Phosphorus-free reverse osmosis scale inhibitor and preparation method thereof

Abstract

The invention discloses a non-phosphorus reverse osmosis scale inhibitor and a preparation method thereof, and relates to the technical field of industrial water treatment.The non-phosphorus reverse osmosis scale inhibitor is prepared from, by weight, 10 parts of purified humic acid, 40-60 parts of alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer, 4-8 parts of sodium polyepoxysuccinate and 5-20 parts of water. Compared with the prior art, the scale inhibitor is high in environment-friendly compliance, excellent in scale inhibition performance, scientific and efficient in raw material treatment and high in product scale inhibition rate, meets the environment-friendly emission standard, and is suitable for reverse osmosis membrane scale inhibition treatment in the industries of electric power, chemical engineering, seawater desalination and the like.

Description

Technical Field

[0001] The invention relates to the technical field of industrial water treatment, in particular to a phosphorus-free reverse osmosis scale inhibitor and a preparation method thereof. Background Art

[0002] Amidst the growing global water shortage and increasing water pollution, reverse osmosis (RO) technology, with its high efficiency and stability, has become a core process for producing pure water in numerous industries, including the power, chemical, and seawater desalination sectors. A membrane-based water treatment technology that rapidly emerged in the late 20th century, RO utilizes its unique semipermeable membrane separation principle to efficiently remove inorganic salts, organic matter, and microorganisms from water. It demonstrates irreplaceable advantages in seawater desalination, brackish water desalination, industrial demineralized water production, and high-purity water production, and is widely recognized as one of the most effective water treatment technologies currently available.

[0003] However, there are two key technical problems in the operation of reverse osmosis process: First, the reverse osmosis process significantly concentrates raw water. For example, a two-stage reverse osmosis process typically maintains a water yield of around 75%. This means that for every 75 cubic meters of demineralized water produced, 100 cubic meters of raw water is consumed, and 25 cubic meters of concentrated brine is produced. Calculations show that the salt concentration in the concentrated brine is approximately four times that of the raw water. Based on the principles of the reverse osmosis process, the discharge of concentrated brine is unavoidable, placing pressure on subsequent treatment and the environment. Secondly, the country has established strict standards for phosphorus content in wastewater discharge. According to GB13456-2012, the "Integrated Wastewater Discharge Standard," the phosphorus content must be below 2.0 mg / L for indirect wastewater discharge and must not exceed 1.0 mg / L for direct wastewater discharge. Excessive phosphorus content can easily lead to eutrophication of water bodies, thereby disrupting the ecological balance. During reverse osmosis system operation, to prevent salt crystallization and clogging of the reverse osmosis membrane due to raw water concentration, a reverse osmosis scale inhibitor must be added to the influent (raw water). Due to the concentration effect of the reverse osmosis system, the phosphate content in the scale inhibitor is concentrated approximately fourfold, making the phosphorus content of the final brine discharge easily exceed national standards. Whether using indirect discharge (transfer to a sewage treatment plant) or direct discharge (discharge into external water bodies), compliance challenges are present.

[0004] Therefore, the research, development and application of new low-phosphorus or even phosphorus-free reverse osmosis scale inhibitors have become the key to solving a series of problems caused by phosphorus-containing scale inhibitors and promoting the sustainable development of reverse osmosis technology. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a phosphorus-free and environmentally friendly phosphorus-free reverse osmosis scale inhibitor and a preparation method thereof.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A phosphorus-free reverse osmosis scale inhibitor is composed of the following raw materials in parts by weight: 10 parts of purified humic acid, 40-60 parts of alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer, 4-8 parts of sodium polyepoxysuccinate, and 5-20 parts of water.

[0007] In the above technical solution, a more specific technical solution can also be that the purification method of the purified humic acid is to first filter the humic acid containing impurities ≤15% through a disc filter, and then filter it through an AFM active filter medium filter, and finally obtain purified humic acid with a purity ≥95%.

[0008] Furthermore: the filtration accuracy of the disc filter is at least 20 microns, and the filtration accuracy of the AFM active filter medium filter is ≤1 micron.

[0009] Furthermore, the simplified method for alkalizing the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is to first add the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer to a stirring tank; then dropwise add 30% sodium hydroxide solution to adjust the pH to 9.0-10.5; and finally continue stirring to ensure uniform dispersion.

[0010] Furthermore, the weight portion of the purified humic acid is 10 parts, the weight portion of the alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is 50 parts, the weight portion of the sodium polyepoxysuccinate is 6 parts, and the weight portion of the water is 15 parts.

[0011] Furthermore, the weight portion of the purified humic acid is 10 parts, the weight portion of the alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is 40 parts, the weight portion of the sodium polyepoxysuccinate is 4 parts, and the weight portion of the water is 20 parts.

[0012] Furthermore, the weight portion of the purified humic acid is 10 parts, the weight portion of the alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is 60 parts, the weight portion of the sodium polyepoxysuccinate is 8 parts, and the weight portion of the water is 5 parts.

[0013] In the above technical solution, the preparation method can be: premixing purified humic acid with water to form a homogeneous solution, and sequentially adding alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and sodium polyepoxysuccinate, with a stirring rate of ≥500 rpm and a mixing time of ≥1 hour.

[0014] This technical solution uses humic acid instead of phosphorus-based scale inhibitors, purifies the humic acid, and cooperates with acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and polyepoxysuccinic acid to prevent the formation of scale in the water on the reverse osmosis membrane.

[0015] Humic acid is a natural organic macromolecular substance, a hybrid compound, which contains abundant functional groups such as carboxyl, phenolic hydroxyl, carbonyl, etc. It can react with calcium (Ca 2+ ), magnesium (Mg 2+ ), iron (Fe 3+ ) and other metal ions to form stable complexes. This chelation can effectively reduce the concentration of free metal ions, thereby reducing their interaction with carbonate (CO3 2- ), sulfate (SO4 2- ) and other anions to form insoluble salts, such as CaCO3 and CaSO4, to achieve sufficient efficiency.

[0016] Before compounding acrylic acid-succinimide-hydroxypropyl methacrylate copolymer with sodium humate, it needs to be alkalized. That is, by adding sodium hydroxide solution, the acidic acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is alkalized to an alkaline agent with a pH value of approximately 9-10.5. The purposes include the following aspects: Enhance the dispersion stability of the agent: Alkaline conditions (higher pH) can fully dissociate the functional groups of the agent (such as carboxylic acid groups, etc.), forming a stronger negatively charged surface. These charges prevent the aggregation of particles such as CaCO3 and CaSO4 through electrostatic repulsion, thereby improving the dispersion effect. In an alkaline environment, the molecular chain segments stretch more fully, forming a spatial barrier through physical adsorption, preventing the collision and combination of particles, and more effectively dispersing the particles in the water.

[0017] Inhibit acidic bacteria: The sodium humate compounded with it is a natural organic macromolecular substance, which is very easy to grow bacteria, causing the liquid to spoil and deteriorate. The alkaline environment is not conducive to the reproduction of acidophilic microorganisms such as sulfate-reducing bacteria (SRB), thus ensuring the long-term effectiveness of the liquid.

[0018] Improve the compatibility of pharmaceuticals: stabilize the formula system. Alkalinization treatment can adjust the compatibility of acrylic acid-succinimide-hydroxypropyl methacrylate copolymer with other water stabilizers such as sodium humate and sodium epoxysuccinate, avoiding precipitation or failure due to pH conflict.

[0019] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. Strong environmental compliance: This scale inhibitor contains no phosphate ingredients at all, which eliminates the problem of excessive phosphorus content in drainage due to the concentration of scale inhibitors from the source. It can strictly meet the requirements of GB13456-2012 "Iron and Steel Industry Water Pollutant Discharge Standard" that the indirect discharge phosphorus content is less than 2.0 mg / L and the direct discharge phosphorus content is 1.0 mg / L, effectively avoiding the risk of eutrophication of water bodies, greatly reducing pollution to the ecological environment, and complying with the national environmental protection policy orientation.

[0020] 2. Excellent scale inhibition performance: The synergistic effect of the alkalinized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer, sodium polyepoxysuccinate and other ingredients in the raw materials can effectively inhibit the salt crystallization caused by the concentration of raw water during the reverse osmosis process, and prevent the reverse osmosis membrane from being blocked by scale. At the same time, the addition of purified humic acid further enhances the dispersion performance, which can better disperse impurities and salts in the water, significantly improve the operational stability and water production efficiency of the reverse osmosis system, and extend the service life of the reverse osmosis membrane.

[0021] 3. Scientific and efficient raw material processing: Humic acid is purified using a combination of a disc filter (filtration accuracy of at least 20 microns) and an AFM active filter medium filter (filtration accuracy ≤1 micron). This method can effectively remove impurities from humic acid, increasing its purity from an initial impurity content of ≤15% to ≥95%, ensuring the purity of the raw materials and, in turn, the stable and reliable quality of the scale inhibitor product. The preparation method of the alkalinized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is simple to operate. By adjusting the pH to 9.0-10.5 and stirring thoroughly, the copolymer can be evenly dispersed, ensuring uniform performance of the scale inhibitor and facilitating large-scale industrial production. DETAILED DESCRIPTION

[0022] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0023] Example 1 - Preparation method of a phosphorus-free reverse osmosis scale inhibitor The preparation method comprises the following steps: 10 parts of purified humic acid and 15 parts of water were premixed to form a homogeneous solution, and 50 parts of alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and 6 parts of sodium polyepoxysuccinate were added in sequence. The mixture was stirred with a stirrer at a stirring rate of ≥500 rpm and a mixing time of ≥1 hour to obtain a phosphorus-free reverse osmosis scale inhibitor.

[0024] Among them, the purification method of purifying humic acid is to first filter the humic acid containing impurities ≤15% through a disc filter with a filtration accuracy of at least 20 microns, and then filter it through an AFM active filter medium filter with a filtration accuracy of ≤1 micron, and finally obtain purified humic acid with a purity ≥95%; the simplified method of alkalizing the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is to first add the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer to a stirring tank; then add 30% sodium hydroxide solution dropwise to adjust the pH to 9.0-10.5; and finally continue stirring to ensure uniform dispersion.

[0025] The phosphorus-free reverse osmosis scale inhibitor prepared in this example was added to the discharge water, and the phosphorus content of the discharge water was detected and no phosphorus content was detected.

[0026] Example 2 - Preparation method of a phosphorus-free reverse osmosis scale inhibitor The preparation method comprises the following steps: 10 parts of purified humic acid and 20 parts of water were premixed to form a homogeneous solution, and 40 parts of alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and 4 parts of sodium polyepoxysuccinate were added in sequence. The mixture was stirred with a stirrer at a stirring rate of ≥500 rpm and a mixing time of ≥1 hour to obtain a phosphorus-free reverse osmosis scale inhibitor.

[0027] Among them, the purification method of purifying humic acid is to first filter the humic acid containing impurities ≤15% through a disc filter with a filtration accuracy of at least 20 microns, and then filter it through an AFM active filter medium filter with a filtration accuracy of ≤1 micron, and finally obtain purified humic acid with a purity ≥95%; the simplified method of alkalizing the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is to first add the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer to a stirring tank; then add 30% sodium hydroxide solution dropwise to adjust the pH to 9.0-10.5; and finally continue stirring to ensure uniform dispersion.

[0028] The phosphorus-free reverse osmosis scale inhibitor prepared in this example was added to the discharge water, and the phosphorus content of the discharge water was detected and no phosphorus content was detected.

[0029] Example 3 - Preparation method of a phosphorus-free reverse osmosis scale inhibitor The preparation method comprises the following steps: 10 parts of purified humic acid and 5 parts of water were premixed to form a homogeneous solution, and 60 parts of alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and 8 parts of sodium polyepoxysuccinate were added in sequence. The mixture was stirred with a stirrer at a stirring rate of ≥500 rpm and a mixing time of ≥1 hour to obtain a phosphorus-free reverse osmosis scale inhibitor.

[0030] Among them, the purification method of purifying humic acid is to first filter the humic acid containing impurities ≤15% through a disc filter with a filtration accuracy of at least 20 microns, and then filter it through an AFM active filter medium filter with a filtration accuracy of ≤1 micron, and finally obtain purified humic acid with a purity ≥95%; the simplified method of alkalizing the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is to first add the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer to a stirring tank; then add 30% sodium hydroxide solution dropwise to adjust the pH to 9.0-10.5; and finally continue stirring to ensure uniform dispersion.

[0031] The phosphorus-free reverse osmosis scale inhibitor prepared in this example was added to the discharge water, and the phosphorus content of the discharge water was detected and no phosphorus content was detected.

[0032] Comparative Example 1 - Preparation Method of a Phosphate-Free Reverse Osmosis Antiscalant This comparative example is a comparative example of Example 1. The difference from Example 1 is that humic acid was not purified, and the other raw materials, weight parts, and preparation processes were the same.

[0033] The preparation method comprises the following steps: 10 parts of unpurified humic acid and 15 parts of water were premixed to form a homogeneous solution, and 50 parts of alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and 6 parts of sodium polyepoxysuccinate were added in sequence. The mixture was stirred with a stirrer at a stirring rate of ≥500 rpm and a mixing time of ≥1 hour to obtain a phosphorus-free reverse osmosis scale inhibitor.

[0034] Among them, the simplified method of alkalizing the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is to first add the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer into a stirring tank; then add 30% sodium hydroxide solution dropwise to adjust the pH to 9.0-10.5; and finally continue stirring to ensure uniform dispersion.

[0035] The phosphorus-free reverse osmosis scale inhibitor prepared in this example was added to the discharge water, and the phosphorus content of the discharge water was detected and no phosphorus content was detected.

[0036] Comparative Example 2 - Preparation Method of a Phosphorus-Free Reverse Osmosis Antiscalant This comparative example is a comparative example of Example 1. The difference from Example 1 is that the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is not alkalized, and the remaining raw materials, weight parts, and preparation process are the same.

[0037] The preparation method comprises the following steps: 10 parts of purified humic acid and 15 parts of water were premixed to form a homogeneous solution, and 50 parts of unalkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and 6 parts of sodium polyepoxysuccinate were added in sequence. The mixture was stirred with a stirrer at a stirring rate of ≥500 rpm and a mixing time of ≥1 hour to obtain a phosphorus-free reverse osmosis scale inhibitor.

[0038] Among them, the purification method of purifying humic acid is to first filter the humic acid containing impurities ≤15% through a disc filter with a filtration accuracy of at least 20 microns, and then filter it through an AFM active filter medium filter with a filtration accuracy of ≤1 micron, and finally obtain purified humic acid with a purity of ≥95%.

[0039] The phosphorus-free reverse osmosis scale inhibitor prepared in this example was added to the discharge water, and the phosphorus content of the discharge water was detected and no phosphorus content was detected.

[0040] Reverse osmosis antiscalant adequate performance test This experiment is a scale inhibition performance test of reverse osmosis scale inhibitors. The static scale inhibition performance test was conducted on the phosphorus-free reverse osmosis scale inhibitors of Examples 1-3 and Comparative Examples 1-2. Referring to the method of GB / T 16632-2019 "Measurement Method for Scale Inhibition Performance of Water Treatment Agents", in the calcium carbonate scale inhibition test, Ca 2+ =250mg / L, HCO3 - =250mg / L, in the calcium sulfate scale inhibition experiment, Ca 2+ =500mg / L, SO4 - =500mg / L. The experimental temperature is 80℃, the time is 10 hours, and the concentration of the reagent is 5mg / L. By comparing the Ca 2+ After adding the scale inhibitor, Ca 2+ The higher the mass concentration, the better the scale inhibition performance.

[0041] The results of the scale inhibition performance test are shown in the following table: Table 1

[0042] Comparative Example 1 uses unpurified humic acid, which contains 15% or more impurities (such as clay, metal ions, and organic matter). These impurities can directly affect the synergistic effect of the scale inhibitor's core ingredients. These impurities may chemically react with ingredients like the alkalinized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and sodium polyepoxysuccinate, weakening their calcium ion chelation ability and salt crystallization inhibition. This accelerates scale deposition on the reverse osmosis membrane surface, significantly reducing the scale inhibitor's ability to disperse crystals of calcium carbonate and calcium sulfate, shortening the reverse osmosis membrane cleaning cycle and affecting the system's water production efficiency.

[0043] Comparative Example 2 uses an unalkalinized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer. The unalkalinized copolymer has no carboxyl groups (-COOH) in its molecular structure that are not converted into carboxylate ions (-CO - ), its dissociation capacity in water is significantly reduced, which leads to a weakening of its chelating ability for calcium and magnesium ions. The carboxylate ion formed after the dissociation of the carboxyl group is a key group for chelating metal ions. When not alkalized, the copolymer has difficulty dispersing calcium carbonate, calcium sulfate and other crystals in the water through electrostatic repulsion, and it cannot effectively inhibit the crystallization of salt. At the concentrate end of the reverse osmosis system, the unalkalized copolymer has a certain degree of reduction in its chelating capacity for calcium and magnesium ions, making it easier for hard scale to form on the membrane surface, which in turn accelerates the rate of decline of the water flux of the reverse osmosis system and shortens the desalination rate decay period.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A phosphorus-free reverse osmosis scale inhibitor, characterized in that The invention is composed of the following raw materials in parts by weight: 10 parts of purified humic acid, 40-60 parts of alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer, 4-8 parts of sodium polyepoxysuccinate, and 5-20 parts of water.

2. The phosphorus-free reverse osmosis scale inhibitor according to claim 1, characterized in that: The purification method of the purified humic acid comprises the following steps: first filtering the humic acid containing impurities ≤15% through a disc filter, then filtering through an AFM active filter medium filter, and finally obtaining purified humic acid with a purity ≥95%.

3. The phosphorus-free reverse osmosis scale inhibitor according to claim 2, characterized in that: The filtration accuracy of the disc filter is at least 20 microns, and the filtration accuracy of the AFM active filter medium filter is ≤1 micron.

4. The phosphorus-free reverse osmosis scale inhibitor according to claim 1, 2 or 3, characterized in that: The simplified method for alkalizing the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is as follows: first, add the acrylic acid-succinimide-hydroxypropyl methacrylate copolymer into a stirring tank; then, dropwise add 30% sodium hydroxide solution to adjust the pH to 9.0-10.5; and finally, continue stirring to ensure uniform dispersion.

5. The phosphorus-free reverse osmosis scale inhibitor according to claim 4, characterized in that: The weight portion of the purified humic acid is 10 parts, the weight portion of the alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is 50 parts, the weight portion of the sodium polyepoxysuccinate is 6 parts, and the weight portion of the water is 15 parts.

6. The phosphorus-free reverse osmosis scale inhibitor according to claim 4, characterized in that: The weight portion of the purified humic acid is 10 parts, the weight portion of the alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is 40 parts, the weight portion of the sodium polyepoxysuccinate is 4 parts, and the weight portion of the water is 20 parts.

7. The phosphorus-free reverse osmosis scale inhibitor according to claim 4, characterized in that: The weight portion of the purified humic acid is 10 parts, the weight portion of the alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer is 60 parts, the weight portion of the sodium polyepoxysuccinate is 8 parts, and the weight portion of the water is 5 parts.

8. A method for preparing the phosphorus-free reverse osmosis scale inhibitor according to any one of claims 1 to 7, characterized in that: The method comprises: premixing purified humic acid with water to form a homogeneous solution, and sequentially adding alkalized acrylic acid-succinimide-hydroxypropyl methacrylate copolymer and sodium polyepoxysuccinate, with a stirring rate of ≥500 rpm and a mixing time of ≥1 hour.

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