CN107970779B - Reverse osmosis membrane and preparation method and application thereof - Google Patents
Reverse osmosis membrane and preparation method and application thereof Download PDFInfo
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- CN107970779B CN107970779B CN201610921389.2A CN201610921389A CN107970779B CN 107970779 B CN107970779 B CN 107970779B CN 201610921389 A CN201610921389 A CN 201610921389A CN 107970779 B CN107970779 B CN 107970779B
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- 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
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D67/0006—Organic membrane manufacture by chemical reactions
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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
- B01D69/10—Supported membranes; Membrane supports
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- 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
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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 cross-linked alginate and polyethylene glycol through complexation. The reverse osmosis membrane provided by the invention adopts the cross-linked alginate and the polyethylene glycol to form the pollution-resistant layer on the polyamide separation layer through complexation, so that the obtained reverse osmosis membrane has good desalting rate and pollution resistance. In addition, the reverse osmosis membrane provided by the invention is simple in preparation method and has great industrial application prospects.
Description
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 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 cross-linked alginate complexed with 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 supporting layer by adopting the crosslinked polyamide, and then forming a pollution-resistant layer on the separation layer by adopting the complexation of the crosslinked alginate and 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 cross-linked alginate and the polyethylene glycol are adopted on the polyamide separation layer to form the pollution-resistant layer through complexation, so that the obtained reverse osmosis membrane not only has good pollution-resistant performance, but also has high desalination 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 cross-linked alginate and polyethylene glycol through complexation.
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, the cross-linked alginate in the stain-resistant layer may be obtained commercially or may be prepared according to a method known to those skilled in the art. According to a particular embodiment of the invention, the cross-linked alginate is obtained by a cross-linking reaction of an alginate and a cross-linking agent in the presence of a catalyst and a solvent. Wherein the alginate is preferably used in an amount of 0.1 to 50 parts by weight, more preferably 0.2 to 25 parts by weight, most preferably 0.5 to 2 parts by weight, relative to 100 parts by weight of the solvent; the amount of the crosslinking agent is preferably 0.001 to 50 parts by weight, more preferably 0.002 to 2.5 parts by weight, most preferably 0.05 to 1 part by weight; the catalyst is an acid and is used in such an amount that the pH of the crosslinking system is preferably in the range of 1 to 5, more preferably in the range of 2 to 5, most preferably in the range of 2 to 4.
The number average molecular weight of the alginate is preferably 10000-. The alginate can be potassium alginate and/or sodium alginate.
The type of the cross-linking agent is not particularly limited in the present invention, and may be any of various existing compounds capable of causing the alginate to undergo a cross-linking reaction, preferably an aldehyde compound, and specific examples thereof include, but are not limited to: at least one of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, glyoxal, malonaldehyde, succinaldehyde, and glutaraldehyde, more preferably at least one of glyoxal, malonaldehyde, succinaldehyde, and glutaraldehyde, and particularly preferably glutaraldehyde.
The catalyst of the present invention is not particularly limited in kind, and may be common acids, and specific examples thereof include, but are not limited to: at least one of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, formic acid and nitric acid, preferably at least one of sulfuric acid, hydrochloric acid and acetic acid, and particularly preferably hydrochloric acid. The catalyst may be used in pure form or in the form of an aqueous solution thereof. When the catalyst is used in the form of an aqueous solution thereof, the concentration thereof may be 0.5 to 1.5mol/L, preferably 0.8 to 1.2 mol/L.
The solvent used in the crosslinking reaction is not particularly limited as long as it can dissolve the alginate, the crosslinking agent and the catalyst, and may be at least one of water, methanol, ethanol, acetone, ethylene glycol monomethyl ether, ethylene glycol and dimethyl sulfoxide, and water is particularly preferable.
The conditions of the crosslinking reaction are not particularly limited in the present invention, and for example, the conditions of the crosslinking reaction generally include: the reaction temperature can be 40-150 ℃, and the reaction time can be 1min-1 h; preferably, the conditions of the crosslinking reaction include: the reaction temperature is 50-120 ℃, and the reaction time is 2-30 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 most preferably 5000 to 2 ten thousand.
The weight ratio of the content of the cross-linked alginate to the content of the polyethylene glycol in the stain-resistant layer is not particularly limited, and may be (0.1-500): 1, preferably (0.5-200): 1, more preferably (5-50):1, most preferably (10-40): 1.
the preparation method of the reverse osmosis membrane comprises the steps of forming a separation layer on a supporting layer by adopting cross-linked polyamide, and forming a pollution-resistant layer on the separation layer by adopting cross-linked alginate and polyethylene glycol through complexation.
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, preferably, the contamination-resistant layer is formed by dissolving alginate, a crosslinking agent and a catalyst in a solvent to prepare a coating liquid, then coating the coating liquid on the separation layer, followed by heating to allow the alginate to undergo a crosslinking reaction, and then soaking the resulting membrane in a solution containing polyethylene glycol. Wherein, in the coating liquid, the alginate is used in an amount of preferably 0.1 to 50 parts by weight, more preferably 0.2 to 25 parts by weight, and most preferably 0.5 to 2 parts by weight, relative to 100 parts by weight of the solvent; the amount of the crosslinking agent is preferably 0.001 to 50 parts by weight, more preferably 0.002 to 2.5 parts by weight, most preferably 0.05 to 1 part by weight; the catalyst is an acid and is used in such an amount that the pH of the crosslinking system is preferably in the range of 1 to 5, more preferably in the range of 2 to 5, most preferably in the range of 2 to 4.
The number average molecular weight of the alginate is preferably 10000-. The alginate can be potassium alginate and/or sodium alginate.
The type of the cross-linking agent is not particularly limited in the present invention, and may be any of various existing compounds capable of causing the alginate to undergo a cross-linking reaction, preferably an aldehyde compound, and specific examples thereof include, but are not limited to: at least one of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, glyoxal, malonaldehyde, succinaldehyde, and glutaraldehyde, more preferably at least one of glyoxal, malonaldehyde, succinaldehyde, and glutaraldehyde, and particularly preferably glutaraldehyde.
The catalyst of the present invention is not particularly limited in kind, and may be common acids, and specific examples thereof include, but are not limited to: at least one of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, formic acid and nitric acid, preferably at least one of sulfuric acid, hydrochloric acid and acetic acid, and particularly preferably hydrochloric acid. The catalyst may be used in pure form or in the form of an aqueous solution thereof. When the catalyst is used in the form of an aqueous solution thereof, the concentration thereof may be 0.5 to 1.5mol/L, preferably 0.8 to 1.2 mol/L.
The solvent used in the crosslinking reaction is not particularly limited as long as it can dissolve the alginate, the crosslinking agent and the catalyst, and may be at least one of water, methanol, ethanol, acetone, ethylene glycol monomethyl ether, ethylene glycol and dimethyl sulfoxide, and water is particularly preferable.
The conditions of the crosslinking reaction are not particularly limited in the present invention, and for example, the conditions of the crosslinking reaction generally include: the reaction temperature can be 40-150 ℃, and the reaction time can be 1min-1 h; preferably, the conditions of the crosslinking reaction include: the reaction temperature is 50-120 ℃, and the reaction time is 2-30 min.
According to the invention, the dissolution of the alginate, the cross-linking agent and the catalyst in the solvent is preferably carried out under stirring. The stirring conditions and the stirring equipment are not particularly limited in the present invention, and conventional stirring equipment well known to those skilled in the art can be used under appropriate stirring conditions as long as the alginate, the crosslinking agent and the catalyst are sufficiently dissolved in the solvent. In addition, in the present invention, the process of dissolving the alginate, the crosslinking agent and the catalyst in the solvent may be performed at normal temperature.
The method of coating the coating liquid on the separation layer is not particularly limited in the present invention, and various methods known to those skilled in the art, for example, spray coating, knife coating, spin coating, etc., may be used.
In addition, in order to make the obtained reverse osmosis membrane more flat, it is preferable that the preparation method of the reverse osmosis membrane provided by the present invention further comprises fixing the membrane formed with the separation layer on a glass plate or a film coating machine before coating the coating liquid on the separation layer.
According to the preparation method of the reverse osmosis membrane provided by the invention, when the membrane attached with the cross-linked alginate is soaked in a solution containing polyethylene glycol, a complexing effect can be formed between carboxylate groups in the cross-linked alginate and oxygen atoms in polyethylene glycol molecules, so that the polyethylene glycol is fixed on the surface of the reverse osmosis membrane. Wherein 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 the soaking in the present invention are not particularly limited, and generally include a temperature of preferably 20 to 100 ℃, more preferably 40 to 100 ℃, and most preferably 50 to 90 ℃, and a time of preferably 1 to 360min, more preferably 5 to 240min, and most preferably 30 to 120 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: 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 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.
(4) The weight ratio of the cross-linked alginate to the polyethylene glycol in the contamination-resistant layer is calculated by a weighing method, and the specific calculation process is as follows: l ═ m1-m0)÷(m2-m1) Wherein L is the weight ratio of the two, m0The dry weight (g), m) of the film after the separation layer was formed and before the anti-fouling layer was formed1The dry weight (g), m) of the membrane after attachment of the cross-linked alginate and before attachment of the polyethylene glycol2Is the dry weight (g) of the corresponding membrane after attachment of the polyethylene glycol.
In the following examples and comparative examples:
polyethylene glycols (number average molecular weights 1000, 2000, 6000, 10000 and 100000), sodium alginate, glutaraldehyde were 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
1.0g of sodium alginate (the number average molecular weight is 42000) and 0.1g of glutaraldehyde are dissolved in 100g of deionized water, and then 1mol/L of dilute hydrochloric acid is added dropwise with stirring to adjust the pH of the solution to 2. After stirring at room temperature for 24h, the clear coating solution was obtained by filtration. The surface of the polyamide separation layer of the reverse osmosis membrane prepared in comparative example 1 was coated with the coating liquid, and then heated at 100 ℃ for 10min to obtain a reverse osmosis membrane M2 comprising a support layer, a separation layer and a fouling resistant layer laminated in this order, wherein the separation layer had a thickness of 0.15 μ M and the fouling resistant layer had a thickness of 0.18 μ M, the separation layer was formed of crosslinked polyamide and the fouling resistant layer was formed of crosslinked alginate.
Soaking the obtained reverse osmosis membrane M2 in water for 24 hr, and measuring water flux under the conditions of pressure of 1.55MPa and temperature of 25 deg.CQuantity (Q)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 3
A reverse osmosis membrane was prepared according to the method of comparative example 2, except that the number average molecular weight of the sodium alginate raw material was 35000, and the heating temperature after coating the coating liquid on the surface of the polyamide separation layer of the reverse osmosis membrane prepared in comparative example 1 was 50 ℃ for 30min, to obtain a reverse osmosis membrane M3. After soaking the reverse osmosis membrane M3 in water for 24 hours, 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 4
A reverse osmosis membrane was prepared according to the method of comparative example 2, except that the number average molecular weight of the sodium alginate raw material was 58000, and the heating temperature after coating the coating liquid on the surface of the polyamide separation layer of the reverse osmosis membrane prepared in comparative example 1 was 120 ℃ for 2min, to obtain a reverse osmosis membrane M4. After soaking the reverse osmosis membrane M4 in water for 24 hours, 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 of the reverse osmosis membrane is calculatedThe flux reduction rate and the water flux recovery rate were as shown in table 1.
Example 1
The reverse osmosis membrane obtained in comparative example 2 was immersed in an aqueous solution of 10 wt% polyethylene glycol (number average molecular weight: 10000) at a temperature of 50 ℃ 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 fouling resistant layer laminated in this order, wherein the separation layer has a thickness of 0.15 μm and the fouling resistant layer has a thickness of 0.20 μm, the separation layer is formed from a crosslinked polyamide, the fouling resistant layer is formed from crosslinked sodium alginate and polyethylene glycol by complexation, and the weight ratio of crosslinked sodium alginate to polyethylene glycol in the fouling resistant layer is 22: 1. 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
The reverse osmosis membrane obtained in comparative example 3 was immersed in an aqueous solution of polyethylene glycol (number average molecular weight: 6000) having a concentration of 15 wt% at a temperature of 80 ℃ for 1 hour, and then washed clean with distilled water to obtain a reverse osmosis membrane N2 comprising a support layer, a separation layer and a fouling resistant layer laminated in this order, wherein the separation layer has a thickness of 0.15 μm and the fouling resistant layer has a thickness of 0.19 μm, the separation layer is formed from a crosslinked polyamide, the fouling resistant layer is formed from crosslinked sodium alginate and polyethylene glycol by complexation, and the weight ratio of crosslinked sodium alginate to polyethylene glycol in the fouling resistant layer is 33: 1. The reverse osmosis membrane is soaked in distilled water for later use.
The obtained reverse osmosisAfter membrane N2 was immersed in water for 24 hours, the water flux (Q) was measured under a pressure of 1.55MPa and 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
The reverse osmosis membrane obtained in comparative example 4 was immersed in an aqueous solution of 20 wt% polyethylene glycol (number average molecular weight 2000) at a temperature of 90 ℃ for 1 hour, and then washed clean with distilled water to obtain a reverse osmosis membrane N3 comprising a support layer, a separation layer and a fouling resistant layer laminated in this order, wherein the separation layer had a thickness of 0.15 μm and the fouling resistant layer had a thickness of 0.22 μm, the separation layer was formed of crosslinked polyamide, the fouling resistant layer was formed by complexing crosslinked sodium alginate with polyethylene glycol, and the weight ratio of crosslinked sodium alginate to polyethylene glycol in the fouling resistant layer was 17: 1. 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 separation layer had a thickness of 0.15. mu.m, and the fouling resistant layerThe thickness of the anti-pollution layer is 0.16 microns, the separation layer is formed by cross-linked polyamide, the anti-pollution layer is formed by complexing cross-linked sodium alginate and polyethylene glycol, and the weight ratio of the cross-linked sodium alginate to the polyethylene glycol in the anti-pollution layer is 20: 1. 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 its water flux (Q) 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
A reverse osmosis membrane was prepared according to the method of example 1, except that the number average molecular weight of polyethylene glycol was 100000, to give a reverse osmosis membrane N5 comprising a support layer, a separation layer and a fouling resistant layer laminated in this order, wherein the separation layer had a thickness of 0.15 μm and the fouling resistant layer had a thickness of 0.26 μm, the separation layer was formed of crosslinked polyamide, the fouling resistant layer was formed of crosslinked sodium alginate by complexation with polyethylene glycol, and the weight ratio of crosslinked sodium alginate to polyethylene glycol in the fouling resistant layer was 15: 1. 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 its water flux (Q) 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 30min, and reverse osmosis membrane N6 comprising a supporting layer, separation layers, which were sequentially stackedThe anti-pollution device comprises a layer and an anti-pollution layer, wherein the thickness of the separation layer is 0.15 micrometers, the thickness of the anti-pollution layer is 0.24 micrometers, the separation layer is formed by cross-linked polyamide, the anti-pollution layer is formed by complexing cross-linked sodium alginate and polyethylene glycol, and the weight ratio of the cross-linked sodium alginate to the polyethylene glycol in the anti-pollution layer is 18: 1. 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 its water flux (Q) 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 solution of polyethylene glycol was 120min, and reverse osmosis membrane N7 comprising a support layer, a separation layer and a fouling resistant layer laminated in this order, wherein the separation layer had a thickness of 0.15 micron, the fouling resistant layer had a thickness of 0.26 micron, the separation layer was formed of crosslinked polyamide, the fouling resistant layer was formed of crosslinked sodium alginate through complexation with polyethylene glycol, and the weight ratio of crosslinked sodium alginate to polyethylene glycol in the fouling resistant layer was 12: 1. The obtained reverse osmosis membrane N7 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 its water flux (Q) 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
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 (55)
1. The reverse osmosis membrane is characterized by comprising a supporting layer, a separation layer and a pollution-resistant layer which are sequentially stacked, wherein the separation layer is formed by crosslinked polyamide, crosslinked alginate is formed on the separation layer, and then the crosslinked alginate and polyethylene glycol form the pollution-resistant layer through complexation;
the weight ratio of the content of the cross-linked alginate to the content of the polyethylene glycol in the pollution-resistant layer is (10-40): 1, the number average molecular weight of the polyethylene glycol is 1000-10 ten thousand.
2. A reverse osmosis membrane according to claim 1 wherein said fouling resistant layer is formed by first forming a cross-linked alginate and then soaking in an aqueous solution of polyethylene glycol.
3. A reverse osmosis membrane according to claim 1 wherein the support layer has a thickness of 90-150 microns; the thickness of the separation layer is 0.05-0.5 micron; the thickness of the pollution-resistant layer is 0.01-0.5 micrometer.
4. A reverse osmosis membrane according to claim 3 wherein the support layer has a thickness of 100 and 120 microns; the thickness of the separation layer is 0.1-0.3 microns; the thickness of the pollution-resistant layer is 0.05-0.25 micrometer.
5. A reverse osmosis membrane according to any one of claims 1-4 wherein in the separation layer the crosslinked polyamide is obtained by interfacial polymerization of a polyamine with a polyacyl chloride.
6. A reverse osmosis membrane according to claim 5 wherein the weight ratio of polyamine to polyacyl chloride is (1-100) to 1.
7. A reverse osmosis membrane according to claim 5 wherein said polyamine is at least one of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, piperazine, and trimesamine and said poly acid chloride is at least one of trimesoyl chloride, isophthaloyl chloride, and terephthaloyl chloride.
8. A reverse osmosis membrane according to claim 5 wherein the conditions for the interfacial polymerization comprise a polymerization temperature of 40 to 150 ℃ and a polymerization time of 0.5 to 20 min.
9. A reverse osmosis membrane according to claim 8 wherein the conditions for the interfacial polymerization comprise a polymerization temperature of 50-120 ℃ and a polymerization time of 1-10 min.
10. A reverse osmosis membrane according to any one of claims 1-4 wherein in the fouling resistant layer the cross-linked alginate is obtained by a cross-linking reaction of an alginate and a cross-linking agent in the presence of a catalyst and a solvent.
11. A reverse osmosis membrane according to claim 10 wherein said alginate has a number average molecular weight of 10000-.
12. A reverse osmosis membrane according to claim 11 wherein said alginate has a number average molecular weight of 20000-.
13. A reverse osmosis membrane according to claim 12, wherein the alginate has a number average molecular weight of 30000-60000.
14. A reverse osmosis membrane according to claim 10 wherein said alginate is potassium alginate and/or sodium alginate.
15. A reverse osmosis membrane according to claim 10 wherein said cross-linking agent is an aldehyde compound.
16. A reverse osmosis membrane according to claim 15 wherein said cross-linking agent is at least one of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, glyoxal, malondialdehyde, succindialdehyde, and glutaraldehyde.
17. A reverse osmosis membrane according to claim 10 wherein said catalyst is an acid.
18. A reverse osmosis membrane according to claim 17 wherein said catalyst is at least one of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, formic acid and nitric acid.
19. A reverse osmosis membrane according to claim 10 wherein said alginate is present in an amount of 0.1 to 50 parts by weight, said cross-linking agent is present in an amount of 0.001 to 50 parts by weight, said catalyst is an acid and is present in an amount such that the pH of the cross-linked system is 1 to 5, relative to 100 parts by weight of said solvent.
20. A reverse osmosis membrane according to claim 10 wherein the conditions for said cross-linking reaction comprise a temperature of 40 ℃ to 150 ℃ for a time of 1min to 1 h.
21. A reverse osmosis membrane according to claim 20 wherein the conditions for said cross-linking reaction comprise a temperature of 50-120 ℃ for a time of 2-30 min.
22. A reverse osmosis membrane according to any one of claims 1 to 4 wherein said polyethylene glycol has a number average molecular weight in the range 1000 to 5 million in said fouling resistant layer.
23. A reverse osmosis membrane according to claim 22 wherein said polyethylene glycol has a number average molecular weight in the range of 5000 to 2 million in said fouling resistant layer.
24. A reverse osmosis membrane according to any one of claims 1-4 wherein the support layer is made from at least one of polyester, polyacrylonitrile, polyvinylidene fluoride, phenolphthalein-type non-sulfonated polyarylethersulfones, polyethersulfones and polysulfones.
25. A preparation method of a reverse osmosis membrane comprises the steps of forming a separation layer on a supporting layer by adopting cross-linked polyamide, forming cross-linked alginate on the separation layer, and forming a pollution-resistant layer by complexing with polyethylene glycol;
the weight ratio of the content of the cross-linked alginate to the content of the polyethylene glycol in the pollution-resistant layer is (10-40): 1, the number average molecular weight of the polyethylene glycol is 1000-10 ten thousand.
26. The method of claim 25, wherein said anti-fouling layer is formed by first forming a cross-linked alginate and then forming an anti-fouling layer by soaking in an aqueous solution of polyethylene glycol.
27. The method of claim 25, wherein forming the separation layer comprises adsorbing a polyamine and a polyacyl chloride onto the support layer followed by interfacial polymerization.
28. The method of claim 27, wherein the weight ratio of polyamine to polyacyl chloride is (1-100): 1.
29. The method of claim 27, 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.
30. The process of claim 27, wherein the interfacial polymerization conditions comprise a polymerization temperature of 40 to 150 ℃ and a polymerization time of 0.5 to 20 min.
31. The process of claim 30, wherein the interfacial polymerization conditions comprise a polymerization temperature of 50-120 ℃ and a polymerization time of 1-10 min.
32. The method according to claim 25, wherein the contamination-resistant layer is formed by dissolving alginate, a cross-linking agent and a catalyst in a solvent to prepare a coating liquid, then coating the coating liquid on the separation layer, followed by heating to allow the alginate to undergo a cross-linking reaction, and then soaking the resulting membrane in a solution containing polyethylene glycol;
the soaking condition comprises 20-100 deg.C and 1-360 min.
33. The method of claim 32, wherein the soaking conditions include a temperature of 40-100 ℃ and a time of 5-240 min.
34. The method of claim 33, wherein the soaking conditions include a temperature of 50-90 ℃ and a time of 30-120 min.
35. The method as claimed in claim 32, wherein the alginate has a number average molecular weight of 10000-.
36. The method as claimed in claim 35, wherein the alginate has a number average molecular weight of 20000-.
37. The method as claimed in claim 36, wherein the alginate has a number average molecular weight of 30000-60000.
38. The method of claim 32, wherein said alginate is potassium alginate and/or sodium alginate.
39. The method of claim 32, wherein the cross-linking agent is an aldehyde compound.
40. The method of claim 39, wherein the cross-linking agent is at least one of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, glyoxal, malondialdehyde, succindialdehyde, and glutaraldehyde.
41. The method of claim 32, wherein the catalyst is an acid.
42. The method of claim 41, wherein the catalyst is at least one of sulfuric acid, hydrochloric acid, acetic acid, phosphoric acid, formic acid, and nitric acid.
43. The method as claimed in claim 32, wherein, in the coating liquid, the alginate is used in an amount of 0.1-50 parts by weight, the cross-linking agent is used in an amount of 0.001-50 parts by weight, the catalyst is an acid and is used in an amount such that the pH of the cross-linked system is 1-5, relative to 100 parts by weight of the solvent.
44. The method of claim 32, wherein the conditions of the crosslinking reaction include a temperature of 40-150 ℃ and a time of 1min-1 h.
45. The method of claim 44, wherein the conditions of the crosslinking reaction comprise a temperature of 50-120 ℃ for a time of 2-30 min.
46. The method of claim 32, wherein the polyethylene glycol has a number average molecular weight of 1000 to 5 ten thousand.
47. The method of claim 46, wherein the polyethylene glycol has a number average molecular weight of 5000-2 ten thousand.
48. The method of claim 32, wherein the concentration of the solution comprising polyethylene glycol is 1-50% by weight.
49. The method of claim 48, wherein the concentration of the solution comprising polyethylene glycol is 2-20% by weight.
50. The method of claim 49, wherein the concentration of the solution comprising polyethylene glycol is 10-20% by weight.
51. The method of any of claims 25-50, wherein the support layer is made of at least one of polyester, polyacrylonitrile, polyvinylidene fluoride, phenolphthalein-type non-sulfonated polyarylethersulfones, polyethersulfones, and polysulfones.
52. The method of any of claims 25-50, wherein the support layer has a thickness of 90-150 microns; the thickness of the separation layer is 0.05-0.5 micron; the thickness of the pollution-resistant layer is 0.01-0.5 micrometer.
53. The method of claim 52 wherein the support layer has a thickness of 100 and 120 microns; the thickness of the separation layer is 0.1-0.3 microns; the thickness of the pollution-resistant layer is 0.05-0.25 micrometer.
54. A reverse osmosis membrane produced by the method of any one of claims 25-53.
55. Use of a reverse osmosis membrane according to any one of claims 1-24 and 54 in the field of water treatment.
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| CN102921314A (en) * | 2012-10-25 | 2013-02-13 | 贵阳时代沃顿科技有限公司 | Compound reverse osmosis membrane with interpenetrating network desalting layer and preparation method of membrane |
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| CN102921314A (en) * | 2012-10-25 | 2013-02-13 | 贵阳时代沃顿科技有限公司 | Compound reverse osmosis membrane with interpenetrating network desalting layer and preparation method of membrane |
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