 hours of operation, but the pure water flux of the modified membrane was higher than that of the original membrane.
Anti-oil testing of the membrane: deionized water with hot side of 65 deg.C and cold side of 25 deg.C, flow rate of both sides controlled at 0.5L/min, effective membrane area of 24cm2. 80mg of mineral oil and 1mL of TWEEN80 were added to 1000mL of 3.5% NaCl solution, stirred for 5 minutes at 10000rpm with a homogenizer, and then subjected to ultrasonic treatment for 10 minutes to obtain an oil-water mixture, and the mixture was used as a feed solution to test the pure water flux and salt rejection of the prepared Janus film, and the results are shown in FIG. 7. The original film is not resistant to being wetted by mineral oil under water, and oil drops can directly wet the film. The Janus membrane has stable flux within 6 hours of operation, and the salt rejection rate is close to 100%.
Claims (10)
1. A Janus type distillation membrane with wetting resistance and oil stain resistance comprises a base membrane, wherein one side of the base membrane is a hydrophilic skin layer, the other side of the base membrane is a fully-hydrophobic skin layer, and the hydrophilic skin layer is a poly-dopamine layer; the whole hydrophobic cortex layer is a PAL layer modified by dopamine.
2. A preparation method of a Janus type distillation membrane with wetting resistance and oil stain resistance comprises the following steps:
the first step is to prepare a hydrophilic skin layer:
placing the basement membrane into a dopamine buffer solution to vibrate so that polydopamine is uniformly attached to the surface of the membrane, and then washing with deionized water to obtain a hydrophilic cortex basement membrane;
step two, preparing a fully hydrophobic skin layer:
(1) adding the all-hydrophobic layer material into a Tirs-HCl buffer solution for ultrasonic treatment to obtain a suspension, adding dopamine into the suspension, stirring and reacting at room temperature for 1-4 hours, washing a product after reaction to be neutral, and drying to obtain a dopamine-modified all-hydrophobic layer material;
(2) adding absolute ethyl alcohol and ammonia water or single toluene into a dopamine-modified all-hydrophobic material, ultrasonically mixing uniformly, adding Tetraethoxysilane (TEOS) and a fluorinating agent, fluorinating at room temperature, and ultrasonically crushing to obtain a uniformly mixed all-hydrophobic material suspension;
step three, preparing Janus type distillation membrane
And spraying the uniformly mixed all-hydrophobic material suspension on the other side of the hydrophilic skin layer base membrane prepared in the first step, and drying to obtain the Janus type distillation membrane with wetting resistance and oil stain resistance.
3. The method according to claim 2, wherein the concentration of dopamine in the PDA buffer solution is 0.125-0.5g/L, the PDA buffer solution is a buffered solution of dopamine in Tirs-HCl, the buffered solution of Tirs-HCl is 10mM, and the pH is 8.5.
4. The preparation method according to claim 2, wherein the basement membrane is a PTFE membrane, a PVDF membrane or a PP membrane, the size of the basement membrane is 3 x 8cm, and more preferably, the basement membrane is a PTFE membrane, the shaking speed of the membrane in the dopamine PDA buffer solution is 50-300r/min, the temperature is 20-30 ℃, and the shaking time is 3-6 hours.
5. The preparation method according to claim 2, wherein in the second step (1), the all-hydrophobic layer material is one of attapulgite PAL, Carbon Nanotube (CNT) or nano-Cellulose (CNF); most preferably, in the second step (1), the all-hydrophobic layer material is attapulgite PAL.
6. The preparation method according to claim 5, wherein in the second step (1), when the all-open layer material is attapulgite PAL, the attapulgite PAL is activated, then added into the Tirs-HCl buffer solution, the attapulgite PAL activation is that the attapulgite PAL is added into the hydrochloric acid solution and stirred for activation, the deionized water is washed after the activation until the pH value is 6, then the attapulgite PAL is dried in a vacuum oven to constant weight, and the attapulgite PAL is ground into powder, wherein the attapulgite PAL in the hydrochloric acid solutionThe concentration is 0.1 g/mL; the concentration of the hydrochloric acid solution is CHCl1 mol/L; the stirring speed is 650 rpm; the drying temperature was 105 ℃.
7. The process according to claim 2, wherein in the second step (1), the concentration of the all-phobic layer material in the suspension is 0.001-0.002g/L, preferably the concentration of the all-phobic layer material in the suspension is 0.0017 g/L; after adding dopamine, the concentration of the dopamine in the suspension is 0.05-1.5 g/L; drying was carried out at 60 ℃ for 10 hours under vacuum.
8. The preparation method according to claim 2, wherein in the second step (2), the mass-to-volume ratio of the dopamine-modified all-hydrophobic layer material to the absolute ethyl alcohol is as follows: (0.1-0.3) and (8-10), wherein the unit is g/mL, and the mass-volume ratio of the dopamine modified all-hydrophobic layer material to ammonia water is as follows: (0.1-0.3): (0.5-3), unit, g/mL; the mass-volume ratio of the dopamine modified all-hydrophobic layer material to Tetraethoxysilane (TEOS) is as follows: (0.1-0.3): (5-15), unit, g/microliter.
9. The process according to claim 2, wherein in the second step (2), the fluorinating agent is 1H,1H,2H, 2H-Perfluorodecyltriethoxysilane (PFDTES), and the volume ratio of 1H,1H,2H, 2H-Perfluorodecyltriethoxysilane (PFDTES) to absolute ethanol is: (0.1-0.3):(8-10).
10. The method according to claim 2, wherein in the second step (2), the ultrasonic disruption is performed using a cell disruptor at a power of 288W for a disruption time of 40 minutes.
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| CN202010430388.4A CN111744369A (en) | 2020-05-20 | 2020-05-20 | Janus type distillation membrane with wetting resistance and oil stain resistance as well as preparation method and application thereof |
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| CN113564918A (en) * | 2021-07-05 | 2021-10-29 | 东莞理工学院 | Janus fabric with liquid drop one-way permeability and preparation method thereof |
| CN113975983A (en) * | 2021-09-26 | 2022-01-28 | 广东工业大学 | Super-hydrophilic/hydrophobic thin-layer composite membrane and preparation and application thereof |
| CN114085409A (en) * | 2021-11-30 | 2022-02-25 | 中国科学院生态环境研究中心 | Super-hydrophobic and super-oleophobic membrane and preparation method thereof |
| CN115138221A (en) * | 2022-07-26 | 2022-10-04 | 南京工业大学 | Application of Janus ceramic membrane in dispersion strengthening gas distribution process and preparation method |
| CN115228305A (en) * | 2022-06-20 | 2022-10-25 | 深圳高性能医疗器械国家研究院有限公司 | Janus film and preparation method thereof |
| CN115382403A (en) * | 2022-09-06 | 2022-11-25 | 南京理工大学 | Composite membrane with volatile substance interception characteristic for membrane distillation and preparation method thereof |
| CN115475526A (en) * | 2022-09-21 | 2022-12-16 | 武汉大学 | In-situ preparation method of hydrophilic and oleophobic asymmetric distillation membrane with controllable hydrophilic layer thickness |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113564918A (en) * | 2021-07-05 | 2021-10-29 | 东莞理工学院 | Janus fabric with liquid drop one-way permeability and preparation method thereof |
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| CN114085409A (en) * | 2021-11-30 | 2022-02-25 | 中国科学院生态环境研究中心 | Super-hydrophobic and super-oleophobic membrane and preparation method thereof |
| CN115228305A (en) * | 2022-06-20 | 2022-10-25 | 深圳高性能医疗器械国家研究院有限公司 | Janus film and preparation method thereof |
| CN115138221A (en) * | 2022-07-26 | 2022-10-04 | 南京工业大学 | Application of Janus ceramic membrane in dispersion strengthening gas distribution process and preparation method |
| CN115382403A (en) * | 2022-09-06 | 2022-11-25 | 南京理工大学 | Composite membrane with volatile substance interception characteristic for membrane distillation and preparation method thereof |
| CN115475526A (en) * | 2022-09-21 | 2022-12-16 | 武汉大学 | In-situ preparation method of hydrophilic and oleophobic asymmetric distillation membrane with controllable hydrophilic layer thickness |
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