Reverse osmosis membrane scale inhibitor and application thereof

Abstract

The application belongs to the technical field of water treatment, and particularly relates to a reverse osmosis membrane scale inhibitor and application thereof. The reverse osmosis membrane scale inhibitor provided by the application comprises a macromolecular scale inhibitor, modified nanoparticles, tartaric acid, ethylenediaminetetraacetic acid and water. The application adopts the macromolecular scale inhibitor and the modified nanoparticles to be compounded as main components of the reverse osmosis membrane scale inhibitor, and adopts the tartaric acid and the ethylenediaminetetraacetic acid as auxiliary scale inhibition components, so that the scale inhibition effect of the reverse osmosis membrane scale inhibitor is effectively improved. The macromolecular scale inhibitor is synthesized by taking acrylic acid, allyl benzene sulfonic acid and N-hydroxymethyl acrylamide as monomers, so that the scale inhibition performance is improved, and the scale inhibitor itself is prevented from being precipitated. The 2-acrylamide-2-methylpropane sulfonic acid is grafted on the amino-functionalized nanoparticles, so that the normal growth of a crystal is destroyed through electrostatic repulsion and steric hindrance effect, and the scale inhibition performance of the reverse osmosis membrane scale inhibitor is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water treatment, and particularly relates to a reverse osmosis membrane scale inhibitor and application thereof. BACKGROUND

[0002] Water resource treatment is not only a basic engineering for guaranteeing human health and maintaining ecological balance, but also a core link for supporting sustainable development. Water resource is a basic resource for economic development, and water resource treatment plays an irreplaceable role in guaranteeing water demand of industrial, agricultural and urban development. An important way for treating industrial and domestic wastewater to transform into drinkable water is reverse osmosis membrane technology.

[0003] The reverse osmosis membrane is a core component in a desalted water system. Once particles, colloids and insoluble salts in the reverse osmosis system are blocked, not only the water production of the membrane is seriously affected, the desalination rate is reduced, but also the service life of the membrane is greatly reduced. In the case of serious blockage, the service life of the reverse osmosis membrane is only one year or even shorter. The particles or colloids causing the blockage of the reverse osmosis membrane often include bacteria, sludge, colloidal silicon, iron corrosion products, etc. If the chemicals such as polyaluminum and ferric chloride or cationic polyelectrolyte used in the pretreatment part of the desalted water system cannot be effectively removed in the clarifier or medium filter, the membrane blockage may also be caused. In the reverse osmosis system, common insoluble salts include calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, calcium fluoride, silicon dioxide or other silicates, etc. Therefore, a scale inhibitor with excellent scale inhibition performance and good dispersion effect needs to be used in the process of treating water quality by reverse osmosis.

[0004] The scale inhibitors on the market at present mainly include phosphate, polycarboxylic acid and polyphosphate, etc. These scale inhibitors have problems such as environmental pollution, high cost and insufficient chemical stability in the process of use. Therefore, it is an urgent problem to be solved in the industry to develop a new type of scale inhibitor which is environmentally friendly, low in cost and has remarkable effect. The Chinese patent application file with the publication number CN110354689A discloses a scale inhibitor for reverse osmosis membrane, and the formula composition is: tetrasodium iminodisuccinate 5-40 parts, organosilicon amine methylene phosphonic acid 5-35 parts, tetrahydroxymethyl sulfate phosphorus 5-30 parts, and citric acid 5-35 parts. This scale inhibitor is suitable for reverse osmosis membrane system, and the influent can be fresh water, seawater, groundwater, etc. However, the citric acid in the formula may affect the chemical stability of the membrane to some extent, and long-term use may cause irreversible influence on the desalination rate and flux of the membrane. At the same time, for the water quality of high-concentration barium sulfate, calcium fluoride and other insoluble salts, the components in the scale inhibitor have weak inhibition effect on the insoluble salts, and cannot effectively prevent the deposition and scale formation of the insoluble salts on the membrane surface. SUMMARY

[0005] In order to solve the technical problems of poor scale inhibition effect, poor dispersibility and self precipitation of the scale inhibitor in the prior art, the application provides a reverse osmosis membrane scale inhibitor and application thereof.

[0006] In order to achieve the above-mentioned application purposes, the technical scheme of the application is as follows:

[0007] The reverse osmosis membrane scale inhibitor comprises the following components in parts by weight:

[0008] The macromolecular scale inhibitor 30-50 parts, modified nanoparticles 18-25 parts, tartaric acid 5-8 parts, ethylenediaminetetraacetic acid 3-7 parts and water 40-60 parts; the macromolecular scale inhibitor is prepared by aqueous solution free radical polymerization of acrylic acid, allylbenzenesulfonic acid and N-hydroxymethyl acrylamide; the modified nanoparticles are obtained by reaction of amino-functionalized nanoparticles and 2-acrylamide-2-methylpropanesulfonic acid.

[0009] By the above technical scheme, the macromolecular scale inhibitor and the modified nanoparticles are used as the main components of the reverse osmosis membrane scale inhibitor, the macromolecular scale inhibitor is obtained by polymerization of acrylic acid, allylbenzenesulfonic acid and N-hydroxymethyl acrylamide, and contains carboxyl, sulfonic acid group, hydroxymethyl and amide group in the molecular structure, the carboxyl can form soluble chelates with metal ions such as calcium ions and magnesium ions, and at the same time, can prevent calcium carbonate, magnesium hydroxide and other crystals from gathering through electrostatic repulsion; the sulfonic acid group has strong hydrophilic property and high ionization degree, avoids self precipitation caused by salting-out effect, and is negatively charged, can disperse sulfate salts such as calcium sulfate, barium sulfate and strontium sulfate through electrostatic repulsion, and the benzene ring structure can enhance the adsorption capacity on the crystal surface, further preventing the crystal from growing; the hydroxymethyl can enhance the hydrogen bond interaction between the polymer and water molecules, and enhance the wrapping property on the crystal, and the amide group can be adsorbed on the membrane surface or the crystal surface, and can destroy the normal growth of the crystal lattice through steric hindrance effect, and the multiple functional groups can synergistically achieve broad-spectrum scale inhibition effect. In addition, the macromolecular scale inhibitor has a chain structure, can adsorb multiple microcrystals with the same charge, so that the microcrystals cannot collide together due to the existence of electrostatic repulsion, so that the crystal grains remain uniformly dispersed, thereby avoiding the generation of large crystals. The amino-functionalized nanoparticles have a nanoscale size, can adsorb a large amount of metal cations, or can be directly adsorbed on the surface of the insoluble salt crystal nucleus to prevent the crystal nucleus from growing, the sulfonic acid group on the nanoparticles can form a double electric layer on the surface of the nanoparticles, prevent the nanoparticles from agglomerating, and also disperse the insoluble salt crystals through electrostatic repulsion, avoid the crystal from gathering and adsorbing on the membrane surface, the amide group can form a weak coordination bond with the metal cations, and the three-dimensional structure of the nanoparticles can also be embedded in the insoluble salt crystal lattice to destroy the normal growth order of the crystal, and form amorphous particles which are loose and easy to be carried away by water flow.

[0010] The hydroxyl and carboxyl in the tartaric acid molecule can interfere with the lattice arrangement of crystals such as calcium carbonate, so that the crystal structure is loose and is not easy to adhere to the membrane surface; the ethylenediaminetetraacetic acid is coordinated with metal ions through amino and carboxyl groups to form a soluble chelate, especially with high chelating efficiency for calcium ions and magnesium ions.

[0011] Further, the preparation method of the macromolecular scale inhibitor is as follows: acrylic acid, allyl benzene sulfonic acid and N-hydroxymethyl acrylamide, tert-butyl alcohol and deionized water are added into a reaction kettle, heated to 80-85 DEG C, stirred and dissolved, then ammonium persulfate solution is added dropwise under stirring, incubated, cooled, the pH value of the system is adjusted to neutral, ethanol is added for precipitation and purification, vacuum filtration is carried out under reduced pressure, the filter cake is vacuum dried, ground, and the macromolecular scale inhibitor is obtained.

[0012] By the above technical solution, the ternary copolymer macromolecular scale inhibitor is synthesized by using acrylic acid, allyl benzene sulfonic acid and N-hydroxymethyl acrylamide as polymer monomers, tert-butyl alcohol as a molecular weight regulator, and ammonium persulfate as an initiator by using aqueous solution radical polymerization method, the solvent system has strong adaptability during the reaction process, ensuring uniform copolymerization, the reaction conditions are mild and controllable, the purification step is simple and efficient, waste liquid discharge is reduced, and the technical effects of broad-spectrum scale inhibition, high salt tolerance, membrane friendliness and environmental protection without phosphorus are realized.

[0013] Further, the mass ratio of the acrylic acid, the allyl benzene sulfonic acid and the N-hydroxymethyl acrylamide in the preparation method of the macromolecular scale inhibitor is 7-10:5-7:2-3.

[0014] By the above technical solution, the mass ratio of the acrylic acid, the allyl benzene sulfonic acid and the N-hydroxymethyl acrylamide is controlled to adjust the chelating capacity, the dispersing performance, the steric hindrance and the water solubility of the macromolecular scale inhibitor, and then the scale inhibition effect is affected. It is found that the use amount of the acrylic acid is too high, which can significantly improve the inhibition effect on carbonates such as calcium carbonate and magnesium hydroxide, but the water solubility of the macromolecular scale inhibitor is reduced, and the inhibition capacity on sulfate scale is weakened; the use amount of the allyl benzene sulfonic acid is too high, which significantly improves the dispersing performance of the sulfate scale, but the inhibition capacity on carbonate scale is reduced; the use amount of the N-hydroxymethyl acrylamide is too high, which enhances the steric hindrance of the macromolecular chain, improves the crystal lattice distortion effect on the crystal, but the proportion of the functional scale inhibition groups (such as carboxyl and sulfonic acid group) is diluted, resulting in that the scale inhibition efficiency of the macromolecular scale inhibitor is obviously reduced.

[0015] Further, the use amount of the tert-butyl alcohol in the preparation method of the macromolecular scale inhibitor is 13%-16% of the sum of the mass of the acrylic acid, the allyl benzene sulfonic acid and the N-hydroxymethyl acrylamide.

[0016] Further, the mass percentage of the ammonium persulfate solution in the preparation method of the macromolecular scale inhibitor is 30%-40%, the dosage of the ammonium persulfate solution is 18%-25% of the sum of the mass of acrylic acid, allyl benzene sulfonic acid and N-hydroxymethyl acrylamide, and the dropping time of the ammonium persulfate solution is controlled to be 2.5-3h.

[0017] Further, the preparation method of the modified nanoparticles is as follows: mixing the nanoparticles with a dilute sulfuric acid solution, ultrasonic dispersion for 1-2h, filtration, water washing until neutral, drying, then dispersing in toluene, adding γ-aminopropyl triethoxysilane, heating and refluxing under nitrogen protection for 14-16h, cooling, washing, first vacuum drying, to obtain amino-functionalized nanoparticles; adding the amino-functionalized nanoparticles and 2-acrylamide-2-methylpropane sulfonic acid into an ethanol aqueous solution, adjusting the pH value to 5.0-7.0, heating to 50-60℃ under stirring for 4-6h, centrifugal separation, washing the precipitate, second vacuum drying, to obtain the modified nanoparticles.

[0018] Through the above technical solution, the surface hydroxyl groups of the nanoparticles activated by the dilute sulfuric acid increase, and the amino groups introduced by the γ-aminopropyl triethoxysilane can adsorb metal ions through coordination or directly anchor on the surface of the crystal nucleus of the insoluble salt to prevent the crystal nucleus from growing, and after the 2-acrylamide-2-methylpropane sulfonic acid is grafted, the strong ionization sulfonic acid groups form a negative layer in water to push away the surrounding scale crystals through electrostatic repulsion, and the amide groups can form a coordination bond with metal ions and destroy the normal growth of the crystal lattice through steric hindrance, so as to improve the scale inhibition performance of the scale inhibitor. In addition, the above process is modified in steps, so that the surface of the nanoparticles is fully functionalized, the density and uniformity of the functional groups on the surface of the nanoparticles are ensured, the solvents used can be recycled, no toxic by-products are discharged, and through the synergistic mechanism of high adsorption of the nano core, amino chelation, electrostatic repulsion of the sulfonic acid groups and steric hindrance, the nanoparticles achieve a broad-spectrum and efficient scale inhibition effect on complex water quality.

[0019] Further, the nanoparticles in the preparation method of the modified nanoparticles are one of nanosilica, nano titanium oxide, nano aluminum oxide and nano zinc oxide; the concentration of the dilute sulfuric acid solution is 1-1.2mol / L; and the temperature of the heating and refluxing is 105-115℃.

[0020] Further, the mass ratio of the nanoparticles, the γ-aminopropyl triethoxysilane and the 2-acrylamide-2-methylpropane sulfonic acid in the preparation method of the modified nanoparticles is 25-28:13-17:11-15.

[0021] By the above scheme, the adsorption-chelation-electrostatic repulsion-space steric hindrance fourfold scale scale mechanism of the modified nanoparticles is regulated by adjusting the mass ratio of the nanoparticles, gamma-aminopropyl triethoxysilane and 2-acrylamide-2-methylpropanesulfonic acid, and further affects the scale inhibition effect of the modified nanoparticles. If the proportion of the nanoparticles is higher, the amino load and the grafting amount of the sulfonic acid group are insufficient, resulting in weakened chelation capacity and electrostatic repulsion, and poor scale inhibition effect; if the proportion of the gamma-aminopropyl triethoxysilane is higher, the excess gamma-aminopropyl triethoxysilane may polymerize in toluene reflux, forming free siloxane polymer, which wraps the surface of the nanoparticles, resulting in agglomeration of the nanoparticles; if the proportion of 2-acrylamide-2-methylpropanesulfonic acid is higher, free 2-acrylamide-2-methylpropanesulfonic acid that is not combined with the amino will enter the reverse osmosis system with the scale inhibitor, adsorb on the surface of the reverse osmosis membrane, and form an organic pollution layer, resulting in flux decay of the reverse osmosis membrane.

[0022] Furthermore, in the preparation method of the modified nanoparticles, the mass percentage of the aqueous ethanol solution is 5%-10%; the temperature of the first vacuum drying is 60-80 DEG C, the time of the vacuum drying is 12-15h, the temperature of the vacuum drying is 50-60 DEG C, and the time of the vacuum drying is 20-24h.

[0023] The application also provides application of the above reverse osmosis membrane scale inhibitor in the fields of seawater and brackish water desalination, municipal sewage regeneration and water reuse.

[0024] By the above scheme, the reverse osmosis membrane scale inhibitor provided by the application is applied in the fields of seawater and brackish water, municipal sewage regeneration and water reuse, and the dual effects of efficient scale inhibition and zero phosphorus discharge can be achieved.

[0025] Compared with the prior art, the reverse osmosis membrane scale inhibitor and the application thereof provided by the application have the following technical advantages:

[0026] (1) The application adopts macromolecular scale inhibitors and modified nanoparticles as the main components of the reverse osmosis membrane scale inhibitor, and adopts tartaric acid and ethylenediaminetetraacetic acid as auxiliary scale inhibition components, so that the scale inhibition effect of the reverse osmosis membrane scale inhibitor is effectively improved;

[0027] (2) The application adopts acrylic acid, allyl benzene sulfonic acid and N-hydroxymethyl acrylamide as polymerization monomers, and synthesizes the macromolecular scale inhibitor by using the aqueous solution free radical polymerization method, so that the scale inhibition performance of the reverse osmosis membrane scale inhibitor is improved, and the self precipitation of the scale inhibitor due to salting-out is avoided;

[0028] (3) The application grafts 2-acrylamide-2-methylpropanesulfonic acid on the amino-functionalized nanoparticles, and destroys the normal growth of crystals through electrostatic repulsion and space steric hindrance, so that the scale inhibition performance of the reverse osmosis membrane scale inhibitor is improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Results of static scale inhibition tests for the scale inhibitors prepared in Examples 1-5;

[0030] Figure 2 Results of static scale inhibition tests for the scale inhibitors prepared in Example 5, Comparative Example 1-5;

[0031] Figure 3 Changes in Ca2+concentration over time in dynamic scale inhibition tests for Examples 1-5; 2+

[0032] Figure 4 Changes in Ca2+concentration over time in dynamic scale inhibition tests for Example 5, Comparative Example 1-5; 2+

[0033] Figure 5 Changes in conductivity over time in dynamic scale inhibition tests for Examples 1-5;

[0034] Figure 6 Changes in conductivity over time in dynamic scale inhibition tests for Example 5, Comparative Example 1-5;

[0035] Figure 7 Dispersing iron oxide performance of the scale inhibitors prepared in Examples 1-5;

[0036] Figure 8 Dispersing iron oxide performance of the scale inhibitors prepared in Example 5, Comparative Example 1-5;

[0037] Figure 9 Infrared spectrum of the macromolecular scale inhibitor prepared in Preparation Example 5. DETAILED DESCRIPTION

[0038] The present application will be further described with reference to the following specific examples, but the present application is not limited to the following examples. Those skilled in the art can make various modifications based on the basic idea of the present application, and such modifications are within the scope of the present application as long as they do not depart from the basic idea of the present application.

[0039] Preparation Example 1

[0040] ​​The preparation method of the macromolecular scale inhibitor is as follows: a three-necked flask, a constant pressure dropping funnel and a reflux condenser are fixed on a constant temperature heating magnetic stirrer, 70 g of acrylic acid, 70 g of allyl benzene sulfonic acid and 30 g of N-methylol acrylamide, 22.1 g of tert-butyl alcohol and 100 mL of deionized water are added, the temperature is increased to 80 DEG C under stirring, 31 g of 30% mass percent ammonium persulfate solution is added dropwise under stirring after the solid is dissolved, the dropping time of the ammonium persulfate solution is controlled to be within 2.5 h, the reaction is kept for 2.5 h, the system is cooled to room temperature after the reaction is completed, the pH value is adjusted to 7.0, ethanol is added for precipitation and purification, the precipitate is extracted by filtration under reduced pressure, the filter cake is placed in a vacuum drying oven and dried at 40 DEG C for 24 h, and then ground to obtain the macromolecular scale inhibitor.

[0041] Preparation Example 2

[0042] The preparation method of the macromolecular scale inhibitor is as follows: a three-necked flask, a constant pressure dropping funnel and a reflux condenser are fixed on a constant temperature heating magnetic stirrer, 70 g of acrylic acid, 70 g of allyl benzene sulfonic acid and 30 g of N-methylol acrylamide, 22.1 g of tert-butyl alcohol and 100 mL of deionized water are added, the temperature is increased to 80 DEG C under stirring, 31 g of 30% mass percent ammonium persulfate solution is added dropwise under stirring after the solid is dissolved, the dropping time of the ammonium persulfate solution is controlled to be within 2.5 h, the reaction is kept for 2.5 h, the system is cooled to room temperature after the reaction is completed, the pH value is adjusted to 7.0, ethanol is added for precipitation and purification, the precipitate is extracted by filtration under reduced pressure, the filter cake is placed in a vacuum drying oven and dried at 40 DEG C for 24 h, and then ground to obtain the macromolecular scale inhibitor.

[0043] Preparation Example 3

[0044] The preparation method of the macromolecular scale inhibitor is as follows: a three-necked flask, a constant pressure dropping funnel and a reflux condenser are fixed on a constant temperature heating magnetic stirrer, 70 g of acrylic acid, 70 g of allyl benzene sulfonic acid and 30 g of N-methylol acrylamide, 22.1 g of tert-butyl alcohol and 100 mL of deionized water are added, the temperature is increased to 80 DEG C under stirring, 31 g of 30% mass percent ammonium persulfate solution is added dropwise under stirring after the solid is dissolved, the dropping time of the ammonium persulfate solution is controlled to be within 2.5 h, the reaction is kept for 2.5 h, the system is cooled to room temperature after the reaction is completed, the pH value is adjusted to 7.0, ethanol is added for precipitation and purification, the precipitate is extracted by filtration under reduced pressure, the filter cake is placed in a vacuum drying oven and dried at 40 DEG C for 24 h, and then ground to obtain the macromolecular scale inhibitor.

[0045] Preparation Example 4

[0046] The preparation method of the macromolecular scale inhibitor is as follows: a three-necked flask, a constant pressure dropping funnel and a reflux condenser are fixed on a constant temperature heating magnetic stirrer, 85 g of acrylic acid, 63 g of allyl benzene sulfonic acid and 28 g of N-methylol acrylamide, 26.4 g of tert-butyl alcohol and 120 mL of deionized water are added, the temperature is increased to 84 DEG C under stirring, 35.2 g of ammonium persulfate solution with a mass percentage of 37% is added dropwise under stirring after the solid is dissolved, the dropping time of the ammonium persulfate solution is controlled within 2.8 h, the reaction is kept for 2.8 h, the system is cooled to room temperature after the reaction is completed, the pH value is adjusted to 7.0, ethanol is added for precipitation and purification, the precipitate is extracted by filtration under reduced pressure, the filter cake is placed in a vacuum drying oven and dried at 45 DEG C for 26 h, and grinding is conducted to obtain the macromolecular scale inhibitor.

[0047] Preparation Example 5

[0048] The preparation method of the macromolecular scale inhibitor is as follows: a three-necked flask, a constant pressure dropping funnel and a reflux condenser are fixed on a constant temperature heating magnetic stirrer, 85 g of acrylic acid, 63 g of allyl benzene sulfonic acid and 28 g of N-methylol acrylamide, 26.4 g of tert-butyl alcohol and 120 mL of deionized water are added, the temperature is increased to 84 DEG C under stirring, 35.2 g of ammonium persulfate solution with a mass percentage of 37% is added dropwise under stirring after the solid is dissolved, the dropping time of the ammonium persulfate solution is controlled within 2.8 h, the reaction is kept for 2.8 h, the system is cooled to room temperature after the reaction is completed, the pH value is adjusted to 7.0, ethanol is added for precipitation and purification, the precipitate is extracted by filtration under reduced pressure, the filter cake is placed in a vacuum drying oven and dried at 45 DEG C for 26 h, and grinding is conducted to obtain the macromolecular scale inhibitor.

[0049] Preparation Example 6

[0050] The preparation method of the modified nanoparticles is as follows: 25 g of nanometer silicon dioxide is mixed with 40 mL of dilute sulfuric acid solution with a concentration of 1 mol / L, ultrasonic dispersion is conducted under the condition of a frequency of 40 kHz for 1 h, filtration is conducted, water washing is conducted until neutral, 120 DEG C drying is conducted, then ultrasonic dispersion is conducted in 100 mL of toluene under the condition of a frequency of 40 kHz, 13 g of γ-aminopropyl triethoxysilane is added, the temperature is increased to 105 DEG C under nitrogen protection for refluxing for 14 h, cooling is conducted, ethanol centrifugal washing is conducted for 3 times, 60 DEG C vacuum drying is conducted for 12 h, and the amino functionalized nanoparticles are obtained; the amino functionalized nanoparticles and 11 g of 2-acrylamide-2-methylpropanesulfonic acid are added into an ethanol aqueous solution with a mass percentage of 5%, the pH value is adjusted to 5.0, the temperature is increased to 50 DEG C under stirring at a rotating speed of 300 rpm for reaction for 4 h, centrifugal separation is conducted, the precipitate is washed with deionized water for 3 times, 50 DEG C vacuum drying is conducted for 20 h, and the modified nanoparticles are obtained.

[0051] Preparation Example 7

[0052] Preparation method of modified nanoparticles: 28 g of nano-titanium oxide was mixed with 50 mL of dilute sulfuric acid solution with a concentration of 1.2 mol / L, ultrasonically dispersed at a frequency of 50 kHz for 2 h, filtered, washed with water until neutral, dried at 130°C, then ultrasonically dispersed in 100 mL of toluene at a frequency of 50 kHz, 17 g of γ-aminopropyl triethoxysilane was added, heated to 115°C under nitrogen protection and refluxed for 16 h, cooled, washed with ethanol by centrifugation for 5 times, and vacuum dried at 80°C for 15 h to obtain amino-functionalized nanoparticles; the amino-functionalized nanoparticles and 15 g of 2-acrylamide-2-methylpropanesulfonic acid were added to an ethanol aqueous solution with a mass percentage of 10%, the pH value was adjusted to 7.0, heated to 60°C under stirring at a rotation speed of 500 rpm for 6 h, centrifuged, the precipitate was washed with deionized water for 5 times, and vacuum dried at 60°C for 24 h to obtain modified nanoparticles.

[0053] Preparation Example 8

[0054] Preparation method of modified nanoparticles: 26 g of nano-zinc oxide was mixed with 45 mL of dilute sulfuric acid solution with a concentration of 1.1 mol / L, ultrasonically dispersed at a frequency of 45 kHz for 1.5 h, filtered, washed with water until neutral, dried at 125°C, then ultrasonically dispersed in 100 mL of toluene at a frequency of 45 kHz, 15 g of γ-aminopropyl triethoxysilane was added, heated to 110°C under nitrogen protection and refluxed for 15 h, cooled, washed with ethanol by centrifugation for 4 times, and vacuum dried at 70°C for 14 h to obtain amino-functionalized nanoparticles; the amino-functionalized nanoparticles and 13 g of 2-acrylamide-2-methylpropanesulfonic acid were added to an ethanol aqueous solution with a mass percentage of 7%, the pH value was adjusted to 5.5, heated to 55°C under stirring at a rotation speed of 400 rpm for 5 h, centrifuged, the precipitate was washed with deionized water for 4 times, and vacuum dried at 55°C for 22 h to obtain modified nanoparticles.

[0055] Preparation Example 9

[0056] Preparation method of modified nanoparticles: 27 g of nano-alumina was mixed with 45 mL of dilute sulfuric acid solution with a concentration of 1.1 mol / L, ultrasonic dispersion was carried out under the condition of a frequency of 48 kHz for 1.6 h, filtration was carried out, water washing was carried out until neutral, drying was carried out at 128℃, then ultrasonic dispersion was carried out in 100 mL of toluene under the condition of a frequency of 46 kHz, 16 g of γ-aminopropyl triethoxysilane was added, heating was carried out to 108℃ under the protection of nitrogen and reflux was carried out for 16 h, cooling was carried out, ethanol centrifugal washing was carried out for 4 times, and vacuum drying was carried out at 70℃ for 14 h to obtain amino-functionalized nanoparticles; the amino-functionalized nanoparticles and 14 g of 2-acrylamide-2-methylpropanesulfonic acid were added into an ethanol aqueous solution with a mass percentage of 8%, the pH value was adjusted to 6.0, heating was carried out to 55℃ under the condition of stirring at a rotation speed of 400 rpm and reaction was carried out for 6 h, centrifugal separation was carried out, the precipitate was washed with deionized water for 4 times, and vacuum drying was carried out at 55℃ for 22 h to obtain modified nanoparticles.

[0057] Preparation Example 10

[0058] Preparation method of modified nanoparticles: 27 g of nano-alumina was mixed with 45 mL of dilute sulfuric acid solution with a concentration of 1.1 mol / L, ultrasonic dispersion was carried out under the condition of a frequency of 48 kHz for 1.6 h, filtration was carried out, water washing was carried out until neutral, drying was carried out at 128℃, then ultrasonic dispersion was carried out in 100 mL of toluene under the condition of a frequency of 46 kHz, 16 g of γ-aminopropyl triethoxysilane was added, heating was carried out to 108℃ under the protection of nitrogen and reflux was carried out for 16 h, cooling was carried out, ethanol centrifugal washing was carried out for 4 times, and vacuum drying was carried out at 70℃ for 14 h to obtain amino-functionalized nanoparticles; the amino-functionalized nanoparticles and 14 g of 2-acrylamide-2-methylpropanesulfonic acid were added into an ethanol aqueous solution with a mass percentage of 8%, the pH value was adjusted to 6.0, heating was carried out to 55℃ under the condition of stirring at a rotation speed of 400 rpm and reaction was carried out for 6 h, centrifugal separation was carried out, the precipitate was washed with deionized water for 4 times, and vacuum drying was carried out at 55℃ for 22 h to obtain modified nanoparticles.

[0059] Example 1

[0060] A reverse osmosis membrane scale inhibitor, comprising the following components in parts by weight:

[0061] 30 parts of a macromolecular scale inhibitor, 25 parts of modified nanoparticles, 5 parts of tartaric acid, 3 parts of ethylenediaminetetraacetic acid, and 40 parts of water; the macromolecular scale inhibitor is prepared by Preparation Example 1, and the modified nanoparticles are prepared by Preparation Example 6.

[0062] Example 2

[0063] A reverse osmosis membrane scale inhibitor, comprising the following components in parts by weight:

[0064] Macromolecular scale inhibitor 50 parts, modified nanoparticles 18 parts, tartaric acid 8 parts, ethylenediaminetetraacetic acid 7 parts, water 60 parts; the macromolecular scale inhibitor is prepared by the preparation example 1, and the modified nanoparticles are prepared by the preparation example 6.

[0065] Example 3

[0066] A reverse osmosis membrane scale inhibitor, comprising the following components in parts by weight:

[0067] Macromolecular scale inhibitor 35 parts, modified nanoparticles 22 parts, tartaric acid 6 parts, ethylenediaminetetraacetic acid 5 parts, water 45 parts; the macromolecular scale inhibitor is prepared by the preparation example 1, and the modified nanoparticles are prepared by the preparation example 6.

[0068] Example 4

[0069] A reverse osmosis membrane scale inhibitor, comprising the following components in parts by weight:

[0070] Macromolecular scale inhibitor 40 parts, modified nanoparticles 20 parts, tartaric acid 7 parts, ethylenediaminetetraacetic acid 6 parts, water 50 parts; the macromolecular scale inhibitor is prepared by the preparation example 1, and the modified nanoparticles are prepared by the preparation example 6.

[0071] Example 5

[0072] A reverse osmosis membrane scale inhibitor, comprising the following components in parts by weight:

[0073] Macromolecular scale inhibitor 45 parts, modified nanoparticles 20 parts, tartaric acid 6 parts, ethylenediaminetetraacetic acid 5 parts, water 55 parts; the macromolecular scale inhibitor is prepared by the preparation example 1, and the modified nanoparticles are prepared by the preparation example 6.

[0074] Comparative Example 1

[0075] The present comparative example is similar to the example 5, and the difference between the present comparative example and the example 5 is that: the preparation method of the macromolecular scale inhibitor in the present comparative example adopts equal amount of deionized water instead of allyl benzene sulfonic acid.

[0076] Comparative Example 2

[0077] The present comparative example is similar to the example 5, and the difference between the present comparative example and the example 5 is that: the preparation method of the macromolecular scale inhibitor in the present comparative example adopts equal amount of deionized water instead of N-hydroxymethyl acrylamide.

[0078] Comparative Example 3

[0079] The present comparative example is similar to the example 5, and the difference between the present comparative example and the example 5 is that: the preparation method of the macromolecular scale inhibitor in the present comparative example adopts the mass ratio of the acrylic acid, the allyl benzene sulfonic acid and the N-hydroxymethyl acrylamide as 1:1:1.

[0080] Comparative Example 4

[0081] This comparative example is similar to Example 5, and the difference between this comparative example and Example 5 is that this comparative example uses an equal amount of nano-silica instead of modified nanoparticles.

[0082] Comparative Example 5

[0083] This comparative example is similar to Example 5, and the difference between this comparative example and Example 5 is that this comparative example uses an equal amount of deionized water instead of 2-acrylamide-2-methylpropanesulfonic acid in the preparation method of the modified nanoparticles.

[0084] Test Example

[0085] Static scale inhibition test: The scale inhibition performance of the scale inhibitors prepared in Examples 1-5 and Comparative Examples 1-5 was tested according to GB / T 16632-2019. The water sample was prepared into a deionized water solution containing Ca 2+ by using anhydrous calcium chloride, and the alkalinity was prepared by using HCO3 - , and the pH value was adjusted to 8.0. The prepared solution was immersed in a constant temperature water bath at 80°C, then 1-6 mg / L of the scale inhibitor was added, and the constant temperature was maintained for 10 h. Then the residual Ca 2+ concentration was measured by titration with EDTA standard titration solution, and the scale inhibition rate (η) on calcium carbonate was calculated according to the following formula. The arithmetic mean of three parallel test results was taken as the test result, and the absolute difference of the parallel test results was ≤5%. The test results are shown in Figure 1 and Figure 2 .

[0086] ;

[0087] In the formula, V0, V1, and V2 are the amounts of EDTA consumed by the water sample without adding the scale inhibitor before the test, the water sample after adding the scale inhibitor, and the water sample after the test without adding the scale inhibitor, respectively, and the unit is mL.

[0088] Dynamic scale inhibition test: The fresh water and concentrated water were both returned to the raw water tank to maintain all components of the raw water unchanged. The scale inhibition ability of the scale inhibitor was evaluated by comparing the changes of the mass concentration of calcium ions and the conductivity in the water tank before and after adding the scale inhibitor. The water sample was prepared according to the deep groundwater water quality standard of the circulating cooling water of the power plant, which is a kind of water quality with high hardness and high alkalinity. The recovery rate of the reverse osmosis device was controlled to be 75%, the raw water temperature was maintained at 25°C, the pH value was adjusted to 7.5 by using a hydrochloric acid-potassium chloride buffer solution, the running time was 120 h, and the dosage of the scale inhibitor was 4 mg / L. The test results are shown in Figures 3-6 .

[0089] Iron oxide dispersion performance test: drop CaCl2 solution into a 250mL volumetric flask, so that the content of calcium ions is 200mg / L, then add 1-6mg / L of scale inhibitor, adjust pH=9 with borax buffer solution, shake and add FeSO4.7H2O solution, so that the content of iron ions is 20mg / L, after constant volume with distilled water, strong stirring, then place in a constant temperature water bath at 80℃, stand for 5h, then take out and cool to room temperature, take the supernatant, measure the light transmittance at 420nm with a spectrophotometer, with distilled water as blank. The test results are shown in Table 1 Figures 7-8 .

[0090] From Figure 1 and Figure 2 it can be known that when the amount of reverse osmosis membrane scale inhibitor provided by the application is 4mg / L, the scale inhibition rate of the scale inhibitor reaches 90.2%-96.7%, with the increase of the amount of scale inhibitor, the complexing solubilization effect of carboxyl and sulfonic acid groups in the scale inhibitor with calcium ions is improved, so the solubility of calcium carbonate crystals is also increased, but when the amount of scale inhibitor exceeds 4mg / L, the dissolution-precipitation equilibrium will move to the precipitation side, and the scale inhibition rate will slightly decrease. In addition, the amount of acrylic acid, allyl benzene sulfonic acid and N-hydroxymethyl acrylamide in the preparation method of the macromolecular scale inhibitor and the amount of 2-acrylamide-2-methylpropane sulfonic acid in the modified nanoparticles are the key factors for controlling the scale inhibition effect of the reverse osmosis membrane scale inhibitor.

[0091] From Figure 3 and Figure 6 it can be known that the concentration and conductivity of calcium ions in the solution decrease with the extension of time, and the decrease is rapid within the first 24h, and then the scaling rate is slower, because the concentration of scale-forming ions is higher within the first 24h, and the ion product exceeds the solubility product constant, so calcium scale is formed, and with the precipitation of a large amount of ions, the possibility and rate of scale formation decrease; the conductivity of the solution will decrease with the generation of calcium scale.

[0092] From Figure 7 and Figure 8 it can be known that the reverse osmosis membrane scale inhibitor provided by the application has high dispersion capacity for iron oxide at a lower concentration.

[0093] In addition, the macromolecular scale inhibitor prepared in Preparation Example 5 is also subjected to infrared spectrum test, and the test results are shown in Table 2 Figure 9 . From Figure 9 it can be known that the stretching vibration peak of hydroxymethyl (-CH2OH) appears at 3428cm -1 , the stretching vibration peak of C-H appears at 2889cm -1 , the stretching vibration peak of carboxyl (-COOH) appears at 1731cm -1 , and the stretching vibration peak of carboxyl (-COOH) appears at 1564cm -1The stretching vibration peak of benzene ring appears at 1529 cm -1 The bending vibration peak of amido (-CONH-) appears at 1243 cm -1 The stretching vibration peak of sulfonic acid group S=O appears at 1116 cm -1 The stretching vibration peak of hydroxymethyl C-O appears, which indicates that the macromolecular scale inhibitor contains carboxyl, sulfonic acid group, benzene ring, amido, hydroxymethyl and other functional groups, and the reaction monomers of the macromolecular scale inhibitor fully participate in the polymerization reaction.

[0094] The above examples are merely illustrative of the present application and are not intended to limit the present application. Those skilled in the art cannot modify the above examples without departing from the spirit and scope of the present application. All equivalent modifications or changes made by those skilled in the art without departing from the technical idea of the present application still belong to the protection scope of the present application.

Claims

1. A reverse osmosis membrane antiscalant, characterized in that, The components include the following parts by weight: The composition comprises 30-50 parts of macromolecular scale inhibitor, 18-25 parts of modified nanoparticles, 5-8 parts of tartaric acid, 3-7 parts of ethylenediaminetetraacetic acid, and 40-60 parts of water; the macromolecular scale inhibitor is prepared by aqueous free radical polymerization of acrylic acid, allylbenzenesulfonic acid, and N-hydroxymethylacrylamide; the modified nanoparticles are obtained by reacting amino-functionalized nanoparticles with 2-acrylamido-2-methylpropanesulfonic acid.

2. The reverse osmosis membrane antiscalant according to claim 1, characterized in that, The preparation method of the macromolecular scale inhibitor is as follows: acrylic acid, allylbenzenesulfonic acid, N-hydroxymethylacrylamide, tert-butanol and deionized water are added to a reaction vessel, heated to 80-85℃, stirred and dissolved, and then ammonium persulfate solution is added dropwise under stirring. The reaction is kept at the temperature, cooled, and the pH value of the system is adjusted to neutral. Ethanol is added for precipitation and purification, vacuum filtration is performed, the filter cake is vacuum dried, and ground to obtain the macromolecular scale inhibitor.

3. The reverse osmosis membrane antiscalant according to claim 2, characterized in that, The mass ratio of acrylic acid, allylbenzenesulfonic acid and N-hydroxymethylacrylamide in the preparation method of macromolecular scale inhibitor is 7-10:5-7:2-3.

4. The reverse osmosis membrane antiscalant according to claim 2, characterized in that, In the preparation method of the macromolecular scale inhibitor, the amount of tert-butanol used is 13%-16% of the sum of the mass of acrylic acid, allylbenzenesulfonic acid and N-hydroxymethylacrylamide.

5. The reverse osmosis membrane antiscalant according to claim 2, characterized in that, In the preparation method of the macromolecular scale inhibitor, the mass percentage of the ammonium persulfate solution is 30%-40%, the amount of ammonium persulfate solution used is 18%-25% of the sum of the mass of acrylic acid, allylbenzenesulfonic acid and N-hydroxymethylacrylamide, and the dropping time of the ammonium persulfate solution is controlled at 2.5-3h.

6. The reverse osmosis membrane antiscalant according to claim 1, characterized in that, The modified nanoparticles are prepared as follows: nanoparticles are mixed with dilute sulfuric acid solution, ultrasonically dispersed for 1-2 hours, filtered, washed with water until neutral, dried, and then dispersed in toluene. γ-aminopropyltriethoxysilane is added, and the mixture is heated under nitrogen protection and refluxed for 14-16 hours. After cooling and washing, the mixture is vacuum dried for the first time to obtain amino-functionalized nanoparticles. The amino-functionalized nanoparticles and 2-acrylamide-2-methylpropanesulfonic acid are added to an ethanol aqueous solution, the pH is adjusted to 5.0-7.0, and the mixture is heated to 50-60℃ under stirring for 4-6 hours. After centrifugation, the precipitate is washed and vacuum dried for the second time to obtain the modified nanoparticles.

7. The reverse osmosis membrane antiscalant according to claim 6, characterized in that, The nanoparticles used in the preparation method of the modified nanoparticles are one of nano-silica, nano-titanium oxide, nano-alumina, and nano-zinc oxide; the concentration of the dilute sulfuric acid solution is 1-1.2 mol / L; and the temperature of the heating and reflux is 105-115℃.

8. The reverse osmosis membrane antiscalant according to claim 6, characterized in that, In the preparation method of modified nanoparticles, the mass ratio of nanoparticles, γ-aminopropyltriethoxysilane and 2-acrylamide-2-methylpropanesulfonic acid is 25-28:13-17:11-15.

9. The reverse osmosis membrane antiscalant according to claim 6, characterized in that, In the preparation method of modified nanoparticles, the mass percentage of the ethanol aqueous solution is 5%-10%; the temperature of the first vacuum drying is 60-80℃ and the vacuum drying time is 12-15h; the temperature of the second vacuum drying is 50-60℃ and the vacuum drying time is 20-24h.

10. The reverse osmosis membrane antiscalant according to any one of claims 1-9 is used in the fields of seawater and brackish water desalination, municipal wastewater regeneration and greywater reuse.

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