CN110449035B - Oil-water separation membrane and preparation method thereof - Google Patents

Oil-water separation membrane and preparation method thereof Download PDF

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CN110449035B
CN110449035B CN201910770122.1A CN201910770122A CN110449035B CN 110449035 B CN110449035 B CN 110449035B CN 201910770122 A CN201910770122 A CN 201910770122A CN 110449035 B CN110449035 B CN 110449035B
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oil
water separation
ceramic powder
separation membrane
ceramic
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CN110449035A (en
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刘伟
黄梅鹏
杨高
梁坚伟
何荣煊
鲁欣欣
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Guangdong University of Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
    • B01D17/02—Separation of non-miscible liquids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
    • B01D17/08—Thickening liquid suspensions by filtration
    • B01D17/085—Thickening liquid suspensions by filtration with membranes
    • 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
    • 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
    • B01D67/0039—Inorganic membrane manufacture
    • B01D67/0041—Inorganic membrane manufacture by agglomeration of particles in the dry state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • 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
    • B01D69/10—Supported membranes; Membrane supports
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/24—Mechanical properties, e.g. strength
    • 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 belongs to the technical field of inorganic nonmetallic materials, and particularly relates to an oil-water separation membrane and a preparation method thereof. The application provides a preparation method of an oil-water separation membrane, which comprises the following steps: step 1, mixing ceramic powder, a solvent and an acid-base regulator to obtain ceramic powder slurry; step 2, mixing and reacting the ceramic powder slurry with organic acid to obtain a first reactant; step 3, mixing the first reactant, a surfactant and an organic solvent for emulsification to obtain a second reactant; step 4, sequentially molding and drying the second reactant to obtain a ceramic membrane biscuit; step 5, sintering the ceramic membrane biscuit to obtain a porous ceramic membrane; and 6, arranging a hydrophobic layer on the surface of the oil-water separation ceramic membrane to obtain the oil-water separation membrane. The invention provides the oil-water separation membrane which has the advantages of high strength of a micro-nano composite structure, difficult abrasion and falling of micro/nano particles, reusability and no pollution.

Description

Oil-water separation membrane and preparation method thereof
Technical Field
The invention belongs to the technical field of inorganic nonmetallic materials, and particularly relates to an oil-water separation membrane and a preparation method thereof.
Background
In recent years, with the attention of our country on environmental protection and the direction of making a good home, people's environmental awareness is generally improved, and corresponding environmental protection industry policies are coming out one after another. Among them, the application requirements of oil-water separation are particularly urgent, such as the oil-water separation problem caused by the oil leakage accident of ocean remote wheels, the separation of oil/water two-phase mixture in organic chemistry laboratories, and the recovery treatment of waste oil in the kitchen industry. Generally, the current separation methods mainly include physical methods, biological methods, chemical methods, electrochemical methods, and the like, wherein the physical separation methods further include gravity separation, centrifugal separation, filtration separation, and the like. The traditional oil-water separation technologies generally have the advantages of simple equipment, low single treatment cost, simple operation method and the like, but on the other hand, the methods generally have the defects of low separation efficiency, large occupied area and the like, and the oil stain recovery efficiency is low, so that the increasingly severe environmental protection requirements are difficult to meet.
In recent years, the progress of material science has greatly promoted the technical development in the field of oil-water separation. For example, a novel oil-water separation membrane material constructed by utilizing the special wettability of the surface of the material has been one of the research focuses in the field of surface interface materials, has gradually become an important method for cleaning floating oil on the water surface and separating oil from water, and is expected to play a crucial role in solving the problems of water pollution and the like. Generally, compared with the traditional separation method, the oil-water separation method by utilizing the special wettability of the material has the advantages of stable material property, good separation effect and high separation efficiency.
In general, oil-water separation materials can be classified into two types according to the material properties: 1) superhydrophobic-superoleophilic separation membranes, also known as "oil-removing" separation membranes; 2) superhydrophilic-superoleophobic separation membranes, also known as "dewatering" separation membranes. The oil-removing type separation membrane is widely applied due to the advantages of strong oil-water selectivity and good separation effect, but the oleophylic nature of the membrane causes the following problems in the use process of the material: is extremely easy to be polluted by oil, and the secondary pollution to the environment is often caused by the disposal or incineration of the used oil. Therefore, how to develop the oil-water separation membrane material of the super-hydrophobic-super-oleophylic separation membrane which is green, environment-friendly, reusable, simple in preparation process and convenient for industrial production is of great importance.
With the increasing urgency of industrial development and ecological environment protection, ecological civilization construction has become a strategic task at the national level, and oil-water mixtures discharged by industry are the first killers for ecologically destroying the ecological environment. Therefore, how to purify industrial wastewater and oil-water mixture has been a popular research topic in academia and industry.
The technical defects of the existing oil-removing type (super-hydrophobic-super-oleophylic) oil-water separation membrane mainly comprise:
1) the process flow is complex, and the controllability of industrial production is not strong, for example, in patent CN201810742339.7, the oil-water separation membrane is prepared by adopting a complex process of electrostatic spinning and layer-by-layer self-assembly, the process is various, and the flow is complex; 2) in the existing process technology, such as coating, crystal growth, electrodeposition and the like, the prepared micro-nano composite structure is generally unstable, and micro/nano particles are easy to wear and fall off; 3) the polymer is adopted as a main material, so that the problems of low material reuse degree, easy environmental pollution and the like exist.
In conclusion, the oil-water separation membrane in the prior art has the technical defects that the micro-nano composite structure is generally unstable, micro/nano particles are easy to wear and fall off, the reuse degree is low, and the environment is easy to pollute.
Disclosure of Invention
The first aspect of the invention provides an oil-water separation membrane which has high strength of a micro-nano composite structure, is not easy to wear and drop micro/nano particles, can be repeatedly used and has no pollution and can perform oil-water separation.
The second aspect of the invention provides a preparation method of the oil-water separation membrane which has simple preparation process flow and strong controllability of industrial production and can perform oil-water separation.
In view of this, the present application provides a method for preparing an oil-water separation membrane, including the following steps:
step 1, mixing ceramic powder, a solvent and an acid-base regulator to obtain ceramic powder slurry;
step 2, mixing and reacting the ceramic powder slurry with organic acid to obtain a first reactant;
step 3, mixing the first reactant, a surfactant and an organic solvent for emulsification to obtain a second reactant;
step 4, sequentially molding and drying the second reactant to obtain a ceramic membrane biscuit;
step 5, sintering the ceramic membrane biscuit to obtain a porous ceramic membrane;
and 6, arranging a hydrophobic layer on the surface of the oil-water separation ceramic membrane to obtain the oil-water separation membrane.
Preferably, in step 1, the pH value of the solvent is adjusted by adding an acid-base modifier to increase the dissolution rate of the ceramic powder in the solvent, and the pH of the solvent is lower than 7, so that the dissolution rate and the solubility of the ceramic powder in the solvent can be increased, and a small amount of solvent can be blended into a large amount of ceramic powder under acidic conditions.
Preferably, the pH adjusting agent is selected from strong acids such as hydrochloric acid, sulfuric acid and nitric acid, weak acids and strong bases such as sodium hydroxide. More preferably, the pH adjusting agent is selected from hydrochloric acid and sodium hydroxide.
Preferably, in the step 1, the pH range is 3.0-7.0.
More preferably, in the step 1, the pH range is 4.3-6.0.
Preferably, in step 1, the pH is 5.3.
Preferably, in step 1, the ceramic powder is selected from one or more of alumina, zirconia toughened alumina ceramic, boron nitride, silicon nitride and aluminum nitride; the solvent is selected from deionized water or/and alcohol.
Preferably, in step 1, the solid phase content of the ceramic powder in the ceramic powder slurry is 5 vol% to 80 vol%.
More preferably, in step 1, the solid phase content of the ceramic powder in the ceramic powder slurry is 30 vol% to 60 vol%.
Preferably, in the step 1, the mixing is ball milling mixing, the ball milling time is 0.5-24 h, and the rotation speed of the ball milling is 200-600 r/min.
More preferably, in the step 1, the ball milling time is 5-12 h, and the rotation speed of the ball milling is 250-350 r/min.
Wherein, the pH regulator is used for regulating pH to form chemical coordination reaction, and ball milling mixing is used for breaking up agglomeration so as to provide dispersibility of the ceramic powder slurry.
Preferably, in step 2, the organic acid is selected from propionic acid or/and pentanoic acid; the addition amount of the organic acid is as follows: adding 0.01mmol-0.1mmol of the organic acid into each gram of the ceramic powder; the mixing time of the mixing reaction is 2-10 minutes.
Preferably, in the step 2, the ceramic powder slurry and the organic acid are mixed and reacted to form a stirring mixture, the stirring time is 0.05-0.5 h, and the stirring rotation speed is 200-300 r/min.
It should be noted that, the present application finds that the modification treatment of the ceramic powder is realized by mixing and reacting the ceramic powder slurry with an organic acid to modify the ceramic powder, so that the carboxyl functional group is grafted on the surface of the ceramic powder slurry, and the subsequent emulsification into the second reactant in the form of micro-droplets is also facilitated.
Preferably, in step 3, the surfactant is selected from one or more of polyvinyl alcohol, polyethylene glycol, sodium stearyl sulfate and sodium stearate; the organic solvent is selected from one or more of n-octane, hexadecane and n-hexane.
Preferably, in step 3, the addition amount of the polyvinyl alcohol in the second reactant is: adding 0.1-10 wt% of polyvinyl alcohol per gram of the solvent; the volume percentage of the organic solvent in the second reactant is less than or equal to 95 percent, wherein the solvent is deionized water or/and alcohol.
It should be noted that, the present application finds that the pore size of the porous structure of the oil-water separation membrane can be controlled by controlling the volume percentage of the polyvinyl alcohol in the second reactant through the through holes, and specifically, the pore size of the oil-water separation membrane is smaller as the proportion of the polyvinyl alcohol in the second reactant is larger.
Preferably, in the step 3, the mixing of the first reactant, the surfactant and the organic solvent includes stirring and mixing, and the stirring time is 0.05h to 0.5 h.
Please refer to fig. 11, fig. 11 is a three-dimensional simulation diagram of the oil-water separation membrane provided by the present application before sintering, which shows that a first reactant, a surfactant and an organic solvent are mixed and then emulsified and foamed, the surfactant divides the organic solvent (for example, one or more of n-octane, hexadecane and n-hexane) into a plurality of oil droplets, the ceramic powder coats the oil droplets to form a self-assembly (the ceramic powder coats the organic solvent), and pores occupied by the organic solvent after the organic solvent is volatilized or/and evaporated form pores of the oil-water separation membrane, that is, the first reactant is ceramic powder with a surface modified with carboxyl functional groups, the coating effect on the micro-droplets realizes the self-assembly function, the micro-droplets of the ceramic powder coating organic solvent are formed, and the regular three-dimensional network porous hollow structure is formed after the organic solvent in the micro-droplets is volatilized.
Specifically, under the action of a surfactant and an organic solvent, the ceramic powder modified with carboxyl functional groups on the surface is self-assembled in ceramic powder slurry to form regularly arranged honeycomb-shaped micron-scale oil droplet groups, and the emulsified ceramic slurry is molded and sintered.
Preferably, in step 4, the molding includes conventional die molding, 3D printing molding, slip casting, pour casting, die casting or tape casting.
Wherein, the preparation of the ceramic membrane with a complex shape can be realized by using 3D printing and forming.
Preferably, in step 4, the 3D printing and forming is free direct write forming 3D printing and forming.
Preferably, in step 4, the drying is performed to remove the solvent or liquid substance, such as oil droplets, formed by the second reactant; drying for subsequent sintering; the drying is natural drying or oven drying; the natural drying time is 72 h.
Preferably, in the step 5, the sintering temperature is 1000-1700 ℃; the sintering temperature is below 800 ℃, the temperature rising speed of sintering is not more than 10 ℃/min, the sintering temperature is above 800 ℃, the temperature rising speed of sintering is not more than 5 ℃/min, and the temperature is kept at the highest temperature for two hours.
More preferably, in the step 5, the sintering temperature is 1200-1700 ℃; the sintering temperature is below 800 ℃, the temperature rising speed of sintering is not more than 10 ℃/min, the sintering temperature is above 800 ℃, the temperature rising speed of sintering is not more than 5 ℃/min, and the temperature is kept at the highest temperature for two hours.
Preferably, in step 6, the hydrophobic layer is made of one or more materials selected from polydimethylsiloxane, stearic acid, polytetrafluoroethylene, polysilazane and trimethoxy (1H, 2H-heptadecafluorodecyl) silane.
More preferably, in step 6, the material of the hydrophobic layer is selected from polydimethylsiloxane.
Preferably, the method for providing a hydrophobic layer on the surface of the ceramic membrane for oil-water separation includes: vapor deposition methods, physical coating or immersion methods.
The surface of the oil-water separation ceramic membrane is provided with a hydrophobic layer, so that the oil-water separation ceramic membrane is a super-hydrophobic-super-oleophylic oil-water separation membrane which water can not pass through and oil can pass through.
Wherein the vapor deposition temperature is 200-300 ℃.
Preferably, the vapor deposition temperature is 235 ℃.
Wherein the temperature of the physical coating and soaking is room temperature.
The invention discloses an oil-water separation membrane in a second aspect, which comprises the oil-water separation membrane prepared by the preparation method.
The preparation method comprises the steps of taking deionized water as a solvent, taking alumina ceramic powder as a powder material, gradually adding 58 vol% of powder in an ultrasonic environment and a stirring environment, gradually adjusting the pH value by using HCl (hydrochloric acid) to be lower than 5.0, carrying out ball milling and mixing, and setting ball milling treatment time and rotation speed to be 12h and 300r/min respectively; then, diluting the suspension subjected to ball milling with deionized water to obtain a slurry sample with the concentration of 46 vol%, taking propionic acid as an organic acid molecule, and adding the propionic acid under vigorous stirring; then, adding a surfactant PVA and an organic solvent n-octane, adding the PVA under a stirring state, uniformly mixing, adding the n-octane, and stirring and foaming for 10 min; the molding preparation of the ceramic biscuit is realized by adopting mold molding, and natural drying is adopted as a drying condition for 72 hours; demoulding and then sintering at 1550 ℃; and after sample grinding, selecting PDMS as hydrophobic molecules, and uniformly coating and plating the hydrophobic molecules on the surface and in the ceramic membrane by adopting a vapor deposition method.
According to the technical scheme, the method has the following advantages:
the application provides an oil-water separation membrane, the surface of ceramic powder is modified and grafted with carboxyl functional groups, the self-assembly of the modified ceramic powder under a specific environment is facilitated, namely, a surfactant divides an organic solvent (such as one or more of n-octane, hexadecane and n-hexane) into countless oil drops, the ceramic powder coats the oil drops to form the self-assembly (the ceramic powder coats the organic solvent), and pores occupied by the organic solvent after the organic solvent is volatilized or/and evaporated form pores of the oil-water separation membrane. Meanwhile, the preparation method of the oil-water separation membrane is simple, the aperture of the oil-water separation membrane can be controlled by controlling the addition amount of the raw materials, and the controllability of industrial production is strong. Experiments show that the oil-water separation membrane has high oil-water separation efficiency and high compressive strength, so that the oil-water separation membrane has high structural strength, and micro-nano particles on the surface are not easy to wear and can not fall off; the oil-water separation membrane has a porous structure, in particular to a regular three-dimensional grid porous hollow structure which is orderly arranged; the structure is three-dimensionally controllable, and the arbitrary size proportion of the pore diameter and the through hole in the porous structure can be realized through the addition amount of the raw materials; and the oil-water separation membrane can be reused and has no pollution.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.
FIG. 1 is a graph of a superhydrophobic contact angle characterization test of the oil-water separation membrane of example 1 provided herein;
FIG. 2 is a graph of an ultra-lipophilic contact angle characterization test for the oil-water separation membrane of example 1 provided herein;
FIG. 3 is a schematic diagram illustrating the wettability of the oil-water separation membrane in example 1;
FIG. 4 is a physical diagram of the oil-water separation wettability of the product of comparative example 1 provided herein;
fig. 5 is a schematic diagram of an oil-water separation test of the oil-water separation membrane of example 1, where a is to drop oil drop 1 and water drop 2 onto the oil-water separation membrane of example 1 at the same time, b is to pass the oil drop 1 through the oil-water separation membrane of example 1, the water drop 2 does not pass through the oil-water separation membrane of example 1, and c is to stop the water drop 2 on the surface of the oil-water separation membrane of example 1 in a drop shape;
FIG. 6 is a scanning electron micrograph of an oil-water separation membrane (PVA1 wt%) of an example of the present application, at 100 times magnification;
FIG. 7 is a scanning electron micrograph of an oil-water separation membrane (PVA1 wt%) according to an example of the present application, at a magnification of 200 times;
FIG. 8 is a scanning electron micrograph of an oil-water separation membrane (PVA1 wt%) of an example of the present application, which is magnified 400 times;
FIG. 9 is a scanning electron micrograph of an oil-water separation membrane (PVA1 wt%) of an example of the present application, which is magnified 1200 times;
FIG. 10 is a scanning electron micrograph of an oil-water separation membrane (PVA1 wt%) according to an example of the present application, magnified 10000 times;
fig. 11 is a three-dimensional simulation diagram of the oil-water separation membrane provided by the present application before sintering.
Detailed Description
The invention provides an oil-water separation membrane and a preparation method thereof, which effectively solve the technical defects that the micro-nano composite structure of the oil-water separation membrane in the prior art is generally unstable, micro/nano particles are easy to wear and fall off, the reuse degree is low, and the environment is easy to pollute.
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Wherein, the raw materials used in the following examplesAre all sold in the market or made by the user; ceramic powder: alpha-Al2O3Purchased from daming alumina TM-DAR (particle size 0.2 um; density 3.98 g/ml; japanese daming chemistry); propionic acid: chemical formula is CH3CH2COOH, purity 99%, MW 74.08, Bailingwei science and technology; polyvinyl alcohol: PVA with alcoholysis degree of 99.0-99.4 mol%; viscosity: 12.0-16.0 mPa.s; MW is 44.05; aladdin reagent Inc.; n-octane: c8H18Purity 96%, MW 114.23; aladdin reagent Inc.; polydimethylsiloxane: PDMS, 184 silicone rubber, SYLGARD, dow corning; polyethylene glycol: HO (CH)2CH2O)nH average Mn 6000, Aladdin reagent company; methyl blue: molecular formula C37H27N3Na2O9S3MW is 799.8 mcelin; oil red O: oil Red O, dimethylphenyl, having the formula C26H24N4O, MW 408.495, Mecang.
SEM used scanning electron microscope SU 8220, Hitachi, Japan.
The Contact Angle measurement adopts XG-CAM Contact Angle measuring instrument, Contact Angle Meter Shanghai Xuan anew Industrie industry equipment Co.
The density adopts an Archimedes drainage method, a constant temperature heating table, an analytical balance and a PTX-FA electronic analytical balance; HZ & HUAZHI, HZ electronics ltd, kang usa.
The sintering experiment was carried out using a muffle furnace model TSX1700, West Nite (Beijing) electric furnace Co.
The polishing experiment used MP-2B grinding and polishing machine, manufactured by Leizhou Mitsu instruments testing apparatus Co.
Example 1
The embodiment of the application provides an oil-water separation membrane, which comprises the following specific preparation steps:
preparation of ceramic powder slurry
1. According to the addition amount of the raw materials in the table 1, alpha-Al is gradually added into deionized water under the action of stirring and ultrasound2O3And (3) adjusting the pH of the powder by using hydrochloric acid to finally prepare an alumina suspension with the solid content of 53.7 vol% and the pH of 5.36. Wherein, the emulsified hairAfter soaking, the deionized water content was 16.2 vol%, α -Al2O3The powder content was 27.6 vol%.
2. Adding alumina ball grinding balls according to the ball-to-material ratio of 1:1, wherein the ball grinding ball ratio of phi 10mm to phi 5mm is 1: 1. Ball milling was carried out overnight (rotation speed 300r/min) using a planetary ball mill.
3. And removing the ball grinding balls after ball milling to obtain ceramic powder slurry.
Secondly, modification treatment of ceramic powder slurry
1. Adding deionized water into the ceramic powder slurry obtained in the first step to dilute until the solid content is 46 vol%;
0.04mmol of propionic acid per gram of alumina powder was added dropwise with stirring. And stirring to realize modification treatment on the ceramic powder to obtain a first reactant.
Thirdly, emulsification foaming treatment
1. Dividing the first reactant in the second step into 6 parts, adding polyvinyl alcohol into each part of the first reactant, and respectively marking as: 0wt% of PVA, 1wt% of PVA, 2 wt% of PVA, 3 wt% of PVA, 4 wt% of PVA and 10wt% of PVA, namely 0wt% of PVA is 0 adding amount of polyvinyl alcohol, 1wt% of PVA is 0.01g of polyvinyl alcohol added to each gram of deionized water in the first reactant, 2 wt% of PVA is 0.02g of polyvinyl alcohol added to each gram of deionized water in the first reactant, 3 wt% of PVA is 0.03g of polyvinyl alcohol added to each gram of deionized water in the first reactant, 4 wt% of PVA is 0.04g of polyvinyl alcohol added to each gram of deionized water in the first reactant, and 10wt% of PVA is 0.1g of polyvinyl alcohol added to each gram of deionized water in the first reactant; then, 70 vol% of n-octane was added thereto in a volume percentage, and the mixture was stirred and foamed for 7 minutes. The direct octane is completely melted into the process emulsion in the suspension. That is, the ratio of the volume of the first reactant to the volume of the added n-octane was 3: and 7, obtaining second reactants of polyvinyl alcohol with different concentrations, namely PVA 0wt%, PVA 1wt%, PVA2 wt%, PVA3 wt%, PVA4 wt% and PVA10 wt%, wherein the pH value of the emulsion is adjusted to 4.4 by NaOH solution under stirring according to needs until the viscosity is suitable for 3D printing.
Fourthly, forming treatment
1. And taking each second reactant in the previous step, and realizing molding and drying treatment of the macroscopic ceramic biscuit by virtue of 3D printing molding equipment, wherein the drying is natural drying at room temperature to obtain ceramic membrane biscuits which are respectively marked as PVA 0wt%, PVA 1wt%, PVA2 wt%, PVA3 wt%, PVA4 wt% and PVA10 wt%.
Fifthly, sintering
1. Sintering each ceramic membrane biscuit in the last step to obtain a porous ceramic membrane, which is respectively marked as PVA 0wt%, PVA 1wt%, PVA2 wt%, PVA3 wt%, PVA4 wt% and PVA10 wt%; the sintering parameters are as follows: the sintering temperature is below 800 ℃, and the temperature is increased at the speed of 10 ℃/min; the temperature is increased at 1550 ℃ in 800-.
Sixthly, oil-water separation ceramic membrane hydrophobic treatment
1. Polishing each porous ceramic membrane in the previous step by using a diamond grinding disc of 200 meshes to manufacture a filtering ceramic membrane sample with the thickness of 0.8mm, carrying out vapor deposition at 235 ℃ (each filtering ceramic membrane sample is placed in a culture dish 1, PDMS liquid glue is placed in the culture dish 2, the culture dishes 1 and 2 are covered by a beaker in an inverted mode, the mouth of the beaker is properly sealed by tin foil paper, then the whole filter ceramic membrane sample is placed in a muffle furnace to be slowly heated to 235 ℃ and is kept warm for 8 hours, PDMS in the culture dish 2 forms steam, a PDMS molecular layer is evaporated and deposited on the surface of the filtering ceramic membrane sample, the vapor deposition parameter is that the temperature is raised to 235 ℃ at the speed of 7.8 ℃/min, the temperature is kept at 235 ℃ for 8 hours, then, the furnace cooling is carried out, a layer of PDMS (polydimethylsiloxane) molecules is plated on the surface of the sample to realize hydrophobic treatment, and 6 separation membranes are obtained and are respectively marked as PVA 0wt%, PVA 1wt%, oil water and water, PVA2 wt%, PVA3 wt%, PVA4 wt% and PVA10 wt%.
TABLE 1
Figure BDA0002173293140000091
Figure BDA0002173293140000101
The properties of the average pore diameter, contact angle, oil-water separation efficiency and compressive strength of the 6 oil-water separation membranes obtained were measured, and the results are shown in table 2.
TABLE 2
Average pore diameter (μm) Contact angle (O) Oil-water separation efficiency (%) Compressive strength (MPa)
PVA0％ 137.5 147.64 99.87 Instability of the film
PVA1％ 18.0 152.85 99.86 51.136
PVA2％ 11.1 152.57 99.87 45.872
PVA3％ 15.5 152.47 99.87 44.752
PVA4％ 10.3 152.75 99.91 36.767
PVA10％ 7.8 153.35 99.91 25.608
As can be seen from table 2, when the polyvinyl alcohol aqueous solution with a concentration of 0wt% was added, the compressive strength of the oil-water separation membrane obtained was unstable, the average pore diameter of the oil-water separation membrane was too large, the pore distribution was not uniform, and the contact angle of oil droplets was too small. With the increase of the concentration of the polyvinyl alcohol, the average pore diameter of the oil-water separation membrane is smaller and smaller. The compressive strength is relatively high, the water contact angles are all higher than the super-hydrophobic boundary by 150 degrees, and the oil-water separation efficiency is all more than 99.8 percent.
As a result of scanning electron microscope examination of the oil-water separation membrane (PVA 1%) of the present example, fig. 6 is a scanning electron microscope image of the oil-water separation membrane (PVA1 wt%) of the present example at 100 times magnification, fig. 7 is a scanning electron microscope image of the oil-water separation membrane (PVA1 wt%) of the present example at 200 times magnification, fig. 8 is a scanning electron microscope image of the oil-water separation membrane (PVA1 wt%) of the present example at 400 times magnification, fig. 9 is a scanning electron microscope image of the oil-water separation membrane (PVA1 wt%) of the present example at 1200 times magnification, fig. 10 is a scanning electron microscope image of the oil-water separation membrane (PVA1 wt%) of the present example at 10000 times magnification, and as can be seen from fig. 6 to 10, the oil-water separation membrane (PVA1 wt%) of the present example has a regular three-dimensional grid porous hollow structure arranged in order, fig. 10 is a scanning electron microscope image at 10000 times, and the porous structure obtained by the self-assembly method of the present application is shown in a scanning electron microscope image at 10000 times, the crystal grains on the hole wall can be stacked into a firm hole shell which is precisely arranged, so that the high-strength compression-resistant performance is achieved on a macroscopic level, and the hole shell is of a porous structure, so that the hole shell has light weight and high strength.
Example 2
The super-hydrophobic and super-oleophilic characteristics of the oil-water separation membrane in embodiment 1 of the present application are determined, please refer to fig. 1-2, fig. 1 is a super-hydrophobic test chart of the oil-water separation membrane in embodiment 1 provided in the present application, fig. 2 is a super-oleophilic test chart of the oil-water separation membrane in embodiment 1 provided in the present application, and it can be known from fig. 1-2 that the oil-water separation membrane in embodiment 1 of the present application has super-hydrophobic and super-oleophilic characteristics.
Comparative example 1
The comparative example of the present application provides a control oil-water separation membrane, which was prepared in the same manner as in example 1 except that the hydrophobic treatment of step six of example 1 was not performed, and the remaining steps were the same as in example 1, to obtain the product of comparative example 1.
Example 3
Referring to fig. 5, fig. 5 is a schematic view of an oil-water separation test of the oil-water separation membrane of example 1 provided in the present application, in which fig. 5a shows that an oil drop 1 and a water drop 2 are simultaneously dropped onto the oil-water separation membrane of example 1, fig. 5b shows that the oil drop 1 passes through the oil-water separation membrane of example 1, the water drop 2 does not pass through the oil-water separation membrane of example 1, and fig. 5c shows that the water drop 2 stays on the surface of the oil-water separation membrane of example 1 in a drop shape. According to the flow chart of fig. 5, an oil-water separation test is further performed on the product of comparative example 1, and the actual results are shown in fig. 3 and fig. 4, fig. 3 is an actual graph of the product of example 1 provided in the present application after the oil-water separation test is performed on the oil-water separation membrane, fig. 4 is an actual graph of the product of comparative example 1 provided in the present application after the oil-water separation test is performed on the product, and it can be seen from fig. 3 to 4 that comparative example 1 obtained without performing the hydrophobic treatment of step six of example 1 does not have the oil-water separation performance.
The terms "first," "second," "third," "fourth," and the like in the description of the application and the above-described figures, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (8)

1. The preparation method of the oil-water separation membrane is characterized by comprising the following steps:
step 1, mixing ceramic powder, a solvent and an acid-base regulator to obtain ceramic powder slurry; the acid-base regulator is selected from hydrochloric acid, sulfuric acid, nitric acid or sodium hydroxide; the pH value of the solvent is adjusted by adding the acid-base regulator so as to improve the dissolving speed of the ceramic powder in the solvent;
step 2, mixing and reacting the ceramic powder slurry with organic acid to obtain a first reactant; the organic acid is selected from propionic acid or/and valeric acid; the addition amount of the organic acid is as follows: adding 0.01mmol-0.1mmol of the organic acid into each gram of the ceramic powder; the mixing time of the mixing reaction is 2-10 minutes; mixing the ceramic powder slurry with the organic acid for reaction, and modifying the ceramic powder to graft carboxyl functional groups on the surface of the ceramic powder slurry;
step 3, mixing the first reactant, a surfactant and an organic solvent for emulsification to obtain a second reactant; the surfactant is selected from one or more of polyvinyl alcohol, polyethylene glycol, sodium stearyl sulfate and sodium stearate; the organic solvent is selected from one or more of n-octane, hexadecane and n-hexane;
step 4, sequentially molding and drying the second reactant to obtain a ceramic membrane biscuit;
step 5, sintering the ceramic membrane biscuit to obtain a porous ceramic membrane;
and 6, arranging a hydrophobic layer on the surface of the oil-water separation ceramic membrane to obtain the oil-water separation membrane.
2. The preparation method according to claim 1, wherein in step 1, the ceramic powder is selected from one or more of alumina, zirconia toughened alumina ceramic, boron nitride, silicon nitride and aluminum nitride; the solvent is selected from deionized water or/and alcohol.
3. The method according to claim 1, wherein in step 1, the solid phase content of the ceramic powder in the ceramic powder slurry is 5 vol% to 80 vol%.
4. The method according to claim 1, wherein in step 3, the polyvinyl alcohol is added to the second reactant in an amount of: adding 0.1-10 wt% of polyvinyl alcohol per gram of the solvent; the volume percentage of the organic solvent in the second reactant is less than or equal to 95 percent.
5. The method of claim 1, wherein in step 5, the sintering temperature is 1000 ℃ to 1700 ℃; the sintering temperature is below 800 ℃, the temperature rising speed of sintering is not more than 10 ℃/min, the sintering temperature is above 800 ℃, the temperature rising speed of sintering is not more than 5 ℃/min, and the temperature is kept at the highest temperature for two hours.
6. The method according to claim 1, wherein in step 6, the hydrophobic layer is made of one or more selected from polydimethylsiloxane, stearic acid, polytetrafluoroethylene, polysilazane, and trimethoxy (1H,1H,2H, 2H-heptadecafluorodecyl) silane.
7. The production method according to claim 1, wherein the step of providing a hydrophobic layer on the surface of the oil-water separation ceramic membrane comprises: vapor deposition, physical coating or immersion.
8. An oil-water separation membrane comprising the oil-water separation membrane produced by the production method according to any one of claims 1 to 7.
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