阅读说明：本技术 一种高通量聚酰胺反渗透复合膜的制备方法 (Preparation method of high-flux polyamide reverse osmosis composite membrane ) 是由 不公告发明人 于 2020-12-29 设计创作，主要内容包括：本发明提供了一种聚酰胺反渗透复合膜的改性方法,包括以下步骤,采用紫外光辐照聚酰胺反渗透复合膜后,得到改性后的聚酰胺反渗透复合膜。本发明利用紫外光这一环境友好且绿色环保的可再生能源,且在不使用其他化学药剂的辅助的条件下,通过紫外光辐照聚酰胺复合膜表面,对膜表面进行亲水改性研究,从而制备得到了具有更高通量的改性聚酰胺复合膜。本发明提供的改性方法具有绿色环保和环境友好的优点,操作过程简单,时间短,操控性强,可控性好,易于实施且成本较低,更加有利于工业化推广和应用。(The invention provides a modification method of a polyamide reverse osmosis composite membrane, which comprises the following steps of irradiating the polyamide reverse osmosis composite membrane by ultraviolet light to obtain the modified polyamide reverse osmosis composite membrane. The invention utilizes the environment-friendly and environment-friendly renewable energy of ultraviolet light, and carries out hydrophilic modification research on the surface of the polyamide composite membrane by irradiating the surface of the polyamide composite membrane with the ultraviolet light under the condition of not using the assistance of other chemical agents, thereby preparing the modified polyamide composite membrane with higher flux. The modification method provided by the invention has the advantages of environmental protection and environmental protection, and is simple in operation process, short in time, strong in controllability, good in controllability, easy to implement, low in cost and more beneficial to industrial popularization and application.)

1. A modification method of a polyamide reverse osmosis composite membrane is characterized by comprising the following steps:

and irradiating the polyamide reverse osmosis composite membrane by using ultraviolet light to obtain the modified polyamide reverse osmosis composite membrane.

2. The modification method according to claim 1, wherein the wavelength of the ultraviolet light is 190 to 400 nm;

the irradiation power of the ultraviolet light is 100-500W;

the irradiation time of the ultraviolet light is 1-5 min.

3. The modification method according to claim 1, wherein the light source of the ultraviolet light comprises one or more of an ultraviolet lamp of a xenon light source, an ultraviolet lamp of a low-pressure mercury lamp light source, and an ultraviolet lamp of a high-efficiency light-emitting diode;

the straight line distance between the light source of the ultraviolet light and the polyamide reverse osmosis composite membrane is 10-50 cm.

4. The modification method of claim 1, wherein after the polyamide reverse osmosis composite membrane is irradiated by ultraviolet light, part of polyamide molecules in the polyamide active layer are subjected to a cleavage reaction to generate a nitro group and a carboxyl group;

the ultraviolet radiation polyamide reverse osmosis composite membrane comprises the following specific components:

the ultraviolet light is positioned above the polyamide active layer on the surface of the polyamide reverse osmosis composite membrane and irradiates the polyamide reverse osmosis composite membrane.

5. The modification method according to claim 1, wherein the water flux and/or salt rejection of the modified polyamide reverse osmosis composite membrane can be adjusted by adjusting the parameter of the ultraviolet irradiation;

the water flux of the polyamide reverse osmosis composite membrane shows a trend of increasing and then decreasing along with the ultraviolet irradiation;

with the ultraviolet irradiation, the desalination rate of the polyamide reverse osmosis composite membrane tends to decrease and then increase.

6. The modification method according to claim 1, wherein the modified polyamide reverse osmosis composite membrane has a water flux of 40-65 GFD;

the desalting rate of the modified polyamide reverse osmosis composite membrane is 88 to 99.5 percent;

the modification includes high throughput modification.

7. The modification method according to claim 1, wherein the polyamide reverse osmosis composite membrane comprises a non-woven fabric-based membrane;

the non-woven fabric base film comprises a polyethylene glycol terephthalate non-woven fabric base film and/or a polyimide non-woven fabric base film;

the thickness of the base film is 100-150 mu m;

the aperture of the basement membrane is 0.1-10 mu m.

8. The modification method according to claim 7, wherein the polyamide reverse osmosis composite membrane comprises a porous support layer compounded on the non-woven fabric base membrane;

the porous supporting layer comprises one or more of a polysulfone porous supporting layer, a polyacrylonitrile porous supporting layer, a polyvinylidene fluoride porous supporting layer, a polyether ketone porous supporting layer, a polyether sulfone porous supporting layer and a polysulfone/polyether sulfone blended ultrafiltration porous supporting layer;

the thickness of the porous support membrane layer is 120-140 mu m;

the aperture of the porous support film layer is 15-35 nm.

9. The modification method according to claim 8, wherein the polyamide reverse osmosis composite membrane comprises a polyamide active layer compounded on the porous support layer;

the thickness of the polyamide active layer is 0.1-0.5 mu m;

the molecular weight of the polyamide is 30-80 kDa.

10. The modified polyamide reverse osmosis composite membrane prepared by the modification method of any one of claims 1-9 is applied to the field of water treatment.

Technical Field

The invention belongs to the technical field of water treatment of polyamide composite membranes, relates to a modification method of a polyamide reverse osmosis composite membrane, and particularly relates to a preparation method of a high-flux polyamide reverse osmosis composite membrane.

Background

RO membrane (Reverse Osmosis), i.e., Reverse Osmosis membrane. The reverse osmosis principle is a method of flowing water from a low concentration to a high concentration and then from a high concentration to a low concentration after pressurizing the water. Since the pore diameter of the RO reverse osmosis membrane is as small as a nanometer (10 × 9 m, 1 nm), water molecules can pass through the RO membrane under a certain pressure, and impurities such as inorganic salts, heavy metal ions, organic matters, colloids, bacteria, viruses and the like in the source water cannot pass through the RO membrane, so that the pure water which can permeate and the concentrated water which cannot permeate are strictly distinguished. In the modern application field, the reverse osmosis technology is an important pure water supply technology, wherein the polyamide type composite separation membrane is the main reverse osmosis membrane material at present due to the extremely thin (<200nm) effective separation layer and the operation pressure which is obviously lower than the previous cellulose acetate separation membrane (micron-sized thickness), and the preparation of the high-flux polyamide composite membrane is the hot point of the recent research.

The polyamide composite membrane is composed of a non-woven fabric mechanical supporting layer, a porous polysulfone supporting layer membrane and an ultrathin polyamide active layer attached to the surface of the porous polysulfone supporting layer membrane, wherein the most common method for preparing the ultrathin polyamide active separation layer is an interfacial polymerization method, namely, two monomers with high reaction activity, namely polyamine and polybasic acyl chloride, are used for carrying out polymerization reaction on mutually incompatible solvent interfaces, so that an ultrathin polyamide active separation layer is formed on the porous supporting layer membrane. The interfacial polymerization reaction rate is very high, the controllability of the thickness and the compactness of the formed ultrathin polyamide active separation layer is poor, and the flux of the composite membrane can be obviously reduced when the ultrathin polyamide active separation layer is thicker or too compact. Therefore, increasing the flux of polyamide composite membranes is an important direction in the development of polyamide composite membranes.

The current methods for improving the flux of the polyamide composite membrane mainly comprise: 1) starting from a membrane material for preparing a polyamide active separation layer, a plurality of polyamine and polyacyl chloride monomers are designed and developed for preparing a high-throughput polyamide composite membrane. Polyamine monomers such as 4-chloro-m-phenylenediamine, 4-nitro-m-phenylenediamine, 2, 4-diaminotoluene, 5-sulfo-m-phenylenediamine and pyromellitic triamide-amine, sulfonated diamine monomer 4, 4' - { [1, 4-phenylenebis (methylene) ] diamino } diphenylsulfonic acid (PMABSA); in addition, the monomer also comprises trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride, and polybasic acyl chloride monomers such as 5-isocyanate-isophthaloyl chloride, 5-chloroformyl oxygen-isopeptide acyl chloride and the like. 2) The modification of the active layer on the surface of the polyamide composite membrane mainly comprises two modes of surface modification and active layer inorganic nano material doping. 3) The doping of various additives in the polyamine aqueous phase solution and the polyacyl chloride oil phase solution can regulate and control the interfacial polymerization reaction rate and improve the water flux of the polyamide composite membrane.

Although each of the above methods can improve interfacial polymerization membrane flux to varying degrees, it either involves complicated chemical synthesis processes or involves more risks of chemical use or design structural instability, thereby limiting its further scale-up applications.

Therefore, how to find a simpler and more suitable way to improve the water flux of the polyamide composite membrane, solve the defects in the technology, is green and environment-friendly, is more suitable for industrial popularization and application, and becomes one of the focuses of great attention of researchers in the same line.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a method for modifying a polyamide reverse osmosis composite membrane, and in particular, a method for preparing a high-flux polyamide reverse osmosis composite membrane.

The invention provides a modification method of a polyamide reverse osmosis composite membrane, which comprises the following steps:

and irradiating the polyamide reverse osmosis composite membrane by using ultraviolet light to obtain the modified polyamide reverse osmosis composite membrane.

Preferably, the wavelength of the ultraviolet light is 190-400 nm;

the irradiation power of the ultraviolet light is 100-500W;

the irradiation time of the ultraviolet light is 1-5 min.

Preferably, the light source of the ultraviolet light comprises one or more of an ultraviolet lamp of a xenon lamp light source, an ultraviolet lamp of a low-pressure mercury lamp light source and an ultraviolet lamp of a high-efficiency light-emitting diode;

the straight line distance between the light source of the ultraviolet light and the polyamide reverse osmosis composite membrane is 10-50 cm.

Preferably, after the polyamide reverse osmosis composite membrane is irradiated by the ultraviolet light, part of polyamide molecules in the polyamide active layer can generate a breaking reaction to generate a nitro group and a carboxyl group;

the ultraviolet radiation polyamide reverse osmosis composite membrane comprises the following specific components:

the ultraviolet light is positioned above the polyamide active layer on the surface of the polyamide reverse osmosis composite membrane and irradiates the polyamide reverse osmosis composite membrane.

Preferably, the water flux and/or the salt rejection rate of the modified polyamide reverse osmosis composite membrane can be adjusted by adjusting the parameters of ultraviolet irradiation;

the water flux of the polyamide reverse osmosis composite membrane shows a trend of increasing and then decreasing along with the ultraviolet irradiation;

with the ultraviolet irradiation, the desalination rate of the polyamide reverse osmosis composite membrane tends to decrease and then increase.

Preferably, the water flux of the modified polyamide reverse osmosis composite membrane is 40-65 GFD;

the desalting rate of the modified polyamide reverse osmosis composite membrane is 88 to 99.5 percent;

the modification includes high throughput modification.

Preferably, the polyamide reverse osmosis composite membrane comprises a non-woven fabric base membrane;

the non-woven fabric base film comprises a polyethylene glycol terephthalate non-woven fabric base film and/or a polyimide non-woven fabric base film;

the thickness of the base film is 100-150 mu m;

the aperture of the basement membrane is 0.1-10 mu m.

Preferably, the polyamide reverse osmosis composite membrane comprises a porous support layer compounded on the non-woven fabric base membrane;

the porous supporting layer comprises one or more of a polysulfone porous supporting layer, a polyacrylonitrile porous supporting layer, a polyvinylidene fluoride porous supporting layer, a polyether ketone porous supporting layer, a polyether sulfone porous supporting layer and a polysulfone/polyether sulfone blended ultrafiltration porous supporting layer;

the thickness of the porous support membrane layer is 120-140 mu m;

the aperture of the porous support film layer is 15-35 nm.

Preferably, the polyamide reverse osmosis composite membrane comprises a polyamide active layer compounded on the porous support layer;

the thickness of the polyamide active layer is 0.1-0.5 mu m;

the molecular weight of the polyamide is 30-80 kDa.

The invention also provides application of the modified polyamide reverse osmosis composite membrane prepared by the modification method in any one of the technical schemes in the field of water treatment.

The invention provides a modification method of a polyamide reverse osmosis composite membrane, which comprises the following steps of irradiating the polyamide reverse osmosis composite membrane by ultraviolet light to obtain the modified polyamide reverse osmosis composite membrane. Compared with the prior art, the method aims at overcoming the defects that in the existing method for improving the flux of the polyamide composite membrane through chemical modification, a large amount of chemical agents are used, a complicated chemical synthesis process is involved, or more chemical use or design structure is not stable, so that the further large-scale application is limited.

The invention creatively utilizes the environment-friendly and environment-friendly renewable energy source of ultraviolet light, and carries out hydrophilic modification research on the surface of the polyamide composite membrane by irradiating the surface of the polyamide composite membrane with ultraviolet light under the condition of not using the assistance of other chemical agents, thereby preparing the modified polyamide composite membrane with higher flux. The invention adopts the mode of irradiating the polyamide active surface layer of the composite membrane by ultraviolet light to carry out hydrophilic modification on the polyamide composite membrane formed by interfacial polymerization reaction, and after the surface of the polyamide composite membrane is irradiated by ultraviolet light for a certain time, polyamide molecules are subjected to fracture reaction to generate nitryl (-NO)₂) And carboxyl (-COOH) groups and the like, wherein the generation of the groups enables the water flux of the polyamide composite membrane to be remarkably improved, so that the high-flux polyamide composite membrane is obtained, and the desalting rate of the obtained high-flux polyamide composite membrane is only slightly reduced. Further, by appropriate modification of the irradiation stripesThe flux and the salt rejection rate of the polyamide composite membrane can be adjusted, and the polyamide composite membrane is more flexible and has strong controllability.

The ultraviolet light is a green and environment-friendly renewable energy source, is directly used for irradiating the surface of the polyamide composite membrane to carry out hydrophilic modification research on the surface of the polyamide composite membrane, and is a renewable energy source as an energy form corresponding to photon motion. Under the large background of energy conservation and emission reduction and environmental protection, the method has important contribution and practical significance for the application of light energy in the technical directions of further reducing the operation pressure of the membrane, improving the water flux of the polyamide composite membrane and the like. Compared with the complex chemical synthesis process and the use of a large amount of chemical agents in the traditional chemical modification research, the modification method provided by the invention has the advantages of environmental protection and environmental friendliness of the applied ultraviolet light, simple operation process, short time, strong controllability, good controllability, easy implementation and lower cost, and is more favorable for industrial popularization and application.

The experimental result shows that after the surface of the polyamide reverse osmosis composite membrane is irradiated for 1min by ultraviolet light with certain intensity, the polyamide reverse osmosis composite membrane remarkably increases the water flux from 41.37GFD to 58.66GFD according to the national standard GB/T32373-2015 reverse osmosis membrane test method, namely that under the conditions of 1500ppm sodium chloride aqueous solution, 1.0MPa pressure, 25 ℃ water temperature and 7.5 +/-0.5 pH, the water flux of the polyamide reverse osmosis membrane is 52.72GFD when the ultraviolet light irradiation time is prolonged to 3min, the water flux is 47.95GFD (increased by 16%) when the ultraviolet light irradiation time is further prolonged to 5min, and the corresponding desalination rate of the polyamide reverse osmosis composite membrane is slightly reduced (less than 0.1%).

Drawings

FIG. 1 is a schematic diagram showing the chemical bond chain cleavage reaction of the polyamide molecule of the present invention after irradiation with ultraviolet light.

Detailed Description

For a further understanding of the invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are included merely to further illustrate the features and advantages of the invention and are not intended to limit the invention to the claims.

All of the starting materials of the present invention, without particular limitation as to their source, may be purchased commercially or prepared according to conventional methods well known to those skilled in the art.

All the raw materials of the present invention are not particularly limited in purity, and the present invention preferably employs a purity which is conventional in the field of analytical purification or reverse osmosis membrane materials.

The invention provides a modification method of a polyamide reverse osmosis composite membrane, which comprises the following steps:

and irradiating the polyamide reverse osmosis composite membrane by using ultraviolet light to obtain the modified polyamide reverse osmosis composite membrane.

The specific wavelength of the ultraviolet light is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements, the flux of the polyamide composite membrane is better improved, the salt rejection rate is ensured, the preparation is better facilitated, the industrial implementation is easy, and the wavelength of the ultraviolet light is preferably 190-400 nm, more preferably 230-360 nm, and more preferably 270-320 nm.

The invention has no special limitation on the irradiation power of the ultraviolet light in principle, and a person skilled in the art can select and adjust the irradiation power according to the actual production condition, the product performance requirement and the quality requirement, in order to better promote the flux of the polyamide composite membrane, ensure the salt rejection rate, better facilitate the preparation and be easy to implement industrially, the irradiation power of the ultraviolet light is preferably 100-500W, more preferably 150-450W, more preferably 200-400W and more preferably 250-350W.

The irradiation time of the ultraviolet light is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements, the flux of the polyamide composite membrane is better improved, the desalination rate is ensured, the preparation is better facilitated, the industrial implementation is easy, and the irradiation time of the ultraviolet light is preferably 1-5 min, more preferably 1.5-4.5 min, more preferably 2-4 min, and more preferably 2.5-3.5 min.

The invention is not particularly limited to the specific selection of the ultraviolet light source in principle, and the skilled person in the art can select and adjust the ultraviolet light source according to the actual production condition, the product performance requirement and the quality requirement, in order to better improve the flux of the polyamide composite membrane, ensure the salt rejection rate, better facilitate the preparation and be easy for industrialized implementation, the ultraviolet light source preferably comprises one or more of an ultraviolet light lamp of a xenon light source, an ultraviolet light lamp of a low-pressure mercury lamp light source and an ultraviolet light lamp of a high-efficiency light-emitting diode, and more preferably comprises the ultraviolet light lamp of the xenon light source, the ultraviolet light lamp of the low-pressure mercury lamp light source or the ultraviolet light lamp of the high-efficiency light.

The linear distance between the light source of the ultraviolet light and the polyamide reverse osmosis composite membrane is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements.

The invention is a complete and refined integral preparation process, the flux of the polyamide composite membrane is better improved, the salt rejection rate is ensured, the preparation is better and convenient, the industrial implementation is easy, after the polyamide reverse osmosis composite membrane is irradiated by ultraviolet light, part of polyamide molecules in the polyamide active layer can generate a fracture reaction, and nitro groups and carboxyl groups are generated.

The invention is not particularly limited in principle to the specific mode of the ultraviolet light irradiation polyamide reverse osmosis composite membrane, and a person skilled in the art can select and adjust the mode according to the actual production condition, the product performance requirement and the quality requirement, in order to better promote the flux of the polyamide composite membrane, ensure the salt rejection rate, better facilitate the preparation and be easy for industrialized implementation, the specific preferable mode of the ultraviolet light irradiation polyamide reverse osmosis composite membrane is as follows:

the ultraviolet light is positioned above the polyamide active layer on the surface of the polyamide reverse osmosis composite membrane and irradiates the polyamide reverse osmosis composite membrane. Namely, the irradiation is carried out in the direction of the active layer of the surface-phase polyamide reverse osmosis composite membrane.

The invention is a complete and refined integral preparation process, better promotes the flux of the polyamide composite membrane, ensures the desalination rate, is better convenient for preparation, is easy for industrialized implementation, and can preferably adjust the water flux and/or the desalination rate of the modified polyamide reverse osmosis composite membrane, more preferably adjust the water flux and the desalination rate of the modified polyamide reverse osmosis composite membrane by adjusting the parameters of ultraviolet irradiation.

The invention is a complete and refined integral preparation process, the flux of the polyamide composite membrane is better improved, the desalination rate is ensured, the preparation is better and convenient, the industrial implementation is easy, and the water flux of the polyamide reverse osmosis composite membrane preferably shows the trend of increasing firstly and then decreasing along with the proceeding of ultraviolet light irradiation.

The invention is a complete and refined integral preparation process, better promotes the flux of the polyamide composite membrane, ensures the salt rejection rate, is better convenient for preparation, is easy for industrialized implementation, and preferably shows the trend of firstly descending and then ascending along with the proceeding of ultraviolet light irradiation.

The water flux of the modified polyamide reverse osmosis composite membrane is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements.

The invention has no particular limitation on the desalination rate of the modified polyamide reverse osmosis composite membrane in principle, and a person skilled in the art can select and adjust the desalination rate according to the actual production condition, the product performance requirement and the quality requirement, in order to better improve the flux of the polyamide composite membrane, ensure the desalination rate, better facilitate the preparation and be easy to industrially implement, the desalination rate of the modified polyamide reverse osmosis composite membrane is preferably 88-99.5%, more preferably 90-99.5%, and more preferably 95-99.5%.

The specific direction of the modification is not particularly limited in principle, and the modification can be selected and adjusted by a person skilled in the art according to the actual production condition, the product performance requirement and the quality requirement.

The invention is a complete and refined integral preparation process, better promotes the flux of the polyamide composite membrane, ensures the salt rejection rate, is better convenient to prepare and is easy to realize industrially, and the polyamide reverse osmosis composite membrane preferably comprises a non-woven fabric base membrane.

The invention has no special limitation on the material of the base membrane in principle, and a person skilled in the art can select and adjust the base membrane according to the actual production condition, the product performance requirement and the quality requirement.

The thickness of the base membrane is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements, the flux of the polyamide composite membrane is better improved, the salt rejection rate is ensured, the preparation is better facilitated, the industrial implementation is easy, and the thickness of the base membrane is preferably 100-150 micrometers, more preferably 110-140 micrometers, and more preferably 120-130 micrometers.

The invention has no special limitation on the aperture of the base membrane in principle, and a person skilled in the art can select and adjust the aperture according to the actual production condition, the product performance requirement and the quality requirement, in order to better improve the flux of the polyamide composite membrane, ensure the salt rejection rate, better facilitate the preparation and be easy to realize industrially, the aperture of the base membrane is preferably 0.1-10 μm, more preferably 2-8 μm, and more preferably 4-6 μm.

The invention is a complete and refined integral preparation process, better promotes the flux of the polyamide composite membrane, ensures the desalination rate, is better convenient to prepare and is easy to realize industrially, and the polyamide reverse osmosis composite membrane preferably comprises a porous support layer compounded on the non-woven fabric base membrane.

The specific selection of the porous support layer is not particularly limited in principle, and a person skilled in the art can select and adjust the porous support layer according to actual production conditions, product performance requirements and quality requirements.

The thickness of the porous support membrane layer is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements, the flux of the polyamide composite membrane is better improved, the salt rejection rate is ensured, the preparation is better facilitated, the industrial implementation is easy, and the thickness of the porous support membrane layer is preferably 120-140 μm, more preferably 124-136 μm, and more preferably 128-132 μm.

The pore diameter of the porous support membrane layer is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements, the flux of the polyamide composite membrane is better improved, the salt rejection rate is ensured, the preparation is better facilitated, the industrial implementation is easy, and the pore diameter of the porous support membrane layer is preferably 15-35 nm, more preferably 18-32 nm, more preferably 21-29 nm, and more preferably 24-26 nm.

The invention is a complete and refined integral preparation process, better promotes the flux of the polyamide composite membrane, ensures the salt rejection rate, is better convenient for preparation, is easy for industrialized implementation, and preferably also comprises a polyamide active layer compounded on the porous supporting layer.

The thickness of the polyamide active layer is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements, the polyamide active layer is preferably 0.1-0.5 μm, more preferably 0.15-0.45 μm, more preferably 0.2-0.4 μm, and more preferably 0.25-0.35 μm, in order to better improve the flux of the polyamide composite membrane, ensure the salt rejection rate, better facilitate preparation and facilitate industrial implementation.

The molecular weight of the polyamide is not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product performance requirements and quality requirements.

The invention is a complete and refined integral preparation process, better promotes the flux of the polyamide composite membrane, ensures the salt rejection rate, is better convenient for preparation, is easy for industrialized implementation, and the modification method of the polyamide reverse osmosis composite membrane can specifically comprise the following steps:

1) selecting an experimental object, namely selecting different polyamide composite membranes to carry out ultraviolet irradiation on the experimental object, wherein the polyamide composite membranes comprise high-cost-performance polyamide reverse osmosis composite membrane ULP-S series membranes independently researched and produced by the company, polyamide reverse osmosis composite membranes of Bishui membrane science and technology Limited and polyamide reverse osmosis composite membranes of Timworth membrane science and technology Limited.

2) Placing the polyamide composite membrane under an ultraviolet light source, wherein a surface active layer of the composite membrane faces the light source, and performing ultraviolet irradiation hydrophilic modification research; the ultraviolet light source comprises a Light Emitting Diode (LED) ultraviolet lamp powered by Direct Current (DC), an ultraviolet lamp (with the power of 100W-500W) of a xenon lamp light source, and a low-pressure mercury lamp commonly used in the current market, and preferably green and environment-friendly LED ultraviolet light is used as an irradiation light source.

3) And (3) carrying out salt rejection and water flux performance tests on the polyamide reverse osmosis composite membrane subjected to ultraviolet radiation and the polyamide reverse osmosis composite membrane not subjected to ultraviolet radiation, and comparing to show the ultraviolet radiation hydrophilic modification effect.

In the present invention, the environmental conditions of the ultraviolet light irradiation include a vacuum environment or an atmospheric environmental condition.

In the invention, the performance test conditions of the polyamide reverse osmosis composite membrane are 1.0MPa pressure, and raw water is 1500ppm sodium chloride aqueous solution.

Referring to fig. 1, fig. 1 is a schematic diagram of a chemical bond chain cleavage reaction of a polyamide molecule according to the present invention after irradiation with ultraviolet light.

In the present invention, the C-N bond in the polyamide composite film is the weakest bond (c.53kcal. mol.) in the polyamide molecule^-1) Which is accompanied by a rapid chemical bond cleavage reaction under ultraviolet light irradiation, as shown in fig. 1. On one hand, the polyamide reverse osmosis composite membrane can generate a free radical mechanism process and a cycle transition state process after being irradiated by ultraviolet light in a vacuum environment, so as to generate a photo-Fries rearrangement (photo-Fries rearrangement) product; on the other hand, the polyamide composite membrane is accompanied with rapid chemical bond breakage under the atmospheric environment condition, but light Fries rearrangement products are not generated, and infrared spectroscopy (IR) shows that nitroso (-NO) and nitro (-NO) exist in the polyamide reverse osmosis composite membrane under the atmospheric environment condition after being irradiated by different ultraviolet light sources₂) And carboxyl (-COOH) and the like, and the formation of the carboxyl illustrates the hydrophilic modification of the polyamide composite membrane, so that the flux of the polyamide composite membrane is greatly improved.

The invention also provides application of the modified polyamide reverse osmosis composite membrane prepared by the modification method in any one of the technical schemes in the field of water treatment.

The steps of the invention provide a preparation method of a high-flux polyamide reverse osmosis composite membrane. The invention utilizes the environment-friendly and environment-friendly renewable energy of ultraviolet light, and carries out hydrophilic modification research on the surface of the polyamide composite membrane by irradiating the surface of the polyamide composite membrane with the ultraviolet light under the condition of not using the assistance of other chemical agents, thereby preparing the modified polyamide composite membrane with higher flux. The invention adopts the mode of irradiating the polyamide active surface layer of the composite membrane by ultraviolet light to carry out hydrophilic modification on the polyamide composite membrane formed by interfacial polymerization reaction, and after the surface of the polyamide composite membrane is irradiated by ultraviolet light for a certain time, polyamide molecules are subjected to fracture reaction to generate nitryl (-NO)₂) And carboxyl (-COOH) groups and the like, wherein the generation of the groups enables the water flux of the polyamide composite membrane to be remarkably improved, so that the high-flux polyamide composite membrane is obtained, and the desalting rate of the obtained high-flux polyamide composite membrane is only slightly reduced. The invention can also adjust the flux and the salt rejection rate of the polyamide composite membrane by properly changing the irradiation conditions and the like, and has more flexibility and strong controllability.

The ultraviolet light is a green and environment-friendly renewable energy source, is directly used for irradiating the surface of the polyamide composite membrane to carry out hydrophilic modification research on the surface of the polyamide composite membrane, and is a renewable energy source as an energy form corresponding to photon motion. Under the large background of energy conservation and emission reduction and environmental protection, the method has important contribution and practical significance for the application of light energy in the technical directions of further reducing the operation pressure of the membrane, improving the water flux of the polyamide composite membrane and the like. Compared with the complex chemical synthesis process and the use of a large amount of chemical agents in the traditional chemical modification research, the modification method provided by the invention has the advantages of environmental protection and environmental friendliness of the applied ultraviolet light, simple operation process, short time, strong controllability, good controllability, easy implementation and lower cost, and is more favorable for industrial popularization and application.

The experimental result shows that after the surface of the polyamide reverse osmosis composite membrane independently developed and produced by the company is irradiated for 5min by ultraviolet light with certain intensity, the polyamide reverse osmosis composite membrane remarkably increases the water flux from 41.37GFD to 47.95GFD (increases by 16%) according to the national standard GB/T32373-2015 reverse osmosis membrane test method under the conditions of 1500ppm sodium chloride aqueous solution, 1.0MPa pressure, 25 ℃ water temperature and 7.5 +/-0.5 pH, and the desalination rate of the corresponding polyamide reverse osmosis composite membrane is slightly reduced (less than 0.1%); after the commercially available polyamide reverse osmosis composite membrane of Bishui Source Membrane science and technology Limited is irradiated by ultraviolet light for 5min, the water flux is increased from 35.24GFD to 39.68GFD (increased by 13%), and the salt rejection rate is reduced by 0.18%; after the commercially available polyamide reverse osmosis composite membrane of Timebon Membrane science and technology Limited is irradiated by ultraviolet light for 5min, the water flux is increased from 36.05GFD to 41.34GFD (increased by 15%), and the desalination is reduced by 0.23%.

According to the invention, after the surface of the polyamide reverse osmosis composite membrane is irradiated by certain ultraviolet light, the water flux of the polyamide reverse osmosis composite membrane is remarkably improved (increased by more than 10%), and the desalting performance of the polyamide reverse osmosis composite membrane is slightly influenced. The invention utilizes the green and environment-friendly renewable energy of the ultraviolet light to effectively improve the water flux of the polyamide reverse osmosis composite membrane, has small influence on the desalting performance, is simple and convenient to operate, is easy to implement and is easy to industrially popularize and apply.

For further illustration of the present invention, the following will describe in detail a modification method of a polyamide reverse osmosis composite membrane according to the present invention with reference to the following examples, but it should be understood that these examples are carried out on the premise of the technical solution of the present invention, and the detailed embodiments and specific procedures are given only for further illustration of the features and advantages of the present invention, not for limitation of the claims of the present invention, and the scope of the present invention is not limited to the following examples.

Example 1

Selecting a polyamide reverse osmosis composite membrane independently researched and developed by the company, placing the polyamide reverse osmosis composite membrane under an LED ultraviolet lamp, wherein the distance between a light source and the membrane surface is 20cm, and the ultraviolet irradiation time is 1min, 3min and 5min, so as to obtain the modified polyamide reverse osmosis composite membrane.

The modified polyamide reverse osmosis composite membrane prepared in example 1 of the present invention was tested.

The results show that under the conditions of 1.0MPa pressure and 1500ppm of sodium chloride aqueous solution as raw water, the water fluxes of the ULP-S series membranes of the polyamide reverse osmosis composite membranes after being irradiated by ultraviolet light for 0min, 1min, 3min and 5min are 41.37, 58.66, 52.72 and 47.95 in sequence, and correspondingly, the salt rejection rates are 99.28%, 88.53%, 98.77% and 99.17%.

Example 2

Selecting a polyamide reverse osmosis composite membrane of Biyu water source membrane science and technology Limited, placing the polyamide reverse osmosis composite membrane under an LED ultraviolet lamp, wherein the distance between a light source and the surface of the membrane is 20cm, and the ultraviolet irradiation time is 1min, 3min and 5min, so as to obtain the modified polyamide reverse osmosis composite membrane.

The modified polyamide reverse osmosis composite membrane prepared in example 2 of the present invention was tested.

The results show that under the conditions of 1.0MPa pressure and 1500ppm of sodium chloride aqueous solution as raw water, the water fluxes of the Beijing Biyu water source polyamide reverse osmosis composite membrane after being irradiated by ultraviolet light for 0min, 1min, 3min and 5min are 35.24, 46.23, 40.13 and 39.68 in sequence, and the corresponding desalination rates are 99.48%, 86.28%, 98.99% and 99.30%.

Example 3

Selecting a polyamide reverse osmosis composite membrane of Timewton science and technology Limited, placing the polyamide reverse osmosis composite membrane under an LED ultraviolet lamp, wherein the distance between a light source and the surface of the membrane is 20cm, and the ultraviolet irradiation time is 1min, 3min and 5min, so as to obtain the modified polyamide reverse osmosis composite membrane.

The modified polyamide reverse osmosis composite membrane prepared in example 3 of the present invention was tested.

The results show that under the conditions of 1.0MPa pressure and 1500ppm of sodium chloride aqueous solution as raw water, the water flux of the Guiyang Timewton polyamide reverse osmosis composite membrane after being irradiated by ultraviolet light for 0min, 1min, 3min and 5min is respectively 36.05, 48.21, 42.36 and 41.34, and the desalination rate is respectively 99.51%, 84.94%, 99.07% and 99.28%.

Example 4

Selecting a polyamide reverse osmosis composite membrane independently researched and developed by the company, and placing the polyamide reverse osmosis composite membrane under an ultraviolet lamp of a 300W xenon lamp light source, wherein the distance between the light source and the membrane surface is 20cm, and the ultraviolet irradiation time is 1min, 3min and 5min, so as to obtain the modified polyamide reverse osmosis composite membrane.

The modified polyamide reverse osmosis composite membrane prepared in example 4 of the present invention was tested.

The results show that under the conditions of 1.0MPa pressure and 1500ppm of sodium chloride aqueous solution as raw water, the water flux of the polyamide reverse osmosis composite membrane after being irradiated by ultraviolet light for 0min, 1min, 3min and 5min is 41.67, 59.35, 53.11 and 48.19 in sequence, and the desalination rate is 99.2%, 87.34%, 99.01% and 99.15% correspondingly.

Example 5

Selecting a polyamide reverse osmosis composite membrane independently researched and developed by the company, placing the polyamide reverse osmosis composite membrane under an ultraviolet lamp of a low-pressure mercury lamp light source, wherein the distance between the light source and the membrane surface is 20cm, and the ultraviolet irradiation time is 1min, 3min and 5min, so as to obtain the modified polyamide reverse osmosis composite membrane.

The modified polyamide reverse osmosis composite membrane prepared in example 5 of the present invention was tested.

The results show that under the conditions of 1.0MPa pressure and 1500ppm of sodium chloride aqueous solution as raw water, the water fluxes of the polyamide reverse osmosis composite membrane after being irradiated by ultraviolet light for 0min, 1min, 3min and 5min are 41.43, 58.23, 53.17 and 48.04 in sequence, and correspondingly, the salt rejection rates are 99.19%, 88.37%, 98.87% and 99.11%.

Referring to table 1, table 1 shows performance parameters of the ultraviolet irradiation modified polyamide reverse osmosis composite membrane in embodiments 1 to 5 of the present invention.

TABLE 1

As can be seen from the results in Table 1, firstly, after different polyamide composite membranes are irradiated for 1min by ultraviolet light, the water flux is remarkably improved by about 30-40%, and the salt rejection rate is remarkably reduced; after the polyamide composite membrane is irradiated by ultraviolet light for 3min, the desalination rate is increased again, and the flux is reduced compared with that when the polyamide composite membrane is irradiated by the ultraviolet light for 1 min; after the polyamide composite membrane is further irradiated for 5min by ultraviolet light, the desalination rate is smaller than that of the polyamide composite membrane irradiated for 0min, and the water flux increasing trend is obvious. On the whole, on one hand, after the polyamide composite membrane is irradiated by ultraviolet light, the desalination rate is increased along with the increase of the ultraviolet light irradiation time, and the water flux is reduced along with the increase of the ultraviolet light irradiation time; on the other hand, the ultraviolet light source has no influence on the performance improvement of the polyamide composite film; finally, the ultraviolet irradiation has the same change trend for the performance improvement of polyamide composite membranes produced by different manufacturers. Therefore, the ultraviolet irradiation has obvious excellent effect on the performance improvement of the polyamide composite film, and the application of the LED ultraviolet light which is green and environment-friendly renewable energy makes the invention have obvious competitive advantage under the strict requirements of the current environment-friendly policy.

The preparation method utilizes the green and environment-friendly renewable energy of ultraviolet light to prepare the high-flux polyamide composite film by irradiating the surface of the polyamide composite film with the ultraviolet light, and the preparation process has the advantages of simple operation, short operation time, easy implementation, lower cost and the like; in addition, the invention can also properly change irradiation conditions and the like to prepare the high-flux polyamide composite membrane.

The foregoing detailed description of the method for preparing a high flux polyamide reverse osmosis composite membrane according to the present invention, and the principles and embodiments of the present invention described herein using specific examples, is provided merely to facilitate an understanding of the method of the present invention and its core concepts, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.