CN107456871B - Preparation method of hollow fiber composite loose nanofiltration membrane - Google Patents
Preparation method of hollow fiber composite loose nanofiltration membrane Download PDFInfo
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- CN107456871B CN107456871B CN201710650527.2A CN201710650527A CN107456871B CN 107456871 B CN107456871 B CN 107456871B CN 201710650527 A CN201710650527 A CN 201710650527A CN 107456871 B CN107456871 B CN 107456871B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- 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
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- B01D63/02—Hollow fibre modules
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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
- B01D67/0088—Physical treatment with compounds, e.g. swelling, coating or impregnation
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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
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- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D1/00—Treatment of filament-forming or like material
- D01D1/02—Preparation of spinning solutions
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
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- D01D5/06—Wet spinning methods
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Abstract
The invention provides a preparation method of a hollow fiber composite loose nanofiltration membrane. The hollow fiber loose nanofiltration membrane with the separation aperture reaching the nanometer level is prepared by mixing and dissolving polyether bravas, dimethylacetamide and polyethylene glycol to prepare spinning membrane casting solution, spinning the spinning membrane casting solution under certain process conditions to prepare a hollow fiber external pressure membrane, and soaking the hollow fiber external pressure membrane in sulfuric acid aqueous solution. The loose nanofiltration membrane has the advantages of simple preparation method, large volume ratio, small occupied area, high treatment efficiency, small separation aperture and the like, has good removal effect on particulate matter colloid, has good removal effect on small molecular organic matters in water, and can intercept molecular weight below 1000 Da. Can be effectively applied to the pretreatment of concentrated water organic matters, such as the separation of antibiotics, dyes and the like with the molecular weight of about 1000 g/mol in water and organic solvents. It also has good effect on removing inorganic substances.
Description
Technical Field
The invention relates to the technical field of polymer material films, in particular to a preparation method of a hollow fiber composite loose nanofiltration membrane.
Background
With the development of economy and science and technology, separation technology plays a significant role in modern industry, especially in the field of chemical industry. In recent years, due to the advantages of low energy consumption, low discharge, high automation degree, small occupied area and the like, the membrane separation technology gradually replaces the traditional separation technologies such as extraction, rectification and the like, is one of the emerging separation technologies, and is an important means for solving the water problems of sewage treatment, seawater desalination, reclaimed water recycling and the like. At present, the membrane separation industry can not only carry out gradient separation on substances with different molecular weights, but also realize the recovery or reutilization of water or organic solvent, reduce the discharge of waste water and organic solvent and achieve the purposes of energy conservation and emission reduction. Therefore, the membrane separation process technology also meets the requirements of China on building resource-saving and environment-friendly society.
Among the membrane separation processes, the nanofiltration separation process is generally considered as a molecular-level separation process, and is suitable for separation of small-molecular organic substances such as dyes, antibiotics, amino acids and the like. The nanofiltration process starts in the middle and later 80 years and is a novel pressure-driven physical separation process without phase change. The average diameter of the nanofiltration membrane is between 0.5 and 2 nm, which is between the pore diameter of the ultrafiltration and reverse osmosis membrane, so the early nanofiltration membrane is also called loose reverse osmosis membrane. Therefore, the nanofiltration process is widely applied to various industrial fields such as hard water softening, desalination and concentration of active substances such as dyes, removal of a small amount of organic matters in water, material separation and purification of organic matters with different molecular weights, separation and purification of intermediates and antibiotics in the field of medicine, recycling of solvents and the like.
The nanofiltration membrane refers to a separation membrane. Since most of the nanofiltration membranes have charges on their surfaces, they have a certain selective effect on the penetration of ions, so the nanofiltration membranes are usually used to separate small-molecular organic substances with molecular weight of 200-1000, and high-valence salt ions. Can be used in the fields of sewage treatment, brackish water desalination, heavy metal ion removal, food, chemical industry, medicine and the like. Like reverse osmosis and ultrafiltration, the nanofiltration membrane separation process has no phase change, can be operated at normal temperature, and has high automation degree and small occupied area. Compared with a reverse osmosis membrane, the nano-filtration membrane is still in the initial stage of development in China, the market is not completely opened, the factory technology for producing the nano-filtration membrane in China is generally from abroad, and few membrane products with independent intellectual property rights exist. Outside the field of water treatment, the molecular weight of a plurality of medicinal active molecules and catalyst molecules is in the separation range of the nanofiltration membrane. The activity of these molecules is ensured by operating at ambient temperature during the isolation of these active substances. Therefore, the nanofiltration membrane has wide demand in practice, the development of the nanofiltration membrane used in different sizes and different solvent environments is beneficial to the upgrade of the existing separation method in China, and meanwhile, the membrane applied to the separation in the fields of medicine and the like is also a high-value-added product and has wide market.
Water pollution is one of the major resource and environmental issues facing the world today. The sewage is the highest proportion of industrial sewage, and then is urban domestic sewage, agricultural sewage and the like, wherein high organic matter wastewater (COD is more than 2000 mg/L) is mainly used. The concentrated water organic matter contained in the fertilizer mainly has the following 3 hazards: (ii) an aerobic hazard. Due to biodegradation, the organic matters in the concentrated water can cause the oxygen deficiency and even the anaerobism of the receiving water body, and most aquatic organisms die, thereby generating stink and deteriorating the water quality and the environment. ② sensory pollution. The organic matter in the concentrated water not only causes the water to lose the use value, but also seriously affects the normal life of people nearby the water. And toxic hazard. The concentrated water contains a large amount of toxic organic matters, which can be continuously accumulated and stored in natural environments such as water body, soil and the like, and finally enter human bodies, thereby harming human health and natural environments. The concentrated water organic matter has large pollution degree to the environmental water body and high treatment difficulty, and is one of the difficult problems in the environmental protection research field at home and abroad. Therefore, the method has practical application value in pretreatment of concentrated water organic matters.
Disclosure of Invention
The invention aims to provide a preparation method of a hollow fiber composite loose nanofiltration membrane, which has small molecular weight cut-off and nano-scale separation aperture, and is simple and easy to operate. The specific steps are that polyether, dimethyl acetamide and polyethylene glycol are mixed and dissolved to prepare spinning membrane casting liquid, hollow fiber external pressure membrane is prepared by spinning under certain technological conditions, and then the hollow fiber composite loose nanofiltration membrane with the separation aperture reaching the nanometer level is prepared by soaking treatment with sulfuric acid aqueous solution. The preparation method of the composite loose nanofiltration membrane is simple, and the minimum cut-off molecular weight can reach 1000 Da. Can be used for pretreatment of concentrated water organic matters, such as separation of antibiotics and dyes with molecular weight of about 1000 g/mol in water and organic solvents.
The invention provides a preparation method of a hollow fiber composite loose nanofiltration membrane, which comprises the following specific steps:
(1) preparing a polyether sulfone casting film liquid:
respectively placing polyether sulfone, dimethylacetamide and polyethylene glycol in a stirring tank for mixing, and stirring and dissolving for 2-24 hours in the stirring tank at the temperature of 50-90 ℃ to obtain a polyether sulfone casting solution; transferring the polyether sulfone casting solution obtained by stirring and dissolving into a spinning storage tank, standing at the temperature of 50-90 ℃, heating for defoaming and curing to obtain the polyether sulfone spinning casting solution; wherein: polyether sulfone: dimethyl acetamide: the mass ratio of the polyethylene glycol is (26-36): (48-58): (10-20);
(2) preparing a polyether sulfone hollow fiber nanofiltration membrane:
providing a pressure of 0.2MPa by a nitrogen steel cylinder, enabling the polyether sulfone spinning casting solution obtained in the step (1) to pass through a feeding metering pump with controllable flow, enter a spinning nozzle at a flow of 5-20 mL/min, and vertically and downwards spraying under the action of a core solution with a flow of 2-15 mL/min; after being subjected to air bath of 20-50 cm, the nascent state membrane enters a water bath at the temperature of 20-40 ℃ for gel curing, is stored at the speed of 10-40 m/min through a wire winding wheel and is continuously soaked intermittently; soaking and cleaning the membrane yarn in clear water for 48 hours after spinning is finished, and changing water for a plurality of times during the soaking and cleaning process to obtain a hollow fiber nanofiltration membrane;
(3) acid treatment of the polyether alum hollow fiber nanofiltration membrane:
preparing a sulfuric acid aqueous solution with the mass concentration of 10-50%, cooling to room temperature, sealing two ends of the hollow fiber nanofiltration membrane prepared in the step (2), soaking in the prepared sulfuric acid aqueous solution for 5-120 min, taking out, and soaking and cleaning with clear water for several times; and soaking the hollow fiber composite loose nanofiltration membrane in 50% glycerol water solution for 48 hours, and drying to obtain the hollow fiber composite loose nanofiltration membrane, wherein the molecular weight cut-off of the obtained hollow fiber composite loose nanofiltration membrane is 800-2000.
According to the invention, the obtained hollow composite loose nanofiltration membrane has a good removal effect on particulate matter colloid, has a good removal effect on high molecular organic matters in a water body, and can intercept the molecular weight of 1000Da at least.
In the invention, the obtained hollow composite loose nanofiltration membrane can be effectively applied to pretreatment of concentrated water organic matters, in particular to separation of antibiotics or dyes with molecular weight of about 1000 g/mol in water and organic solvents.
In the invention, the hollow composite loose nanofiltration membrane is stored by a dry method, and the unused hollow composite loose nanofiltration membrane is prepared by glycerol: water: soaking the fresh-keeping film in a solution with the mass ratio of formaldehyde of 49:50:1 for more than 24 hours, taking out, airing and placing in the fresh-keeping film; the membrane was soaked with water 3 times for 12 hours or more before use to remove residual glycerol.
The manufacturing method of the membrane component for testing comprises the following steps: the membrane wire is firstly dried after being soaked in 50% glycerol aqueous solution for 48 hours, then both ends of the membrane wire are sealed by AB glue, then the membrane assembly is poured and packaged in a membrane assembly packaging head by epoxy resin glue, after the membrane wire is hardened, the packaging head is cut to expose a membrane wire water outlet, and the membrane assembly is manufactured by inserting a purchased membrane shell to carry out external pressure type filtration test. The molecular weight cut-off is 800-2000.
The invention has the beneficial effects that:
(1) compared with the traditional nanofiltration membrane, the loose nanofiltration membrane has the advantages of simple preparation method, large volume fraction, small occupied area, high treatment efficiency, small separation pore diameter and the like, and has good removal effect on particulate matter colloid.
(2) The loose nanofiltration membrane has good removal effect on small molecular organic matters in water, and the molecular weight capable of being intercepted is below 1000 Da. Can be effectively applied to the pretreatment of concentrated water organic matters, and has good effect on the separation of antibiotics in medical wastewater, dyes in printing and dyeing wastewater and the like in water and organic solvents.
Drawings
FIG. 1 is a graph showing the change of different acid treatment times of the loose nanofiltration membrane prepared in example 1 of the present invention versus the water flux of the membrane filaments;
fig. 2 is a graph showing the change of the rejection rate of PEG1000 by membrane filaments for different acid treatment times of the porous nanofiltration membrane prepared in example 1 of the present invention.
Fig. 3 is a curve showing the variation of the humic acid rejection efficiency of the loose nanofiltration membrane prepared in example 1 of the present invention at different treatment times.
Fig. 4 is a graph showing the change of the retention efficiency of tannic acid for different treatment times of the porous nanofiltration membrane prepared in example 1 of the present invention.
Fig. 5 is a graph showing the variation of alginic acid interception efficiency of the porous nanofiltration membrane prepared in example 1 of the present invention at different treatment times.
Detailed Description
The invention is further illustrated by the following examples.
Example 1
(1) Preparing a polyether sulfone casting film liquid:
the weight ratio is as follows: polyether sulfone in a mass ratio: dimethyl acetamide: polyethylene glycol is 34: 50: 16 mixing and dissolving the mixture in a stirring tank for 12 hours at the temperature of 65 ℃; and transferring the polyether sulfone casting solution obtained by stirring and dissolving into a spinning storage tank, standing at the temperature of 65 ℃, heating for defoaming and curing to obtain the polyether sulfone spinning casting solution.
(2) Preparing a polyether sulfone hollow fiber nanofiltration membrane:
the pressure of 0.2MPa is provided by a nitrogen steel cylinder, so that the casting solution enters a spinning nozzle at the flow rate of 15mL/min through a feeding metering pump with controllable flow rate, and is vertically sprayed downwards under the action of core solution with the flow rate of 5 mL/min. The nascent-state membrane is subjected to air bath of 40cm, then enters water bath of 25 ℃ for gel curing, is stored at the speed of 20m/min through a wire winding wheel, and is continuously soaked intermittently for a certain time. And after spinning is finished, soaking and cleaning the membrane yarn in clear water for 48 hours, and changing water for a plurality of times. Obtaining the hollow fiber nanofiltration membrane.
(3) Acid treatment of the polyether alum hollow fiber nanofiltration membrane:
preparing a sulfuric acid aqueous solution with the mass concentration of 40%, cooling to room temperature, sealing two ends of the hollow fiber membrane prepared in the step (2), soaking in the prepared acid solution for 40min, taking out, and soaking and cleaning with clear water for several times. Soaking in 50% glycerin water solution for 48 hr, and drying to obtain hollow fiber composite loose nanofiltration membrane with cut-off molecular weight of about 1000.
The selection of the acid treatment time has great influence on the treatment effect, a plurality of membrane assemblies made of membrane filaments with the preferred polymer concentration of 34% are respectively tested for water flux and the retention rate of PEG1000, and then the membrane assemblies are placed in an organic glass tube filled with a sulfuric acid solution with the mass fraction of 20% for acid treatment experiments, wherein the treatment time is respectively 0min, 10min, 20min, 30min, 40min and 50 min. Then soaking and cleaning the mixture for 48 hours by using clean water, and changing the water for a plurality of times during the period.
The method has good effect of removing concentrated water organic matters, takes organic matter raw material humic acid which is widely applied to various fields of agriculture, forestry, pasture, petroleum, chemical industry, building materials, medicine, health, environmental protection and the like, organic matter raw material tannic acid which is commonly used in industries such as printing and dyeing and organic raw material alginic acid which is commonly used in papermaking, textile and medicine industries as processing targets, and treats the concentrated water organic matters with the time processing effect shown in figures 3-5.
Claims (4)
1. A preparation method of a hollow fiber composite loose nanofiltration membrane is characterized by comprising the following specific steps:
(1) preparing a polyether sulfone casting film liquid:
respectively placing polyether sulfone, dimethylacetamide and polyethylene glycol in a stirring tank for mixing, and stirring and dissolving for 2-24 hours in the stirring tank at the temperature of 50-90 ℃ to obtain a polyether sulfone casting solution; transferring the polyether sulfone casting solution obtained by stirring and dissolving into a spinning storage tank, standing at the temperature of 50-90 ℃, heating for defoaming and curing to obtain the polyether sulfone casting solution; wherein: polyether sulfone: dimethyl acetamide: the mass ratio of the polyethylene glycol is (26-36): (48-58): (10-20);
(2) preparing a polyether sulfone hollow fiber nanofiltration membrane:
providing a pressure of 0.2MPa by a nitrogen steel cylinder, enabling the polyether sulfone casting solution obtained in the step (1) to pass through a feeding metering pump with controllable flow, enter a spinning nozzle at a flow of 5-20 mL/min, and vertically and downwards spraying under the action of core liquid with a flow of 2-15 mL/min; after being subjected to air bath of 20-50 cm, the nascent state membrane enters a water bath at the temperature of 20-40 ℃ for gel curing, is stored at the speed of 10-40 m/min through a wire winding wheel and is continuously soaked intermittently; after spinning is finished, soaking and cleaning the membrane yarn in clear water for 48 hours, and changing water for a plurality of times during the soaking and cleaning process to obtain the polyether sulfone hollow fiber nanofiltration membrane;
(3) acid treatment of the polyethersulfone hollow fiber nanofiltration membrane:
preparing a sulfuric acid aqueous solution with the mass concentration of 10-50%, cooling to room temperature, sealing two ends of the polyether sulfone hollow fiber nanofiltration membrane prepared in the step (2), soaking in the prepared sulfuric acid aqueous solution for 5-120 min, taking out, and soaking and cleaning with clear water for several times; and soaking the hollow fiber composite loose nanofiltration membrane in 50% glycerol water solution for 48 hours, and drying to obtain the hollow fiber composite loose nanofiltration membrane, wherein the molecular weight cut-off of the obtained hollow fiber composite loose nanofiltration membrane is 800-2000.
2. The preparation method of the hollow fiber composite loose nanofiltration membrane of claim 1, wherein the obtained hollow fiber composite loose nanofiltration membrane has good removal effect on particulate matter colloid, has good removal effect on high molecular organic matters in water, and has a minimum trapped molecular weight of 1000 Da.
3. The preparation method of the hollow fiber composite loose nanofiltration membrane according to claim 1, wherein the hollow fiber composite loose nanofiltration membrane can be effectively applied to pretreatment of concentrated water organic matters, in particular to separation of antibiotics or dyes with molecular weight of about 1000 g/mol in water and organic solvents.
4. The preparation method of the hollow fiber composite loose nanofiltration membrane according to claim 1, wherein the hollow fiber composite loose nanofiltration membrane is stored by a dry method, and the unused hollow fiber composite loose nanofiltration membrane is glycerol: water: soaking the fresh-keeping film in a solution with the mass ratio of formaldehyde of 49:50:1 for more than 24 hours, taking out, airing and placing in the fresh-keeping film; the membrane was soaked with water 3 times for 12 hours or more before use to remove residual glycerol.
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| US4983291A (en) * | 1989-12-14 | 1991-01-08 | Allied-Signal Inc. | Dry high flux semipermeable membranes |
| CN101641818A (en) * | 2006-12-26 | 2010-02-03 | 东洋纺织株式会社 | Method for manufacturing polymeric electrolyte membrane |
| CN101844041A (en) * | 2010-06-07 | 2010-09-29 | 苏州信望膜技术有限公司 | Hollow fiber nanofiltration membrane and preparation method thereof |
| CN104941461A (en) * | 2014-03-27 | 2015-09-30 | 贵阳时代沃顿科技有限公司 | Nanofiltration membrane for seawater desalination and preparation method thereof |
| CN105233710A (en) * | 2015-09-23 | 2016-01-13 | 三达膜科技（厦门）有限公司 | Preparation method of asymmetric polyether sulfone hollow fiber nanofiltration membrane |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4983291A (en) * | 1989-12-14 | 1991-01-08 | Allied-Signal Inc. | Dry high flux semipermeable membranes |
| CN101641818A (en) * | 2006-12-26 | 2010-02-03 | 东洋纺织株式会社 | Method for manufacturing polymeric electrolyte membrane |
| CN101844041A (en) * | 2010-06-07 | 2010-09-29 | 苏州信望膜技术有限公司 | Hollow fiber nanofiltration membrane and preparation method thereof |
| CN104941461A (en) * | 2014-03-27 | 2015-09-30 | 贵阳时代沃顿科技有限公司 | Nanofiltration membrane for seawater desalination and preparation method thereof |
| CN105233710A (en) * | 2015-09-23 | 2016-01-13 | 三达膜科技（厦门）有限公司 | Preparation method of asymmetric polyether sulfone hollow fiber nanofiltration membrane |
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