Formulation of antiscalant system solution and method of forming on reverse osmosis membrane using the same

Abstract

The application provides a formula of a scale inhibitor system solution and a method for forming the scale inhibitor system solution on a reverse osmosis membrane, the formula of the scale inhibitor system solution is composed of polyaspartic acid, a crosslinking agent, a buffer, a catalyst and pure water, and the catalyst is 4-(4, 6-dimethoxytriazin-2-yl)-4-methyl morpholine hydrochloride (DMTMM). The scale inhibitor system solution capable of forming a scale inhibitor layer in the application uses DMTMM as a catalyst, thereby greatly accelerating the crosslinking reaction speed of polyaspartic acid on the surface of a desalination layer, and forming a stable connection between the scale inhibitor layer and the desalination layer during the reaction process. The formed scale inhibitor layer can be continuously and stably connected to the desalination layer, thereby maintaining the scale inhibition effect.

Description

TECHNICAL FIELD

[0001] This application is a divisional application of the application with the application number 2025103439659, the application date of March 22, 2025, and the invention name of a production method of a composite scale inhibition reverse osmosis membrane.

[0002] The present application relates to the technical field of reverse osmosis membrane production, in particular to a scale inhibitor system solution formula and a method of forming the same on a reverse osmosis membrane. BACKGROUND

[0003] Currently, in water treatment technology, reverse osmosis membrane technology is widely used in fields such as purified water, industrial water treatment, ultrapure water preparation, and seawater desalination. To ensure the long-term stable operation of reverse osmosis membranes, scale inhibitors are commonly used to prevent scale formation on the surface of reverse osmosis membranes, which can lead to a decrease in reverse osmosis effect. The significance of scale inhibitors mainly lies in the following aspects:

[0004] 1. Inhibit crystallization and scale formation: Scale inhibitors can react with hardness ions such as calcium and magnesium in water and other easily scaling ions to form stable soluble complexes, thereby preventing these ions from depositing on the surface of reverse osmosis membranes as hard scale;

[0005] 2. Disperse small crystals: For small crystals that have already formed, scale inhibitors can adsorb on their surfaces, changing the growth pattern and morphology of the crystals, making them less likely to aggregate and grow, thereby preventing them from adhering and accumulating on the surface of reverse osmosis membranes;

[0006] 3. Improve water production and quality: Effective use of scale inhibitors can significantly reduce scale formation on the membrane surface, maintain good permeability of the membrane element, and thus improve the water production and quality of the reverse osmosis system;

[0007] 4. Prolong the service life of the membrane: Scale inhibitors can reduce membrane damage caused by scale formation, thereby prolonging the service life of reverse osmosis membranes;

[0008] 5. Energy saving: Due to the reduction in cleaning frequency and membrane replacement frequency caused by scale formation, the use of scale inhibitors reduces operating costs and energy consumption;

[0009] 6. Protect equipment: Scale inhibitors can prevent equipment damage caused by scale formation, such as blockage or corrosion of pressure vessels, pipelines, and reverse osmosis membrane components, ensuring long-term stable operation of the entire reverse osmosis water treatment system.

[0010] Common types of scale inhibitors mainly include the following categories:

[0011] 1. Organic phosphonate scale inhibitors: Commonly used are hydroxyethylenediphosphonic acid (HEDP), amino trimethylene phosphonic acid (ATMP), etc. These scale inhibitors can form stable complexes with hardness ions such as calcium and magnesium in water, preventing the formation of scale on the membrane surface.

[0012] 2. Polycarboxylic acid scale inhibitors: Such as polyacrylic acid (PAA), polyaspartic acid (PASP), etc. These scale inhibitors prevent the deposition of hardness ions in water on the membrane surface through dispersion.

[0013] 3. Inorganic salt scale inhibitors: Such as silicates, polyphosphates (including sodium tripolyphosphate, sodium hexametaphosphate, etc.). Silicates can form a protective film on the metal surface, reducing corrosion; polyphosphates react with calcium and magnesium ions in water to prevent scale crystal growth.

[0014] 4. Organic polyphosphonic acid scale inhibitors: Such as ATMP (amino trimethylene phosphonic acid), HEDP (hydroxy ethylene diphosphonic acid), etc. These agents have good chelating ability and can effectively complex metal ions, preventing them from combining with anions to form insoluble precipitates.

[0015] However, the use of scale inhibitors in reverse osmosis membranes has the following disadvantages: 1. Increased cost: The preparation of scale inhibitors requires advanced chemical formulations and processes, resulting in relatively high prices and increased water treatment costs. 2. Risk of excessive use: If the amount of scale inhibitor is too high, it can change the chemical composition and pH of the water, affecting the treatment effect of the reverse osmosis system and shortening its service life. 3. Potential environmental impact: Certain chemicals in scale inhibitors may pose a slight risk to human health and the environment (especially those containing phosphorus and polyacrylic acid).

[0016] In summary, in the water treatment process using reverse osmosis membranes, the use of appropriate scale inhibitors is essential, but traditional production processes have many shortcomings (economic efficiency and water quality matching). Therefore, an integrated composite scale-inhibiting reverse osmosis water purification membrane has great practical value and application market.

[0017] Chinese invention patent application CN114162980B discloses a reverse osmosis membrane scale inhibitor and its preparation method. The reverse osmosis membrane scale inhibitor includes 20-30 parts of polyaspartic acid, 20-30 parts of tannin, 10-20 parts of alkyl epoxy carboxylate, 8-12 parts of non-oxidizing bactericide, and 100 parts of deionized water. The polyaspartic acid is a sulfonic acid-modified polyaspartic acid. The preparation method optimizes the addition order of each component and the pH value of the scale inhibitor, ensuring the effective and uniform dispersion of each component and improving the stability of each component. However, this patent scale inhibitor and reverse osmosis membrane are manufactured separately, which is less economical and cannot be applied in more fields.

[0018] A Chinese invention patent application with the publication number CN113908705A discloses a high-flux inorganic scale-resistant medium desalination nanofiltration membrane and a preparation method thereof, and specifically relates to a high-flux inorganic scale-resistant medium desalination nanofiltration membrane and a preparation method thereof. The polymer-based film is treated by using an aqueous amine solution, an oil phase solution and a dimethylformamide solution. The special component ratio in the aqueous amine solution and the oil phase solution enables the prepared high-flux inorganic scale-resistant medium desalination nanofiltration membrane to have a higher water production rate than the traditional nanofiltration membrane and the reverse osmosis membrane under the same operating pressure, can desalinate moderately, and improves the inorganic scale resistance of the membrane. However, the medicament used in the method is an ether, and the small equivalent cannot maintain stability for a long time under a large flux, and does not have long-term stable use value. SUMMARY

[0019] The technical problem to be solved by the embodiments of the present application is to provide a production method of a composite scale-inhibiting reverse osmosis water purification membrane, which solves the problem that the existing reverse osmosis membrane needs to add a scale inhibitor separately in the water treatment process.

[0020] To solve the above technical problems, the present application provides a production method of a composite scale-inhibiting reverse osmosis water purification membrane, comprising:

[0021] Step one, providing a non-woven fabric support substrate;

[0022] Step two, providing a high molecular polymer solution, and making the high molecular polymer in the high molecular polymer solution combine with the surface of the non-woven fabric support substrate to form a polymer porous support base layer through liquid-solid phase conversion on the non-woven fabric support substrate;

[0023] Step three, preparing a desalination layer on the polymer porous support base layer;

[0024] Step four, providing a scale inhibitor system solution, coating the scale inhibitor system solution on the surface of the desalination layer, and combining with the surface of the desalination layer to form a scale inhibition layer after dehydration.

[0025] The non-woven fabric support substrate adopts a wet process polyester substrate.

[0026] The high molecular polymer solution is composed of a high molecular polymer and a solvent, and the components thereof include, calculated according to the mass percentage concentration, 15-20% of the high molecular polymer and 80-85% of the solvent; the high molecular polymer is polysulfone, and the solvent is dimethylformamide (DMF).

[0027] The step of configuring the high molecular polymer mixed solution includes: adding the high molecular polymer into the solvent according to the mass ratio, stirring at 100-140°C for 6-12 hours until the high molecular polymer is completely dissolved to form a primary solution; and then vacuumizing the primary solution and keeping for 10-12 hours to obtain the high molecular polymer mixed solution.

[0028] The step two further comprises soaking the prepared polymer porous support base layer in deionized water, dissolving the solvent in the deionized water and separating the polymer porous support base layer, forming a mixed waste liquid of deionized water and solvent, and then recycling and utilizing the mixed waste liquid.

[0029] The recycling and utilization of the mixed waste liquid comprises:

[0030] Step A: concentrating the mixed waste liquid through a reverse osmosis membrane to form a concentrated liquid with a higher solvent concentration, and separating the deionized water;

[0031] Step B: obtaining high-purity DMF and deionized water by distillation separation of the concentrated liquid obtained in step A;

[0032] Step C: mixing the high-purity DMF obtained in step B with the high-molecular polymer, heating, and vacuuming to prepare a high-molecular polymer solution; at the same time, using the deionized water obtained in steps A and B to soak the polymer porous support base layer, thereby realizing full recycling of DMF and deionized water.

[0033] The step three of preparing a desalination layer on the polymer porous support base layer comprises:

[0034] The non-woven fabric support substrate with the polymer porous support base layer on the surface obtained in step two is first soaked in an aqueous amine solution, then in an oil phase solution, and then subjected to heat treatment, pure water cleaning, glycerol soaking and drying.

[0035] The heat treatment refers to heating the polymer porous support base layer to 60-100℃, and then cooling to room temperature.

[0036] Specifically, the non-woven fabric support substrate with the polymer porous support base layer on the surface is soaked in an aqueous amine solution for 0.3-5 min, and the excess aqueous phase is squeezed out; then an oil phase solution is coated on the polymer porous support base layer for 0.3-2 min for interfacial reaction, and then soaked in lye for 0.5-2 min for alkaline washing, immersed in hot water for 10-30 min for setting, and glycerol moisturizing for 0.5-2 min, to form a desalination layer.

[0037] The aqueous amine solution comprises, according to mass percentage concentration: m-phenylenediamine 1.5-4.5%, triethylamine hydrochloride 1-5%, sodium hydroxide 0.01-0.05%, and sodium bisulfite 0.01-0.2%.

[0038] The oil phase solution comprises, according to mass percentage concentration: trimesoyl chloride 0.1-0.28%, tripropyl phosphate 0.6-1%, and organic solvent ISOPAR M as the balance.

[0039] The scale inhibitor system solution is composed of polyaspartic acid, hexamethylene diamine / pentamethylene diamine, potassium dihydrogen phosphate / tripotassium phosphate, catalyst and pure water, and the composition is calculated according to mass percentage, and the composition is as follows: polyaspartic acid 0.1-2%, hexamethylene diamine / pentamethylene diamine 0.1-1%, potassium dihydrogen phosphate / tripotassium phosphate 0.01-0.1%, 4-(4,6-dimethoxytriazin-2-yl)-4-methyl morpholine hydrochloride (DMTMM) 0.1%-1%, and the balance is pure water.

[0040] The polyaspartic acid is used as a film forming material, the hexamethylene diamine / pentamethylene diamine is used as a crosslinking agent, and the potassium dihydrogen phosphate / tripotassium phosphate is used as a buffer.

[0041] The coating thickness of the scale inhibitor system solution is 15-80 um; after coating is completed, drying is performed at 60-100 DEG C for 1-5 min, so that the scale inhibitor system solution forms a scale inhibition layer on the surface of the desalination layer, and the reaction formula is as follows:

[0042]

[0043] The application further provides a composite scale inhibition reverse osmosis water purification membrane, which comprises a non-woven fabric support base material, a polymer porous support base layer, a desalination layer and a scale inhibition layer, wherein the polymer porous support base layer is formed on the surface of the non-woven fabric support base material, the desalination layer is formed on the surface of the polymer porous support base layer, and the scale inhibition layer is formed on the surface of the desalination layer.

[0044] The non-woven fabric support base material adopts a wet process polyester base material.

[0045] The polymer porous support base layer is formed by combining high molecular polymers on the surface of the non-woven fabric support base material through liquid-solid phase conversion of a high molecular polymer mixed solution on the non-woven fabric support base material.

[0046] The high molecular polymer solution is composed of high molecular polymers and a solvent, and the components include, according to mass percentage concentration, 15-20% high molecular polymers and 80-85% solvent; the high molecular polymers are polysulfone, and the solvent is dimethylformamide.

[0047] The scale inhibition layer is formed by coating a scale inhibitor system solution on the surface of the desalination layer, and after dehydration by heating, the polyaspartic acid and the hexamethylene diamine / pentamethylene diamine are crosslinked under the action of the catalyst, so that the scale inhibition layer is formed on the surface of the desalination layer.

[0048] Compared with the conventional reverse osmosis membrane, the application adds the scale inhibition layer, so that a scale inhibitor does not need to be added in the water treatment process; compared with the slow forming speed of the conventional scale inhibitor, the application uses DMTMM as a catalyst to quickly react the polyaspartic acid with the crosslinking agent, forms a stable structure on the surface of the desalination layer, and forms a stable structure.

[0049] The method for producing a composite scale-inhibiting reverse osmosis water purification membrane provided by this invention forms a scale-inhibiting layer on the surface of the desalination layer of the reverse osmosis membrane. This method offers greater economic efficiency in the water purification field and maximizes space utilization for home users. Compared to other similar technologies that add insufficient scale inhibitors to the desalination or polysulfone layers, which are prone to loss, this method ensures continuous system stability. This invention employs a quantitative coating of cross-linked grafts to form the scale-inhibiting layer on the desalination layer, achieving effective scale inhibition (-CONH-, preventing aggregation, sedimentation, and dissolution through complexation) and long-term operational stability (due to the condensation grafting of amino groups with the carboxyl groups of the third polyamide membrane, as well as the electrostatic adsorption effect of residual end groups).

[0050] In this invention, a polyamide reverse osmosis membrane is first formed through solid-liquid phase transformation and interfacial polymerization. Then, a mixed solution containing polyaspartic acid, hexamethylenediamine / pentanediamine, buffer, and catalyst (DMTMM) is coated onto the desalination layer. Under weakly alkaline, high-temperature thermal crosslinking reaction, an integrated composite scale-inhibiting reverse osmosis water purification membrane scale inhibitor layer is formed. The crosslinked polyaspartic acid molecule contains alternating polyamide bonds, which can complex calcium and magnesium ions in the operating water, effectively reducing flux reduction and clogging caused by ion precipitation. Through the electrostatic interaction of the carboxyl and amino groups on the polyamide bonds, the attractive force between particles is reduced, preventing aggregation and deposition. The molecule exists in a chain structure, which can adsorb particles deposited in the water, inhibit their growth, and dissolve together in the water after adsorption. This greatly delays the degradation of membrane performance and improves long-term operational stability.

[0051] This invention involves coating a polyester substrate with a polymer solution composed of polysulfone and DMF using a wet process, obtaining a porous polymer support layer formed of polysulfone through a solid-liquid phase separation method, and then cleaning and heat-setting the substrate.

[0052] Then, through the interfacial crosslinking reaction of aqueous phase and oil phase impregnation, followed by heat treatment, pure water washing, heat setting, and humectant protection, a desalination layer formed of polyamide is obtained.

[0053] A scale inhibitor system solution with scale inhibition function is quantitatively coated on the front side of the desalination layer and crosslinked by catalytic heat treatment under weak alkaline and high temperature conditions to form a composite scale-inhibiting reverse osmosis water purification membrane with surface scale inhibition function.

[0054] This invention also provides a formulation for a scale inhibitor system solution capable of forming a scale inhibitor layer, solving the problem that existing reverse osmosis membranes cannot form a stable scale inhibitor layer on the surface of the desalination layer.

[0055] The formulation of the scale inhibitor system solution capable of forming a scale inhibitor layer provided by the present invention is composed of polyaspartic acid, crosslinking agent, buffer, catalyst and pure water, wherein the catalyst is 4-(4,6-dimethoxytriazine-2-yl)-4-methylmorpholine hydrochloride (DMTMM).

[0056] The mass percentage of the polyaspartic acid is 0.1-2%;

[0057] The mass percentage of the catalyst is 0.1-1%;

[0058] The cross-linking agent is hexanediamine or pentanediamine, and the mass percentage is 0.1-1%;

[0059] The buffer is potassium dihydrogen phosphate or tripotassium phosphate, and the mass percentage is 0.1-1%;

[0060] The pure water is the rest.

[0061] The application also provides a method for forming a reverse osmosis membrane using a scale inhibitor system solution, comprising:

[0062] Providing a reverse osmosis membrane carrier with a desalination layer surface;

[0063] Coating the scale inhibitor system solution on the desalination layer surface and heating to form a scale inhibition layer on the surface of the desalination layer.

[0064] The coating thickness is 15-80um, the heating temperature is 60-100℃, and the heating lasts for 15min.

[0065] The scale inhibitor system solution forms a scale inhibition layer on the surface of the desalination layer, and the reaction formula is:

[0066]

[0067] The heating is performed in an oven.

[0068] The method for providing a reverse osmosis membrane carrier with a desalination layer surface comprises:

[0069] Step one, providing a non-woven fabric support substrate;

[0070] Step two, providing a high molecular polymer solution, and combining the high molecular polymer in the high molecular polymer solution on the surface of the non-woven fabric support substrate by liquid-solid phase conversion to form a polymer porous support base layer;

[0071] Step three, preparing a desalination layer on the polymer porous support base layer.

[0072] The application also provides a reverse osmosis membrane prepared by the method for forming a reverse osmosis membrane using a scale inhibitor system solution.

[0073] The scale inhibitor system solution capable of forming a scale inhibition layer of the present application uses DMTMM as a catalyst, thereby greatly accelerating the cross-linking reaction speed of polyaspartic acid on the surface of the desalination layer, and forming a stable connection between the scale inhibition layer and the desalination layer during the reaction process. The formed scale inhibition layer can be continuously and stably connected to the desalination layer, thereby maintaining the scale inhibition effect.

[0074] Compared with the traditional reverse osmosis membrane, the present application increases the scale inhibition layer, thereby not needing to add a scale inhibitor in the water treatment process; compared with the slow forming speed of the traditional scale inhibitor, the present application uses DMTMM as a catalyst to rapidly react polyaspartic acid with a cross-linking agent, forms on the surface of the desalination layer, and forms a stable structure. BRIEF DESCRIPTION OF DRAWINGS

[0075] Figure 1 It is a whole flow structure schematic diagram in the embodiment of the present application.

[0076] In the figure:

[0077] 1-nonwoven fabric support base material; 2-polymer porous support base layer; 3-desalination layer; 4-scale inhibition layer. DETAILED DESCRIPTION

[0078] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below in combination with the drawings. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0079] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0080] The present application provides a production method of a composite scale inhibition reverse osmosis water purification membrane, comprising:

[0081] Step one, providing a non-woven fabric support base material; the non-woven fabric support base material uses a wet process polyester base material.

[0082] Step two, provide a high molecular polymer solution, and make the high molecular polymer solution on the non-woven fabric support substrate through liquid-solid phase transformation to make the high molecular polymer in the high molecular polymer solution combined on the surface of the non-woven fabric support substrate to form a polymer porous support base layer; the high molecular polymer solution is composed of high molecular polymer and solvent, and the components include: high molecular polymer 15-20%, solvent 80-85% according to the mass percentage concentration; the high molecular polymer is polysulfone, and the solvent is dimethylformamide (DMF). The step of configuring the high molecular polymer mixed solution includes: adding the high molecular polymer into the solvent according to the mass ratio, stirring at 100-140℃ for 6-12 hours until the high molecular polymer is completely dissolved to form a primary solution; then vacuumizing the primary solution and keeping for 10-12 hours to obtain the high molecular polymer mixed solution. In step two, generally, the higher the temperature, the less the stirring time, for example, the stirring temperature can be 100℃, 110℃, 120℃, 130℃, 140℃, and the corresponding stirring time can be 12 hours, 11 hours, 10 hours, 9 hours, 8 hours, 7 hours, 6 hours; the vacuum keeping time can be selected as 10 hours, 11 hours or 12 hours according to the implementation.

[0083] Step three, preparing a desalination layer on the polymer porous support base layer, including:

[0084] The non-woven fabric support substrate with the polymer porous support base layer on the surface obtained in step two is first treated with aqueous amine solution, oil phase solution, and alkali washing, and then washed with pure water, heat treated, and washed with pure water again, and then soaked in moisturizing agent glycerol and dried to obtain the product.

[0085] Specifically, the non-woven fabric support substrate with the polymer porous support base layer on the surface is soaked in the aqueous amine solution for 0.3-5min, and the excess aqueous phase is squeezed out; then the oil phase solution is coated on the polymer porous support base layer for 0.3-2min for interfacial reaction, and then soaked in alkali solution for alkali washing for 0.5-2min, soaked in hot water for 10-30min for shaping, and soaked in glycerol for 0.5-2min for moisturizing to form the desalination layer.

[0086] The aqueous amine solution contains: m-phenylenediamine 1.5-4.5%, triethylamine hydrochloride 1-5%, sodium hydroxide 0.01-0.05%, and sodium bisulfite 0.01-0.2% according to the mass percentage concentration. The value of m-phenylenediamine can be 1.5%, 1%, 2.5%, 3%, 3.5%, 4%, or 4.5%; the value of triethylamine hydrochloride can be 1%, 2%, 3%, 4%, or 5%; the value of sodium hydroxide can be 0.01%, 0.02%, 0.03%, 0.04%, or 0.05%; and the value of sodium bisulfite can be 0.01%, 0.05%, 0.1%, 0.15%, or 0.2%.

[0087] The oil phase solution comprises, in terms of mass percentage concentration: 0.1-0.28% of trimesoyl chloride, 0.6-1% of tripropyl phosphate, and the rest of ISOPAR M organic solvent. The value of trimesoyl chloride can be 0.1%, 0.15%, 0.18%, 0.2%, 0.24%, or 0.28%; the value of tripropyl phosphate can be 0.6%, 0.7%, 0.8%, 0.9%, or 1%.

[0088] The temperature of the heat treatment can be 60-100℃; the duration of the heat treatment can be 1-30 min. The above-mentioned heat curing temperature and duration are more conducive to further increasing the cross-linking density of the coating, and are more conducive to further enhancing the stability and bonding force between the coatings.

[0089] Step four: providing a scale inhibitor system solution, coating the scale inhibitor system solution on the surface of the desalination layer, and combining to form a scale inhibition layer on the surface of the desalination layer after dehydration.

[0090] The scale inhibitor system solution is composed of polyaspartic acid, hexamethylene diamine / pentamethylene diamine, potassium dihydrogen phosphate / tripotassium phosphate, a catalyst, and pure water, and has a composition calculated in terms of mass percentage as follows: 0.1-2% of polyaspartic acid, 0.1-1% of hexamethylene diamine / pentamethylene diamine, 0.01-0.1% of potassium dihydrogen phosphate / tripotassium phosphate, 0.1-1% of 4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholinium chloride (DMTMM), and the rest of pure water. The value of polyaspartic acid can be 0.1%, 1.5%, or 2%; the value of hexamethylene diamine / pentamethylene diamine can be 0.1%, 0.4%, 0.6%, 0.8%, or 1%; the value of potassium dihydrogen phosphate / tripotassium phosphate can be 0.01%, 0.05%, 0.08%, or 0.1%; and the value of 4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholinium chloride (DMTMM) can be 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, or 1%.

[0091] The coating thickness of the scale inhibitor system solution is 15-80 um; and after the coating is completed, the scale inhibitor system solution is dried in an environment at 60-100℃ for 1-5 min, so as to form a scale inhibition layer on the surface of the polymer porous support base layer.

[0092] Step two further comprises immersing the prepared polymer porous support base layer in deionized water, so that the solvent is dissolved in the deionized water and separated from the polymer porous support base layer to form a mixed waste liquid of deionized water and the solvent, and then the mixed waste liquid is recycled and utilized.

[0093] The recycling and utilization of the mixed waste liquid comprises:

[0094] Step A, the mixed waste liquid is concentrated by reverse osmosis membrane to form a concentrated liquid with higher solvent concentration, and the deionized water is separated out;

[0095] Step B, the concentrated liquid obtained in step A is separated by distillation to obtain high-purity DMF and deionized water;

[0096] Step C, the high-purity DMF obtained in step B and the high-molecular polymer are mixed, heated, and vacuumed to prepare a high-molecular polymer solution; at the same time, the deionized water obtained in steps A and B is used to soak the polymer porous support base layer, so as to realize the full recycling of DMF and deionized water.

[0097] The recycling and utilization method of the mixed waste liquid can ensure that all DMF and deionized water can be recycled in the production process, avoiding the discharge of DMF wastewater and pollution of the environment.

[0098] In a preferred embodiment, the preparation method of the application comprises the following steps:

[0099] 15-20% polysulfone is dissolved in dimethylformamide (DMF) solvent at 120°C, and is coated on a 100-micron-thick non-woven fabric support substrate (polyester PET non-woven fabric) at a thickness of 40 microns to form a solid porous support polysulfone film (polymer porous support base layer) by liquid-solid phase separation. After cleaning and heat setting, an aqueous amine solution (m-phenylenediamine 1.5-4.5%, triethylamine hydrochloride 1-5%, sodium hydroxide 0.01-0.05%, sodium bisulfite 0.01-0.2%) and an oil-phase solvent (trimesoyl chloride 0.1-0.28%, tripropyl phosphate 0.6-1%, organic solvent ISOPAR M in residual amount) are respectively immersed and coated on the surface of the desalination layer to perform interfacial polymerization, and then treated in a heat oven for 3 min, cleaned in a water tank for 5 min, and immersed in a humectant to obtain a 0.2-0.4-micron polyamide desalination layer. Then, a scale inhibitor system solution (polyaspartic acid 0.1-2%, hexanediamine / pentanediamine 0.1-1%, buffer potassium dihydrogen phosphate / tripotassium phosphate 0.01-0.1%, catalyst 4-(4,6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride (DMTMM) 0.1%-1%, and pure water in residual amount) is coated on the surface of the desalination layer, and is crosslinked in a weak base and a 70°C oven for 3 min to form a scale inhibition layer with a thickness of 1-4 microns. The crosslinked polyaspartic acid molecular structure contains alternatingly arranged polyamide bonds, which can form a complex with calcium and magnesium ions in the running water body, effectively reducing the ion precipitation and the resulting flux reduction and blockage. Furthermore, through the charges of the carboxyl and amino groups on the polyamide bond, the attraction between particles is reduced through electrostatic interaction, preventing aggregation and deposition. At the same time, the molecule exists in a chain state structure, which can adsorb the deposited particles in water, inhibit their growth, and dissolve together after adsorption, thereby forming an integrated composite scale inhibition and reverse osmosis water purification membrane.

[0100] Example 1 (blank example)

[0101] In this embodiment 1, a preparation method and application of an integrated composite scale inhibition reverse osmosis water purification membrane are provided, including the following steps:

[0102] A non-woven fabric support substrate is provided: thickness 100 μm, weight 75 g / m 3 , air permeability 3 cc / c㎡ / sec;

[0103] A polymer porous support base layer is prepared: 17% polysulfone is dissolved in dimethylformamide (DMF) solvent under high-speed stirring for 8 h at 120°C, vacuum standing under negative pressure for 10 h, and coating 40 microns on a 100-micron polyester PET non-woven fabric, forming a solid porous support polysulfone base film by liquid-solid phase separation, and cleaning and quenching (heating to 80°C and cooling to room temperature);

[0104] An aqueous amine solution is configured: 3% m-phenylenediamine, 3% triethylamine hydrochloride, 0.02% sodium hydroxide, 0.05% sodium bisulfite, and pure water are configured into an aqueous solution;

[0105] An oil phase solution is configured: 0.2% trimesoyl chloride, 0.8% tripropyl phosphate, and ISOPAR M as an organic solvent are configured into an oil phase solution;

[0106] A desalination layer (interfacial polymerization) is prepared: the polymer porous support base layer is immersed in the aqueous amine solution for 1 min, then removed, and the excess amine solution is removed with nitrogen or a rubber roller, and then immersed in the oil phase solution for 1 min and removed;

[0107] Oven heat treatment: the product after interfacial polymerization is sent to an oven for heat treatment, wherein the heat treatment temperature is 70°C, and the heat treatment time is 5 min, to increase the coating cross-linking density and enhance the coating stability and bonding force;

[0108] Water tank cleaning treatment: the product after heat treatment is cleaned with hot pure water for 5 min and immersed in a moisturizing agent for 2 min.

[0109] Heat drying treatment: drying in a 70°C oven for 3 min to form a conventional reverse osmosis membrane.

[0110] Example 2 (preferred example)

[0111] The difference between this embodiment 2 and embodiment 1 is that after the heat drying treatment of embodiment 1, the antifouling agent system solution is coated on the reverse osmosis membrane after S7 cleaning, and is crosslinked to form an antifouling layer with 2 microns under 70℃ oven for 3 minutes; the antifouling agent system solution is composed of the following components: polyaspartic acid 0.3%, crosslinking agent hexanediamine 0.1%, buffer potassium dihydrogen phosphate / potassium phosphate 0.02%, catalyst 4-(4, 6-dimethoxytriazin-2-yl)-4-methyl morpholine hydrochloride (DMTMM) 0.1%-1%, and pure water as the balance.

[0112] Embodiment 3

[0113] The difference between this embodiment 3 and embodiment 2 is that 0.1% pentanediamine is used instead of hexanediamine, so that the heat treatment crosslinking obtains an antifouling layer with 2 microns;

[0114] The remaining steps are the same as embodiment 2, and an integrated composite antifouling reverse osmosis water purification membrane is obtained.

[0115] Embodiment 4

[0116] The difference between this embodiment 4 and embodiment 2 is that 0.1% polyaspartic acid is used for crosslinking grafting reaction after heat drying treatment;

[0117] The remaining steps are the same as embodiment 2, and an integrated composite antifouling reverse osmosis water purification membrane is obtained.

[0118] Embodiment 5

[0119] The difference between this embodiment 5 and embodiment 2 is that 0.5% polyaspartic acid is used for crosslinking grafting reaction after heat drying treatment;

[0120] The remaining steps are the same as embodiment 2, and an integrated composite antifouling reverse osmosis water purification membrane is obtained.

[0121] Embodiment 6

[0122] The difference between this embodiment 6 and embodiment 2 is that crosslinking grafting reaction is carried out under 50℃ oven for 3 minutes after heat drying treatment;

[0123] The remaining steps are the same as embodiment 2, and an integrated composite antifouling reverse osmosis water purification membrane is obtained.

[0124] Embodiment 7

[0125] The difference between this embodiment 7 and embodiment 2 is that crosslinking grafting reaction is carried out under 90℃ oven for 3 minutes after heat drying treatment;

[0126] The remaining steps are the same as embodiment 2, and an integrated composite antifouling reverse osmosis water purification membrane is obtained.

[0127] Initial performance, scale inhibition performance test evaluation

[0128] The scale inhibition reverse osmosis water purification membrane prepared by the embodiment was subjected to desalination and flux, water efficiency life operation scale inhibition test, respectively.

[0129] I. Initial performance

[0130] The integrated composite scale inhibition reverse osmosis water purification membrane prepared by the methods of embodiments 1-7 was cut respectively, and the DuPont Dow reverse osmosis water purification membrane XLE was used as a commercial comparative example. The membrane pieces were placed on a cross-flow membrane piece test bench to test the initial performance of the membrane pieces: the operating pressure was 0.69 MPa, the test solution was 2 g / L sodium chloride solution, the solution temperature was 25°C, the pH was 7-8, and the water flux and desalination rate of the test membrane pieces after 30 min of operation were tested. The test results are shown in Table 1.

[0131] Table 1: Sodium chloride performance test

[0132] Test subjects Flux (LMH) Desalination rate (%) Example 1 (blank example) 61.5 97 Example 2 (preferred example) 55.7 98.5 Example 3 52.3 98.6 Example 4 57.2 98 Example 5 50.6 98.7 Example 6 59.6 97.5 Example 7 53.2 98.5 Commercial comparative example 50 98.3

[0133] According to the test results, the scale inhibition reverse osmosis water purification membrane prepared by the method described in the patent has higher flux than the commercial reverse osmosis water purification membrane, and the desalination rate is stable at more than 98%.

[0134] II. Water efficiency life operation test - scale inhibition effect

[0135] The flux decay rate of the membrane pieces in Table 1 was tested. According to the water standard for testing in GB34914-2017 "Water efficiency limit value and water efficiency grade of reverse osmosis water purification machine", the initial flux and initial desalination rate of the test membrane pieces were tested under the operating pressure of 0.69 MPa, the solution temperature of 25°C, and the pH of 7-8. After 48 h of continuous operation, the water flux and desalination rate of the membrane pieces were tested again, and the flux decay rate of the membrane pieces was calculated. The results are shown in Table 2.

[0136] Among them, the flux decay rate = (initial water flux - final water flux of operation) / initial water flux * 100%, and the desalination decay rate = (initial desalination rate - final desalination rate of operation) / initial desalination rate * 100%;

[0137] Table 2: Membrane piece water efficiency life operation test

[0138]

[0139] According to the test results, the preferred integrated composite scale inhibition reverse osmosis water purification membrane prepared by the method described in the patent has lower flux and desalination rate than the commercial reverse osmosis water purification membrane and better initial performance after 24 hours of life operation, indicating excellent scale inhibition performance.

[0140] The application adopts integral quantitative coating cross-linking grafting in the desalination layer, and the cross-linked polyaspartic acid molecular structure contains polyamide bonds arranged alternately, which can form complex with calcium and magnesium ions in the running water body, effectively reduce ion precipitation, and reduce flux reduction and blockage. Furthermore, through the charges of the carboxyl and amino groups on the polyamide bond, the attraction between particles is reduced through electrostatic interaction, preventing aggregation and deposition. At the same time, the molecule exists in a chain state structure, can adsorb the deposited microparticles in water, inhibit the growth of the microparticles, and dissolve together after adsorption, thereby forming a composite scale inhibition reverse osmosis water purification membrane.

[0141] The production method of the composite scale inhibition reverse osmosis water purification membrane provided by the application forms a scale inhibition layer on the surface of the desalination layer of the reverse osmosis membrane, has higher economy in the field of water purification, and fully utilizes the use space of the household user relative to other patents. A small amount of scale inhibition is added in the desalination layer or the polysulfone layer, which is insufficient and easy to lose, and cannot guarantee the continuous stability of the system. The application adopts quantitative coating cross-linking grafting in the desalination layer to form a scale inhibition layer, has the effects of effective scale inhibition (-CONH-, preventing aggregation, sedimentation and complexation dissolution), long-term operation stability (amino and carboxyl of the third layer of polyamide membrane are polycondensation grafted, and residual end groups are electrostatically adsorbed).

[0142] As shown in Figure 1 , the embodiment of the application also provides a composite scale inhibition reverse osmosis water purification membrane, comprising: a non-woven fabric support base material 1, a polymer porous support base layer 2, a desalination layer 3 and a scale inhibition layer 4, wherein the polymer porous support base layer is formed on the surface of the non-woven fabric support base material, the desalination layer is formed on the surface of the polymer porous support base layer, and the scale inhibition layer is formed on the surface of the desalination layer.

[0143] The non-woven fabric support base material adopts a wet process polyester base material, the thickness is 100 microns, the weight is 75 g / m 3 , and the air permeability is 3 cc / c㎡ / sec.

[0144] The polymer porous support base layer is combined on the surface of the non-woven fabric support base material by a liquid-solid phase conversion method of a high molecular polymer mixed solution on the non-woven fabric support base material. The thickness of the polymer porous support base layer is 40 microns.

[0145] The high molecular polymer solution is composed of a high molecular polymer and a solvent, and the components include, according to the mass percentage concentration, 15-20% of the high molecular polymer and 80-85% of the solvent. The high molecular polymer is polysulfone, and the solvent is dimethylformamide.

[0146] The desalination layer is 0.2-0.4 microns thick.

[0147] The antifouling layer is formed by coating the antifouling agent system solution on the surface of the desalination layer and combining on the surface of the desalination layer after dehydration. The thickness of the antifouling layer is 1-4 microns.

[0148] The application also provides a formula of the antifouling agent system solution capable of forming the antifouling layer, which is composed of polyaspartic acid, a crosslinking agent, a buffer, a catalyst and pure water, wherein the catalyst is 4-(4, 6-dimethoxytriazin-2-yl)-4-methyl morpholine hydrochloride (DMTMM).

[0149] The application mainly uses 4-(4, 6-dimethoxytriazin-2-yl)-4-methyl morpholine hydrochloride (DMTMM) as the catalyst to catalyze the crosslinking reaction of polyaspartic acid and the crosslinking agent, which can greatly accelerate the reaction rate; the crosslinked polyaspartic acid molecular structure contains alternating polyamide bonds, which can form complexes with calcium and magnesium ions in the running water body, effectively reducing the ion precipitation and the flux reduction and blockage; through the charges of the carboxyl and amino groups on the polyamide bond, the attraction between the particles is reduced through electrostatic interaction, and the aggregation and deposition are prevented; the molecule exists in a chain structure, can adsorb the deposited particles in water, inhibit the growth of the particles, and dissolve in water together after adsorption; thereby greatly delaying the performance degradation of the membrane and improving the long-time running stability.

[0150] The mass percentage of the polyaspartic acid is 0.1, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2% or other values between 0.1-2%;

[0151] The mass percentage content of the catalyst is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.8%, 1% or other values between 0.1-1%;

[0152] The crosslinking agent is hexanediamine or pentanediamine, and the mass percentage content is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.8%, 1% or other values between 0.1-1%;

[0153] The buffer is potassium dihydrogen phosphate or tripotassium phosphate, and the mass percentage content is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%, 0.8%, 1% or other values between 0.1-1%;

[0154] The pure water is the balance.

[0155] The application also provides a method for forming the antifouling agent system solution on the reverse osmosis membrane, which comprises the following steps:

[0156] providing a reverse osmosis membrane carrier with a desalination layer surface;

[0157] The antifouling agent system solution is coated on the surface of the desalination layer, and heated to form an antifouling layer on the surface of the desalination layer.

[0158] The coating thickness is 15-80 um, the heating temperature is 60-100 DEG C, and the duration is 15 min.

[0159] The antifouling agent system solution forms an antifouling layer on the surface of the desalination layer, and the reaction formula is:

[0160]

[0161] The heating is performed in an oven.

[0162] A method for providing a reverse osmosis membrane carrier with a desalination layer surface is provided, which can refer to the above embodiments, comprising:

[0163] Step one, providing a non-woven fabric support substrate;

[0164] Step two, providing a high polymer solution, and combining the high polymer in the high polymer solution on the surface of the non-woven fabric support substrate to form a polymer porous support base layer through liquid-solid phase conversion;

[0165] Step three, preparing a desalination layer on the polymer porous support base layer.

[0166] The application further provides a reverse osmosis membrane, which is prepared by the method for forming an antifouling agent system solution on a reverse osmosis membrane.

[0167] The application provides an antifouling agent system solution capable of forming an antifouling layer, which uses DMTMM as a catalyst, thereby greatly accelerating the cross-linking reaction speed of polyaspartic acid on the surface of the desalination layer, and forming a stable connection between the antifouling layer and the desalination layer during the reaction process, so that the formed antifouling layer can be continuously and stably connected to the desalination layer, thereby maintaining the antifouling effect.

[0168] Compared with the traditional reverse osmosis membrane, the application adds an antifouling layer, so that no antifouling agent needs to be added in the water treatment process; compared with the slow forming speed of the traditional antifouling agent, the application uses DMTMM as a catalyst to quickly react polyaspartic acid with a cross-linking agent, forms a stable structure on the surface of the desalination layer.

[0169] The technical features of the above embodiments can be combined in any way, and for the sake of brevity, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0170] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A reverse osmosis membrane, characterized by, The application discloses a method for forming a reverse osmosis membrane by using a scale inhibitor system solution capable of forming a scale inhibition layer on the reverse osmosis membrane, wherein the scale inhibitor system solution capable of forming a scale inhibition layer is composed of polyaspartic acid, a crosslinking agent, a buffer, a catalyst and pure water, and the catalyst is 4-(4, 6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride. The application discloses a method for forming a reverse osmosis membrane by using a scale inhibitor system solution capable of forming a scale inhibition layer on the reverse osmosis membrane, wherein the scale inhibitor system solution capable of forming a scale inhibition layer is composed of polyaspartic acid, a crosslinking agent, a buffer, a catalyst and pure water, and the catalyst is 4-(4, 6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride. The application discloses a method for forming a reverse osmosis membrane by using a scale inhibitor system solution capable of forming a scale inhibition layer on the reverse osmosis membrane, wherein the scale inhibitor system solution capable of forming a scale inhibition layer is composed of polyaspartic acid, a crosslinking agent, a buffer, a catalyst and pure water, and the catalyst is 4-(4, 6-dimethoxytriazin-2-yl)-4-methylmorpholine hydrochloride.

2. The reverse osmosis membrane according to claim 1, wherein the mass percentage of the polyaspartic acid is 0.1-2%; the mass percentage of the catalyst is 0.1-1%; the crosslinking agent is hexanediamine or pentanediamine, and the mass percentage is 0.1-1%; the buffer is potassium dihydrogen phosphate or tri-potassium phosphate, and the mass percentage is 0.1-1%; and the pure water is the rest.

3. The reverse osmosis membrane according to claim 1, wherein the coating thickness is 15-80, the heating temperature is 60-100 DEG C, and the heating time is 15 min; and the heating is performed in an oven.

4. The reverse osmosis membrane according to claim 1, wherein the scale inhibitor system solution forms a scale inhibition layer on the surface of the desalination layer, and the reaction formula is:

5. The reverse osmosis membrane according to claim 1, wherein the method for providing the reverse osmosis membrane carrier with a desalination layer surface comprises the following steps: step one, providing a non-woven fabric support substrate; step two, providing a high polymer solution, and making the high polymer solution on the non-woven fabric support substrate form a polymer porous support base layer by means of liquid-solid phase conversion; and step three, preparing a desalination layer on the polymer porous support base layer.

6. The reverse osmosis membrane according to claim 5, wherein the step of configuring the high polymer mixed solution comprises the following steps: adding the high polymer into the solvent according to the mass ratio, stirring at 100-140 DEG C for 6-12 hours until the high polymer is completely dissolved to form a primary solution; then vacuumizing the primary solution and keeping for 10-12 hours to obtain the high polymer mixed solution.

7. The reverse osmosis membrane according to claim 5, wherein the step two further comprises the following steps: immersing the prepared polymer porous support base layer into deionized water, dissolving the solvent in the deionized water, and separating the solvent from the polymer porous support base layer to form a mixed waste liquid of deionized water and solvent, and then recycling and utilizing the mixed waste liquid.

8. The reverse osmosis membrane according to claim 7, wherein the recycling and utilizing of the mixed waste liquid comprises the following steps: ​ ​ ​ ​ ​ 。 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Step A, the mixed waste liquid is concentrated by reverse osmosis membrane to form a concentrated liquid with higher solvent concentration, and the deionized water is separated out; Step B, the concentrated liquid obtained in step A is separated by distillation to obtain high-purity DMF and deionized water; Step C, using the high-purity DMF obtained in step B and the high-molecular polymer to mix, heat and vacuum to prepare a high-molecular polymer solution; at the same time, using the deionized water obtained in step A and step B to soak the polymer porous support base layer, so as to realize the full recycling of DMF and deionized water.

9. The reverse osmosis membrane according to claim 5, characterized in that, Step three, the preparation of desalination layer on the polymer porous support base layer, comprising: The non-woven fabric support substrate with polymer porous support base layer obtained in step two is soaked in water phase amine solution and oil phase solution in sequence, and then is subjected to heat treatment, pure water cleaning, moisturizing agent glycerol soaking and drying to obtain.

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