CN109012236B - Casting membrane liquid, ultrafiltration membrane and method for preparing ultrafiltration membrane - Google Patents
Casting membrane liquid, ultrafiltration membrane and method for preparing ultrafiltration membrane Download PDFInfo
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- CN109012236B CN109012236B CN201810892619.6A CN201810892619A CN109012236B CN 109012236 B CN109012236 B CN 109012236B CN 201810892619 A CN201810892619 A CN 201810892619A CN 109012236 B CN109012236 B CN 109012236B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/56—Polyamides, e.g. polyester-amides
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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
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/145—Ultrafiltration
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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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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
Abstract
The invention provides a membrane casting solution, an ultrafiltration membrane and a method for preparing the ultrafiltration membrane. Wherein, the casting solution comprises: a polyamide; a pore-forming additive; and a solvent, wherein the relative molecular mass of the polyamide is 20 to 30 ten thousand. Therefore, the viscosity of the casting solution is proper, and the casting solution has almost no bubbles, thereby being beneficial to film formation.
Description
Technical Field
The invention relates to the technical field of membrane preparation, in particular to a membrane casting solution, an ultrafiltration membrane and a method for preparing the ultrafiltration membrane.
Background
The membrane separation technology mainly comprises four separation technologies of Reverse Osmosis (RO), Nanofiltration (NF), Ultrafiltration (UF) and Microfiltration (MF), wherein the ultrafiltration separation technology is widely applied to water treatment, medical industry, food industry and the like due to the advantages of low use pressure, large water yield, convenience in operation and the like, and has high development speed and wide prospect. The practical properties of ultrafiltration membranes, such as pressure resistance, high temperature resistance and acid and alkali resistance, which are currently widely used in ultrafiltration separation technology, are still to be improved.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a membrane casting solution, wherein an ultrafiltration membrane prepared by using the membrane casting solution has good pressure resistance, high temperature resistance or acid and alkali resistance, large water flux, high membrane strength and good practicability.
In one aspect of the invention, the invention provides a casting solution. According to an embodiment of the invention, the casting solution comprises: a polyamide; a pore-forming additive; and a solvent, wherein the relative molecular mass of the polyamide is 20 to 30 ten thousand. Therefore, the viscosity of the membrane casting solution is appropriate, almost no bubbles exist in the membrane casting solution, the membrane forming is facilitated, the ultrafiltration membrane obtained by utilizing the membrane casting solution has good acid and alkali resistance, pressure tolerance and high temperature resistance, the water flux of the ultrafiltration membrane is large, the retention rate is high, and the ultrafiltration membrane is particularly suitable for the field of sewage treatment or material separation with strict requirements on separation conditions.
According to an embodiment of the present invention, the polyamide includes at least one of meta-aromatic polyamide and para-aromatic polyamide. Therefore, the meta-aromatic polyamide and the para-aromatic polyamide have better acid-base resistance and heat resistance, so that the ultrafiltration membrane has better acid-base resistance and heat resistance, and the ultrafiltration membrane prepared by at least one of the meta-aromatic polyamide and the para-aromatic polyamide has excellent pressure resistance, and has outstanding advantages in the field of high-difficulty sewage treatment or material separation with more strict requirements on separation conditions (such as high temperature, high pressure or high pH value).
According to an embodiment of the present invention, the meta aromatic polyamide comprises poly (m-phenylene isophthalamide) and the para aromatic polyamide comprises poly (p-phenylene terephthalamide). Therefore, the poly (m-phenylene isophthalamide) and the poly (p-phenylene terephthalamide) have better acid-base resistance and heat resistance, so that the ultrafiltration membrane has better acid-base resistance and heat resistance, has better pressure resistance, and is more suitable for the field of high-difficulty sewage treatment or material separation with strict requirements on separation conditions.
According to an embodiment of the present invention, the pore-forming additive includes at least one of polyvinylpyrrolidone, polyethylene glycol, ethanol, propanol, lithium chloride, and phosphoric acid. Therefore, the pore-forming additive is added into the membrane casting solution, so that the pore structure of the ultrafiltration membrane is increased in the process of preparing the ultrafiltration membrane, the pore size is proper, the water flux and the retention rate of the ultrafiltration membrane are high, and the service performance is good.
According to an embodiment of the present invention, the solvent includes at least one of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and chloroform. Therefore, the polyamide can be fully dissolved in the solvent, and the preparation of the subsequent ultrafiltration membrane is facilitated.
According to the embodiment of the invention, the casting solution comprises 15-25 parts by weight of the polyamide; 4-10 parts by weight of the pore-forming additive; 65 to 81 parts by weight of the solvent. Therefore, the viscosity of the membrane casting solution is proper, the polyamide and the pore-forming additive are dispersed uniformly, the preparation of a subsequent ultrafiltration membrane is facilitated, and the formed ultrafiltration membrane has more pore structures with proper pore diameters, so that the water flux and the interception rate of the ultrafiltration membrane are improved.
In another aspect of the invention, an ultrafiltration membrane is provided. According to an embodiment of the present invention, the ultrafiltration membrane is prepared from the casting solution described above. Therefore, the ultrafiltration membrane has better acid and alkali resistance, pressure tolerance or high temperature resistance, has larger water flux and higher retention rate, and is particularly suitable for the field of sewage treatment or material separation with more strict requirements on separation conditions.
According to the embodiment of the invention, the ultrafiltration membrane is prepared by an immersion precipitation phase inversion method. Therefore, the preparation method is simple, convenient and easy to realize, and is suitable for large-scale production.
In another aspect of the present invention, a method of treating wastewater is provided. According to an embodiment of the invention, the method is to pass the wastewater to be treated through the ultrafiltration membrane as described above.
According to the embodiment of the invention, the concentration of hydrogen ions in the sewage to be treated can be as high as 3mol/L or the concentration of hydroxyl ions in the sewage to be treated can be as high as 1 mol/L. Therefore, the device is suitable for the field of material separation with harsh requirements on sewage treatment conditions, and has high separation efficiency.
According to an embodiment of the present invention, the waste water is at least one selected from waste water generated in a coating production process of an image recording material or waste water generated in a manufacturing process of a printing material. Therefore, the types of the treated sewage are more, the application of the ultrafiltration membrane is wider, and the method is suitable for industrially treating the sewage on a large scale.
Drawings
FIG. 1 is a schematic flow diagram of a method for preparing an ultrafiltration membrane in one embodiment of the present invention.
Detailed Description
The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
In one aspect of the invention, the invention provides a casting solution. According to an embodiment of the invention, the casting solution comprises: a polyamide; a pore-forming additive; and a solvent, wherein the relative molecular mass of the polyamide is 20 to 30 ten thousand. Therefore, the viscosity of the membrane casting solution is appropriate, almost no bubbles exist in the membrane casting solution, the membrane forming is facilitated, the ultrafiltration membrane obtained by utilizing the membrane casting solution has good acid and alkali resistance, pressure tolerance and high temperature resistance, the water flux of the ultrafiltration membrane is large, the retention rate is high, and the ultrafiltration membrane is particularly suitable for the field of sewage treatment or material separation with strict requirements on separation conditions. When the relative molecular mass of the polyamide is too large, difficulty is caused in the dissolving process of the polyamide, the viscosity of the dissolved casting solution is large, the dispersion is insufficient, and a large number of bubbles exist in the casting solution, so that the appearance of the coating is easy to form an appearance defect, and the obtained ultrafiltration membrane cannot be normally used; when the relative molecular mass of the polyamide is too small, the mechanical strength of the ultrafiltration membrane formed by using the polyamide as a high polymer material is insufficient, and the ultrafiltration membrane is easy to break under high use pressure so as to cause leakage, so that the obtained ultrafiltration membrane has poor compression resistance and use performance.
According to an embodiment of the present invention, the polyamide includes at least one of meta-aromatic polyamide and para-aromatic polyamide. Therefore, the meta-aromatic polyamide and the para-aromatic polyamide have better acid-base resistance and heat resistance, so that the ultrafiltration membrane has better acid-base resistance and heat resistance, and the ultrafiltration membrane prepared by at least one of the meta-aromatic polyamide and the para-aromatic polyamide has excellent pressure resistance, and has outstanding advantages in the field of high-difficulty sewage treatment or material separation with more strict requirements on separation conditions (such as high temperature, high pressure or high pH value). In some embodiments of the invention, the meta-aromatic polyamide comprises poly (m-phenylene isophthalamide) and the para-aromatic polyamide comprises poly (p-phenylene terephthalamide). Therefore, the poly (m-phenylene isophthalamide) and the poly (p-phenylene terephthalamide) have better acid-base resistance and heat resistance, so that the ultrafiltration membrane has better acid-base resistance and heat resistance, has better pressure resistance, and is more suitable for the field of high-difficulty sewage treatment or material separation with strict requirements on separation conditions.
According to the embodiment of the invention, the polyamide can be stored in a dark dry place, if the polyamide absorbs moisture, the polyamide is not easy to dissolve in a solvent such as dimethylacetamide, and the polyamide can be stored for a long time in the dark dry place, so that the polyamide can be kept dry, and the polyamide can be easily dissolved in an organic solvent.
According to an embodiment of the present invention, the pore-forming additive includes at least one of polyvinylpyrrolidone, polyethylene glycol, ethanol, propanol, lithium chloride, and phosphoric acid. Therefore, the pore-forming additive is added into the membrane casting solution, so that the pore structure of the ultrafiltration membrane is increased in the process of preparing the ultrafiltration membrane, the pore size is proper, the water flux and the retention rate of the ultrafiltration membrane are high, and the service performance is good.
According to an embodiment of the present invention, the solvent includes at least one of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and chloroform. Therefore, the polyamide can be fully dissolved in the solvent, and the preparation of the subsequent ultrafiltration membrane is facilitated.
According to the embodiment of the invention, the casting solution comprises 15-25 parts by weight of the polyamide; 4-10 parts by weight of the pore-forming additive; 65 to 81 parts by weight of the solvent. Therefore, the viscosity of the membrane casting solution is proper, the polyamide and the pore-forming additive are dispersed uniformly, the preparation of a subsequent ultrafiltration membrane is facilitated, and the formed ultrafiltration membrane has more pore structures with proper pore diameters, so that the water flux and the interception rate of the ultrafiltration membrane are improved. When the content of the polyamide is too high, the porosity of the ultrafiltration membrane is relatively low, so that the water flux of the ultrafiltration membrane is relatively low, the requirement of practical use cannot be met, the viscosity of the membrane casting solution is relatively large, air bubbles cannot be discharged completely, and the defect of appearance of the ultrafiltration membrane is relatively easily caused; when the content of the polyamide is too low, the viscosity of the casting solution is too low, and when the casting solution is coated on a porous non-woven fabric substrate, the casting solution may leak into pores of the non-woven fabric, and a film is not easily formed on the surface of the non-woven fabric substrate. When the content of the pore-forming additive is too high, large finger-shaped pores are easily formed in the ultrafiltration membrane, so that the rejection rate and the pressure resistance of the ultrafiltration membrane are relatively low; when the pore-forming additive is present in an excessively low amount, the ultrafiltration membrane has a relatively small pore structure, so that its water flux is relatively low.
In another aspect of the invention, an ultrafiltration membrane is provided. According to an embodiment of the present invention, the ultrafiltration membrane is prepared from the casting solution described above. Therefore, the ultrafiltration membrane has better acid and alkali resistance, pressure tolerance or high temperature resistance, has larger water flux and higher retention rate, and is particularly suitable for the field of sewage treatment or material separation with more strict requirements on separation conditions.
According to the embodiment of the invention, the ultrafiltration membrane is prepared by an immersion precipitation phase inversion method. Therefore, the preparation method is simple and convenient, and the ultrafiltration membrane with better service performance can be obtained.
According to an embodiment of the present invention, referring to fig. 1, a method of preparing an ultrafiltration membrane includes:
s100: drying the polyamide and the solid raw materials in the pore-forming additive.
The polyamides and the pore-forming additives according to the examples of the invention are in accordance with the previous description and will not be described in any greater detail here. Polyamide is a solid raw material (for example, polyamide powder), and is stored in a dry environment, and it is necessary to dry it before dissolving it in a solvent so that it is sufficiently dissolved in the solvent. The components of the pore-forming additive are also solid materials when they have a relatively high molecular weight (e.g., polyethylene glycol is solid when it has a molecular weight of more than 600).
According to the embodiment of the invention, the drying treatment temperature is 40-100 ℃, and the drying treatment time is 2-6 hours. Therefore, a very small amount of water in the polyamide can be removed in time, and the polyamide is favorably and fully dissolved in the solvent.
S200: and mixing the polyamide, the pore-forming additive and the solvent, heating for dissolving, and standing for defoaming after the dissolving is finished so as to obtain a casting solution.
According to embodiments of the present invention, the casting solution is consistent with the foregoing description and will not be described in excessive detail herein.
According to the embodiment of the invention, before standing and defoaming, the step of filtering the mixed solution of the polyamide, the pore-forming additive and the solvent can be further included, so that the mixed solution is more fine and smooth and is beneficial to subsequent film-forming treatment.
According to the embodiment of the invention, the heating and dissolving temperature is 50-80 ℃, the dissolving time is 5-6 hours, and the standing and defoaming temperature is 25-80 ℃, and the time is 2-6 hours. Therefore, the operation is favorable for obtaining the mixed and uniform membrane casting solution, the standing defoaming is favorable for discharging bubbles in the membrane casting solution, the uniformity of the thickness of the ultrafiltration membrane is favorably improved, the pore structure of the ultrafiltration membrane is more stable, and the water flux and the retention rate of the ultrafiltration membrane are favorably improved.
S300: and coating the membrane casting solution on a carrier to form a nascent-state membrane, and putting the nascent-state membrane into a coagulating bath for gel membrane forming treatment after the nascent-state membrane is evaporated in an air bath to form the ultrafiltration membrane.
According to the embodiment of the invention, the casting solution can be uniformly coated on the surface of the non-woven fabric substrate by using the scraper coater so as to form the nascent membrane, so that the operation is simple and convenient, the realization is easy, and the subsequent steps can be favorably carried out.
According to the embodiment of the invention, the time for evaporating the nascent film in the air bath is 10-20 seconds. Therefore, the method is beneficial to the densification of the nascent-state membrane, can slow down the diffusion rate of water in the coagulation bath process, reduces the formation of macropores and improves the retention rate of the ultrafiltration membrane. When the time of the air bath evaporation is too short, the retention rate of the ultrafiltration membrane is relatively low; when the time of the air bath evaporation is too long, the nascent state membrane becomes too compact, the water flux becomes low, and the use requirement cannot be met.
According to the embodiment of the invention, the temperature of the coagulating bath is 5-60 ℃. Therefore, the method is beneficial to improving the porosity of the ultrafiltration membrane, and the ultrafiltration membrane with higher flux or rejection rate can be obtained.
According to an embodiment of the invention, the coagulation bath is a water bath. Therefore, the method has less pollution to the environment by using water as the coagulating bath and has higher practicability. In some embodiments of the invention, a small amount of organic solvent may be added to the water bath in order to further improve the performance of the ultrafiltration membrane. Therefore, the organic solvent is added into the water bath, which is favorable for controlling the phase separation rate and time in the immersion precipitation phase inversion method, so that the pore structure of the ultrafiltration membrane is improved, and the ultrafiltration membrane with high flux and high retention rate, which has better permeability and proper surface pore size, is formed. In some embodiments of the invention, the organic solvent comprises at least one of dimethylacetamide, dimethylformamide, N-methylpyrrolidone, and dimethylsulfoxide. Therefore, the method is more beneficial to improving the pore structure of the ultrafiltration membrane, and the ultrafiltration membrane with high flux and high retention rate, which has better permeability and more suitable surface pore size, is formed.
According to the embodiment of the invention, the method for preparing the ultrafiltration membrane is simple and convenient to operate and easy to realize, the ultrafiltration membrane with better acid and alkali resistance, pressure resistance or high-temperature resistance can be obtained, and the water throughput and rejection rate of the ultrafiltration membrane are higher.
In another aspect of the present invention, a method of treating wastewater is provided. According to an embodiment of the invention, the method is to pass the wastewater to be treated through the ultrafiltration membrane described above. Therefore, the operation is simple and convenient, and the realization is easy.
In accordance with an embodiment of the present invention,the concentration of hydrogen ions in the wastewater to be treated can be as high as 3mol/L (for example, the concentration of hydrogen ions in the wastewater to be treated can be 10-7mol/L、10-6mol/L、10-5mol/L、10-4mol/L、10- 3mol/L、10-2mol/L、10-1mol/L, 1mol/L, 1.2mol/L, 1.4mol/L, 1.6mol/L, 1.8mol/L, 2mol/L, 2.2mol/L, 2.4mol/L, 2.6mol/L, 2.8mol/L, 3mol/L and the like) or the concentration of hydroxide ions in the sewage to be treated can be as high as 1mol/L (for example, the concentration of hydroxide ions in the sewage to be treated can be 10-7mol/L、10- 6mol/L、10-5mol/L、10-4mol/L、10-3mol/L、10-2mol/L、10-1mol/L, 1mol/L, etc.). Therefore, the device is suitable for the field of material separation with harsh requirements on sewage treatment conditions, and has high separation efficiency.
According to an embodiment of the present invention, the contaminated water is waste water generated under high temperature, high pressure or high ph conditions. In some embodiments of the present invention, the waste water is at least one selected from waste water generated during coating production of the image recording material or waste water generated during manufacturing of the printing material. Therefore, the types of the treated sewage are more, the application of the ultrafiltration membrane is wider, and the method is suitable for industrially treating the sewage on a large scale.
Embodiments of the present application are described below.
Examples
In the following examples, the performance of the ultrafiltration membrane was tested by the following procedure, unless otherwise specified.
Performance testing of Ultrafiltration membranes
1. Water flux
The test method comprises the following steps: putting the ultrafiltration membrane into a membrane pool, prepressing the ultrafiltration membrane for 0.5 hour under the pressure of 0.2MPa, measuring the water permeability Q within 1 hour under the conditions of the pressure of 0.1MPa and the temperature of 25 ℃, and calculating the water flux J by the following formula:
J＝Q/(S·t)
wherein J, Q, S, t respectively represent the following meanings:
j: water flux in L/m2h；
Q: water permeability in units of L;
s: the area of the ultrafiltration membrane is m2；
t: time, unit is h.
2. Retention rate
The test method comprises the following steps: putting the ultrafiltration membrane into a membrane pool, prepressing for 0.5 hours under the pressure of 0.2MPa, respectively testing the concentration of the stock solution of the bovine serum albumin and the concentration of the bovine serum albumin in the permeate under the conditions of the pressure of 0.1MPa and the temperature of 25 ℃, and calculating the retention rate by the following formula:
R＝(Cp-Cf)/Cp×100％
wherein, R, Cp、Cf、CpRespectively, the meanings are as follows:
r: rejection, in%;
Cp: the concentration of bovine serum albumin in raw water is mg/L;
Cf: the concentration of bovine serum albumin in the permeate was in mg/L.
3. Pressure resistance
The test method comprises the following steps: the retention rate of the ultrafiltration membrane on bovine serum albumin is tested under 0.1MPa and 0.5MPa, and the pressure resistance of the ultrafiltration membrane is represented by the change before and after the retention rate (wherein, the larger the change before and after the retention rate is, the worse the pressure resistance of the ultrafiltration membrane is). The bovine serum albumin retention rate is tested in 2.
4. Acid and alkali resistance
The test method comprises the following steps: soaking the ultrafiltration membrane in pure water, an alkali solution with the pH value of 13.0 and an acid solution with the pH value of 1 respectively for 24 hours at the temperature of 25 ℃, and then testing the change of the water flux and the retention rate of the ultrafiltration membrane, wherein the test method of the water flux is shown in 1, and the test method of the retention rate is shown in 2.
The casting solution comprises 15-25 parts by weight of the polyamide; 4-10 parts by weight of the pore-forming additive; 65 to 81 parts by weight of the solvent.
Example 1
Weighing 15 g of dried poly (m-phenylene isophthalamide) (the relative molecular mass is 25 ten thousand) raw material and 4 g of polyethylene glycol (the relative molecular mass is 400), adding the raw material and the polyethylene glycol into a solvent of 81 g of dimethylacetamide, stirring and soaking for 1 hour at room temperature, heating to 80 ℃ to dissolve for 6 hours, preparing a casting solution which comprises 15 parts by weight of polyamide, 4 parts by weight of additive and the balance of solvent, filtering, standing and defoaming.
Flatly sticking the non-woven fabric on a smooth glass plate, controlling the humidity in a film casting chamber to be 40%, controlling the temperature in the film casting chamber to be 25 ℃, pouring the completely defoamed film casting solution on the non-woven fabric in a clean film casting chamber, scraping the non-woven fabric into a film by using a stainless steel scraper with the thickness of a scraping groove of 0.25mm, evaporating the nascent state film in an air bath for 10 seconds, quickly putting the film into a coagulating bath with the temperature of 25 ℃, and taking out the film after the film is coagulated for 24 hours to obtain the ultrafiltration membrane.
Example 2
Weighing 15 g of dried poly (m-phenylene isophthalamide) (the relative molecular mass is 25 ten thousand) raw material and 10 g of polyethylene glycol (the relative molecular mass is 400), adding the raw material and the polyethylene glycol into 75 g of a solvent of dimethylacetamide, stirring and soaking for 1 hour at room temperature, heating to 80 ℃ to dissolve for 6 hours, preparing a casting solution which comprises 15 parts by weight of polyamide, 10 parts by weight of additive and the balance of solvent, filtering, standing and defoaming.
The ultrafiltration membrane was prepared under the same conditions as in example 1.
Example 3
Weighing 15 g of dried poly (m-phenylene isophthalamide) (the relative molecular mass is 25 ten thousand) raw material and 4 g of polyvinylpyrrolidone, adding the raw material and the polyvinylpyrrolidone into 81 g of dimethylacetamide solvent, stirring and soaking for 1 hour at room temperature, heating to 80 ℃, dissolving for 6 hours, and preparing a casting solution which comprises 15 parts by weight of polyamide, 4 parts by weight of additive and the balance of solvent, filtering, standing and defoaming.
The ultrafiltration membrane was prepared under the same conditions as in example 1.
Example 4
Weighing 15 g of dried poly (m-phenylene isophthalamide) (the relative molecular mass is 25 ten thousand) raw material and 10 g of polyvinylpyrrolidone, adding the raw material and the polyvinylpyrrolidone into 75 g of dimethylacetamide solvent, stirring and soaking for 1 hour at room temperature, heating to 80 ℃, dissolving for 6 hours, and preparing a casting solution which comprises 15 parts by weight of polyamide, 10 parts by weight of additive and the balance of solvent, filtering, standing and defoaming.
The ultrafiltration membrane was prepared under the same conditions as in example 1.
Example 5
Weighing 25 g of dried polyisophthaloyl metaphenylene diamine (the relative molecular weight is 20 ten thousand) and 8 g of polyvinylpyrrolidone, adding the weighed materials into 67 g of dimethylacetamide solvent, stirring and soaking for 1 hour at room temperature, heating to 80 ℃, heating and dissolving for 6 hours, preparing a casting solution which comprises 25 parts by weight of polyamide, 8 parts by weight of additive and the balance of solvent, filtering, standing and defoaming.
The ultrafiltration membrane was prepared under the same conditions as in example 1.
Example 6
Weighing 20 g of dried poly (m-phenylene isophthalamide) (the relative molecular mass is 30 ten thousand) raw material and 10 g of polyvinylpyrrolidone, adding the raw material and the polyvinylpyrrolidone into 70 g of dimethylacetamide solvent, stirring and soaking for 1 hour at room temperature, heating to 80 ℃, dissolving for 6 hours, and preparing a casting solution which comprises 20 parts by weight of polyamide, 10 parts by weight of additive and the balance of solvent, filtering, standing and defoaming.
The ultrafiltration membrane was prepared under the same conditions as in example 1.
Example 7
The raw materials and conditions for preparing an ultrafiltration membrane were the same as those in example 1, except that the polyamide in this example was poly (p-phenylene terephthalamide) (having a relative molecular mass of 25 ten thousand).
Comparative example 1
Weighing 15 g of dried polyisophthaloyl metaphenylene diamine (the relative molecular weight is 15 ten thousand) and 4 g of polyethylene glycol (the relative molecular weight is 400) into 81 g of dimethylacetamide solvent, stirring and soaking for 1 hour at room temperature, heating to 80 ℃ to dissolve for 6 hours, preparing a casting solution containing 15 parts by weight of polyamide resin, 4 parts by weight of additive and the balance of solvent, filtering, standing and defoaming.
The ultrafiltration membrane was prepared under the same conditions as in example 1.
Comparative example 2
Weighing 15 g of dried polyisophthaloyl metaphenylene diamine (the relative molecular weight is 35 ten thousand) and 4 g of polyethylene glycol (the relative molecular weight is 400), adding the weighed materials into 81 g of dimethylacetamide solvent, stirring and soaking for 1 hour at room temperature, heating to 80 ℃ to dissolve for 6 hours, preparing a casting solution containing 15 parts by weight of polyamide resin, 4 parts by weight of additive and the balance of solvent, filtering, sealing, standing and defoaming.
The ultrafiltration membrane was prepared under the same conditions as in example 1.
Comparative example 3
Weighing 15 g of polysulfone (the relative molecular mass is 8 ten thousand) and 10 g of polyvinylpyrrolidone, adding the polysulfone and the polyvinylpyrrolidone into 75 g of dimethylacetamide solvent, stirring and soaking for 1 hour at room temperature, heating to 80 ℃ to dissolve for 6 hours, preparing a casting solution containing 15 parts by weight of polyamide, 10 parts by weight of additive and the balance of solvent, filtering, sealing, standing and defoaming.
The ultrafiltration membrane was prepared under the same conditions as in example 1.
The performance test data for examples 1-7 and comparative examples 1-3 are shown in Table 1.
TABLE 1
Comparing the examples with comparative example 3, it was found that the ultrafiltration membrane containing polyamide had a higher water flux with the same rejection. Meanwhile, the ultrafiltration membrane of the embodiment can bear the pressure of 0.5MPa, the flux of the ultrafiltration membrane is improved to some extent under the condition of high pressure, and the retention rate is basically unchanged. While the flux of the ultrafiltration membrane of the comparative example 3 is increased along with the increase of the pressure, the retention rate is greatly reduced to 14 percent, and the use requirement cannot be met. After 24 hours of acid liquor soaking (pH is 1), the flux and rejection rate of the ultrafiltration membrane containing polysulfone are reduced by about 40%, and the ultrafiltration membrane containing polyamide shows better acid and alkali resistance.
Compared with the comparative example 1, when the relative molecular weight of the polyamide is less than 20 ten thousand and 15 ten thousand, the ultrafiltration membrane can be normally formed into a membrane, and has better acid and alkali resistance and normal flux and rejection rate performance under 0.1MPa, but when the pressure is increased to 0.5MPa, the ultrafiltration membrane is easy to break due to insufficient mechanical strength, so that the membrane layer is easy to leak, the flux of the ultrafiltration membrane is extremely high, and the interception performance is not provided, so that the pressure resistance of the ultrafiltration membrane obtained when the molecular weight of the polyamide is smaller is poorer.
In the examples, when the relative molecular mass of the polyamide is more than 30 ten thousand and 35 ten thousand as compared with that of comparative example 2, the viscosity of the casting solution is large, a large number of bubbles are formed, and thus a normal coating film cannot be obtained, the appearance of the coating film is liable to be defective, and the polyamide cannot be used normally under a pressure of 0.1 MPa.
In conclusion, the ultrafiltration membrane prepared by the invention has high flux, high retention rate and high temperature resistance, has good pressure resistance and acid and alkali resistance, and is very suitable for the field of separation of industrial materials or waste liquid with strict requirements on sewage treatment and separation conditions.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (7)
1. A membrane casting solution for preparing an ultrafiltration membrane is characterized by comprising the following components:
15 to 25 parts by weight of polyamide;
4-10 parts by weight of pore-forming additive; and
65 to 81 parts by weight of a solvent,
wherein the relative molecular mass of the polyamide is 20-30 ten thousand;
the polyamide comprises at least one of meta-aromatic polyamide and para-aromatic polyamide;
the meta-aromatic polyamide comprises poly (m-phenylene isophthalamide) and the para-aromatic polyamide comprises poly (p-phenylene terephthalamide).
2. The membrane casting solution for preparing the ultrafiltration membrane according to claim 1, wherein the pore-forming additive comprises at least one of polyvinylpyrrolidone, polyethylene glycol, ethanol, propanol, lithium chloride and phosphoric acid;
the solvent includes at least one of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and chloroform.
3. An ultrafiltration membrane formed from the membrane casting solution for producing an ultrafiltration membrane according to claim 1 or 2.
4. An ultrafiltration membrane according to claim 3 which is prepared by immersion precipitation phase inversion.
5. A wastewater treatment method characterized in that the wastewater to be treated is passed through the ultrafiltration membrane according to claim 3 or 4.
6. The method according to claim 5, wherein the concentration of hydrogen ions in the wastewater to be treated is up to 3mol/L or the concentration of hydroxide ions in the wastewater to be treated is up to 1 mol/L.
7. The method of claim 5, wherein the waste water is at least one selected from waste water generated during coating production of the image recording material or waste water generated during manufacturing of the printing material.
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| CN109966928B (en) * | 2019-03-18 | 2024-02-23 | 浙江泰林生命科学有限公司 | Preparation method of high-flux high-strength polyamide flat plate micro-filtration membrane |
| CN110064312B (en) * | 2019-04-29 | 2022-03-08 | 袁书珊 | High-flux solvent-resistant interfacial polymerization composite membrane and preparation method thereof |
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| CN110756064A (en) * | 2019-10-25 | 2020-02-07 | 中国乐凯集团有限公司 | Casting solution, ultrafiltration base membrane, preparation method and separation membrane |
| CN111603948B (en) * | 2020-05-21 | 2023-06-30 | 杭州科百特科技有限公司 | Nylon membrane and preparation method and application thereof |
| CN111603946A (en) * | 2020-05-21 | 2020-09-01 | 杭州科百特科技有限公司 | Nylon membrane and preparation method and application thereof |
| CN111603947B (en) * | 2020-05-21 | 2023-08-01 | 杭州科百特科技有限公司 | Nylon membrane with support and preparation method and application thereof |
| CN111603949B (en) * | 2020-05-21 | 2023-06-30 | 杭州科百特科技有限公司 | Nylon membrane and preparation method and application thereof |
| CN111921386A (en) * | 2020-09-08 | 2020-11-13 | 北京理工大学 | Preparation method of polyisophthaloyl metaphenylene diamine ultrafiltration membrane |
| CN112694515A (en) * | 2021-01-20 | 2021-04-23 | 佳木斯冬梅大豆食品有限公司 | Deep processing method for extracting soybean protein peptide by membrane method |
| CN112957931A (en) * | 2021-01-28 | 2021-06-15 | 中国乐凯集团有限公司 | Ultrafiltration membrane and preparation method thereof |
| CN113750804B (en) * | 2021-09-15 | 2022-07-19 | 北京理工大学 | Modified polyisophthaloyl metaphenylene diamine ultrafiltration membrane as well as preparation method and application thereof |
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