CN107970784B - Reverse osmosis membrane and preparation method and application thereof - Google Patents

Reverse osmosis membrane and preparation method and application thereof Download PDF

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CN107970784B
CN107970784B CN201610922133.3A CN201610922133A CN107970784B CN 107970784 B CN107970784 B CN 107970784B CN 201610922133 A CN201610922133 A CN 201610922133A CN 107970784 B CN107970784 B CN 107970784B
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membrane
reverse osmosis
osmosis membrane
layer
polyethylene glycol
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CN107970784A (en
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张杨
刘轶群
潘国元
严昊
徐健
郭敏
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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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
    • B01D69/02—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
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/025—Reverse osmosis; Hyperfiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0088—Physical treatment with compounds, e.g. swelling, coating or impregnation
    • 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
    • B01D69/10—Supported membranes; Membrane supports
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/56—Polyamides, e.g. polyester-amides
    • 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
    • B01D2325/00—Details relating to properties of membranes

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

Abstract

The invention relates to the field of separation membranes, and discloses a reverse osmosis membrane and a preparation method and application thereof. The reverse osmosis membrane comprises a supporting layer, a separation layer and a pollution-resistant layer which are sequentially stacked, wherein the separation layer is formed by cross-linked polyamide, and the pollution-resistant layer is formed by polyethylene glycol. According to the reverse osmosis membrane provided by the invention, the polyethylene glycol is adopted to form the pollution-resistant layer on the polyamide separation layer, so that the obtained reverse osmosis membrane has good pollution-resistant performance and high salt rejection rate. In addition, the reverse osmosis membrane provided by the invention is simple in preparation method and has great industrial application prospects.

Description

Reverse osmosis membrane and preparation method and application thereof
Technical Field
The invention relates to the field of separation membranes, in particular to a reverse osmosis membrane, a preparation method of the reverse osmosis membrane, the reverse osmosis membrane prepared by the method and application of the reverse osmosis membrane in the field of water treatment.
Background
Membrane separation is a new technique of separation that emerged at the beginning of the 20 th century and rises rapidly after the 60's of the 20 th century. Because the membrane separation technology has the functions of separation, concentration, purification and refining, and has the characteristics of high efficiency, energy conservation, environmental protection, molecular level filtration, simple filtration process, easy control and the like, the membrane separation technology is widely applied to the fields of food, medicine, biology, environmental protection, chemical industry, metallurgy, energy, petroleum, water treatment, electronics, bionics and the like at present, generates great economic benefit and social benefit, and becomes one of the most important means in the current separation science. The core of membrane separation technology is the separation membrane. The porous membrane can be classified into a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane and a reverse osmosis membrane according to the pore size of the membrane.
Among them, the reverse osmosis membrane is one of the key technologies for water treatment because of its advantages of good separation performance for organic small molecules and inorganic salt ions, safety, environmental protection, easy operation, etc. Up to now, the main applications of reverse osmosis membranes are in the fields of seawater and brackish water desalination, hard water softening, reclaimed water recovery, industrial wastewater treatment, and ultrapure water preparation. At present, the mainstream product in the market adopts an interfacial polymerization mode to compound a polyamide film on the surface of a microporous support base film. The general process is described in detail in US 4277344. The reverse osmosis membrane product not only has higher desalination rate, but also has the advantages of good water permeability, wide pH range (2-12), low operation pressure and the like. However, membrane fouling has been an important factor affecting membrane performance and reducing its useful life. The membrane pollution refers to an irreversible change phenomenon that the membrane aperture is reduced or blocked due to adsorption and deposition in the membrane surface or membrane pores caused by the physical and chemical actions of particles, colloidal particles or solute macromolecules in feed liquid contacting with the membrane and the membrane or the concentration of certain solutes on the membrane surface exceeds the solubility and the mechanical action of the solutes due to concentration polarization, so that the membrane flux and the separation characteristics are obviously reduced. Adsorption of contaminants on the membrane surface and within the membrane pores can cause flux decay and a reduction in membrane separation capacity, and in particular protein adsorption is the primary cause of membrane flux decay. The current solution is to prevent and post-treat membrane fouling. The development and development of reverse osmosis composite membrane materials with stain resistance, as opposed to post-treatment, is the most fundamental and direct approach to solving this problem.
In order to improve the anti-pollution capability of the polyamide composite membrane, a great deal of work is done at home and abroad, and the surface modification treatment, surface grafting and surface coating are mainly focused.
Methods for the surface modification treatment of the membrane are numerous, for example, US patent application US5028453 discloses the use of plasma treatment to improve the contamination resistance of the composite membrane, but the current plasma treatment is limited by technical conditions and costs and cannot be realized in mass production; U.S. patent application 5151183 discloses that fluorine gas is used for fluorination treatment of the membrane surface to improve the anti-pollution property of the membrane, and the fluorine gas treatment is easy to break the polyamide molecular chains on the membrane surface, thereby affecting the separation performance and the service life of the membrane; mukherjee et al (decontamination, 1996,104:239-249) immerse the polyamide composite membrane in a mixed solution of hydrofluoric acid/silicofluoric acid/isopropanol/water for modification, thereby obtaining the contamination-resistant composite membrane.
Compared with surface modification treatment, the surface grafting method involves more complex chemical reaction and relatively complicated process. Freer and Gilron et al (decontamination, 2001,140:167-179) use redox method to graft acrylic acid and methacrylic acid on the surface of polyamide, thereby reducing the adsorption of contaminants on the membrane surface. Belfer et al (Journal of membrane science,1998,139: 175-. In addition, Belfer et al (Journal of membrane science,1998,139: 175-.
The surface coating method is a modification method which is most easy to realize industrial production due to the relative simple process. Both chinese patent application CN1468649A and US patent application US6913694 disclose that the contamination resistance of the composite film is improved by coating the surface of the composite film with a coating layer of epoxy compound containing more than 2 epoxy groups, but the contamination resistance of the composite film is improved to a limited extent due to the limitation of the density of hydrophilic groups.
Disclosure of Invention
The invention aims to overcome the defect of poor pollution resistance of the conventional reverse osmosis membrane, and provides a reverse osmosis membrane with excellent pollution resistance and high salt rejection rate, a preparation method thereof and application of the reverse osmosis membrane in the field of water treatment.
In order to achieve the above object, the present invention provides a reverse osmosis membrane, wherein the reverse osmosis membrane comprises a support layer, a separation layer and a contamination-resistant layer, which are sequentially laminated, the separation layer is formed of cross-linked polyamide, and the contamination-resistant layer is formed of polyethylene glycol.
The invention also provides a preparation method of the reverse osmosis membrane, which comprises the steps of forming a separation layer on a support layer by adopting the crosslinked polyamide and then forming a pollution-resistant layer on the separation layer by adopting the polyethylene glycol.
The invention also provides a reverse osmosis membrane prepared by the method.
In addition, the invention also provides application of the reverse osmosis membrane in the field of water treatment.
After intensive research, the inventor of the invention finds that the reverse osmosis membrane obtained by adopting polyethylene glycol to form the pollution-resistant layer on the polyamide separation layer has good pollution-resistant performance and high salt rejection rate. In addition, the reverse osmosis membrane provided by the invention is simple in preparation method and has great industrial application prospects.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The reverse osmosis membrane provided by the invention comprises a supporting layer, a separation layer and a pollution-resistant layer which are sequentially stacked, wherein the separation layer is formed by cross-linked polyamide, and the pollution-resistant layer is formed by polyethylene glycol.
The thicknesses of the support layer, the separation layer and the contamination-resistant layer are not particularly limited in the present invention, and can be selected conventionally in the field, but in order to enable the three layers to have better synergistic effect, so that the obtained reverse osmosis membrane has better contamination-resistant performance and higher salt rejection rate, preferably, the thickness of the support layer is 90-150 micrometers, and more preferably 100-120 micrometers; the thickness of the separation layer is 0.05-0.5 micron, more preferably 0.1-0.3 micron; the thickness of the stain-resistant layer is 0.01 to 0.5 microns, more preferably 0.05 to 0.25 microns.
The material of the support layer is not particularly limited, and the support layer may be made of various materials having certain strength and being used for a reverse osmosis membrane, and may be generally made of at least one of polyester, polyacrylonitrile, polyvinylidene fluoride, phenolphthalein type non-sulfonated polyarylethersulfone, polyethersulfone and polysulfone. According to a specific embodiment of the present invention, the support layer includes a polyester non-woven fabric layer and a polymer layer made of at least one of polyacrylonitrile, polyvinylidene fluoride, phenolphthalein type non-sulfonated polyarylethersulfone, polyethersulfone and polysulfone attached on a surface of the polyester non-woven fabric layer. Wherein, the thickness of the polyester non-woven fabric layer can be 60-100 microns, and the thickness of the polymer layer can be 10-50 microns.
According to the reverse osmosis membrane provided by the invention, in the separation layer, the crosslinked polyamide can be obtained by carrying out interfacial polymerization on polyamine and polybasic acid chloride. Among them, examples of the polyamine include, but are not limited to, at least one of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, piperazine and sym-phenylenediamine, and the polyamine is particularly preferably m-phenylenediamine from the viewpoint of availability of raw materials. Examples of the polybasic acid chloride include, but are not limited to, at least one of trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride, and the polybasic acid chloride is particularly preferably trimesoyl chloride from the viewpoint of availability of raw materials. In order to form a crosslinked polyamide, at least one of the polyamine and the polybasic acid chloride needs to contain a compound having at least three functional groups, and for example, a ternary (or higher) amine or a polyamine containing a ternary (or higher) amine may be subjected to interfacial polymerization with an arbitrary polybasic acid chloride, or a ternary (or higher) acid chloride or a polybasic acid chloride containing a ternary (or higher) acid chloride may be subjected to interfacial polymerization with an arbitrary polybasic amine. In addition, the weight ratio between the polyamine and the polybasic acid chloride can be (1-100):1, preferably (5-50): 1.
The interfacial polymerization between the polyamine and the polyacid chloride is generally carried out in the presence of a solvent. The solvent may be any of various known inert liquid substances capable of dissolving the polyamine and the polyacyl chloride and not reacting with the reactants and the reaction products, and specific examples thereof include, but are not limited to: at least one of water, n-hexane, n-heptane, dodecane, Isopar E, Isopar G, Isopar H, Isopar L, and Isopar M.
The conditions for the interfacial polymerization in the present invention are not particularly limited, and generally include a polymerization temperature of 40 to 150 ℃ and preferably 50 to 120 ℃; the polymerization time may be from 0.5 to 20min, preferably from 1 to 10 min.
According to the present invention, in the contamination-resistant layer, the number average molecular weight of the polyethylene glycol is preferably 200 to 10 ten thousand, more preferably 1000 to 5 ten thousand, and still more preferably 5000 to 2 ten thousand.
The preparation method of the reverse osmosis membrane provided by the invention comprises the steps of forming a separation layer on a support layer by adopting cross-linked polyamide, and then forming a pollution-resistant layer on the separation layer by adopting polyethylene glycol.
The thicknesses of the support layer, the separation layer and the contamination-resistant layer are not particularly limited and can be selected conventionally in the field, but in order to enable the three layers to play a better synergistic effect and enable the obtained reverse osmosis membrane to have more excellent contamination-resistant performance and higher salt rejection rate, preferably, the thickness of the support layer is 90-150 micrometers, the thickness of the separation layer is 0.05-0.5 micrometers, and the thickness of the contamination-resistant layer is 0.01-0.5 micrometers; more preferably, the thickness of the support layer is 100-120 microns, the thickness of the separation layer is 0.1-0.3 microns, and the thickness of the contamination-resistant layer is 0.05-0.25 microns.
The material of the support layer is not particularly limited, and the support layer may be made of various materials having certain strength and being used for a reverse osmosis membrane, and may be generally made of at least one of polyester, polyacrylonitrile, polyvinylidene fluoride, phenolphthalein type non-sulfonated polyarylethersulfone, polyethersulfone and polysulfone. According to a specific embodiment of the present invention, the support layer includes a polyester non-woven fabric layer and a polymer layer made of at least one of polyacrylonitrile, polyvinylidene fluoride, phenolphthalein type non-sulfonated polyarylethersulfone, polyethersulfone and polysulfone attached on a surface of the polyester non-woven fabric layer. Wherein, the thickness of the polyester non-woven fabric layer can be 60-100 microns, and the thickness of the polymer layer can be 10-50 microns.
According to the present invention, preferably, the separation layer is formed by adsorbing a polyamine and a polyacyl chloride on the support layer, followed by interfacial polymerization. According to one embodiment of the present invention, the separation layer is formed by immersing the support layer in a polyamine solution and a polyacyl chloride solution in this order, followed by interfacial polymerization. As described above, examples of the polyamine include, but are not limited to, at least one of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, piperazine, and sym-phenylenediamine, and the polyamine is particularly preferably m-phenylenediamine from the viewpoint of availability of raw materials. Examples of the polybasic acid chloride include, but are not limited to, at least one of trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride, and the polybasic acid chloride is particularly preferably trimesoyl chloride from the viewpoint of availability of raw materials. In order to form a crosslinked polyamide, at least one of the polyamine and the polybasic acid chloride needs to contain a compound having at least three functional groups, and for example, a ternary (or higher) amine or a polyamine containing a ternary (or higher) amine may be subjected to interfacial polymerization with an arbitrary polybasic acid chloride, or a ternary (or higher) acid chloride or a polybasic acid chloride containing a ternary (or higher) acid chloride may be subjected to interfacial polymerization with an arbitrary polybasic amine. The weight ratio between the polyamine and the polybasic acid chloride can be (1-100):1, preferably (5-50): 1. The solvents in the polyamine solution and the polyacyl chloride solution can be the same or different, and can be at least one of water, n-hexane, n-heptane, dodecane, Isopar E, Isopar G, Isopar H, Isopar L and Isopar M respectively and independently. Further, the concentration of the polyamine solution may be 0.5 to 10% by weight, preferably 1 to 5% by weight. The concentration of the polyacyl chloride solution may be 0.025 to 1 wt%, preferably 0.05 to 0.5 wt%.
In the present invention, the conditions for immersing the support layer in the polyamine solution and in the polyacyl chloride solution are not particularly limited, and each of the conditions generally independently includes: the dipping temperature can be 10-50 ℃, and preferably 20-40 ℃; the impregnation time may be from 5 to 100s, preferably from 10 to 60 s.
The conditions for the interfacial polymerization reaction in the present invention are not particularly limited, and generally include a polymerization temperature which may be 40 to 150 ℃, preferably 50 to 120 ℃; the polymerization time may be from 0.5 to 20min, preferably from 1 to 10 min.
According to the present invention, the contamination-resistant layer may be formed by coating and drying a coating liquid containing polyethylene glycol. According to a preferred embodiment of the present invention, the manner of forming the contamination-resistant layer includes sequentially immersing the membrane formed with the separation layer in an alkali metal hydroxide solution and a solution containing polyethylene glycol. The purpose of soaking the membrane in the alkali metal hydroxide solution is to hydrolyze and neutralize residual acyl chloride groups on the crosslinked polyamide in the separation layer to form carboxylate groups, and the carboxylate groups can form interaction with oxygen atoms in polyethylene glycol molecules, so that the polyethylene glycol is fixed on the surface of the polyamide separation layer through complexation, and the obtained reverse osmosis membrane has high mechanical strength and long service life. Wherein the alkali metal hydroxide in the alkali metal hydroxide solution is preferably potassium hydroxide and/or sodium hydroxide. The concentration of the alkali metal hydroxide solution is preferably 0.05 to 5mol/L, more preferably 0.1 to 1 mol/L. The conditions for immersing the membrane in the alkali metal hydroxide solution include a temperature of preferably 10 to 50 deg.C, more preferably 20 to 40 deg.C, and a time of preferably 10s to 10min, more preferably 30s to 5 min. The number average molecular weight of the polyethylene glycol is preferably 200 to 10 ten thousand, more preferably 1000 to 5 ten thousand, and most preferably 5000 to 2 ten thousand. The concentration of the polyethylene glycol-containing solution is preferably 1 to 50% by weight, more preferably 2 to 20% by weight, and most preferably 10 to 20% by weight. The conditions for soaking the membrane in the solution containing polyethylene glycol include a temperature of preferably 20 to 100 deg.C, more preferably 40 to 100 deg.C, most preferably 50 to 90 deg.C, and a time of preferably 1 to 360min, more preferably 5 to 240min, most preferably 30 to 150 min.
The invention also provides a reverse osmosis membrane prepared by the method.
The invention also provides application of the reverse osmosis membrane in the field of water treatment.
The present invention will be described in detail below by way of examples.
In the following examples and comparative examples:
(1) the water flux of the reverse osmosis membrane is obtained by testing the following method: putting the reverse osmosis membrane into a membrane pool, prepressing for 0.5h under 1.2MPa, measuring the water permeability of the reverse osmosis membrane within 1h under the conditions of pressure of 1.55MPa and temperature of 25 ℃, and calculating the water flux by the following formula: q1J/(a · t), wherein J is the water permeability (L), Q1Is the water flux (L/m)2h) A is the effective membrane area (m) of the reverse osmosis membrane2) T is time (h);
(2) the salt rejection of the reverse osmosis membrane is measured by the following method: loading the reverse osmosis membrane into a membrane pool, prepressing for 0.5h under 1.2MPa, measuring the concentration change of the sodium chloride raw water solution with initial concentration of 2000ppm and the sodium chloride in the permeate within 1h under the conditions of pressure of 1.55MPa and temperature of 25 ℃, and calculating by the following formula:
R＝(Cp-Cf)/Cpx 100%, wherein R is the salt rejection, CpIs the concentration of sodium chloride in the stock solution, CfIs the concentration of sodium chloride in the permeate.
(3) The contamination resistance of the reverse osmosis membrane was tested as follows: loading the reverse osmosis membrane into a membrane pool, prepressing at 1.2MPa for 0.5h, and then loading the reverse osmosis membrane into a membrane pool under the pressure of 1.55Measuring the water flux of the reverse osmosis membrane within 1h under the conditions of MPa and 25 ℃, and calculating the water flux by the following formula: q1J/(a · t), wherein J is the water permeability (L), Q1Is the water flux (L/m)2h) A is the effective membrane area (m) of the reverse osmosis membrane2) And t is time (h). Replacing the circulating test solution with a mixed water solution of NaCl and Bovine Serum Albumin (BSA) (wherein the concentration of NaCl is 2000ppm, and the concentration of BSA is 1000ppm), operating at 25 deg.C under 1.55MPa for 6h, and measuring the water flux Q of the reverse osmosis membrane at 25 deg.C under 1.55MPa2(ii) a Then, after the reverse osmosis membrane was washed with clean water for 0.5 hour, the water flux Q was measured at a pressure of 1.55MPa and a temperature of 25 ℃ in the case where the circulating liquid was a 2000ppm NaCl aqueous solution3(ii) a The water flux reduction rate of the reverse osmosis membrane is calculated by the following formula: d ═ Q1-Q2)/Q1X is 100%; the water flux recovery rate of the reverse osmosis membrane after washing is calculated by the following formula: h ═ Q3/Q1X 100%. Wherein, the lower the water flux reduction rate and the higher the water flux recovery rate, the better the pollution resistance of the reverse osmosis membrane is.
In the following examples and comparative examples:
polyethylene glycols (number average molecular weights 1000, 2000, 6000, 10000 and 100000), m-phenylenediamine and trimesoyl chloride are all available from carbofuran technologies ltd.
The supporting layer is prepared by adopting a phase inversion method, and the method comprises the following specific steps: polysulfone (number average molecular weight 80000) is dissolved in N, N-dimethylformamide to prepare a polysulfone solution with a concentration of 18 wt%, the polysulfone solution is kept still and defoamed for 120min at 25 ℃, then the polysulfone solution is coated on a polyester non-woven fabric with a thickness of 75 microns by using a scraper to obtain an initial membrane, the initial membrane is then soaked in water with a temperature of 25 ℃ for 60min, so that a polysulfone layer on the surface of the polyester non-woven fabric is subjected to phase conversion into a porous membrane, and finally, the porous membrane is subjected to multiple water washes to obtain a supporting layer with a total thickness of 115 microns.
Comparative example 1
Contacting the upper surface of the supporting layer (the surface of the polysulfone layer, the same below) with a 2 wt% m-phenylenediamine aqueous solution, contacting for 10s at 25 ℃, and discharging liquid; then, the upper surface of the supporting layer is contacted with Isopar E solution containing 0.1 weight percent of trimesoyl chloride solution for 10 seconds at 25 ℃, and then liquid drainage is carried out; then, the membrane was placed in an oven and heated at 70 ℃ for 3min to give a reverse osmosis membrane M1 comprising a support layer and a separation layer, wherein the separation layer had a thickness of 0.15 μ M.
The obtained reverse osmosis membrane M1 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Comparative example 2
And (3) soaking the polyamide composite reverse osmosis membrane obtained in the comparative example 1 in a 0.1mol/L NaOH aqueous solution at the temperature of 30 ℃ for 5min, taking out, and washing with distilled water to obtain the reverse osmosis membrane M2. The reverse osmosis membrane is soaked in distilled water for later use.
The obtained reverse osmosis membrane M2 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Example 1
The reverse osmosis membrane obtained in the comparative example 1 is soaked in a 0.1mol/L NaOH aqueous solution for 5min at the temperature of 30 ℃, taken out and washed clean by distilled water. Then, the reverse osmosis membrane was soaked in a 10 wt% polyethylene glycol (number average molecular weight: 10000) aqueous solution at a temperature of 80 ℃ for 1 hour, and then washed clean with distilled water to obtain a reverse osmosis membrane N1 comprising a support layer, a separation layer and a contamination-resistant layer laminated in this order, wherein the separation layer had a thickness of 0.15 μm and the contamination-resistant layer had a thickness of 0.08. mu.m. The reverse osmosis membrane is soaked in distilled water for later use.
The obtained reverse osmosis membrane N1 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Example 2
And (3) soaking the reverse osmosis membrane obtained in the comparative example 1 in a 0.5mol/L NaOH aqueous solution at the temperature of 30 ℃ for 5min, taking out, and washing with distilled water. Then, the reverse osmosis membrane was soaked in a 15 wt% polyethylene glycol (number average molecular weight: 6000) aqueous solution at a temperature of 50 ℃ for 150min, and then washed clean with distilled water to obtain a reverse osmosis membrane N2 comprising a support layer, a separation layer and a contamination-resistant layer laminated in this order, wherein the separation layer had a thickness of 0.15 μm and the contamination-resistant layer had a thickness of 0.095. mu.m. The reverse osmosis membrane is soaked in distilled water for later use.
The obtained reverse osmosis membrane N2 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Example 3
And (3) soaking the reverse osmosis membrane obtained in the comparative example 1 in a NaOH aqueous solution with the temperature of 30 ℃ and the concentration of 1mol/L for 5min, taking out, and washing with distilled water. Then, the reverse osmosis membrane was soaked in a 20 wt% polyethylene glycol (number average molecular weight 2000) aqueous solution at a temperature of 90 ℃ for 30min, and then washed clean with distilled water to obtain a reverse osmosis membrane N3 comprising a support layer, a separation layer and a contamination-resistant layer laminated in this order, wherein the separation layer had a thickness of 0.15 μm and the contamination-resistant layer had a thickness of 0.12. mu.m. The reverse osmosis membrane is soaked in distilled water for later use.
The obtained reverse osmosis membrane N3 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Example 4
A reverse osmosis membrane was prepared according to the procedure of example 1, except that the number average molecular weight of polyethylene glycol was 1000, to give a reverse osmosis membrane N4 comprising a support layer, a separation layer and a fouling resistant layer laminated in this order, wherein the thickness of the separation layer was 0.15 μm and the thickness of the fouling resistant layer was 0.08. mu.m. The obtained reverse osmosis membrane N4 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Example 5
Prepared according to the method of example 1The reverse osmosis membrane is different from the reverse osmosis membrane, wherein the number average molecular weight of polyethylene glycol is 100000, and the reverse osmosis membrane N5 is obtained and comprises a supporting layer, a separation layer and a pollution-resistant layer which are sequentially stacked, wherein the thickness of the separation layer is 0.15 micrometer, and the thickness of the pollution-resistant layer is 0.08 micrometer. The obtained reverse osmosis membrane N5 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Example 6
A reverse osmosis membrane was prepared according to the method of example 1, except that the soaking time in the aqueous polyethylene glycol solution was 10min, and reverse osmosis membrane N6 comprising a support layer, a separation layer and a fouling-resistant layer, which were sequentially stacked, wherein the separation layer had a thickness of 0.15 μm and the fouling-resistant layer had a thickness of 0.07. mu.m. The obtained reverse osmosis membrane N6 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Example 7
A reverse osmosis membrane was prepared according to the method of example 1, except that the soaking time in the aqueous polyethylene glycol solution was 30min, and reverse osmosis membrane N7 comprising a support layer, a separation layer and a fouling-resistant layer, which were sequentially stacked, wherein the thickness of the separation layer was 0.15 μm and the thickness of the fouling-resistant layer was 0.075 μm. The obtained reverse osmosis membrane N7 was immersed in water for 24 hours under a pressure of 1.55MPa,Measuring the water flux (Q) at a temperature of 25 DEG C1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
Example 8
A reverse osmosis membrane was prepared according to the method of example 1, except that the soaking time in the aqueous polyethylene glycol solution was 120min, and reverse osmosis membrane N8 comprising a support layer, a separation layer and a fouling-resistant layer, which were sequentially stacked, wherein the separation layer had a thickness of 0.15 μm and the fouling-resistant layer had a thickness of 0.10. mu.m. The obtained reverse osmosis membrane N8 was immersed in water for 24 hours, and then the water flux (Q) was measured under a pressure of 1.55MPa and at a temperature of 25 ℃1) And the salt rejection for NaCl (2000ppm), the results are shown in Table 1. The membrane was tested for stain resistance under the same conditions of temperature and pressure, and specifically, the water flux (Q) of the membrane was measured after running for 6 hours in a mixed aqueous solution containing 2000ppm NaCl and 1000ppm BSA2) And water flux (Q) after washing3) From this, the water flux reduction rate and the water flux recovery rate of the reverse osmosis membrane were calculated, and the results are shown in table 1.
TABLE 1
Figure BDA0001136145350000141
From the above results, it can be seen that the reverse osmosis membrane provided by the invention not only has a high desalination rate, but also has a low water flux reduction rate and a high water flux recovery rate, i.e., has a good contamination resistance. In addition, the reverse osmosis membrane provided by the invention is simple in preparation method and has great industrial application prospects.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims (15)

1. A method for preparing a reverse osmosis membrane, which comprises forming a separation layer on a support layer using crosslinked polyamide, and then forming a contamination-resistant layer on the separation layer using polyethylene glycol;
the thickness of the support layer is 90-150 microns; the thickness of the separation layer is 0.05-0.5 micron; the thickness of the pollution-resistant layer is 0.08 micrometer;
the number average molecular weight of the polyethylene glycol is 2000-1 ten thousand;
wherein the stain-resistant layer is formed in a manner comprising sequentially immersing the membrane on which the separation layer is formed in an alkali metal hydroxide solution and a solution containing polyethylene glycol; the concentration of the solution containing polyethylene glycol is 10-20 wt%.
2. The method of claim 1, wherein forming the separation layer comprises adsorbing a polyamine and a polyacyl chloride onto the support layer followed by interfacial polymerization.
3. The process of claim 2, wherein the weight ratio of polyamine to polyacyl chloride is (1-100): 1.
4. The method of claim 2, wherein the polyamine is at least one of meta-phenylene diamine, para-phenylene diamine, ortho-phenylene diamine, piperazine, and pyromellitic triamine, and the poly acid chloride is at least one of trimesoyl chloride, isophthaloyl chloride, and terephthaloyl chloride.
5. The process of claim 2, wherein the interfacial polymerization conditions include a polymerization temperature of 40 to 150 ℃ and a polymerization time of 0.5 to 20 min.
6. The process of claim 5, wherein the interfacial polymerization conditions include a polymerization temperature of 50-120 ℃ and a polymerization time of 1-10 min.
7. The method according to claim 1, wherein the concentration of the alkali metal hydroxide solution is 0.05 to 5 mol/L.
8. The method according to claim 7, wherein the concentration of the alkali metal hydroxide solution is 0.1 to 1 mol/L.
9. The method of claim 1, wherein the conditions under which the membrane is soaked in the alkali metal hydroxide solution comprise a temperature of 10-50 ℃ for a time of 10s-10 min.
10. The method of claim 9, wherein the conditions under which the membrane is soaked in the alkali metal hydroxide solution comprise a temperature of 20-40 ℃ for 30s-5 min.
11. The method according to claim 1, wherein the conditions for immersing the membrane in the solution containing polyethylene glycol include a temperature of 20-100 ℃ and a time of 1-360 min.
12. The method of claim 11, wherein the conditions for immersing the membrane in the solution comprising polyethylene glycol comprise a temperature of 40-100 ℃ for a time of 5-240 min.
13. The method of any one of claims 1-12, wherein the support layer is made of at least one of polyester, polyacrylonitrile, polyvinylidene fluoride, phenolphthalein-type non-sulfonated polyarylethersulfones, polyethersulfones, and polysulfones.
14. The method of any of claims 1-12, wherein the support layer has a thickness of 100-120 microns; the thickness of the separation layer is 0.1-0.3 microns.
15. A reverse osmosis membrane prepared by the method of any one of claims 1-14.
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