Reverse osmosis scale inhibitor as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of sewage treatment, and particularly relates to a reverse osmosis scale inhibitor and a preparation method and application thereof. The reverse osmosis scale inhibitor is prepared from the following components in percentage by mass: 15 to 30 percent of polyepoxysuccinic acid, 10 to 25 percent of 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer, 5 to 15 percent of polyaspartic acid, 3 to 8 percent of dodecanedioic acid and the balance of deionized water. The reverse osmosis scale inhibitor has the beneficial effects that the strong polarity of the AMPS in the reverse osmosis scale inhibitor and the sulfonic acid group provide excellent dispersity and calcium ion tolerance; the PASP and the DDA enhance the chelation and lattice distortion effects; bTA provides copper material corrosion inhibition protection, and corrosion of metal parts of a membrane system is prevented; the PESA, the AMPS / HPA copolymer, the PASP and the DDA are synergistically compounded, so that the calcium sulfate scale inhibitor has ultrahigh inhibition capability on calcium sulfate scale, and the scale inhibition effect of the calcium sulfate scale inhibitor is far better than that of a single component; the preparation process of the reverse osmosis scale inhibitor is physical mixing, conditions are mild, high-temperature and high-pressure or complex polymerization reaction is not needed, energy consumption is low, and industrial production is easy to achieve.

Description

TECHNICAL FIELD

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

[0002] Reverse osmosis technology is one of the core processes of modern water treatment and is widely used in the fields of seawater desalination, brackish water desalination, industrial pure water and ultra-pure water preparation. During the operation of the reverse osmosis system, due to the continuous concentration of water, the concentration of the insoluble salt will exceed the solubility product and crystallize on the membrane surface to form scale, resulting in a decrease in water production, a decrease in desalination rate, an increase in operating pressure, and even irreversible damage to the expensive membrane element.

[0003] Among various scales, calcium sulfate (CaSO4) scale is particularly troublesome due to its low solubility, dense crystallization and hard texture. Once formed, conventional acid cleaning agents (such as citric acid and hydrochloric acid) cannot effectively remove it, and special cleaning agents or mechanical cleaning that may damage the membrane element are often required, increasing the cost and risk of operation and maintenance.

[0004] The commonly used scale inhibitors on the market, such as polyacrylic acid (PAA) and hydrolyzed polymaleic anhydride (HPMA), have good inhibitory effect on calcium carbonate scale, but have limited inhibitory effect on calcium sulfate scale. Although some organic phosphonates (such as HEDP and ATMP) have some effect on calcium sulfate, they have high phosphorus content, are easy to cause eutrophication of water bodies, and may become a source of nutrition for microorganisms, promoting biological pollution. In addition, the use of phosphorus-based scale inhibitors is restricted in areas where phosphorus emissions are strictly limited.

[0005] Therefore, it is of important industrial application value and market prospect to develop a high-efficiency, environmentally friendly, and phosphorus-free or low-phosphorus scale inhibitor specifically used to inhibit calcium sulfate scale in reverse osmosis systems. SUMMARY

[0006] The application provides a reverse osmosis scale inhibitor and a preparation method and application thereof, and aims to solve the problem that the existing scale inhibitors have limited inhibitory effect on calcium sulfate scale and are easy to cause eutrophication of water bodies.

[0007] The first aspect of the application provides a reverse osmosis scale inhibitor, which comprises the following components in mass percentage: 15%-30% of polyepoxysuccinic acid, 10%-25% of 2-acrylamide-2-methylpropanesulfonic acid / acrylic acid hydroxypropyl ester copolymer, 5%-15% of polyaspartic acid, 3%-8% of dodecanedioic acid, and the balance of deionized water.

[0008] The strong polarity and sulfonic acid group of AMPS in the reverse osmosis scale inhibitor described in the present application provide excellent dispersibility and calcium ion tolerance; PASP and DDA enhance the chelation and lattice distortion effect; BTA provides corrosion protection for copper materials, preventing corrosion of metal parts of the membrane system; the synergistic compounding of PESA, AMPS / HPA copolymer, PASP and DDA shows ultra-high inhibition capacity for calcium sulfate scale, far exceeding the scale inhibition effect of single component or conventional compounded products.

[0009] According to some embodiments of the reverse osmosis scale inhibitor described in the present application, the number average molecular weight of the 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is 3000-5000.

[0010] According to some embodiments of the reverse osmosis scale inhibitor described in the present application, the molar ratio of 2-acrylamide-2-methylpropanesulfonic acid and hydroxypropyl acrylate in the 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is (1-4):1.

[0011] According to some embodiments of the reverse osmosis scale inhibitor described in the present application, the pH of the reverse osmosis scale inhibitor is 6-8.

[0012] The second aspect of the present application provides a preparation method of a reverse osmosis scale inhibitor, comprising the following steps: mixing polyepoxysuccinic acid, 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer, polyaspartic acid, dodecanedioic acid and water, adjusting the pH to obtain the reverse osmosis scale inhibitor. The preparation process of the reverse osmosis scale inhibitor described in the present application is physical mixing, which is mild in conditions, does not require high temperature and pressure or complex polymerization reaction, has low energy consumption and is easy to realize industrialized production.

[0013] According to some embodiments of the preparation method of the reverse osmosis scale inhibitor described in the present application, the temperature of the mixing is 20-50°C, and the time of the mixing is 60-150 min.

[0014] According to some embodiments of the preparation method of the reverse osmosis scale inhibitor described in the present application, the method comprises the following steps: mixing polyepoxysuccinic acid, polyaspartic acid, dodecanedioic acid and water, adding 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer to the mixed solution and heating to 40-50°C, continuing to stir for 60-90 min; adjusting the pH to obtain the reverse osmosis scale inhibitor.

[0015] According to some embodiments of the preparation method of the reverse osmosis scale inhibitor described in the present application, sodium hydroxide is used to adjust the pH.

[0016] The third aspect of the present application provides a use of the reverse osmosis scale inhibitor described in the first aspect of the present application or obtained by the preparation method described in the second aspect of the present application in reverse osmosis water treatment.

[0017] According to some embodiments of the application described in this application, the reverse osmosis antiscalant is used in inhibiting calcium sulfate scaling in reverse osmosis water treatment.

[0018] According to some embodiments of the application described in this application, the amount of the reverse osmosis antiscalant added is 3-10 ppm.

[0019] The beneficial effects of this application include: the strong polarity and sulfonic acid groups of AMPS in the reverse osmosis antiscalant of this application provide excellent dispersibility and calcium ion tolerance; PASP and DDA enhance the chelation and lattice distortion effects; BTA provides corrosion protection for copper materials and prevents corrosion of metal components in the membrane system; the synergistic compounding of PESA, AMPS / HPA copolymer, PASP and DDA exhibits extremely high inhibition ability against calcium sulfate scale, far exceeding the scale inhibition effect of single components or conventional compound products.

[0020] The reverse osmosis antiscalant described in this application does not contain phosphorus, thus achieving the scale inhibition effect while avoiding eutrophication of water bodies, meeting environmental protection requirements, and having a wider range of applications. Furthermore, the components contained in the reverse osmosis antiscalant described in this application are all low molecular weight polymers or environmentally friendly chemicals, which are safe for mainstream reverse osmosis membrane materials such as polyamide composite membranes and will not cause degradation of membrane performance.

[0021] The reverse osmosis antiscalant described in this application is prepared by physical mixing under mild conditions, without the need for high temperature, high pressure or complex polymerization reactions, and has low energy consumption, making it easy to achieve industrial production. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0024] This application provides a reverse osmosis antiscalant, which, by mass percentage, comprises the following components: 15%-30% polyepoxysuccinic acid, 10%-25% 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer, 5%-15% polyaspartic acid, 3%-8% dodecanoic acid, and the balance being deionized water. The reverse osmosis antiscalant described in this application exhibits extremely high inhibition capacity against calcium sulfate scale (static inhibition rate can reach over 98%) through the synergistic compounding of polyepoxysuccinic acid, 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer, polyaspartic acid, and dodecanoic acid, far exceeding single-component or conventional compound products. Furthermore, the reverse osmosis antiscalant described in this application does not contain phosphorus, thus avoiding eutrophication of water bodies, meeting environmental protection requirements, and broadening its application range.

[0025] The components of the reverse osmosis antiscalant described in this application are all low molecular weight polymers or environmentally friendly chemicals, which are safe for mainstream reverse osmosis membrane materials such as polyamide composite membranes and will not cause degradation of membrane performance.

[0026] In some embodiments of this application, the number average molecular weight of the 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is 3000-5000.

[0027] The structural formula of the 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is:

[0028] Where: x:y:z=1:4:2.

[0029] In some embodiments of this application, the molar ratio of 2-acrylamide-2-methylpropanesulfonic acid to hydroxypropyl acrylate in the 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is (1-4):1, for example, 1:1, 2:1, 3:1, 4:1, etc. The strong polarity and sulfonic acid groups of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) provide excellent dispersibility and calcium ion tolerance.

[0030] In some embodiments of this application, the pH of the reverse osmosis antiscalant is 6-8, such as 6, 7, 8, etc.

[0031] This application embodiment also provides a method for preparing the reverse osmosis antiscalant described in the first aspect of this application, comprising the following steps: mixing polyepoxysuccinic acid, 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer, polyaspartic acid, dodecanoic acid, benzotriazole and water, adjusting the pH to obtain the reverse osmosis antiscalant.

[0032] In some embodiments of this application, the mixing temperature is 20-50°C, such as 20°C, 25°C, 30°C, 35°C, 43°C, 50°C, etc., and the mixing time is 60-150 min, such as 60 min, 80 min, 100 min, 120 min, 126 min, 133 min, 146 min, 150 min, etc.

[0033] In some embodiments of this application, polyepoxysuccinic acid, polyaspartic acid, dodecanoic acid, and water are mixed. 2-Acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is added to the mixture, and the temperature is raised to 40-50°C, with stirring continued for 60-90 minutes. After the resulting material cools to 20-30°C, benzotriazole is added, and the mixture is stirred to obtain the reverse osmosis antiscalant. The preparation method of the reverse osmosis antiscalant described in this application is a physical mixing method with mild conditions, requiring no high temperature, high pressure, or complex polymerization reactions. It has low energy consumption and is easy to implement for industrial production.

[0034] In some embodiments of this application, sodium hydroxide is used to adjust the pH.

[0035] This application also provides an application of the reverse osmosis antiscalant described in the first aspect of this application or the reverse osmosis antiscalant obtained by the preparation method described in the second aspect of this application in reverse osmosis water treatment.

[0036] In some embodiments of this application, the reverse osmosis antiscalant is used to inhibit calcium sulfate scaling in reverse osmosis water treatment.

[0037] In some embodiments of this application, the amount of the reverse osmosis antiscalant added is 3-10 ppm, such as 3 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, 10 ppm, etc.

[0038] The technical solution of this application will be further described below with reference to specific embodiments.

[0039] Example 1 A method for preparing a reverse osmosis antiscalant includes the following steps: At 25°C, 250g of deionized water was added to a 500mL glass reactor equipped with a stirrer. Stirring was started (150rpm), and 100g of polyepoxysuccinic acid (PESA), 50g of polyaspartic acid (PASP), and 25g of dodecanoic acid (DDA) were added sequentially, stirring for 15 minutes after each addition. Then, 90g of 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer (AMPS / HPA) was added. The water bath temperature was raised to 45°C, the stirring speed was increased to 350rpm, and the mixture was stirred at a constant temperature for 80 minutes. Heating was stopped, and the mixture was cooled to room temperature. The remaining deionized water was added to bring the total mass to 500g, and the pH was adjusted to 7 using sodium hydroxide. The mixture was then filtered through a 1μm filter bag to obtain the reverse osmosis antiscalant.

[0040] The mass percentage of PESA is 20%, the mass percentage of AMPS / HPA copolymer (number average molecular weight of about 6000, AMPS:HPA=3:1) is 18%, the mass percentage of PASP is 10%, the mass percentage of DDA is 5%, and the mass percentage of deionized water is 47%.

[0041] Example 2 The only difference between the preparation method of the reverse osmosis antiscalant in Example 2 and that in Example 1 is that the amount of polyepoxysuccinic acid and polyaspartic acid added during the preparation of the reverse osmosis antiscalant in Example 2 is different from that in Example 1.

[0042] The specific operating steps include: At 25°C, 250g of deionized water was added to a 500mL glass reactor equipped with a stirrer. Stirring was started (150rpm), and 125g of polyepoxysuccinic acid (PESA), 40g of polyaspartic acid (PASP), and 25g of dodecanoic acid (DDA) were added sequentially, stirring for 15 minutes after each addition. Then, 90g of 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer (AMPS / HPA) was added. The water bath temperature was raised to 45°C, the stirring speed was increased to 350rpm, and the mixture was stirred at a constant temperature for 80 minutes. Heating was stopped, and the mixture was cooled to room temperature. The remaining deionized water was added to bring the total mass to 500g, and the pH was adjusted to 7 using sodium hydroxide. The mixture was then filtered through a 1μm filter bag to obtain the reverse osmosis antiscalant.

[0043] The mass percentage of PESA is 25%, the mass percentage of AMPS / HPA copolymer (number average molecular weight of about 6000, AMPS:HPA=3:1) is 18%, the mass percentage of PASP is 8%, the mass percentage of DDA is 5%, and the mass percentage of deionized water is 44%.

[0044] Comparative Example 1 The only difference between the preparation method of the reverse osmosis antiscalant in Comparative Example 1 and Example 1 is that aminotrimethylphosphonic acid (ATMP) is used instead of polyepoxysuccinic acid (PESA) in the preparation process of the reverse osmosis antiscalant in Comparative Example 1.

[0045] The specific operating steps include: At 25°C, 250g of deionized water was added to a 500mL glass reactor equipped with a stirrer. Stirring was started (150rpm), and 100g of aminotrimethylphosphonic acid (ATMP), 50g of polyaspartic acid (PASP), and 25g of dodecanoic acid (DDA) were added sequentially, stirring for 15 minutes after each addition. Then, 90g of 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer (AMPS / HPA) was added. The water bath temperature was raised to 45°C, the stirring speed was increased to 350rpm, and the mixture was stirred at a constant temperature for 80 minutes. Heating was stopped, and the mixture was cooled to room temperature. The remaining deionized water was added to bring the total mass to 500g, and the pH was adjusted to 7 using sodium hydroxide. The mixture was then filtered through a 1μm filter bag to obtain the reverse osmosis antiscalant.

[0046] Comparative Example 2 The only difference between the preparation method of the reverse osmosis antiscalant in Comparative Example 2 and that in Example 1 is that hydroxyethylidene diphosphate (HEDP) is used instead of polyaspartic acid (PASP) in the preparation process of the reverse osmosis antiscalant in Comparative Example 2.

[0047] The specific operating steps include: At 25°C, 250g of deionized water was added to a 500mL glass reactor equipped with a stirrer. Stirring was started (150rpm), and 100g of polyepoxysuccinic acid (PESA), 50g of hydroxyethylidene diphosphate (HEDP), and 25g of dodecanoic acid (DDA) were added sequentially, stirring for 15 minutes after each addition. Then, 90g of 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer (AMPS / HPA) was added. The water bath temperature was raised to 45°C, the stirring speed was increased to 350rpm, and the mixture was stirred at a constant temperature for 80 minutes. Heating was stopped, and the mixture was cooled to room temperature. The remaining deionized water was added to bring the total mass to 500g, and the pH was adjusted to 7 using sodium hydroxide. The mixture was then filtered through a 1μm filter bag to obtain the reverse osmosis antiscalant.

[0048] Comparative Example 3 The only difference between the preparation method of the reverse osmosis antiscalant in Comparative Example 3 and Example 1 is that the raw material polyepoxysuccinic acid (PESA) was not used in the preparation process of the reverse osmosis antiscalant in Comparative Example 3.

[0049] The specific operating steps include: At 25°C, 250g of deionized water was added to a 500mL glass reactor equipped with a stirrer. Stirring was started (150rpm), and 50g of polyaspartic acid (PASP) and 25g of dodecanoic acid (DDA) were added sequentially, stirring for 15 minutes after each addition. Then, 90g of 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer (AMPS / HPA) was added. The water bath temperature was raised to 45°C, the stirring speed was increased to 350rpm, and the mixture was stirred at a constant temperature for 80 minutes. Heating was stopped, and the mixture was cooled to room temperature. The remaining deionized water was added to bring the total mass to 500g, and the pH was adjusted to 7 using sodium hydroxide. The mixture was then filtered through a 1μm filter bag to obtain the reverse osmosis antiscalant.

[0050] Comparative Example 4 The only difference between the preparation method of the reverse osmosis antiscalant in Comparative Example 4 and Example 1 is that polyaspartic acid (PASP) was not used in the preparation process of the reverse osmosis antiscalant in Comparative Example 4.

[0051] The specific operating steps include: At 25°C, 250g of deionized water was added to a 500mL glass reactor equipped with a stirrer. Stirring was started (150rpm), and 100g of polyepoxysuccinic acid (PESA) and 25g of dodecanoic acid (DDA) were added sequentially, stirring for 15 minutes after each addition. Then, 90g of 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer (AMPS / HPA) was added. The water bath temperature was raised to 45°C, the stirring speed was increased to 350rpm, and the mixture was stirred at a constant temperature for 80 minutes. Heating was stopped, and the mixture was cooled to room temperature. The remaining deionized water was added to bring the total mass to 500g, and the pH was adjusted to 7 using sodium hydroxide. The mixture was then filtered through a 1μm filter bag to obtain the reverse osmosis antiscalant.

[0052] Performance Study of the Reverse Osmosis Antiscalant Descaling Agents Described in Examples 1-2 and Comparative Examples 1-4 of this Application Test method: Static scale inhibition rate test Referring to the principle of GB / T 16632-2019 "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Carbonate Deposition Method", the test scale sample was changed to calcium sulfate. A calcium-rich solution was prepared. 2+ and SO4 2- The test water sample ([Ca 2+ ] = 6800 mg / L, [SO4 2- [7000 mg / L]. The reaction was carried out at a constant temperature of 60℃ for 10 hours. The scale inhibition rate η was calculated by measuring the change in calcium ion concentration in the solution after the reaction. η = (C2-C0) / (C1-C0) × 100% Wherein, C0 is the calcium ion concentration after the blank test (the blank test refers to the test without the addition of reverse osmosis antiscalant), C1 is the calcium ion concentration before the test, and C2 is the calcium ion concentration after the test with the reverse osmosis antiscalant described in Examples 1-2 or Comparative Examples 1-4 of this application. The test results are shown in Table 1: Table 1

[0053] As can be seen from Table 1, the reverse osmosis antiscalant described in this application exhibits significant scale inhibition effects at extremely low dosages (3-5 ppm), demonstrating both high efficiency and economy. Furthermore, a comparison of Example 1 and Comparative Examples 1-4 shows that only a combination of PESA and PASP as base agents can achieve better calcium sulfate scale inhibition effects.

[0054] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A reverse osmosis antiscalant, characterized in that, By weight percentage, it comprises the following components: 15%-30% polyepoxysuccinic acid, 10%-25% 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer, 5%-15% polyaspartic acid, 3%-8% dodecanoic acid, and the balance being deionized water.

2. The reverse osmosis antiscalant according to claim 1, characterized in that, The number-average molecular weight of the 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is 3000-5000. And / or, the molar ratio of 2-acrylamide-2-methylpropanesulfonic acid to hydroxypropyl acrylate in the 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is (1-4):

1.

3. The reverse osmosis antiscalant according to claim 1, characterized in that, The pH of the reverse osmosis antiscalant is 6-8.

4. A method for preparing the reverse osmosis antiscalant according to any one of claims 1-3, characterized in that, Includes the following steps: Polyepoxysuccinic acid, 2-acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer, polyaspartic acid, dodecanoic acid and water are mixed and the pH is adjusted to obtain the reverse osmosis antiscalant.

5. The method for preparing the reverse osmosis antiscalant according to claim 4, characterized in that, The mixing temperature is 20-50℃, and the mixing time is 60-150 min.

6. The method for preparing the reverse osmosis antiscalant according to claim 4, characterized in that, Includes the following steps: Polyepoxysuccinic acid, polyaspartic acid, dodecanoic acid and water are mixed. 2-Acrylamide-2-methylpropanesulfonic acid / hydroxypropyl acrylate copolymer is added to the mixture and the temperature is raised to 40-50℃. Stirring is continued for 60-90 min. The pH is adjusted to obtain the reverse osmosis antiscalant.

7. The method for preparing the reverse osmosis antiscalant according to claim 4, characterized in that, Sodium hydroxide was used to adjust the pH.

8. The application of the reverse osmosis antiscalant according to any one of claims 1-3 or the reverse osmosis antiscalant obtained by the preparation method according to any one of claims 4-7 in reverse osmosis water treatment.

9. The application according to claim 8, characterized in that, The reverse osmosis antiscalant is used to inhibit calcium sulfate scaling in reverse osmosis water treatment.

10. The application according to claim 8, characterized in that, The amount of the reverse osmosis antiscalant added is 3-10 ppm.

Images