Phosphorus-free scale inhibitor for water treatment and preparation method thereof

Abstract

This application relates to the technical field of scale inhibitors and specifically discloses a phosphorus-free scale inhibitor for water treatment and its preparation method. This application designs a scale-inhibiting copolymer as the main component of the phosphorus-free scale inhibitor and selects oxidized starch solution, amine additives, and emulsifiers for synergistic combination. The use of the scale inhibitor of this application not only avoids eutrophication of water bodies due to phosphorus, but also effectively prevents the accumulation of scale and slows the corrosion of metal pipes, fully meeting the scale inhibition requirements of industrial cooling water.

Description

Technical Field

[0001] The present application relates to the technical field of scale inhibitors, and more specifically, to a phosphorus-free scale inhibitor for water treatment and a preparation method thereof. Background Art

[0002] Water is essential for human survival. With the increase in population and the expansion of human activities, the demand for water continues to grow. Saving cooling water is the primary goal of industrial water use, and is of great significance from the perspectives of energy conservation, economy, and environmental protection. During the circulating cooling process of industrial cooling water, the carbon dioxide in the water is desorbed and dissipated due to heating, which causes calcium carbonate to form scale and precipitate on the heat transfer surface. Simultaneously, the evaporation of water causes the minerals in the water to continuously increase, and when they reach a certain level, insoluble salts precipitate. Furthermore, the growth of bacteria and algae in the cooling water forms precipitates, as well as precipitates caused by electrochemical corrosion. Consequently, the interior of the cooling water pipelines is often covered with precipitates.

[0003] At present, the prevention of scaling in cooling water systems can be summarized into three categories in principle: (1) eliminating the conditions for crystallization and reducing the concentration of scaling ions in the water to keep it within the allowable range; (2) adding acid or carbon dioxide to the circulating water to reduce the pH value and stabilize the balance of scaling ions in the water; (3) using scale inhibitors to destroy the crystal growth of scaling ions. Among them, adding scale inhibitors is the most commonly used method in actual operation. The more commonly used traditional scale inhibitors include inorganic phosphate scale inhibitors and organic phosphates. Common types of inorganic phosphates include sodium hexametaphosphate and sodium tripolyphosphate, and common types of organic phosphates include aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, etc.

[0004] Regarding the aforementioned technologies, while phosphorus-containing scale inhibitors offer good scale inhibition, the phosphorus in them can easily cause eutrophication. Existing phosphorus-free scale inhibitors, while not subject to this drawback, offer relatively poor scale inhibition, making them inadequate for industrial cooling water. Summary of the Invention

[0005] In the related art, the scale inhibition effect of phosphorus-free scale inhibitors is relatively poor, and it is difficult to fully meet the scale inhibition requirements of industrial cooling water. In order to improve this defect, the present application provides a phosphorus-free scale inhibitor for water treatment and a preparation method thereof.

[0006] In the first aspect, the present application provides a phosphorus-free scale inhibitor for water treatment, which adopts the following technical solution:

[0007] A phosphorus-free scale inhibitor for water treatment comprises the following components in parts by weight: 10-12 parts of a scale inhibition copolymer, 1.2-1.4 parts of an oxidized starch solution, 1.5-1.7 parts of an amine auxiliary agent, 8-10 parts of an emulsifier, and 68-74 parts of water. The scale inhibition copolymer is copolymerized with acrylic acid, allyl polyalkyloxy ammonium sulfonate, and a functional monomer, wherein the functional monomer comprises polysaccharide maleate and methacryloyloxyethyl trimethyl ammonium chloride.

[0008] By adopting the above technical solution, the present application designs a scale-inhibiting copolymer as the main component of a phosphorus-free scale inhibitor, and selects oxidized starch liquid, amine additives and emulsifiers for synergistic combination. In the scale-inhibiting copolymer, the carboxyl group introduced by acrylic acid and the sulfonic acid group introduced by allyl polyalkoxy ammonium sulfonate jointly chelate calcium and magnesium ions to form a stable soluble multi-chelate ring, which reduces the concentration of free calcium and magnesium ions in water and inhibits the further growth of scale. Allyl polyalkoxy ammonium sulfonate can also increase the length of the side chain through the polyether segment. At the same time, the sulfonic acid group also improves the water solubility of the copolymer, so that the scale-inhibiting copolymer can fully extend in water, which is conducive to full combination with calcium and magnesium ions. The polysaccharide maleate in the functional monomer can introduce a large number of hydroxyl groups into the copolymer, and the oxidized starch in the oxidized starch liquid also has a large number of hydrophilic groups. These hydrophilic groups can form hydrogen bonds with oxygen-containing acid anions in water, hindering the combination of calcium and magnesium ions with oxygen-containing acid anions. The quaternary ammonium salt group introduced by methacryloyloxyethyl trimethylammonium chloride has a wetting and corrosion-inhibiting effect, which can increase the adsorption of the scale-inhibiting copolymer, making it easier to adsorb on the metal surface, thereby hindering the growth of scale. Amine additives have an affinity for metals and can form a smooth protective film on the inner wall surface of the pipe together with the scale-inhibiting copolymer, isolating the contact of dissolved oxygen and ions in the water with the metal, thereby playing a role in slowing down metal corrosion. By using the scale inhibitor of the present application, not only can the eutrophication of water bodies caused by phosphorus be avoided, but the accumulation of scale can also be effectively prevented, and the corrosion of metal pipes can also be slowed down, which can fully meet the scale inhibition needs of industrial cooling water.

[0009] Preferably, the molar ratio of acrylic acid, allyl polyalkyloxy ammonium sulfonate and functional monomer is 3:(2-3):(1-2).

[0010] By adopting the above technical solution, the present application optimizes the molar ratio of the three monomers, and the scale-inhibiting copolymer can be prepared within the above range.

[0011] Preferably, the scale inhibition copolymer is prepared according to the following method:

[0012] (1) adding acrylic acid, allyl polyalkyloxy ammonium sulfonate and functional monomer into water and mixing to obtain a monomer mixture, which is kept warm for later use; mixing water and a telogen to obtain a base solution, which is kept warm for later use;

[0013] (2) Adding the monomer mixture and the initiator to the base liquid under nitrogen protection and heating the mixture; after all the monomer mixture is added, increasing the heating temperature to continue the reaction; after the reaction is completed, stopping the heating, cooling to room temperature and discharging the mixture to obtain a scale-inhibiting copolymer;

[0014] By adopting the above technical solution, the present application first prepares a monomer mixture and a base liquid, then adds a monomer mixture and an initiator to the base liquid, initiates a copolymerization reaction between the monomers under heating conditions, and obtains a scale-inhibiting copolymer.

[0015] Preferably, the polysaccharide maleate is prepared according to the following method:

[0016] Hemicellulose and lithium chloride are added to DMF, heated and stirred until the hemicellulose and lithium chloride are completely dissolved, then the heating temperature is lowered, bromosuccinimide and maleic anhydride are added and the reaction is continued until the acid value is constant. After the reaction is completed, the product is washed with ethanol and the remaining product is vacuum dried to obtain polysaccharide maleate.

[0017] By adopting the above technical solution, the present application esterifies hemicellulose with maleic anhydride to obtain hemicellulose maleate containing a large number of carboxyl groups and double bonds at the end. Hemicellulose maleate can fully participate in the complexation of calcium and magnesium ions and also participate in copolymerization reactions, thereby enhancing the scale inhibition effect of the scale inhibitor.

[0018] Preferably, in the method for preparing the polysaccharide maleate, the amount of bromosuccinimide used is 3.5-4.5% of the total weight of hemicellulose and maleic anhydride.

[0019] By adopting the above technical solution, the present application optimizes the dosage of bromosuccinimide, which helps to increase the number of branched carboxyl groups in the hemicellulose maleate molecule, thereby improving the hydrophilicity of the hemicellulose maleate and enhancing the scale inhibition effect of the scale inhibitor.

[0020] Preferably, in the method for preparing the polysaccharide maleate, the reaction temperature is 50-60°C.

[0021] By adopting the above technical solution, the present application optimizes the reaction temperature, which helps to increase the number of branched carboxyl groups in the hemicellulose maleate molecule, thereby improving the hydrophilicity of the hemicellulose maleate and enhancing the scale inhibition effect of the scale inhibitor.

[0022] Preferably, in the method for preparing the polysaccharide maleate, β-cyclodextrin and hemicellulose are used as raw materials.

[0023] By adopting the above technical solution, the present application preferably uses β-cyclodextrin as the raw material for preparing polysaccharide maleate, so that the product contains a portion of cyclodextrin maleate. Cyclodextrin maleate can introduce cyclodextrin cavities into the scale-inhibiting copolymer, which can cause lattice distortion during the crystal growth of calcium carbonate, slowing down the growth rate of scaling, and the carboxyl groups in cyclodextrin maleate can also participate in the complexation of calcium and magnesium ions, thereby helping to enhance the scale inhibition effect of the scale inhibitor.

[0024] Preferably, the amine auxiliary agent includes silylated polyethyleneimine, which is prepared according to the following method:

[0025] (1) adding polyethyleneimine to methanol to dissolve it to obtain a polyethyleneimine solution for later use;

[0026] (2) Adding a silane coupling agent, 1-chlorooctane and a phase transfer catalyst to a polyethyleneimine solution, stirring the solution under heating conditions in a water bath, adding a sodium hydroxide solution during the stirring process to continue the reaction, and obtaining silylated polyethyleneimine after the reaction is completed.

[0027] By adopting the above technical solution, the present application modified polyethyleneimine with a silane coupling agent to obtain silanized polyethyleneimine. Silylated polyethyleneimine has strong dispersibility and adsorption properties, as well as high steric hindrance. After hydrophobic modification, it also carries a certain amount of negative charge, exhibiting excellent scale inhibition and dispersion properties. It can fully improve the scale inhibition performance of the scale inhibitor through synergistic action with the scale inhibition copolymer.

[0028] Preferably, the silane coupling agent includes at least one of dodecyltriethoxysilane and phenyltriethoxysilane.

[0029] By adopting the above technical solution, the present application optimizes the type of silane coupling agent and introduces dodecyl and phenyl groups, which can improve the hydrophobicity of silanized polyethyleneimine and enhance the steric hindrance of silanized polyethyleneimine, which helps to improve the scale inhibition performance of the scale inhibitor.

[0030] In a second aspect, the present application provides a method for preparing a phosphorus-free scale inhibitor for water treatment, which adopts the following technical solution.

[0031] A method for preparing a phosphorus-free scale inhibitor for water treatment comprises the following steps:

[0032] (1) mixing an amine auxiliary agent, an emulsifier and water and stirring to obtain an emulsion for standby use;

[0033] (2) adding the scale-inhibiting copolymer and the oxidized starch solution into the emulsion and stirring and dispersing them to obtain a phosphorus-free scale inhibitor for water treatment.

[0034] By adopting the above technical solution, the present application first prepares an emulsifier containing an amine auxiliary agent, then adds a scale-inhibiting copolymer and an oxidized starch solution, and obtains a phosphorus-free scale inhibitor after stirring and dispersing.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. This application designs a scale-inhibiting copolymer as the primary component of a phosphorus-free scale inhibitor, and uses oxidized starch solution, an amine additive, and an emulsifier in synergistic combination. This scale inhibitor not only avoids phosphorus-induced eutrophication of water bodies, but also effectively prevents scale accumulation and slows corrosion of metal pipes, fully meeting the scale-inhibiting requirements of industrial cooling water.

[0037] 2. In the scale-inhibiting copolymer of the present application, the carboxyl group introduced by acrylic acid and the sulfonic acid group introduced by allyl polyalkyloxy ammonium sulfonate jointly chelate calcium and magnesium ions to form a stable soluble multi-chelate ring, thereby reducing the concentration of free calcium and magnesium ions in water and inhibiting the further growth of scale.

[0038] 3. In the scale-inhibiting copolymer of the present application, allyl polyalkoxy ammonium sulfonate can also increase the length of the side chain through the polyether segment. At the same time, the sulfonic acid group also improves the water solubility of the copolymer, so that the scale-inhibiting copolymer can fully stretch in water, which is conducive to full combination with calcium and magnesium ions. DETAILED DESCRIPTION

[0039] The present application is further described in detail below with reference to the Examples, Preparation Examples and Comparative Examples. The raw materials involved in the present application can all be obtained commercially.

[0040] Preparation Example of Scale Inhibiting Copolymer

[0041] The following is an explanation using Preparation Example 1.

[0042] Preparation Example 1

[0043] In this preparation example, the allyl polyalkyloxy ammonium sulfonate is allyl polyethoxy ammonium sulfonate, wherein the polymerization degree of the polyethoxy group is n=7, and the functional monomer is prepared by mixing polysaccharide maleate and methacryloyloxyethyl trimethyl ammonium chloride in a weight ratio of 2:1.

[0044] Polysaccharide maleate was prepared as follows:

[0045] 10.2 g of hemicellulose and 34.5 g of lithium chloride were added to 200 mL of DMF, heated and stirred at 85° C. until the hemicellulose and lithium chloride were completely dissolved, then the heating temperature was reduced to 45° C., and bromosuccinimide and 70.8 g of maleic anhydride were added at this reaction temperature in an amount equivalent to 3% of the total weight of hemicellulose and maleic anhydride, and the reaction was continued until the acid value was constant. After the reaction was completed, the product was washed with 95% ethanol, and the remaining product after washing was vacuum dried to obtain polysaccharide maleate.

[0046] This preparation example provides a scale-inhibiting copolymer, which is prepared according to the following method:

[0047] (1) acrylic acid, allyl polyalkyloxy ammonium sulfonate (APES), and functional monomers were added to water in a weight ratio of 3:2:2 and mixed to obtain a monomer mixture with a solid content of 20 wt%, which was kept warm for later use; water and telogen isopropyl alcohol were mixed to obtain a base solution with a telogen content of 16%, which was kept warm for later use; in this step, the weight ratio of the base solution to the monomer mixture was 1:1;

[0048] (2) Adding the monomer mixture and the initiator to the base liquid under nitrogen protection and heating the mixture; after all the monomer mixture is added, increasing the heating temperature to continue the reaction; after the reaction is completed, stopping the heating, cooling to room temperature and discharging the mixture to obtain a scale-inhibiting copolymer;

[0049] As shown in Table 1, the difference between Preparation Examples 1-3 is that the weight ratios of acrylic acid, allyl polyalkyloxy ammonium sulfonate and functional monomer are different.

[0050] Table 1 Weight ratio of three monomers

[0051]

[0052]

[0053] Preparation Example 4

[0054] The difference between this preparation example and preparation example 3 is that, in the method for preparing polysaccharide maleate, the amount of bromosuccinimide used is equivalent to 3.5% of the total weight of hemicellulose and maleic anhydride.

[0055] Preparation Example 5

[0056] The difference between this preparation example and preparation example 3 is that, in the method for preparing polysaccharide maleate, the amount of bromosuccinimide used is equivalent to 4% of the total weight of hemicellulose and maleic anhydride.

[0057] Preparation Example 6

[0058] The difference between this preparation example and preparation example 3 is that, in the method for preparing polysaccharide maleate, the amount of bromosuccinimide used is equivalent to 4.5% of the total weight of hemicellulose and maleic anhydride.

[0059] Preparation Example 7

[0060] The difference between this Preparation Example and Preparation Example 6 is that in the method for preparing polysaccharide maleate, the reaction temperature is 50°C.

[0061] Preparation Example 8

[0062] The difference between this Preparation Example and Preparation Example 6 is that in the method for preparing polysaccharide maleate, the reaction temperature is 55°C.

[0063] Preparation Example 9

[0064] The difference between this Preparation Example and Preparation Example 6 is that in the method for preparing polysaccharide maleate, the reaction temperature is 60°C.

[0065] Preparation Example 10

[0066] The difference between this Preparation Example and Preparation Example 9 is that in the method for preparing polysaccharide maleate, β-cyclodextrin and hemicellulose are used as raw materials, and the weight ratio of β-cyclodextrin to hemicellulose is 1:10.

[0067] Preparation Example of Silylated Polyethyleneimine

[0068] The following is an illustration of Preparation Example 11.

[0069] Preparation Example 11

[0070] In this preparation example, methyltriethoxysilane was selected as the silane coupling agent.

[0071] In this preparation example, silylated polyethyleneimine was prepared according to the following method:

[0072] (1) 10 g of polyethyleneimine (weight average molecular weight: 1500) was dissolved in 30 g of methanol to obtain a polyethyleneimine solution for later use;

[0073] (2) 2 g of a silane coupling agent, 1 g of 1-chlorooctane, and 1 g of a phase transfer catalyst (tetrabutylammonium bromide) were added to the polyethyleneimine solution, and the mixture was stirred in a water bath at 75° C. During the stirring process, 58 g of a 3 wt % sodium hydroxide solution was added to continue the reaction. After 6 h of reaction, silylated polyethyleneimine was obtained.

[0074] Preparation Example 12

[0075] The difference between this preparation example and Example 11 is that dodecyltriethoxysilane is used as the silane coupling agent.

[0076] Preparation Example 13

[0077] The difference between this preparation example and Example 11 is that dodecyltriethoxysilane and phenyltriethoxysilane are selected as silane coupling agents, and the weight ratio of dodecyltriethoxysilane to phenyltriethoxysilane is 1:0.4.

[0078] Preparation example of oxidized starch solution

[0079] The following is an explanation using Preparation Example 14 as an example.

[0080] Preparation Example 14

[0081] In this preparation example, the oxidized starch solution was prepared as follows:

[0082] Starch and water were added to a reactor in a mass ratio of 1:10, heated to 90°C with stirring, and gelatinized for 0.5 h. Then, ferrous sulfate equivalent to 80% of the mass of starch was added under stirring, followed by hydrogen peroxide equivalent to 2.8% of the mass of starch. The mixture was reacted for 1 h to obtain an oxidized starch solution.

[0083] Example

[0084] Examples 1-3

[0085] The following description will be given using Example 1 as an example.

[0086] Example 1

[0087] In this embodiment, the scale-inhibiting copolymer was prepared according to the method of Preparation Example 1, the oxidized starch solution was prepared according to the method of Preparation Example 14, octadecylamine was selected as the amine auxiliary agent, and the emulsifier was a mixture of Span-80 and Tween-80 in a weight ratio of 3:2.

[0088] This embodiment provides a phosphorus-free scale inhibitor for water treatment, comprising the following components in parts by weight: 10 kg of a scale inhibition copolymer, 1.2 kg of an oxidized starch solution, 1.5 kg of an amine auxiliary agent, 8 kg of an emulsifier, and 68 kg of water.

[0089] This embodiment provides a method for preparing a phosphorus-free scale inhibitor for water treatment, comprising the following steps:

[0090] (1) mixing an amine auxiliary agent, an emulsifier and water and stirring to obtain an emulsion for standby use;

[0091] (2) adding the scale-inhibiting copolymer and the oxidized starch solution into the emulsion and stirring and dispersing them to obtain a phosphorus-free scale inhibitor for water treatment.

[0092] For example, 2. The difference between Examples 1-3 mainly lies in the different raw material ratios of the scale inhibitor.

[0093] Table 2 Raw material ratio of scale inhibitor

[0094] sample Example 1 Example 2 Example 3 Scale inhibition copolymer / kg 10 11 12 Oxidized starch solution / kg 1.2 1.3 1.4 Amine additives / kg 1.5 1.6 1.7 Emulsifier / kg 8 9 10 Water / kg 68 71 74

[0095] Examples 4-13

[0096] As shown in Table 3, the difference between Examples 4-13 is that the scale inhibition copolymers are prepared in different ways.

[0097] Table 3 Preparation example of scale inhibition copolymer

[0098] sample Preparation Example Example 4 Preparation Example 1 Example 5 Preparation Example 2 Example 6 Preparation Example 3 Example 7 Preparation Example 4 Example 8 Preparation Example 5 Example 9 Preparation Example 6 Example 10 Preparation Example 7 Example 11 Preparation Example 8 Example 12 Preparation Example 9 Example 13 Preparation Example 10

[0099] Example 14

[0100] The difference between this embodiment and embodiment 13 is that the amine auxiliary agent is the silylated polyethyleneimine of preparation example 11.

[0101] Example 15

[0102] The difference between this example and Example 14 is that the silylated polyethyleneimine is prepared according to the method of Preparation Example 12.

[0103] Example 16

[0104] The difference between this example and Example 14 is that the silylated polyethyleneimine is prepared according to the method of Preparation Example 13.

[0105] Comparative Example

[0106] Comparative Example 1

[0107] A phosphorus-free corrosion and scale inhibitor is prepared according to the following steps:

[0108] (1) Chitosan was first dispersed in an isopropanol-sodium hydroxide mixed solution at a mass ratio of 1:5, heated to 45°C, stirred for alkalization for 2h, then monochloroacetic acid was added, reacted at 50°C for 6h, hydrochloric acid solution was added to adjust the pH to 7, and then ammonium persulfate was added under stirring, and then polyhexamethyleneguanidine hydrochloride and polyhexamethylene biguanidine hydrochloride were gradually added, and reacted at 45°C for 6h to obtain a modified chitosan quaternary ammonium salt mixture; the mass ratio of chitosan: monochloroacetic acid: polyhexamethyleneguanidine hydrochloride: polyhexamethylene biguanidine hydrochloride was 1:1:1:6, and the amount of ammonium persulfate was 0.01% of the total mass of chitosan.

[0109] (2) Starch and water were added to a reactor in a mass ratio of 1:20, stirred and heated to 70°C, and gelatinized for 1 hour. Then, ferrous sulfate (15% by mass of starch) was added under stirring, and then hydrogen peroxide (0.8% by mass of starch) was slowly added. The mixture was reacted for 3 hours to obtain an oxidized starch mixture.

[0110] (3) First, octadecylamine and fatty amine polyoxyethylene ether are heated to melt and stirred evenly, and then water is slowly added and stirred evenly to obtain an alkylamine emulsion; in this step, the mass ratio of octadecylamine: fatty amine polyoxyethylene ether: water is 3:4:40.

[0111] (4) Weigh 40 g of the prepared modified chitosan quaternary ammonium salt mixture, 20 g of the oxidized starch mixture, and 10 g of the alkylamine emulsion into a reactor, stir for 0.5 h to mix the materials evenly, and then discharge the materials to obtain the phosphorus-free corrosion and scale inhibitor.

[0112] Comparative Example 2

[0113] The difference between this comparative example and Example 1 is that allyl polyalkyloxy ammonium sulfonate is not added when preparing the scale-inhibiting copolymer.

[0114] Comparative Example 3

[0115] The difference between this comparative example and Example 1 is that no polysaccharide maleate is added when preparing the scale inhibition copolymer.

[0116] Comparative Example 4

[0117] The difference between this comparative example and Example 1 is that methacryloyloxyethyltrimethylammonium chloride is not added when preparing the scale-inhibiting copolymer.

[0118] Performance testing methods

[0119] A scale inhibition test was conducted in accordance with the chemical industry standard HG / T2160-2008, "Dynamic Simulation Test Method for Cooling Water." The scale inhibitor concentration was controlled at 100 mg / L. The heat exchanger test tubes were 316L stainless steel tubes measuring 19 x 2 x 1250 mm. Test water containing corrosion and scale inhibitors was routed through the tubes. The test tubes were heated externally with saturated steam. The test water inlet temperature was controlled at 30 ± 1°C, with a 10°C inlet / outlet temperature differential and a flow rate of 0.6-1.2 m / s. The test water composition was: 5 mmol / L calcium chloride, 2 mmol / L sodium bicarbonate, 11.25 mmol / L sodium chloride, 4 mmol / L magnesium sulfate, and 6 mmol / L alkalinity. The circulating water concentration was 8 ± 0.5, based on the volume of water. The test was run continuously for 27 days, and the scale deposition rate was measured. The results are shown in Table 4.

[0120] Table 4 Dirt deposition rate

[0121]

[0122] Combining Examples 1-6 with Comparative Example 1 and Table 4, it can be seen that the scale deposition rates measured in Examples 1-6 are relatively low. This is because the chain segments of the scale-inhibiting copolymer of the present application can fully extend in water, and the concentration of calcium and magnesium ions in the water is reduced through the chelation of carboxyl and sulfonic acid groups, inhibiting the further growth of scale. In addition, hydrophilic groups such as hydroxyl groups form hydrogen bonds with oxygen-containing acid anions, hindering the binding of calcium and magnesium ions with oxygen-containing acid anions. It can also form a smooth protective film together with amine additives, isolating the contact of dissolved oxygen and ions in the water with the metal, thereby playing a role in slowing down metal corrosion. By using the scale inhibitor of the present application, not only can the eutrophication of water bodies caused by phosphorus be avoided, but the accumulation of scale can also be effectively prevented, and the corrosion of metal pipes can be slowed down, which can fully meet the scale inhibition requirements of industrial cooling water.

[0123] Combining Example 1 and Comparative Example 2 with Table 4, it can be seen that the scale deposition rate of Example 1 is relatively low. This is because the scale inhibition copolymer of Comparative Example 2 lacks the structural unit introduced by allyl polyalkoxy ammonium sulfonate, resulting in the chain segments of the scale inhibition copolymer failing to fully extend. In addition, the lack of sulfonic acid groups has limited chelating effect on calcium and magnesium ions, resulting in more scaling.

[0124] Combining Example 1 and Comparative Example 3 with Table 4, it can be seen that the scale deposition rate of Example 1 is relatively low. This is because the scale-inhibiting copolymer of Comparative Example 3 lacks the structural unit introduced by polysaccharide maleate, which makes it difficult for the scale-inhibiting copolymer to fully form hydrogen bonds with oxygen-containing acid anions and cannot effectively hinder the combination of calcium and magnesium ions with anionic oxygen-containing acid anions, thereby generating more scaling.

[0125] Combining Example 1 and Comparative Example 4 with Table 4, it can be seen that the scale deposition rate of Example 1 is relatively low. This is because the scale-inhibiting copolymer of Comparative Example 4 lacks methacryloyloxyethyltrimethylammonium chloride, resulting in limited adsorption of the scale-inhibiting copolymer and failure to fully inhibit the growth of scale, resulting in more scale.

[0126] From Examples 6-9, Examples 9-12 and Table 4, it can be seen that when the amount of bromosuccinimide is 3.5-4.5% of the total weight of hemicellulose and maleic anhydride, or the reaction temperature is 50-60°C, the scale inhibition effect of the scale inhibitor can be effectively enhanced after the participation of polysaccharide maleate in copolymerization.

[0127] Combining Example 12 and Example 13 with Table 4, it can be seen that the scale deposition rate measured in Example 13 is relatively low. This is because cyclodextrin maleate can introduce a cyclodextrin cavity into the scale inhibition copolymer, which can cause lattice distortion during the growth of calcium carbonate crystals, slowing down the growth rate of scaling, and the carboxyl group in cyclodextrin maleate can also participate in the complexation of calcium and magnesium ions, thereby helping to enhance the scale inhibition effect of the scale inhibitor.

[0128] Combining Examples 13, 14-16, and Table 4, we can see that the scale deposition rates measured in Examples 15-16 are relatively low. This is due to the strong dispersibility and adsorption properties of the silylated polyethyleneimine, as well as its significant steric hindrance. After hydrophobic modification, it also carries a certain amount of negative charge, resulting in excellent scale inhibition and dispersion. This synergistic effect with the scale-inhibiting copolymer significantly improves the scale inhibition performance of the scale inhibitor. Furthermore, the introduction of dodecyl and phenyl groups enhances the hydrophobicity and steric hindrance of the silylated polyethyleneimine, contributing to improved scale inhibition performance.

[0129] The above embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments of the present application as needed without any creative contribution. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A phosphorus-free scale inhibitor for water treatment, characterized in that: The invention comprises the following components in parts by weight: 10-12 parts of a scale-inhibiting copolymer, 1.2-1.4 parts of an oxidized starch solution, 1.5-1.7 parts of an amine auxiliary agent, 8-10 parts of an emulsifier, and 68-74 parts of water; the scale-inhibiting copolymer is copolymerized by acrylic acid, allyl polyalkyloxy ammonium sulfonate, and a functional monomer, wherein the functional monomer comprises polysaccharide maleate and methacryloyloxyethyl trimethyl ammonium chloride.

2. The phosphorus-free scale inhibitor for water treatment according to claim 1, characterized in that The molar ratio of the acrylic acid, allyl polyalkyloxy ammonium sulfonate and functional monomer is 3:(2-3):(1-2).

3. The phosphorus-free scale inhibitor for water treatment according to claim 1, characterized in that The scale inhibition copolymer is prepared according to the following method: (1) adding acrylic acid, allyl polyalkyloxy ammonium sulfonate and functional monomer into water and mixing to obtain a monomer mixture, which is kept warm for later use; mixing water and a telogen to obtain a base solution, which is kept warm for later use; (2) Adding the monomer mixture and the initiator to the base liquid under nitrogen protection and heating the mixture; after all the monomer mixture is added, increasing the heating temperature to continue the reaction; after the reaction is completed, stopping the heating, cooling to room temperature and discharging the mixture to obtain a scale-inhibiting copolymer; 4. The phosphorus-free scale inhibitor for water treatment according to claim 1, characterized in that The polysaccharide maleate is prepared as follows: Hemicellulose and lithium chloride are added to DMF, heated and stirred until the hemicellulose and lithium chloride are completely dissolved, then the heating temperature is lowered, bromosuccinimide and maleic anhydride are added and the reaction is continued until the acid value is constant. After the reaction is completed, the product is washed with ethanol and the remaining product is vacuum dried to obtain polysaccharide maleate.

5. The phosphorus-free scale inhibitor for water treatment according to claim 4, characterized in that: In the method for preparing the polysaccharide maleate, the amount of bromosuccinimide used is 3.5-4.5% of the total weight of hemicellulose and maleic anhydride.

6. The phosphorus-free scale inhibitor for water treatment according to claim 5, characterized in that: In the method for preparing the polysaccharide maleate, the reaction temperature is 50-60°C.

7. The phosphorus-free scale inhibitor for water treatment according to claim 4, characterized in that: In the method for preparing the polysaccharide maleate, β-cyclodextrin and hemicellulose are used as raw materials.

8. The phosphorus-free scale inhibitor for water treatment according to claim 1, characterized in that: The amine auxiliary agent includes silylated polyethyleneimine, which is prepared according to the following method: (1) adding polyethyleneimine to methanol to dissolve it to obtain a polyethyleneimine solution for later use; (2) Adding a silane coupling agent, 1-chlorooctane and a phase transfer catalyst to a polyethyleneimine solution, stirring the solution under heating conditions in a water bath, adding a sodium hydroxide solution during the stirring process to continue the reaction, and obtaining silylated polyethyleneimine after the reaction is completed.

9. The phosphorus-free scale inhibitor for water treatment according to claim 8, characterized in that: The silane coupling agent includes at least one of dodecyltriethoxysilane and phenyltriethoxysilane.

10. The method for preparing the phosphorus-free scale inhibitor for water treatment according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) mixing an amine auxiliary agent, an emulsifier and water and stirring to obtain an emulsion for standby use; (2) adding the scale-inhibiting copolymer and the oxidized starch solution into the emulsion and stirring and dispersing them to obtain a phosphorus-free scale inhibitor for water treatment.

Images