CN107983175B - High flux aromatic polyamide reverse osmosis membrane using additives and method of making - Google Patents
High flux aromatic polyamide reverse osmosis membrane using additives and method of making Download PDFInfo
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- CN107983175B CN107983175B CN201711250742.XA CN201711250742A CN107983175B CN 107983175 B CN107983175 B CN 107983175B CN 201711250742 A CN201711250742 A CN 201711250742A CN 107983175 B CN107983175 B CN 107983175B
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- B01D69/12—Composite membranes; Ultra-thin membranes
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- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
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Abstract
The invention relates to a high-flux aromatic polyamide reverse osmosis membrane using an additive and a preparation method thereof; the aromatic polyamide composite reverse osmosis membrane uses an amide compound containing carbon-carbon double bonds as an additive of an aqueous phase solution and carries out ultraviolet-initiated polymerization on the amide compound; is formed by connecting amido bonds in the aromatic polyamide layer and on the surface with carbon-carbon double bonds of the amide compounds. Preparing an aqueous phase solution containing 0.1-1.0% of amide compounds containing carbon-carbon double bonds and 0.1% of photoinitiator 2959 for reaction; after the interfacial polymerization reaction is finished, carrying out free radical polymerization reaction on the primary membrane; and (4) placing the irradiated reverse osmosis membrane in an oven for heat treatment, and drying the membrane to obtain the reverse osmosis membrane. The preparation process is simple, the operation time is short, the implementation is easy, the cost is low, and the water flux of the reverse osmosis membrane is greatly improved on the basis of keeping the salt rejection rate of the reverse osmosis membrane without the additive.
Description
Technical Field
The invention relates to an aromatic polyamide composite reverse osmosis membrane which takes amide compounds containing carbon-carbon double bonds as additives and causes the amide compounds to carry out ultraviolet polymerization and a preparation method thereof; belongs to the field of composite reverse osmosis membrane preparation.
Background
In the past decades, a great deal of research is put into improving the separation performance, the pollution resistance and the chlorine resistance of the reverse osmosis membrane, but few people can improve the flux without losing the salt rejection rate, and at present, the improvement of the flux of the reverse osmosis membrane means that the energy consumption is reduced and the energy utilization rate is improved due to the fact that the problem of energy shortage is increasingly severe. Therefore, it becomes critical how to design a reverse osmosis membrane with high flux and little decrease in rejection.
At present, the mainstream preparation method of the polyamide reverse osmosis membrane is an interfacial polymerization method, and the polyamide reverse osmosis membrane is obtained by firstly uniformly spreading a layer of water phase solution containing m-phenylenediamine (MPD) in a certain proportion on the surface of a polysulfone membrane serving as a supporting layer, removing the redundant water phase solution, pouring oil phase solution taking trimesoyl chloride (TMC) as a solute on the membrane surface, carrying out interfacial polymerization reaction, and reacting for a period of time. There are two main ways to increase the flux of reverse osmosis membranes today, one is post-treatment of nascent reverse osmosis membranes, for example, by treatment of the membrane with various acids, alcohols, oxidants, and alcamines. However, this type of treatment has the disadvantage that the chemicals used for the post-treatment generally cause irreversible damage to the polyamide film. Another method of increasing the flux of reverse osmosis membranes is to introduce additives into either the aqueous or oil phase used for interfacial polymerization.
The flux of the membrane is improved by the additive mainly through two modes, namely, the diffusion of MPD to an oil phase is influenced, so that the form of a polyamide membrane surface is influenced, and a 'water channel' is constructed in a polyamide structure, so that a path is provided for the passing of water molecules. Khorshi di et al, the water flux of polyamide membranes was increased by adding monohydric and polyhydric alcohols (ethanol, ethylene glycol and xylitol) to the aqueous solvent (B.Khorshi di et al, journal of Membrane Science 523(2017) 336-). Yang Zhang et al hinder MPD from diffusing in the oil phase by adding 1, 3-Propane Sultone (PS) into the oil phase solution, utilize two oxygen atoms in PS sulfonic acid group to connect with the hydrogen atom of primary amino group in MPD through the hydrogen bond, hinder MPD, make MPD in the local concentration of water-oil interface rise, and then influenced whole interface polymerization process, different from conventional interface polymerization process, MPD receives the hindrance effect that PS brought in the process of diffusing to oil phase one side, make MPD hardly pass near the interface region, therefore after the interface polymerization reaction, formed "multilayer structure". Unlike conventional peak-valley structures, this "multilayer structure" has a larger surface area, which means that the contact area of water molecules with the membrane surface is increased, resulting in an increased water flux (Yang Zhang, Xiaohei Miao et al. journal of Polymer Research January 2017,24: 5). Jeong et al, which has a group with a strong charge, and which, when added to a polyamide separation layer, enhances the electronegativity and hydrophilicity of the surface of the separation layer, enhances the binding between the surface of the membrane and water molecules, thereby enhancing water flux. On the other hand, in the experimental design, the authors used two different zeolite nanoparticles, respectively of the "pore-filling" type and the "pore-opening" type, which, as the name implies, possessed a pore structure, and the characterization results showed a pore diameter of about 4 angstroms, and a permeability coefficient higher for the latter than for the former, demonstrating that the presence of water channels indeed had a positive effect on the increase in water flux (b. — h. The above mentioned research results, although all can improve the flux of the membrane to different extent, but the retention performance of the membrane is lost, and the method of the present invention can improve the retention rate of the membrane while greatly improving the flux of the membrane, which is an advantage that the general additive can not achieve.
Disclosure of Invention
The invention aims to provide a high-flux aromatic polyamide reverse osmosis membrane using an additive and a preparation method thereof, and the aromatic polyamide composite reverse osmosis membrane has high flux and does not lose salt rejection rate; the reverse osmosis membrane has good selective permeability and large flux improvement. The preparation method is simple and easy to operate.
The invention is realized by the following technical scheme:
a high flux aromatic polyamide reverse osmosis membrane using an additive; the aromatic polyamide composite reverse osmosis membrane uses an amide compound containing carbon-carbon double bonds as an additive of an aqueous phase solution and carries out ultraviolet-initiated polymerization on the amide compound; is formed by connecting amido bonds in the aromatic polyamide layer and on the surface with carbon-carbon double bonds of the amide compounds.
The preparation method of the high-flux aromatic polyamide reverse osmosis membrane using the additive comprises the steps of preparing an aqueous solution containing 0.1-1.0 mass percent of amide compounds containing carbon-carbon double bonds and 0.1 mass percent of photoinitiator 2959 for reaction; after the interfacial polymerization reaction is finished, carrying out free radical polymerization reaction on the primary membrane; and (4) placing the irradiated reverse osmosis membrane in an oven for heat treatment, and drying the membrane to obtain the reverse osmosis membrane.
Preferably, the free radical polymerization is initiated under UV light.
The amide compound containing a carbon-carbon double bond is preferably one of acrylamide and N-vinyl pyrrolidone.
According to the invention, the double bond-containing amide compounds and the ultraviolet light initiator are added into the aqueous phase solution, and the idea of selecting the substances as the additives is mainly that amido bonds can form hydrogen bonds with water molecules, and the hydrophilicity of the reverse osmosis membrane can be obviously improved due to the large number of amido bonds, so that the effect of improving the membrane flux is achieved; secondly, in order to keep the amide-based compound in the interior and on the surface of the membrane, the unsaturation of the double bond is used to polymerize and bond the additive to the polyamide structure of the reverse osmosis membrane. The amide bond in the additive can form a strong hydrogen bond with the amino on MPD, so that MPD is brought into an oil phase reagent to promote the diffusion of MPD into an oil phase; secondly, after ultraviolet polymerization, a large amount of polymers formed by additives stay in the reverse osmosis membrane and on the surface of the reverse osmosis membrane, amide bonds in the polymers can form strong hydrogen bonds with water molecules, the acting force between the membrane and the water molecules is enhanced, and the hydrophilicity of the membrane is improved. Both of the above effects can enhance the flux of the membrane, and no one is involved in the method of introducing an additive into an aqueous phase reagent and performing ultraviolet treatment. After the interfacial polymerization reaction is finished, carrying out ultraviolet irradiation on the nascent reverse osmosis membrane to enable double-bond amide compounds staying in the polyamide layer to carry out polymerization reaction, thereby preparing the high-flux aromatic polyamide reverse osmosis membrane; in the interfacial polymerization process, amide bonds contained in the additive can form hydrogen bonds with MPD, so that the MPD can be promoted to diffuse into an oil phase, and under the action of an initiator and ultraviolet light, the additive can generate homopolymerization and be grafted to a polyamide chain, so that the additive stays in the inner part and the surface of a polyamide layer, and a large number of amide structures can improve the flux of a membrane; the structure is schematically shown in figure 1. The aromatic polyamide reverse osmosis membrane is mainly divided into three parts, namely a non-woven fabric as a base, a polysulfone layer as a supporting layer and a polyamide layer as a separating layer. Taking N-vinyl pyrrolidone as an example, the polymerization reaction equation is shown as follows (R is an ultraviolet light initiator 2959):
the invention has the advantages that: the preparation process is simple, the operation time is short, the implementation is easy, the cost is low, and the water flux of the reverse osmosis membrane is greatly improved on the basis of keeping the salt rejection rate of the reverse osmosis membrane without the additive. The invention basically keeps the selective permeability of the unmodified aromatic polyamide composite reverse osmosis membrane; the modified membrane has the characteristic of greatly improving flux.
Drawings
FIG. 1 is a schematic diagram of a high flux aromatic polyamide reverse osmosis membrane configuration.
FIG. 2 is a scanning electron microscope image of the surface structure of an aromatic polyamide reverse osmosis membrane with added acrylamide.
FIG. 3 is a scanning electron microscope image of the surface structure of an N-vinylpyrrolidone-added aromatic polyamide reverse osmosis membrane.
FIG. 4 is a scanning electron microscope image of the surface structure of an aromatic polyamide reverse osmosis membrane without additives.
Detailed Description
Example 1
Preparing an aqueous phase solution containing 0.1% of N-vinyl pyrrolidone and 0.1% of ultraviolet initiator 2959; pouring the prepared water phase solution onto the surface of the polysulfone basal membrane, removing the redundant water phase solution after reacting for 1min, and pouring the oil phase solution after the membrane surface is dried for reacting for 30 s; removing the redundant oil phase to prepare a reverse osmosis membrane; placing the newly prepared reverse osmosis membrane under an ultraviolet lamp for irradiation; and then the reverse osmosis membrane is placed in an oven for heat treatment for 5min to prepare the high-flux aromatic polyamide reverse osmosis membrane prepared by adding the N-vinyl pyrrolidone. The electron microscope image is shown in FIG. 3.
The permeation flux and salt rejection of the N-vinylpyrrolidone added high flux aromatic polyamide reverse osmosis membrane was 69.09L/(m 2. h) and 98.90% as measured at 1.55MPa, 25 ℃ using 2000mg/L aqueous sodium chloride.
Example 2
Preparing an aqueous phase solution containing 0.5% of N-vinyl pyrrolidone and 0.1% of ultraviolet initiator 2959; pouring the prepared water phase solution onto the surface of the polysulfone basal membrane, removing the redundant water phase solution after reacting for 1min, and pouring the oil phase solution after the membrane surface is dried for reacting for 30 s; removing the redundant oil phase to prepare a reverse osmosis membrane; placing the newly prepared reverse osmosis membrane under an ultraviolet lamp for irradiation; and then the reverse osmosis membrane is placed in an oven for heat treatment for 5min to prepare the high-flux aromatic polyamide reverse osmosis membrane prepared by adding the N-vinyl pyrrolidone. The electron microscope image is shown in FIG. 3.
The permeation flux and salt rejection of the N-vinylpyrrolidone added high flux aromatic polyamide reverse osmosis membrane was 72.17L/(m 2. h) and 98.94% as measured at 1.55MPa, 25 ℃ using 2000mg/L aqueous sodium chloride.
Example 3
Preparing an aqueous phase solution containing 1.0% of N-vinyl pyrrolidone by mass concentration and 0.1% of ultraviolet initiator 2959; pouring the prepared water phase solution onto the surface of the polysulfone basal membrane, removing the redundant water phase solution after reacting for 1min, and pouring the oil phase solution after the membrane surface is dried for reacting for 30 s; removing the redundant oil phase to prepare a reverse osmosis membrane; placing the newly prepared reverse osmosis membrane under an ultraviolet lamp for irradiation; and then the reverse osmosis membrane is placed in an oven for heat treatment for 5min to prepare the high-flux aromatic polyamide reverse osmosis membrane prepared by adding the N-vinyl pyrrolidone. The electron microscope image is shown in FIG. 3.
The permeation flux and salt rejection of the N-vinylpyrrolidone added high flux aromatic polyamide reverse osmosis membrane was 75.84L/(m 2. h) and 99.16% as measured at 1.55MPa, 25 ℃ using 2000mg/L aqueous sodium chloride solution.
Example 4
Preparing an aqueous phase solution containing acrylamide with the mass concentration of 0.1% and 0.1% of ultraviolet initiator 2959; pouring the prepared water phase solution onto the surface of the polysulfone basal membrane, removing the redundant water phase solution after reacting for 1min, and pouring the oil phase solution after the membrane surface is dried for reacting for 30 s; removing the redundant oil phase to prepare a reverse osmosis membrane; placing the newly prepared reverse osmosis membrane under an ultraviolet lamp for irradiation; and then the reverse osmosis membrane is placed in an oven for heat treatment for 5min to prepare the high-flux aromatic polyamide reverse osmosis membrane added with acrylamide. The electron microscope image is shown in FIG. 2.
The permeation flux and salt rejection of the acrylamide-added high flux aromatic polyamide reverse osmosis membrane was 79.90L/(m 2. h) and 98.71% as measured at 1.55MPa, 25 ℃ using 2000mg/L aqueous sodium chloride.
Example 5
Preparing an aqueous phase solution containing acrylamide with the mass concentration of 0.5% and 0.1% of ultraviolet initiator 2959; pouring the prepared water phase solution onto the surface of the polysulfone basal membrane, removing the redundant water phase solution after reacting for 1min, and pouring the oil phase solution after the membrane surface is dried for reacting for 30 s; removing the redundant oil phase to prepare a reverse osmosis membrane; placing the newly prepared reverse osmosis membrane under an ultraviolet lamp for irradiation; and then the reverse osmosis membrane is placed in an oven for heat treatment for 5min to prepare the high-flux aromatic polyamide reverse osmosis membrane added with acrylamide. The electron microscope image is shown in FIG. 2.
The permeation flux and salt rejection of the acrylamide-added high flux aromatic polyamide reverse osmosis membrane was 75.22L/(m 2. h) and 99.14% as tested at 1.55MPa, 25 ℃ using 2000mg/L aqueous sodium chloride.
Example 6
Preparing an aqueous phase solution containing 1.0% of acrylamide and 0.1% of ultraviolet initiator 2959 by mass; pouring the prepared water phase solution onto the surface of the polysulfone basal membrane, removing the redundant water phase solution after reacting for 1min, and pouring the oil phase solution after the membrane surface is dried for reacting for 30 s; removing the redundant oil phase to prepare a reverse osmosis membrane; placing the newly prepared reverse osmosis membrane under an ultraviolet lamp for irradiation; and then the reverse osmosis membrane is placed in an oven for heat treatment for 5min to prepare the high-flux aromatic polyamide reverse osmosis membrane added with acrylamide. The electron microscope image is shown in FIG. 2.
The permeation flux and salt rejection of the acrylamide-added high flux aromatic polyamide reverse osmosis membrane was 89.95L/(m 2. h) and 98.52% as tested at 1.55MPa, 25 ℃ using 2000mg/L aqueous sodium chloride.
Comparative example
And (3) adding no additive and initiator into the aqueous phase solution, keeping the rest steps unchanged, and carrying out heat treatment on the reverse osmosis membrane to obtain the aromatic polyamide composite reverse osmosis membrane without the additive. The electron microscope image is shown in FIG. 4.
The permeation flux and the salt rejection of the primary aromatic polyamide reverse osmosis membrane were 60.66L/(m 2. multidot.h) and 98.82% as measured at 1.55MPa, 25 ℃ using 2000mg/L aqueous sodium chloride solution.
The experimental results show that: the flux of the high-flux aromatic polyamide reverse osmosis membrane prepared by adding the amide compound containing the double bond and carrying out ultraviolet initiation is improved, and the salt rejection rate is kept almost unchanged.
The flux and salt rejection of the membranes prepared in the examples and comparative examples of the present invention are shown in the table.
As can be seen from table 1, the reverse osmosis membrane prepared by adding acrylamide and performing ultraviolet polymerization has better selective permeability; secondly, adding N-vinyl pyrrolidone and carrying out ultraviolet polymerization to prepare a reverse osmosis membrane; the flux of the reverse osmosis membrane prepared without the additive and without ultraviolet initiation is lower.
Claims (1)
1. A preparation method of a high-flux aromatic polyamide reverse osmosis membrane using an additive is characterized in that an aqueous phase solution containing 0.1-1.0 mass percent of amide compounds containing carbon-carbon double bonds and 0.1 mass percent of ultraviolet initiator 2959 is prepared; performing interfacial polymerization reaction on a polysulfone-based membrane by using a prepared water phase solution and an oil phase reagent to obtain a reverse osmosis membrane; after the interfacial polymerization reaction is finished, placing the prepared reverse osmosis membrane under an ultraviolet lamp for irradiation; finally, placing the reverse osmosis membrane initiated by ultraviolet in an oven for heat treatment to prepare an aromatic polyamide composite reverse osmosis membrane which takes an amide compound containing carbon-carbon double bonds as an additive and enables the amide compound to be polymerized by ultraviolet; the amide compound containing carbon-carbon double bonds is N-vinyl pyrrolidone.
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| CN109433028B (en) * | 2018-12-27 | 2021-10-08 | 成都硕特科技股份有限公司 | Polyamide reverse osmosis membrane and application thereof in sea water desalination field |
| CN112844075A (en) * | 2020-12-29 | 2021-05-28 | 宁波日新恒力科技有限公司 | Preparation method of high-flux polyamide reverse osmosis composite membrane |
| CN112426894B (en) * | 2021-01-28 | 2021-04-23 | 湖南澳维新材料技术有限公司 | Preparation method of polyamide composite reverse osmosis membrane and obtained reverse osmosis membrane |
| CN115475540B (en) * | 2022-09-29 | 2024-05-03 | 万华化学集团股份有限公司 | Polyamide composite membrane and preparation method and application thereof |
| CN116159446B (en) * | 2023-03-24 | 2023-11-28 | 泰州九润环保科技有限公司 | Molecular sieve/polyamide mixed matrix membrane |
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| CN1043143A (en) * | 1988-12-01 | 1990-06-20 | 南朝鲜化学研究所 | The manufacture method of Dropless high polymer |
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