CN111001311B - High-desalination reverse osmosis membrane containing polyethylene glycol epoxide coating - Google Patents

High-desalination reverse osmosis membrane containing polyethylene glycol epoxide coating Download PDF

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CN111001311B
CN111001311B CN201911415518.0A CN201911415518A CN111001311B CN 111001311 B CN111001311 B CN 111001311B CN 201911415518 A CN201911415518 A CN 201911415518A CN 111001311 B CN111001311 B CN 111001311B
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reverse osmosis
membrane
polyethylene glycol
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film layer
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CN111001311A (en
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不公告发明人
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Ningbo Rixin Hengli Technology Co ltd
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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
    • 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
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/12—Layered products comprising a layer of synthetic resin next to a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B32B5/022—Non-woven fabric
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/34—Use of radiation
    • B01D2323/345—UV-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/02—Coating on the layer surface on fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/26—Polymeric coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
    • B32B2260/02—Composition of the impregnated, bonded or embedded layer
    • B32B2260/021—Fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
    • B32B2262/02—Synthetic macromolecular fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
    • B32B2262/02—Synthetic macromolecular fibres
    • B32B2262/0276—Polyester fibres
    • B32B2262/0284—Polyethylene terephthalate [PET] or polybutylene terephthalate [PBT]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Textile Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

The invention provides a reverse osmosis composite membrane, which comprises a base membrane; an intermediate transition support film layer compounded on the base film; an active film layer compounded on the intermediate transition support film layer; and the polyethylene glycol epoxide coating film layer is compounded on the active film layer. The reverse osmosis composite membrane provided by the invention comprises a four-layer structure, wherein a bottom layer is a non-woven fabric base membrane, a middle transition support layer, an active layer polyamide and a polyethylene glycol epoxide coating layer. According to the invention, the polyethylene glycol epoxide is coated on the surface of the polyamide active layer of the reverse osmosis composite membrane, so that the rejection rate of the reverse osmosis membrane is greatly improved, and the high-desalination reverse osmosis membrane with the polyethylene glycol epoxide coating layer is obtained. The preparation method provided by the invention is simple, mild in conditions and suitable for large-scale production and application.

Description

High-desalination reverse osmosis membrane containing polyethylene glycol epoxide coating
Technical Field
The invention belongs to the technical field of wastewater treatment, relates to a reverse osmosis composite membrane and a preparation method thereof, and particularly relates to a high-desalination reverse osmosis membrane containing a polyethylene glycol epoxide coating and a preparation method thereof.
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. Therefore, the method is adopted in all seawater desalination processes and spaceman wastewater recovery treatment, and the RO reverse osmosis technology is a membrane separation and filtration technology using osmotic pressure difference as power, is derived from the research of aerospace science and technology in the sixties of the twentieth century in the United states, is gradually converted into civil use, and is widely applied to the fields of scientific research, medicines, foods, beverages, seawater desalination and the like.
High purity water plays a very important role in modern industries, for example, the pharmaceutical and microelectronics industries require high purity water for production purposes. In the pharmaceutical industry, water is the most common component of all drugs and must therefore be free of bacteria, organic matter and all soluble substances. RO systems with Ultraviolet (UV) sterilizers are commonly used for industrial-level water treatment and disinfection to produce ultra-pure water required for many pharmaceutical manufacturing processes. In the microelectronics industry, high purity water is required at the manufacturing stage and is used to rinse the finished microelectronic elements. For example, after processing, the capacitors and transistors require ultra pure water from the RO system for cooling. However, if the water has trace impurities, the product may be contaminated or corroded before leaving the production plant. The high purity water provided by RO technology enables manufacturers to produce microelectronic products of optimal quality while reducing the operational and maintenance costs of the manufacturing equipment. Reverse osmosis membranes have been greatly improved over the years, with most of the development being achieved by modifying the membrane surface itself or by modifying the element or module design. However, as the requirements of downstream industries on the function and performance of RO membranes are continuously increased, researchers are still looking for better materials or methods to better improve the performance of RO reverse osmosis membranes.
Therefore, how to find a better RO reverse osmosis membrane with better performance has become one of the focuses of many researchers.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a reverse osmosis composite membrane and a preparation method thereof, and particularly to a high desalination reverse osmosis membrane containing a polyethylene glycol epoxide coating.
The invention provides a reverse osmosis composite membrane, which comprises a base membrane;
an intermediate transition support film layer compounded on the base film;
an active film layer compounded on the intermediate transition support film layer;
and the polyethylene glycol epoxide coating film layer is compounded on the active film layer.
Preferably, the base film comprises a non-woven base film;
the middle transition support film layer comprises a modified polyacrylonitrile middle transition support film layer;
the active film layer comprises a polyamide active film layer;
the polyethylene glycol epoxide coating layer is bonded with the active film layer through a chemical bond.
Preferably, the non-woven fabric base film comprises a polyethylene terephthalate non-woven fabric base film and/or a polyimide non-woven fabric base film;
the thickness of the base film is 140-160 mu m;
the modified polyacrylonitrile intermediate transition supporting film layer comprises a hydrophilic modified polyacrylonitrile intermediate transition supporting film layer;
the thickness of the middle transition support film layer is 50-120 mu m;
the thickness of the active film layer is 0.1-0.5 μm;
the thickness of the polyethylene glycol epoxide coating film layer is 0.01-0.03 mu m;
said chemical linkage comprises through-O-N-linkage;
the polyethylene glycol epoxide may have one epoxide moiety or multiple epoxide moieties.
Preferably, the modified polyacrylonitrile intermediate transition supporting film layer comprises a m-phenylenediamine/sodium dodecyl sulfate plasma modified polyacrylonitrile intermediate transition supporting film layer;
the molecular weight of the polyacrylonitrile is 80000-150000;
the aperture of the polyacrylonitrile intermediate transition support film layer is 0.05-0.1 mu m;
the polyamide active membrane layer is synthesized by TMC-MPDA interfacial polymerization;
the polyethylene glycol epoxide comprises one or more of a four-arm polyethylene glycol epoxide, a five-arm polyethylene glycol epoxide, a six-arm polyethylene glycol epoxide, a seven-arm polyethylene glycol epoxide and an eight-arm polyethylene glycol epoxide.
Preferably, the water flux of the reverse osmosis composite membrane is 40-50L/m2·h；
The rejection rate of the reverse osmosis composite membrane to sodium ions is more than or equal to 99.75 percent;
the rejection rate of the reverse osmosis composite membrane to chloride ions is more than or equal to 99.75 percent;
the rejection rate of the reverse osmosis composite membrane to nitrate ions is more than or equal to 99.5 percent;
the rejection rate of the reverse osmosis composite membrane to divalent calcium ions is more than or equal to 99.9 percent.
Preferably, the preparation method of the reverse osmosis composite membrane comprises the following steps:
under the condition of protective gas purging, the polyethylene glycol epoxide solution is coated on the surface of an active membrane layer of the reverse osmosis membrane, and then the reverse osmosis composite membrane is obtained after ultraviolet irradiation.
Preferably, the wavelength of the ultraviolet radiation is 290-360 nm;
the ultraviolet irradiation time is 30-120 seconds;
the polyethylene glycol epoxide solution comprises a polyethylene glycol epoxide aqueous solution;
the mass concentration of the polyethylene glycol epoxide is 0.05-0.5%.
Preferably, the preparation process of the reverse osmosis membrane comprises the following steps:
1) mixing polyacrylonitrile and a solvent to obtain intermediate transition support membrane layer liquid, and coating the intermediate transition support membrane layer liquid on a base membrane to obtain a first carrier compounded with an intermediate transition support membrane layer;
2) after the first carrier obtained in the step is subjected to oxygen plasma treatment, the first carrier is immersed into a mixed solution of m-phenylenediamine and sodium dodecyl sulfate, and a second carrier compounded with a modified intermediate transition support film layer is obtained;
3) and (3) contacting the second carrier obtained in the step with a trimesoyl chloride organic solution, and then drying to obtain the reverse osmosis membrane.
Preferably, the solvent comprises one or more of butyrolactone, triethyl phosphate, N-dimethylformamide and dimethyl sulfoxide;
the mass ratio of polyacrylonitrile to solvent is (15-30): 100, respectively;
the mass ratio of the polyacrylonitrile to the base film is (30-60): 100, respectively;
the step of removing the solvent is also included after the coating;
the plasma power of the oxygen plasma treatment is 10-30W;
the exposure time of the oxygen plasma treatment is 10-30 seconds.
Preferably, the mass ratio of the m-phenylenediamine to the base film is (2-10): 100, respectively;
the mass ratio of the sodium dodecyl sulfate to the base membrane is (0.02-0.08): 100, respectively;
the trimesoyl chloride organic solution comprises a trimesoyl chloride n-hexane solution;
the mass ratio of the trimesoyl chloride to the basement membrane is (0.1-0.2): 100;
the drying time is 3-6 minutes;
the drying temperature is 60-85 ℃.
The invention provides a reverse osmosis composite membrane, which comprises a base membrane; an intermediate transition support film layer compounded on the base film; an active film layer compounded on the intermediate transition support film layer; and the polyethylene glycol epoxide coating film layer is compounded on the active film layer. Compared with the prior art, the reverse osmosis composite membrane provided by the invention comprises a four-layer structure, wherein the bottom layer is a non-woven fabric base membrane, the middle transition supporting layer, the active layer polyamide and the polyethylene glycol epoxide coating layer. According to the invention, the polyethylene glycol epoxide is coated on the surface of the polyamide active layer of the reverse osmosis composite membrane, so that the desalination rate and rejection rate of the reverse osmosis membrane are greatly improved, and the high-desalination reverse osmosis membrane with the polyethylene glycol epoxide coating layer is obtained. And the preparation method is simple, mild in condition and suitable for large-scale production and application.
Experimental results show that the water flux of the reverse osmosis composite membrane prepared by the invention under specific conditions is 40-50L/m2H (test stock solution 1.5MPa pressure, 2000ppm sodium chloride, 1000ppm calcium chloride, 150ppm sodium nitrate, pH 7, temperature 25 deg.C, extremely high rejection rate for sodium ions and chloride ions>99.75, rejection rate of nitrate ions>99.5% retention rate of divalent calcium ion>99.9％。
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 reverse osmosis composite membrane, which comprises a base membrane;
an intermediate transition support film layer compounded on the base film;
an active film layer compounded on the intermediate transition support film layer;
and the polyethylene glycol epoxide coating film layer is compounded on the active film layer.
In the present invention, the base film preferably includes a non-woven fabric base film, more preferably includes a polyethylene terephthalate non-woven fabric base film and/or a polyimide non-woven fabric base film, and more preferably a polyethylene terephthalate non-woven fabric base film or a polyimide non-woven fabric base film.
The thickness of the base film is preferably 140-160 μm, more preferably 143-158 μm, more preferably 145-155 μm, and more preferably 147-153 μm.
In the present invention, the intermediate transition support membrane layer preferably includes a modified polyacrylonitrile intermediate transition support membrane layer, more preferably a hydrophilic modified polyacrylonitrile intermediate transition support membrane layer, and more preferably a m-phenylenediamine/sodium dodecyl sulfate plasma (oxygen plasma) modified polyacrylonitrile intermediate transition support membrane layer.
The thickness of the intermediate transition support film layer is preferably 50-120 μm, more preferably 70-100 μm, and more preferably 80-90 μm. The molecular weight (weight average) of the polyacrylonitrile is preferably 80000-150000, more preferably 90000-140000, and more preferably 100000-120000. The aperture of the polyacrylonitrile intermediate transition support film layer is preferably 0.05-0.1 μm, more preferably 0.06-0.09 μm, and more preferably 0.07-0.08 μm.
In the present invention, the active film layer preferably includes a polyamide active film layer.
The thickness of the active film layer is preferably 0.1-0.5 μm, and more preferably 0.2-0.4 μm. The polyamide active membrane layer is preferably synthesized by TMC-MPDA interfacial polymerization, namely, synthesized by m-phenylenediamine and trimesoyl chloride through interfacial synthesis, and the active layer is a compact membrane.
In the present invention, the polyethylene glycol epoxide may preferably have one epoxy compound moiety or a plurality of epoxy compound moieties in the polyethylene glycol epoxide coating layer. That is, a polyethylene glycol epoxide (PEG-epoxide) may have one epoxide moiety, two epoxide moieties (PEG diglycidyl ether; "PEGDDE"), or may have three or more epoxide moieties ("multi-branched PEG" or "multi-arm PEG"). Among these, multi-arm polyethylene glycol epoxides are those in which multiple polyethylene glycol polymer chains are linked together through a "central" moiety, the polyethylene glycol chains having one or more epoxide moieties. The polyethylene glycol epoxide of the present invention may specifically include one or more of a four-arm polyethylene glycol epoxide, a five-arm polyethylene glycol epoxide, a six-arm polyethylene glycol epoxide, a seven-arm polyethylene glycol epoxide, and an eight-arm polyethylene glycol epoxide, and more preferably a four-arm polyethylene glycol epoxide, a five-arm polyethylene glycol epoxide, a six-arm polyethylene glycol epoxide, a seven-arm polyethylene glycol epoxide, or an eight-arm polyethylene glycol epoxide.
The thickness of the polyethylene glycol epoxide coating film layer is preferably 0.01-0.03 mu m, and more preferably 0.015-0.025 mu m. The polyethylene glycol epoxide coating layer and the active film layer are preferably bonded through a chemical bond, and more preferably through an-O-N-bond (epoxy-O-N-bond). In the present invention, the chemical bond between the polyethylene glycol epoxide and the polyamide active membrane layer is combined by the reaction of the epoxy of the polyethylene glycol and-NH of the polyamide layer, finally forming-O-N-. The polyethylene glycol epoxides of the present invention are preferably commercially available.
The reverse osmosis composite membrane obtained by the steps has the water flux of preferably 40-50L/m2H, may be 42 to 48L/m2H, may be 44 to 46L/m2H. The rejection rate of the reverse osmosis composite membrane to sodium ions is preferably greater than or equal to 99.75%; the rejection rate of the reverse osmosis composite membrane to chloride ions is preferably greater than or equal to 99.75%; the rejection rate of the reverse osmosis composite membrane to nitrate ions is preferably greater than or equal to 99.5%; the reverse osmosis composite membrane preferably has a divalent calcium ion rejection rate of 99.9% or more.
The invention also provides a preparation method of the reverse osmosis composite membrane, which comprises the following steps:
under the condition of protective gas purging, the polyethylene glycol epoxide solution is coated on the surface of an active membrane layer of the reverse osmosis membrane, and then the reverse osmosis composite membrane is obtained after ultraviolet irradiation.
The wavelength of the ultraviolet radiation is preferably 290-360 nm, more preferably 300-350 nm, and more preferably 320-340 nm. The time for the ultraviolet irradiation is preferably 30 to 120 seconds, and more preferably 60 to 90 seconds.
In the present invention, the polyethylene glycol epoxide solution preferably comprises an aqueous polyethylene glycol epoxide solution. The mass concentration of the polyethylene glycol epoxide is preferably 0.05-0.5%, more preferably 0.15-0.4%, and more preferably 0.25-0.3%.
In the present invention, the reverse osmosis membrane is preferably prepared by a process comprising the steps of:
1) mixing polyacrylonitrile and a solvent to obtain intermediate transition support membrane layer liquid, and coating the intermediate transition support membrane layer liquid on a base membrane to obtain a first carrier compounded with an intermediate transition support membrane layer;
2) after the first carrier obtained in the step is subjected to oxygen plasma treatment, the first carrier is immersed into a mixed solution of m-phenylenediamine and sodium dodecyl sulfate, and a second carrier compounded with a modified intermediate transition support film layer is obtained;
3) and (3) contacting the second carrier obtained in the step with a trimesoyl chloride organic solution, and then drying to obtain the reverse osmosis membrane.
The solvent of the present invention preferably comprises one or more of butyrolactone, triethyl phosphate, N-dimethylformamide and dimethyl sulfoxide. The mass ratio of the polyacrylonitrile to the solvent is preferably (15-30): 100, more preferably (20 to 25): 100. the mass ratio of the polyacrylonitrile to the base film is preferably (30-60): 100, more preferably (35-55): 100, more preferably (40 to 50): 100. the coating preferably further comprises a step of removing the solvent.
The plasma power of the oxygen plasma treatment is preferably 10-30W, and more preferably 15-25W. The exposure time of the oxygen plasma treatment is preferably 10 to 30 seconds, and more preferably 15 to 25 seconds.
The mass ratio of the m-phenylenediamine to the base film is preferably (2-10): 100, more preferably (4-8): 100, more preferably (5-7): 100. the mass ratio of the sodium dodecyl sulfate to the base membrane is preferably (0.02-0.08): 100, more preferably (0.03 to 0.07): 100, more preferably (0.04 to 0.06): 100.
in the present invention, the trimesoyl chloride organic solution preferably comprises a trimesoyl chloride n-hexane solution. The mass ratio of the trimesoyl chloride to the base membrane is preferably (0.1-0.2): 100, more preferably (0.12-0.18): 100, and even more preferably (0.14-0.16): 100.
In the present invention, the drying time is preferably 3 to 6 minutes, and more preferably 4 to 5 minutes. The drying temperature is preferably 60-85 ℃, more preferably 65-80 ℃, and more preferably 70-75 ℃.
The invention is a complete and refined integral preparation process, which can better improve the rejection rate of a reverse osmosis membrane, and the preparation process can specifically comprise the following steps:
1) and dissolving organic polyacrylonitrile in N, N-dimethylformamide and defoaming. Obtaining membrane liquid A. And quantitatively coating the membrane liquid A on the non-woven fabric, and evaporating to remove the solvent to form the intermediate transition supporting layer.
2) In order to increase the water wettability of the polyacrylonitrile carrier, the polyacrylonitrile carrier is hydrophilized by plasma treatment before the interfacial polymerization.
3) The plasma-modified polyacrylonitrile support was impregnated with an aqueous solution of m-phenylenediamine (MPD)/Sodium Dodecyl Sulfate (SDS), and then rubbed with a roller to remove excess solution.
4) The use of sodium lauryl sulfate helps to further improve the wettability with supporting water and accelerates the migration of metaphenylene diamine into the organic phase, thereby promoting interfacial polymerization.
5) Next, the support was contacted with trimesoyl chloride (TMC) organic (n-hexane) solution. The membrane was then rinsed with n-hexane and dried.
6) The whole reverse osmosis membrane is coated in the nitrogen purging process, and the reverse osmosis membrane is irradiated by ultraviolet rays.
7) After the liquid polyethylene glycol epoxide mixture is applied to the reverse osmosis membrane, it is exposed to ultraviolet radiation. The coated film was rinsed and dipped in glycerin and then dried.
The invention provides a reverse osmosis composite membrane, which comprises a four-layer structure, wherein a bottom layer is a non-woven fabric base membrane, a middle transition supporting layer, an active layer polyamide and a polyethylene glycol epoxide coating layer. According to the invention, the polyethylene glycol epoxide is coated on the surface of the polyamide active layer of the reverse osmosis composite membrane, so that the desalination rate and rejection rate of the reverse osmosis membrane are greatly improved, and the high-desalination reverse osmosis membrane with the polyethylene glycol epoxide coating layer is obtained.
The preparation method of the polyethylene glycol epoxide coated high desalting reverse osmosis membrane provided by the invention adopts polyacrylonitrile as a middle supporting layer, and carries out plasma treatment before interfacial polymerization so as to hydrophilize a polyacrylonitrile carrier. The liquid polyethylene glycol epoxide mixture reacts with the polyamide layer of the reverse osmosis membrane in an ultraviolet irradiation mode, so that the polyethylene glycol epoxide is effectively coated on the surface of the reverse osmosis membrane, and the obtained reverse osmosis membrane has quite high salt rejection rate. The invention obtains the high-desalination reverse osmosis membrane with the polyethylene glycol epoxide coating and higher desalination rate by adopting specific membrane structure and membrane parameters and based on the special connection relation between the membrane structure and the membrane parameters. The preparation method is simple, the reverse osmosis composite membrane is formed by specific nitrogen purging technology and UV irradiation under special conditions, and the method is mild in conditions, strong in controllability and good in repeatability, and is beneficial to industrial popularization and application.
Experimental results show that the water flux of the reverse osmosis composite membrane prepared by the invention under specific conditions is 40-50L/m2H (test stock solution 1.5MPa pressure, 2000ppm sodium chloride, 1000ppm calcium chloride, 150ppm sodium nitrate, pH 7, temperature 25 ℃), extremely high rejection rate for sodium ions and chloride ions>99.75, rejection rate of nitrate ions>99.5% retention rate of divalent calcium ion>99.9％。
For further illustration of the present invention, a reverse osmosis composite membrane and a method for preparing the same according to the present invention will be described in detail with reference to the following examples, but it should be understood that the present invention is not limited to the following examples, and the detailed embodiments and specific procedures are given based on the technical scheme of the present invention.
Example 1
Preparing a middle transition supporting layer, putting 100g of organic polyacrylonitrile into 900g N, stirring and dissolving in N-dimethylformamide, and defoaming to obtain a middle transition supporting layer membrane solution. And quantitatively coating the intermediate layer membrane liquid on the non-woven fabric, and evaporating to remove the solvent to form the intermediate layer. The polyacrylonitrile carrier is processed by oxygen plasma with 15 watts of plasma power and 30 seconds of exposure time. The plasma modified polyacrylonitrile carrier was impregnated with an aqueous solution of m-phenylenediamine (5 wt%)/sodium lauryl sulfate (0.08 wt%) for 5 minutes, and then rubbed with a roller to remove excess solution. Next, the support was contacted with trimesoyl chloride (0.25 wt%) in organic (n-hexane) solution. The membrane was then rinsed with n-hexane and dried at 70 ℃ for 3 minutes.
The whole reverse osmosis membrane is coated in the nitrogen purging process, and the reverse osmosis membrane is irradiated by ultraviolet rays. After a 45 ℃ aqueous solution of a tetraarm polyethylene glycol epoxide (0.09 wt%) was applied to the polyamide layer of the reverse osmosis membrane, it was exposed to ultraviolet light at an irradiation wavelength of 331nm for a period of 100 seconds. The coated film was rinsed and dipped in glycerol and then dried at 100 c for 2 minutes.
The reverse osmosis composite membrane prepared in example 1 of the present invention was subjected to performance testing.
Cutting the reverse osmosis coated with polyethylene glycol epoxide into 38.5cm of effective area2The raw sheet of (a), was tested using a membrane filtration test system. The system test pressure is 1.5 MPa.
The feed stock solution was tested to contain 2000ppm sodium chloride, 1000ppm calcium chloride, 150ppm sodium nitrate, a stock solution pH of 7.0 and a temperature of 25 ℃. All reverse osmosis membranes prepared in the examples were tested under the same conditions.
Referring to table 1, table 1 shows performance test data of the reverse osmosis composite membrane prepared according to the example of the present invention and the reverse osmosis membrane not coated with the polyethylene glycol epoxide coating layer.
Example 2
Preparing a middle transition supporting layer, putting 100g of organic polyacrylonitrile into 900g N, stirring and dissolving in N-dimethylformamide, and defoaming to obtain a middle transition supporting layer membrane solution. And quantitatively coating the intermediate layer membrane liquid on the non-woven fabric, and evaporating to remove the solvent to form the intermediate layer. The polyacrylonitrile carrier was subjected to oxygen plasma treatment with a plasma power of 25 watts and an exposure time of 20 seconds. The plasma modified polyacrylonitrile carrier was impregnated with an aqueous solution of m-phenylenediamine (5 wt%)/sodium lauryl sulfate (0.08 wt%) for 5 minutes, and then rubbed with a roller to remove excess solution. Next, the support was contacted with trimesoyl chloride (0.25 wt%) in organic (n-hexane) solution. The membrane was then rinsed with n-hexane and dried at 70 ℃ for 3 minutes.
The whole reverse osmosis membrane is coated in the nitrogen purging process, and the reverse osmosis membrane is irradiated by ultraviolet rays. After a 45 ℃ aqueous solution of hexa-armed polyethylene glycol epoxide (0.12 wt%) was applied to the polyamide layer of the reverse osmosis membrane, it was exposed to ultraviolet light at an irradiation wavelength of 331nm for a period of 100 seconds. The coated film was rinsed and dipped in glycerol and then dried at 100 c for 2 minutes.
The reverse osmosis composite membrane prepared in example 2 of the present invention was subjected to performance testing.
Cutting the reverse osmosis coated with polyethylene glycol epoxide into 38.5cm of effective area2The raw sheet of (a), was tested using a membrane filtration test system. The system test pressure is 1.5 MPa.
The feed stock solution was tested to contain 2000ppm sodium chloride, 1000ppm calcium chloride, 150ppm sodium nitrate, a stock solution pH of 7.0 and a temperature of 25 ℃. All reverse osmosis membranes prepared in the examples were tested under the same conditions.
Referring to table 1, table 1 shows performance test data of the reverse osmosis composite membrane prepared according to the example of the present invention and the reverse osmosis membrane not coated with the polyethylene glycol epoxide coating layer.
Example 3
Preparing a middle transition supporting layer, putting 100g of organic polyacrylonitrile into 900g N, stirring and dissolving in N-dimethylformamide, and defoaming to obtain a middle transition supporting layer membrane solution. And quantitatively coating the intermediate layer membrane liquid on the non-woven fabric, and evaporating to remove the solvent to form the intermediate layer. The polyacrylonitrile carrier was subjected to oxygen plasma treatment with a plasma power of 30 watts and an exposure time of 10 seconds. The plasma modified polyacrylonitrile carrier was impregnated with an aqueous solution of m-phenylenediamine (5 wt%)/sodium lauryl sulfate (0.08 wt%) for 5 minutes, and then rubbed with a roller to remove excess solution. Next, the support was contacted with trimesoyl chloride (0.25 wt%) in organic (n-hexane) solution. The membrane was then rinsed with n-hexane and dried at 70 ℃ for 3 minutes.
The whole reverse osmosis membrane is coated in the nitrogen purging process, and the reverse osmosis membrane is irradiated by ultraviolet rays. After a 45 ℃ aqueous solution of octamer polyethylene glycol epoxide (0.15 wt%) was applied to the reverse osmosis membrane polyamide layer, it was exposed to ultraviolet radiation at a wavelength of 331nm for a period of 100 seconds. The coated film was rinsed and dipped in glycerol and then dried at 100 c for 2 minutes.
The reverse osmosis composite membrane prepared in example 3 of the invention was subjected to performance testing.
Cutting the reverse osmosis coated with polyethylene glycol epoxide into 38.5cm of effective area2The raw sheet of (a), was tested using a membrane filtration test system. The system test pressure is 1.5 MPa.
The feed stock solution was tested to contain 2000ppm sodium chloride, 1000ppm calcium chloride, 150ppm sodium nitrate, a stock solution pH of 7.0 and a temperature of 25 ℃. All reverse osmosis membranes prepared in the examples were tested under the same conditions.
Referring to table 1, table 1 shows performance test data of the reverse osmosis composite membrane prepared according to the example of the present invention and the reverse osmosis membrane not coated with the polyethylene glycol epoxide coating layer.
TABLE 1
Figure BDA0002351093290000121
While the present invention has been described in detail with respect to a polyethylene glycol epoxide coated reverse osmosis membrane and method of making the same, the principles and embodiments of the present invention are described herein using specific examples, which are included to assist in understanding the method and its core concepts, including the best mode, and 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.

Claims (9)

1. A reverse osmosis composite membrane, comprising a base membrane;
an intermediate transition support film layer compounded on the base film;
an active film layer compounded on the intermediate transition support film layer;
a polyethylene glycol epoxide coating film layer compounded on the active film layer;
the reverse osmosis composite membrane comprises a four-layer structure;
the active film layer comprises a polyamide active film layer;
the polyethylene glycol epoxide comprises one or more of a four-arm polyethylene glycol epoxide, a five-arm polyethylene glycol epoxide, a six-arm polyethylene glycol epoxide, a seven-arm polyethylene glycol epoxide and an eight-arm polyethylene glycol epoxide;
the preparation method of the reverse osmosis composite membrane comprises the following steps:
under the condition of protective gas purging, the polyethylene glycol epoxide solution is coated on the surface of an active membrane layer of the reverse osmosis membrane, and then the reverse osmosis composite membrane is obtained after ultraviolet irradiation.
2. The reverse osmosis composite membrane of claim 1, wherein the base membrane comprises a non-woven base membrane;
the middle transition support film layer comprises a modified polyacrylonitrile middle transition support film layer;
the polyethylene glycol epoxide coating layer is bonded with the active film layer through a chemical bond.
3. The reverse osmosis composite membrane of claim 2, wherein the non-woven fabric base film comprises a polyethylene terephthalate non-woven fabric base film and/or a polyimide non-woven fabric base film;
the thickness of the base film is 140-160 mu m;
the modified polyacrylonitrile intermediate transition supporting film layer comprises a hydrophilic modified polyacrylonitrile intermediate transition supporting film layer;
the thickness of the middle transition support film layer is 50-120 mu m;
the thickness of the active film layer is 0.1-0.5 μm;
the thickness of the polyethylene glycol epoxide coating film layer is 0.01-0.03 mu m;
the chemical bonding includes bonding via-O-N-.
4. The composite reverse osmosis membrane of claim 2, wherein the modified polyacrylonitrile intermediate transition support membrane layer comprises a m-phenylenediamine/sodium dodecyl sulfate plasma modified polyacrylonitrile intermediate transition support membrane layer;
the molecular weight of the polyacrylonitrile is 80000-150000;
the aperture of the polyacrylonitrile intermediate transition support film layer is 0.05-0.1 mu m;
the polyamide active membrane layer is synthesized by TMC-MPDA interfacial polymerization.
5. The reverse osmosis composite membrane according to claim 2, wherein the water flux of the reverse osmosis composite membrane is 40-50L/m2·h；
The rejection rate of the reverse osmosis composite membrane to sodium ions is more than or equal to 99.75 percent;
the rejection rate of the reverse osmosis composite membrane to chloride ions is more than or equal to 99.75 percent;
the rejection rate of the reverse osmosis composite membrane to nitrate ions is more than or equal to 99.5 percent;
the rejection rate of the reverse osmosis composite membrane to divalent calcium ions is more than or equal to 99.9 percent.
6. The reverse osmosis composite membrane according to claim 1, wherein the ultraviolet radiation has a wavelength of 290 to 360 nm;
the ultraviolet irradiation time is 30-120 seconds;
the polyethylene glycol epoxide solution comprises a polyethylene glycol epoxide aqueous solution;
the mass concentration of the polyethylene glycol epoxide is 0.05-0.5%.
7. The reverse osmosis composite membrane according to claim 1, wherein the reverse osmosis membrane is prepared by a process comprising the steps of:
1) mixing polyacrylonitrile and a solvent to obtain intermediate transition support membrane layer liquid, and coating the intermediate transition support membrane layer liquid on a base membrane to obtain a first carrier compounded with an intermediate transition support membrane layer;
2) after the first carrier obtained in the step is subjected to oxygen plasma treatment, the first carrier is immersed into a mixed solution of m-phenylenediamine and sodium dodecyl sulfate, and a second carrier compounded with a modified intermediate transition support film layer is obtained;
3) and (3) contacting the second carrier obtained in the step with a trimesoyl chloride organic solution, and then drying to obtain the reverse osmosis membrane.
8. The reverse osmosis composite membrane of claim 7, wherein the solvent comprises one or more of butyrolactone, triethyl phosphate, N-dimethylformamide, and dimethyl sulfoxide;
the mass ratio of polyacrylonitrile to solvent is (15-30): 100, respectively;
the mass ratio of the polyacrylonitrile to the base film is (30-60): 100, respectively;
the step of removing the solvent is also included after the coating;
the plasma power of the oxygen plasma treatment is 10-30W;
the exposure time of the oxygen plasma treatment is 10-30 seconds.
9. The reverse osmosis composite membrane according to claim 7, wherein the mass ratio of the m-phenylenediamine to the base membrane is (2-10): 100;
the mass ratio of the sodium dodecyl sulfate to the base membrane is (0.02-0.08): 100, respectively;
the trimesoyl chloride organic solution comprises a trimesoyl chloride n-hexane solution;
the mass ratio of the trimesoyl chloride to the basement membrane is (0.1-0.2): 100;
the drying time is 3-6 minutes;
the drying temperature is 60-85 ℃.
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