CN111467969A - Polyamide high-flux composite loose nanofiltration membrane and preparation method thereof - Google Patents
Polyamide high-flux composite loose nanofiltration membrane and preparation method thereof Download PDFInfo
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- CN111467969A CN111467969A CN202010364568.7A CN202010364568A CN111467969A CN 111467969 A CN111467969 A CN 111467969A CN 202010364568 A CN202010364568 A CN 202010364568A CN 111467969 A CN111467969 A CN 111467969A
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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
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0083—Thermal after-treatment
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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
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/027—Nanofiltration
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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
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0093—Chemical modification
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- 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
- B01D69/08—Hollow fibre membranes
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- 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
- B01D69/12—Composite membranes; Ultra-thin membranes
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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
- B01D2325/00—Details relating to properties of membranes
- B01D2325/22—Thermal or heat-resistance properties
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Abstract
The invention provides a preparation method of a polyamide high-flux composite loose nanofiltration membrane, which comprises the following steps: (1) treating the polyamide film by using plasma; (2) immersing the polyamide membrane treated in the step (1) into a carboxymethyl cellulose solution for heat treatment, and airing at room temperature after treatment; (3) and (3) placing the dried polyamide membrane obtained in the step (2) in a modification solution for modification treatment to obtain the composite loose nanofiltration membrane. According to the invention, the polyamide membrane is pretreated by using the plasma, the plasma can be used for pretreating the surface of the polyamide, and then the stability of the membrane is increased and the permeability is improved by modification treatment.
Description
Technical Field
The invention relates to the field of nanofiltration membrane preparation, in particular to a preparation method of a polyamide high-flux composite loose nanofiltration membrane.
Background
Nanofiltration is a novel membrane separation technology developed in the later 80 s of the 20 th century, the interception relative molecular weight of the novel membrane separation technology is 200-2000, and the membrane aperture is about 1 nm. The separation process is carried out at normal temperature, phase change and chemical reaction can not occur, so the biological cleanness of the separated substances can not be damaged, and high-valence metal ions and organic micromolecules with relative molecular weight higher than 200 can be effectively intercepted due to the functions of pore size screening and charge repulsion. Compared with reverse osmosis, the nano-filtration has low operation pressure required by nano-filtration, and has greater application potential in the fields of high-quality drinking water production, food, chemical industry, medicine, biochemistry, environmental protection and the like.
According to the prediction of the Chinese film industry Association, the global film market demand will reach $ 270 million in 2015, wherein the Chinese market accounts for more than 10%. Compared with reverse osmosis, nanofiltration has the characteristics of low price and flexible application, the global nanofiltration membrane market is expected to reach 4 billion dollars in 2015 according to the current trend, and the nanofiltration membrane is expected to replace part of reverse osmosis membranes.
The market demands nanofiltration membrane products with controlled salt rejection. For example, in the field of industrial water and seawater desalination pretreatment, a nanofiltration membrane is required to have a high rejection rate for various salts, so that the load of a subsequent system is reduced. The design of a nanofiltration membrane with high salt rejection rate (especially high NaCl rejection rate) is feasible from the aspect of membrane formulation, but a great deal of time and financial resources are spent. Meanwhile, a separation membrane with high monovalent ion rejection rate (such as a low-pressure reverse osmosis membrane) often causes the separation layer to be too compact in physical structure, and the water flux of the separation layer is seriously influenced.
The dye wastewater is a type of organic wastewater which is difficult to purify due to the characteristics of thick color, poor water quality, diversified organic structures and the like. Along with the development of chemical fiber fabrics and the improvement of a printing and dyeing after-finishing technology in recent years, a large amount of organic matters difficult to degrade biochemically, such as PVA slurry, novel auxiliaries and the like, enter printing and dyeing wastewater, and the shortage and pollution of water resources are further aggravated. Therefore, the effective treatment of the printing and dyeing wastewater has important significance for saving water resources and protecting the environment. The membrane technology is one of the sewage treatment technologies with the greatest development prospect in the 21 st century, and because the membrane technology has the characteristics of simple operation, remarkable treatment effect, low energy consumption and the like, the advanced treatment of printing and dyeing wastewater by utilizing the membrane technology becomes one of the research hotspots in recent years.
The nanofiltration membrane for treating printing and dyeing wastewater at present shrinks when heated, the filtration performance is reduced in the using process, and the flux of the membrane is low and the filtration precision is not high.
Disclosure of Invention
The invention provides a preparation method of a polyamide high-flux composite loose nanofiltration membrane, which takes a polyamide membrane treated by plasma as a matrix and carries out heat treatment and modification treatment on the polyamide membrane, so that the flux of the membrane can be increased, and the stability of the nanofiltration membrane can be maintained.
The technical scheme for realizing the invention is as follows:
a preparation method of a polyamide high-flux composite loose nanofiltration membrane comprises the following steps:
(1) treating the polyamide film by using plasma;
(2) immersing the polyamide membrane treated in the step (1) into a carboxymethyl cellulose solution for heat treatment, and airing at room temperature after treatment;
(3) and (3) placing the dried polyamide membrane obtained in the step (2) in a modification solution for modification treatment to obtain the composite loose nanofiltration membrane.
In the step (2), the concentration of the carboxymethyl cellulose solution is 1-3wt%, the heat treatment temperature is 40-60 ℃, and the treatment time is 3-5 h.
The modification treatment in the step (3) comprises the following steps: and (2) placing the polyamide membrane into a mixed solution of polyvinyl alcohol and p-hydroxybenzyl alcohol, heating in a water bath to 30-40 ℃, adding nano silicon dioxide and a cross-linking agent for reaction, and drying after the reaction to obtain the composite loose nanofiltration membrane.
The mass ratio of the polyvinyl alcohol to the p-hydroxybenzyl alcohol is (3-6): 1, the mass ratio of polyvinyl alcohol to nano silicon dioxide is (2-4): 1, adding nano silicon dioxide to react for 1-2 h.
The cross-linking agent is sodium hexametaphosphate, and the mass of the sodium hexametaphosphate is 5-10% of that of the polyvinyl alcohol.
The invention has the beneficial effects that:
(1) according to the invention, the polyamide membrane is pretreated by using the plasma, the plasma can modify the surface of the polyamide, and simultaneously, the interior of the polyamide membrane is also modified synchronously. The method has the advantages that the internal and external active sites of the polyamide film are increased, the adhesion among the active sites is realized, the activity degree of the solidified polyamide is increased, the multilayer hollow fiber film is further prepared, the permeability of the hollow fiber film is increased, the multilayer structure can realize quantitative filtration, and the quantitative filtration is further realized by changing the parameters of plasma treatment, for example, the filtration precision is controlled to be 1 mu m;
(2) in order to improve the problem of the thermal shrinkage of the polyamide film, carboxymethyl cellulose is bonded on the surface of the polyamide film by utilizing the bonding property of carboxymethyl cellulose, polyvinyl alcohol and p-hydroxybenzyl alcohol are subjected to a crosslinking reaction under the action of a sodium hexametaphosphate crosslinking agent to generate a three-dimensional crosslinked reticular macromolecular polymer, and the three-dimensional crosslinked reticular compound is bonded on the surface of the polyamide film by utilizing the hydrogen bonding effect of partial hydroxyl of the three-dimensional crosslinked reticular compound and the hydroxyl on the carboxymethyl cellulose and the viscosity of the carboxymethyl cellulose. When polyvinyl alcohol and p-hydroxybenzyl alcohol are crosslinked, nano silicon dioxide is deposited and embedded into a grid of a three-dimensional crosslinked reticular macromolecular polymer formed by crosslinking polyvinyl alcohol and p-hydroxybenzyl alcohol, and the silicon dioxide can prevent the relative movement between molecular chains in the macromolecular polymer, so that the enhancement effect on the three-dimensional crosslinked reticular macromolecular polymer is achieved, a benzene ring structure with good heat resistance is introduced into the three-dimensional crosslinked reticular macromolecular polymer, the heat resistance is good, the three-dimensional crosslinked reticular macromolecular polymer is not shrunk when being heated, and a supporting layer with high heat resistance is formed.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.
Example 1
A preparation method of a polyamide high-flux composite loose nanofiltration membrane comprises the following steps:
(1) treating the polyamide film by using plasma;
(2) immersing the polyamide membrane treated in the step (1) into a carboxymethyl cellulose solution with the concentration of 1wt% for heat treatment, wherein the heat treatment temperature is 40 ℃, the treatment time is 3 hours, and drying at room temperature after the treatment;
(3) placing the polyamide membrane dried in the step (2) into a mixed solution of polyvinyl alcohol and p-hydroxybenzyl alcohol, wherein the mass ratio of the polyvinyl alcohol to the p-hydroxybenzyl alcohol is 3: 1; heating the water bath to 30 ℃, adding nano silicon dioxide and sodium hexametaphosphate to react, wherein the mass ratio of the polyvinyl alcohol to the nano silicon dioxide is 2: 1, the mass of the sodium hexametaphosphate is 5 percent of that of the polyvinyl alcohol, and the composite loose nanofiltration membrane is obtained after the reaction for 1 hour and the drying.
Example 2
A preparation method of a polyamide high-flux composite loose nanofiltration membrane comprises the following steps:
(1) treating the polyamide film by using plasma;
(2) immersing the polyamide membrane treated in the step (1) into a carboxymethyl cellulose solution with the concentration of 2wt% for heat treatment, wherein the heat treatment temperature is 50 ℃, the treatment time is 4 hours, and drying at room temperature after the treatment;
(3) placing the polyamide membrane dried in the step (2) into a mixed solution of polyvinyl alcohol and p-hydroxybenzyl alcohol, wherein the mass ratio of the polyvinyl alcohol to the p-hydroxybenzyl alcohol is 5: 1; heating the water bath to 35 ℃, adding nano silicon dioxide and sodium hexametaphosphate to react, wherein the mass ratio of the polyvinyl alcohol to the nano silicon dioxide is 3: 1, the mass of the sodium hexametaphosphate is 8 percent of that of the polyvinyl alcohol, and the composite loose nanofiltration membrane is obtained after the reaction for 1.5h and drying.
Example 3
A preparation method of a polyamide high-flux composite loose nanofiltration membrane comprises the following steps:
(1) treating the polyamide film by using plasma;
(2) immersing the polyamide membrane treated in the step (1) into a carboxymethyl cellulose solution with the concentration of 3wt% for heat treatment, wherein the heat treatment temperature is 60 ℃, the treatment time is 5 hours, and drying at room temperature after the treatment;
(3) placing the polyamide membrane dried in the step (2) into a mixed solution of polyvinyl alcohol and p-hydroxybenzyl alcohol, wherein the mass ratio of the polyvinyl alcohol to the p-hydroxybenzyl alcohol is 6: 1; heating the water bath to 40 ℃, adding nano silicon dioxide and sodium hexametaphosphate to react, wherein the mass ratio of the polyvinyl alcohol to the nano silicon dioxide is (2-4): 1, the mass of the sodium hexametaphosphate is 10 percent of that of the polyvinyl alcohol, and the composite loose nanofiltration membrane is obtained after the reaction for 2 hours and drying.
Comparative example 1
The procedure of example 1 was followed except that the polyamide film was directly treated with carboxymethyl cellulose without plasma treatment.
Comparative example 2
The heat treatment step of step (2) was eliminated, and the polyamide film was treated only by steps (1) and (3), and the rest of the procedure was the same as in example 1.
Evaluation of Membrane separation Performance
The nanofiltration membranes of the examples 1-3 and the comparative examples 1-2 are used for treating the printing and dyeing wastewater with pH of 9-11, COD content of 930-1050 mg/L and NaCl concentration of 16wt%, and the treatment effects are as follows:
the nanofiltration membrane adopted by the invention is cut into a proper size, placed in pure water, pre-pressed under 0.8Mpa, the pressure is reduced to be below 0.7Mpa after the membrane flux is stable, the volume is recorded every 10min, the pure water flux is calculated, then the pure water is changed into printing and dyeing wastewater, the flux is tested after the membrane flux is stabilized for 5min, the anti-pollution performance of the composite nanofiltration membrane is represented by inspecting the pure water flux before and after the printing and dyeing wastewater is treated by the membrane, and the result is shown in Table 2:
therefore, the modified polyamide membrane is stable, the filtering layer is not easy to fall off from the polyamide base membrane under the action of continuous water pressure in the operation process of the nanofiltration membrane, the filtering performance of the nanofiltration membrane is reduced along with time, and the filtering layer is easy to fall off under the action of pressure of the nanofiltration membrane without modification treatment, so that the filtering performance is gradually reduced along with time.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (5)
1. A preparation method of a polyamide high-flux composite loose nanofiltration membrane is characterized by comprising the following steps:
(1) treating the polyamide film by using plasma;
(2) immersing the polyamide membrane treated in the step (1) into a carboxymethyl cellulose solution for heat treatment, and airing at room temperature after treatment;
(3) and (3) placing the dried polyamide membrane obtained in the step (2) in a modification solution for modification treatment to obtain the composite loose nanofiltration membrane.
2. The preparation method of the polyamide high-flux composite loose nanofiltration membrane according to claim 1, wherein the preparation method comprises the following steps: in the step (2), the concentration of the carboxymethyl cellulose solution is 1-3wt%, the heat treatment temperature is 40-60 ℃, and the treatment time is 3-5 h.
3. The preparation method of the polyamide high-flux composite loose nanofiltration membrane according to claim 1, wherein the modification treatment in the step (3) comprises the following steps: and (2) placing the polyamide membrane into a mixed solution of polyvinyl alcohol and p-hydroxybenzyl alcohol, heating in a water bath to 30-40 ℃, adding nano silicon dioxide and a cross-linking agent for reaction, and drying after the reaction to obtain the composite loose nanofiltration membrane.
4. The preparation method of the polyamide high-flux composite loose nanofiltration membrane according to claim 3, wherein the preparation method comprises the following steps: the mass ratio of the polyvinyl alcohol to the p-hydroxybenzyl alcohol is (3-6): 1, the mass ratio of polyvinyl alcohol to nano silicon dioxide is (2-4): 1, adding nano silicon dioxide to react for 1-2 h.
5. The preparation method of the polyamide high-flux composite loose nanofiltration membrane according to claim 3, wherein the preparation method comprises the following steps: the cross-linking agent is sodium hexametaphosphate, and the mass of the sodium hexametaphosphate is 5-10% of that of the polyvinyl alcohol.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2604331A1 (en) * | 2011-12-15 | 2013-06-19 | Gambro Lundia AB | Doped membranes |
| CN104998562A (en) * | 2015-07-15 | 2015-10-28 | 上海交通大学 | Hydrophilic modification method for polytetrafluoroethylene membrane |
| CN110559879A (en) * | 2019-09-26 | 2019-12-13 | 刘琴 | Preparation method of polyvinylidene fluoride composite nanofiltration membrane for treating printing and dyeing wastewater |
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2020
- 2020-04-30 CN CN202010364568.7A patent/CN111467969A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2604331A1 (en) * | 2011-12-15 | 2013-06-19 | Gambro Lundia AB | Doped membranes |
| CN104998562A (en) * | 2015-07-15 | 2015-10-28 | 上海交通大学 | Hydrophilic modification method for polytetrafluoroethylene membrane |
| CN110559879A (en) * | 2019-09-26 | 2019-12-13 | 刘琴 | Preparation method of polyvinylidene fluoride composite nanofiltration membrane for treating printing and dyeing wastewater |
Non-Patent Citations (2)
| Title |
|---|
| 张增志 主编: "《中国战略性新兴产业 新材料 环境工程材料》", 30 November 2018, 北京：中国铁道出版社 * |
| 王国全 主编: "《聚合物改性 第3版》", 30 May 2016, 北京：中国轻工业出版社 * |
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