Corrosion and scale inhibitor and preparation method thereof

Abstract

The application relates to the technical field of bactericides, in particular to an anti-corrosion and scale-inhibiting bactericide and a preparation method thereof. The anti-corrosion and scale-inhibiting bactericide is an aqueous solution containing special polyaspartic acid derivatives, wherein a polymer chain simultaneously contains polyaspartic acid carboxylic acid units, benzyl quaternary ammonium units, dodecyl quaternary ammonium units and carboxymethyl betaine units. The preparation method comprises the following steps: taking L-aspartic acid as a starting raw material, and performing polycondensation, ring-opening amination, two-step quaternary ammonium, hydrolysis and betaineization and the like. Through integrated molecular structure design, the application makes the functional groups synergistically act, can realize excellent anti-corrosion, scale-inhibiting and bactericidal performances under low dosage, has good long-term dynamic stability, and solves the technical problems that the synergism of existing compounded agents is poor and the performance is prone to attenuation.

Description

Technical Field

[0001] This invention relates to the field of bactericide technology, and in particular to a corrosion and scale inhibitor bactericide and its preparation method. Background Technology

[0002] Circulating cooling water and high-hardness industrial makeup water are crucial water treatment systems in industrial production, and their stable operation directly affects production safety and economic benefits. To maintain long-term system stability, chemical agents need to be added to the water to simultaneously control three core issues: corrosion, scale buildup, and microbial growth. Currently, the mainstream solution involves a physical compounding of multiple functional agents. For example, corrosion inhibitors such as polyaspartic acid, sodium polyepoxysuccinate, and zinc salts are simply mixed with bactericidal agents such as quaternary ammonium salts and isothiazolinones. While this method can achieve certain short-term effects under specific water quality and operating conditions, its core problem lies in the fact that each component acts independently, making it difficult to achieve a synergistic effect.

[0003] Specifically, in physically compounded systems, the diffusion, adsorption, and film-forming behaviors of different functional agent molecules in water are independent, and they may even exhibit antagonistic effects due to competition for adsorption sites. This antagonism becomes increasingly pronounced, particularly during long-term operation at high concentrations, resulting in a sharp decline in the synergistic efficiency of the agents. For example, high concentrations of scale inhibitors and dispersants (such as polycarboxylic acids) may hinder the effective adsorption and film formation of corrosion inhibitors on metal surfaces, while cationic bactericides, after adsorption onto metal or scale surfaces, may repel similarly positively charged corrosion inhibitor molecules due to their charge. This makes it difficult for a single compounded agent to stably and simultaneously provide high levels of corrosion inhibition, scale inhibition, and bactericidal performance under long-term dynamic operating conditions.

[0004] Furthermore, to enhance single functions, existing technologies have explored chemical modifications of biodegradable and environmentally friendly scale inhibitors such as polyaspartic acid. For example, long-chain alkyl or quaternary ammonium groups are introduced into the polyaspartic acid backbone to impart certain bactericidal or corrosion-inhibiting properties. However, such modifications typically focus only on introducing a single type of functional group, resulting in limited functional enhancement. For instance, introducing only hydrophobic long chains to enhance bactericidal properties often significantly sacrifices the polymer's water solubility and scale inhibition and dispersion capabilities, leading to decreased stability in hard water and a tendency for localized aggregation and precipitation. Conversely, introducing only hydrophilic groups to improve scale inhibition often results in unsatisfactory bactericidal efficiency. Designing a molecular structure that can achieve long-term, stable, and comprehensive water treatment performance under harsh conditions such as hard water and high concentration ratios through the synergistic effect of various functional groups has become a critical technological bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a corrosion inhibitor, scale inhibitor, and bactericide and its preparation method, so as to solve the problems of poor synergy among the components of existing compound water treatment agents, rapid performance degradation over long-term operation, and the difficulty of a single modified polymer to simultaneously achieve efficient corrosion inhibition, scale inhibition, and bactericidal performance.

[0006] Based on the above objectives, the present invention provides a corrosion-inhibiting, scale-inhibiting, and bactericidal agent, comprising a polyaspartic acid derivative with polyaspartic acid as the backbone; based on the mass fractions of the raw materials used to prepare the polyaspartic acid derivative, taking 20 parts of L-aspartic acid as a reference, the raw materials include 4.0-5.3 parts of 3-dimethylaminopropylamine, 1.1-1.9 parts of benzyl chloride, 3.0-4.4 parts of 1-bromododecane, and 1.7-2.8 parts of sodium chloroacetate; the polyaspartic acid derivative is prepared by polysuccinimide obtained by polycondensation of L-aspartic acid, followed by ring-opening reaction with 3-dimethylaminopropylamine, then reacting sequentially with benzyl chloride and 1-bromododecane, followed by alkaline hydrolysis, and finally reacting with sodium chloroacetate.

[0007] Preferably, the corrosion inhibitor, scale inhibitor, and bactericide is an aqueous solution.

[0008] Preferably, the solid content of the corrosion inhibitor, scale inhibitor, and bactericide is 26.8wt%-29.0wt%.

[0009] Preferably, based on the mass fraction of the raw materials used to prepare the polyaspartic acid derivative, taking 20 parts of L-aspartic acid as a reference, the raw materials also include 1.6-2.4 parts of phosphoric acid with a mass fraction of 85% and 4.0-4.6 parts of sodium hydroxide.

[0010] Furthermore, the present invention also provides a method for preparing a corrosion-inhibiting, scale-inhibiting, and bactericidal agent, comprising the following steps: (1) L-aspartic acid was polycondensed to obtain a polysuccinimide intermediate; (2) React the polysuccinimide intermediate with 3-dimethylaminopropylamine to obtain a polysuccinimide intermediate with tertiary amine side chain modification; (3) The tertiary amine side chain modified polysuccinimide intermediate is reacted sequentially with benzyl chloride and 1-bromododecane to obtain a bipara hydrophobic quaternized intermediate; (4) The bi-stage hydrophobic quaternized intermediate is subjected to alkaline hydrolysis, then reacted with sodium chloroacetate, and then dialyzed and concentrated to obtain a corrosion inhibitor, scale inhibitor and bactericide.

[0011] Preferably, in step (1), L-aspartic acid and phosphoric acid are stirred and heated to 148-152°C under nitrogen protection and kept at that temperature for 15-25 min. Then, the temperature is raised to 178-182°C, and the system pressure is reduced to 30-35 kPa within 30 min before the reaction continues for 2.5-3.5 h.

[0012] Preferably, in step (2), the reaction temperature is 54-58℃ and the time is 2.5-3.5h.

[0013] Preferably, in step (3), the reaction temperature of the tertiary amine side-chain modified polysuccinimide intermediate with benzyl chloride is 68-72℃ and the reaction time is 2-2.5h, and the reaction temperature with 1-bromododecane is 86-90℃ and the reaction time is 5-7h.

[0014] Preferably, in step (4), the alkaline hydrolysis temperature is 44-46℃ and the time is 2.5-3.5h; the reaction temperature with sodium chloroacetate is 70-74℃ and the time is 4-6h.

[0015] Preferably, in step (4), dialysis and concentration are performed as follows: some of the mixed solvent is removed under reduced pressure at 48-52°C, the concentrate is placed in a dialysis bag with a molecular weight cutoff of 1000, and dialysis is performed with deionized water for 36-48 hours. The dialysis solution is replaced every 8 hours, and the concentration is performed under reduced pressure after dialysis.

[0016] The beneficial effects of this invention are: (1) This invention abandons the simple physical compounding approach and creatively uses polyaspartic acid as a common backbone to sequentially construct polyaspartic acid carboxylic acid units, benzyl quaternary ammonium units, dodecyl quaternary ammonium units, and carboxymethyl betaine units on the same polymer chain through a specific reaction sequence. This integrated structure avoids competition and interference between different molecules, enabling synergistic effects of each functional site at the molecular level. Test data show that at a low dosage of 60 mg / L, the corrosion inhibition rate of this invention can reach 94.7%, and the scale inhibition rate can reach 96.8%, demonstrating comprehensive performance far exceeding that of conventional compounded agents.

[0017] (2) The specific preparation sequence adopted in this invention—first constructing a bilevel hydrophobic quaternary ammonium site, then hydrolyzing and opening the ring, and finally introducing the betaine inner salt—is crucial. The first introduced benzyl quaternary ammonium unit provides a strong initial adsorption anchor, the subsequently introduced dodecyl long chain enhances the hydrophobic bactericidal effect, while the carboxylic acid unit generated by subsequent hydrolysis ensures excellent scale inhibition and corrosion inhibition film-forming ability. Finally, the introduced carboxymethyl betaine unit forms an outer hydration layer, significantly improving the dispersion stability and antifouling ability of the product. Comparative and dynamic operation tests (30 days) show that the product prepared under this specific sequence has a dynamic heat transfer coefficient decrease rate of less than 7.4% and a dynamic corrosion rate of less than 0.034 mm / a, proving that it can effectively maintain the long-term efficient and stable operation of the system and solve the problem of synergistic performance degradation under high concentration ratios.

[0018] (3) By precisely controlling the introduction ratio and sequence of each functional unit, this invention successfully reconciles the traditionally mutually restrictive performance contradictions. For example, while maintaining a sufficient density of carboxylic acid units to ensure a high scale inhibition rate, the synergistic effect of benzyl and long-chain quaternary ammonium compounds still achieves highly efficient killing of slime-forming bacteria (killing rate >99%), breaking the traditional limitation that scale inhibition performance and bactericidal performance are mutually exclusive. At the same time, the presence of betaine units effectively improves the solubility and dispersibility of molecules in high-hardness water, inhibits slime adhesion, and gives the product both excellent static performance and long-term dynamic stability. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0020] Example 1 Step 1: Add 20g of L-aspartic acid and 2g of 85% phosphoric acid to a reaction flask. Under nitrogen protection, stir and heat to 150℃ and maintain this temperature for 20min. Then, heat to 180℃ and reduce the system pressure to 30kPa within 30min, continuing the reaction for 3h. After the reaction is complete, cool to 80℃, add 80g of ethanol to disperse the material, wash twice with 40g of ethanol, and dry under reduced pressure at 60℃ for 6h to obtain the polysuccinimide intermediate.

[0021] Step 2: Add 14g of polysuccinimide intermediate to 70g of N,N-dimethylformamide, stir at 55℃ until basically dissolved, then add 4.6g of 3-dimethylaminopropylamine dropwise over 20min, and continue the reaction at 55℃ for 3h. After the reaction is complete, pour the reaction solution into 250g of ethanol to precipitate the intermediate, filter, wash twice with 40g of ethanol, and dry under reduced pressure at 45℃ for 4h to obtain the tertiary amine side chain modified polysuccinimide intermediate.

[0022] Step 3: 17g of tertiary amine side-chain modified polysuccinimide intermediate was redissolved in 60g of N,N-dimethylformamide, and 1.5g of benzyl chloride was added under nitrogen protection. The reaction was carried out at 70℃ for 2h. Then, 3.7g of 1-bromododecane was added, and the reaction was carried out at 88℃ for another 6h to obtain a bipara hydrophobic quaternized intermediate.

[0023] Step 4: Cool the reaction solution obtained in Step 3 to 45°C, add an alkaline solution prepared with 4.3g sodium hydroxide and 120g deionized water dropwise over 30 minutes, and maintain the reaction at 45°C for 3 hours to hydrolyze the remaining unopened imide sites into polyaspartic acid carboxylic acid units; then add 2.1g sodium chloroacetate and 40g isopropanol, raise the temperature to 72°C and react for 5 hours to further convert the remaining tertiary amine sites into carboxymethyl betaine-type internal salt sites; after the reaction is complete, remove part of the mixed solvent under reduced pressure at 50°C, and put the concentrated solution into a dialysis bag with a molecular weight cutoff of 1000, dialyze with deionized water for 48 hours, changing the dialysate every 8 hours, and concentrate under reduced pressure after dialysis to obtain a corrosion inhibitor, scale inhibitor and bactericide with a solid content of 27.5wt%.

[0024] Example 2 Step 1: Add 20g of L-aspartic acid and 1.6g of 85% phosphoric acid to a reaction flask. Under nitrogen protection, stir and heat to 148℃ and hold for 15min. Then raise the temperature to 178℃ and reduce the system pressure to 35kPa within 30min, and continue the reaction for 2.5h. After the reaction is complete, cool to 80℃, add 75g of ethanol to disperse the material, wash twice with 35g of ethanol, and dry under reduced pressure at 58℃ for 5h to obtain the polysuccinimide intermediate.

[0025] Step 2: Add 13.8g of polysuccinimide intermediate to 72g of N,N-dimethylformamide, stir at 54℃ until basically dissolved, then add 4.0g of 3-dimethylaminopropylamine dropwise over 20min, and continue the reaction at 54℃ for 2.5h. After the reaction is complete, pour the reaction solution into 240g of ethanol to precipitate the intermediate, filter, wash twice with 35g of ethanol, and dry under reduced pressure at 45℃ for 4h to obtain the tertiary amine side-chain modified polysuccinimide intermediate.

[0026] Step 3: 16.5g of tertiary amine side-chain modified polysuccinimide intermediate was redissolved in 62g of N,N-dimethylformamide, and 1.1g of benzyl chloride was added under nitrogen protection. The reaction was carried out at 68℃ for 2h. Then, 3.0g of 1-bromododecane was added, and the reaction was carried out at 86℃ for another 5h to obtain a bipara hydrophobic quaternized intermediate.

[0027] Step 4: Cool the reaction solution obtained in Step 3 to 44°C, and add an alkaline solution prepared with 4.0g sodium hydroxide and 118g deionized water dropwise over 30 minutes. Maintain the reaction at 44°C for 2.5 hours to hydrolyze the remaining unopened imide sites into polyaspartic acid carboxylic acid units. Subsequently, add 1.7g sodium chloroacetate and 35g isopropanol, raise the temperature to 70°C, and react for 4 hours to further convert the remaining tertiary amine sites into carboxymethyl betaine-type internal salt sites. After the reaction is complete, remove part of the mixed solvent under reduced pressure at 48°C. Place the concentrated solution into a dialysis bag with a molecular weight cutoff of 1000 and dialyze with deionized water for 36 hours, changing the dialysate every 8 hours. After dialysis, concentrate under reduced pressure to obtain a corrosion, scale, and bactericide with a solid content of 26.8 wt%.

[0028] Example 3 Step 1: Add 20g of L-aspartic acid and 2.2g of 85% phosphoric acid to a reaction flask. Under nitrogen protection, stir and heat to 150℃ and maintain this temperature for 18min. Then, raise the temperature to 181℃ and reduce the system pressure to 32kPa within 30min, continuing the reaction for 3h. After the reaction is complete, cool to 80℃, add 80g of ethanol to disperse the material, wash twice with 40g of ethanol, and dry under reduced pressure at 60℃ for 6h to obtain the polysuccinimide intermediate.

[0029] Step 2: Add 14.2g of polysuccinimide intermediate to 70g of N,N-dimethylformamide, stir at 56℃ until basically dissolved, then add 5.0g of 3-dimethylaminopropylamine dropwise over 20min, and continue the reaction at 56℃ for 3h. After the reaction is complete, pour the reaction solution into 250g of ethanol to precipitate the intermediate, filter, wash twice with 40g of ethanol, and dry under reduced pressure at 46℃ for 4h to obtain the tertiary amine side-chain modified polysuccinimide intermediate.

[0030] Step 3: 17.2g of tertiary amine side-chain modified polysuccinimide intermediate was redissolved in 60g of N,N-dimethylformamide, and 1.8g of benzyl chloride was added under nitrogen protection. The reaction was carried out at 70℃ for 2.5h. Then, 3.5g of 1-bromododecane was added, and the reaction was carried out at 88℃ for another 6h to obtain a bipara hydrophobic quaternized intermediate.

[0031] Step 4: Cool the reaction solution obtained in Step 3 to 45°C, and add an alkaline solution prepared with 4.4g sodium hydroxide and 120g deionized water dropwise over 30 minutes. Maintain the reaction at 45°C for 3 hours to hydrolyze the remaining unopened imide sites into polyaspartic acid carboxylic acid units. Subsequently, add 2.0g sodium chloroacetate and 40g isopropanol, raise the temperature to 72°C, and react for 5 hours to further convert the remaining tertiary amine sites into carboxymethyl betaine-type internal salt sites. After the reaction is complete, remove part of the mixed solvent under reduced pressure at 50°C. Place the concentrated solution into a dialysis bag with a molecular weight cutoff of 1000 and dialyze with deionized water for 48 hours, changing the dialysate every 8 hours. After dialysis, concentrate under reduced pressure to obtain a corrosion, scale, and bactericide with a solid content of 28.1 wt%.

[0032] Example 4 Step 1: Add 20g of L-aspartic acid and 2.0g of 85% phosphoric acid to a reaction flask. Under nitrogen protection, stir and heat to 151℃ and maintain this temperature for 20min. Then, raise the temperature to 182℃ and reduce the system pressure to 30kPa within 30min, continuing the reaction for 3h. After the reaction is complete, cool to 80℃, add 82g of ethanol to disperse the material, wash twice with 40g of ethanol, and dry under reduced pressure at 60℃ for 6h to obtain the polysuccinimide intermediate.

[0033] Step 2: Add 14.0 g of polysuccinimide intermediate to 69 g of N,N-dimethylformamide. Stir at 55 °C until basically dissolved, then add 4.8 g of 3-dimethylaminopropylamine dropwise over 20 min, and continue the reaction at 55 °C for 3 h. After the reaction is complete, pour the reaction solution into 250 g of ethanol to precipitate the intermediate. Filter and wash twice with 40 g of ethanol, then dry under reduced pressure at 45 °C for 4 h to obtain the tertiary amine side-chain modified polysuccinimide intermediate.

[0034] Step 3: 17.0g of tertiary amine side-chain modified polysuccinimide intermediate was redissolved in 58g of N,N-dimethylformamide, and 1.3g of benzyl chloride was added under nitrogen protection. The reaction was carried out at 69℃ for 2h. Then, 4.4g of 1-bromododecane was added, and the reaction was carried out at 90℃ for another 6.5h to obtain a bipara hydrophobic quaternized intermediate.

[0035] Step 4: Cool the reaction solution obtained in Step 3 to 45°C, and add an alkaline solution prepared with 4.3g sodium hydroxide and 121g deionized water dropwise over 30 minutes. Maintain the reaction at 45°C for 3 hours to hydrolyze the remaining unopened imide sites into polyaspartic acid carboxylic acid units. Subsequently, add 1.8g sodium chloroacetate and 38g isopropanol, raise the temperature to 72°C, and react for 5 hours to further convert the remaining tertiary amine sites into carboxymethyl betaine-type internal salt sites. After the reaction is complete, remove part of the mixed solvent under reduced pressure at 50°C. Place the concentrated solution into a dialysis bag with a molecular weight cutoff of 1000 and dialyze with deionized water for 48 hours, changing the dialysate every 8 hours. After dialysis, concentrate under reduced pressure to obtain a corrosion, scale, and bactericide with a solid content of 27.9 wt%.

[0036] Example 5 Step 1: Add 20g of L-aspartic acid and 1.8g of 85% phosphoric acid to a reaction flask. Under nitrogen protection, stir and heat to 149℃ and hold for 16min. Then raise the temperature to 180℃ and reduce the system pressure to 33kPa within 30min, and continue the reaction for 2.8h. After the reaction is complete, cool to 80℃, add 78g of ethanol to disperse the material, wash twice with 38g of ethanol, and dry under reduced pressure at 59℃ for 5.5h to obtain the polysuccinimide intermediate.

[0037] Step 2: Add 14.1g of polysuccinimide intermediate to 71g of N,N-dimethylformamide, stir at 55℃ until basically dissolved, then add 4.7g of 3-dimethylaminopropylamine dropwise over 20min, and continue the reaction at 55℃ for 3h. After the reaction is complete, pour the reaction solution into 255g of ethanol to precipitate the intermediate, filter, wash twice with 40g of ethanol, and dry under reduced pressure at 45℃ for 4h to obtain the tertiary amine side-chain modified polysuccinimide intermediate.

[0038] Step 3: 16.9g of tertiary amine side-chain modified polysuccinimide intermediate was redissolved in 61g of N,N-dimethylformamide, and 1.6g of benzyl chloride was added under nitrogen protection. The reaction was carried out at 70℃ for 2h. Then, 3.6g of 1-bromododecane was added, and the reaction was carried out at 88℃ for another 6h to obtain a bipara hydrophobic quaternized intermediate.

[0039] Step 4: Cool the reaction solution obtained in Step 3 to 45°C, and add an alkaline solution prepared with 4.2g sodium hydroxide and 122g deionized water dropwise over 30 minutes. Maintain the reaction at 45°C for 3 hours to hydrolyze the remaining unopened imide sites into polyaspartic acid carboxylic acid units. Subsequently, add 2.8g sodium chloroacetate and 45g isopropanol, raise the temperature to 73°C, and react for 5.5 hours to further convert the remaining tertiary amine sites into carboxymethyl betaine-type internal salt sites. After the reaction is complete, remove part of the mixed solvent under reduced pressure at 50°C. Place the concentrated solution into a dialysis bag with a molecular weight cutoff of 1000 and dialyze with deionized water for 44 hours, changing the dialysate every 8 hours. After dialysis, concentrate under reduced pressure to obtain a corrosion, scale, and bactericide with a solid content of 28.4 wt%.

[0040] Example 6 Step 1: Add 20g of L-aspartic acid and 2.4g of 85% phosphoric acid to a reaction flask. Under nitrogen protection, stir and heat to 152℃ and maintain this temperature for 25min. Then, heat to 182℃ and reduce the system pressure to 30kPa within 30min, continuing the reaction for 3.5h. After the reaction is complete, cool to 80℃, add 85g of ethanol to disperse the material, wash twice with 45g of ethanol, and dry under reduced pressure at 62℃ for 7h to obtain the polysuccinimide intermediate.

[0041] Step 2: Add 13.9g of polysuccinimide intermediate to 74g of N,N-dimethylformamide, stir at 58℃ until basically dissolved, then add 5.3g of 3-dimethylaminopropylamine dropwise over 25min, and continue the reaction at 58℃ for 3.5h. After the reaction is complete, pour the reaction solution into 260g of ethanol to precipitate the intermediate, filter, wash twice with 45g of ethanol, and dry under reduced pressure at 46℃ for 4.5h to obtain the tertiary amine side-chain modified polysuccinimide intermediate.

[0042] Step 3: 17.5g of tertiary amine side-chain modified polysuccinimide intermediate was redissolved in 64g of N,N-dimethylformamide, and 1.9g of benzyl chloride was added under nitrogen protection. The reaction was carried out at 72℃ for 2.5h. Then, 4.0g of 1-bromododecane was added, and the reaction was carried out at 89℃ for another 7h to obtain a bipara hydrophobic quaternized intermediate.

[0043] Step 4: Cool the reaction solution obtained in Step 3 to 46°C, and add an alkaline solution prepared with 4.6g sodium hydroxide and 120g deionized water dropwise over 30 minutes. Maintain the reaction at 46°C for 3.5 hours to hydrolyze the remaining unopened imide sites into polyaspartic acid carboxylic acid units. Subsequently, add 2.5g sodium chloroacetate and 42g isopropanol, raise the temperature to 74°C, and react for 6 hours to further convert the remaining tertiary amine sites into carboxymethyl betaine-type internal salt sites. After the reaction is complete, remove part of the mixed solvent under reduced pressure at 52°C. Place the concentrated solution into a dialysis bag with a molecular weight cutoff of 1000 and dialyze with deionized water for 48 hours, changing the dialysate every 8 hours. After dialysis, concentrate under reduced pressure to obtain a corrosion, scale, and bactericide with a solid content of 29.0 wt%.

[0044] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the amount of 3-dimethylaminopropylamine added dropwise over 20 minutes in step two was changed from 4.6 g to 8.8 g to increase the ring-opening degree of the polysuccinimide intermediate. All other conditions were the same as in Example 1. After completing the steps of Example 1, the Comparative Example 1 sample was obtained.

[0045] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that in step three, 1.5 g of benzyl chloride and 3.7 g of 1-bromododecane were simultaneously added to the tertiary amine side-chain modified polysuccinimide intermediate solution. The reaction was first carried out at 70°C for 2 hours, and then the temperature was raised to 88°C for another 6 hours. The two-step addition method of adding benzyl chloride first and then 1-bromododecane was not used. The other conditions were the same as in Example 1. After completing the steps of Example 1, the sample of Comparative Example 2 was obtained.

[0046] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that in step three, 3.7 g of 1-bromododecane was added first and reacted at 88°C for 6 hours, followed by the addition of 1.5 g of benzyl chloride and the reaction at 70°C for 2 hours. The order of adding benzyl chloride first and then 1-bromododecane was not followed. The other conditions were the same as in Example 1. After completing the steps of Example 1, the sample of Comparative Example 3 was obtained.

[0047] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that step three of Example 1 is adjusted so that 1.5g of benzyl chloride and 3.7g of 1-bromododecane are not added initially. Instead, the tertiary amine side-chain modified polysuccinimide intermediate is directly introduced into step four. The remaining unopened ring-shaped imide sites are hydrolyzed first according to the method of Example 1. After hydrolysis is completed, 1.5g of benzyl chloride and 3.7g of 1-bromododecane are added sequentially for subsequent reactions, and the remaining conditions are the same as in Example 1. After completing the steps of Example 1, the sample of Comparative Example 4 is obtained.

[0048] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that 2.1g of sodium chloroacetate was not added in step four, but the reaction conditions of 40g isopropanol, 72°C, and 5h were kept unchanged, and the other conditions were the same as in Example 1. After completing the steps of Example 1, the sample of Comparative Example 5 was obtained.

[0049] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that 1.5g of benzyl chloride was not added in step three; instead, the reduced mass was made up with 1.5g of N,N-dimethylformamide, while keeping the remaining temperature and time conditions in step three unchanged. All other conditions were the same as in Example 1. After completing the steps of Example 1, the sample of Comparative Example 6 was obtained.

[0050] Comparative Example 7: The difference between Comparative Example 7 and Example 1 is that 3.7 g of 1-bromododecane was not added in step three; instead, the reduced mass was made up with 3.7 g of N,N-dimethylformamide, while keeping the remaining temperature and time conditions in step three unchanged. All other conditions were the same as in Example 1. After completing the steps of Example 1, the sample of Comparative Example 7 was obtained.

[0051] Sample preparation before performance testing: The samples obtained in Examples 1-6 and Comparative Examples 1-7 were thoroughly stirred at 25°C and prepared into test stock solutions with a solid content of 10.0 wt% using deionized water. Unless otherwise specified, the same batch of artificially prepared water was used for all tests. The water contained 180 mg / L calcium ions, 45 mg / L magnesium ions, 220 mg / L bicarbonate ions, 180 mg / L chloride ions, 120 mg / L sulfate ions, 630 mg / L total hardness (calculated as CaCO3), and a pH of 8.50 ± 0.05. The dosage of the reagents used for evaluating corrosion inhibition performance, scale inhibition performance, and dynamic operation effect was uniformly 60 mg / L, and the dosage of the reagents used for controlling slime-forming bacteria was uniformly 80 mg / L. Each group was tested in triplicate, and the average value of the results was taken.

[0052] Intrinsic physicochemical properties of the samples: In accordance with GB / T 22592-2008 "General Method for Determination of pH Value of Water Treatment Agents", GB / T22594-2018 "General Method for Determination of Density of Water Treatment Agents", GB / T 22593-2008 "General Method for Determination of Limiting Viscosity of Water Treatment Agents" and GB / T Standard 22237-2008, "Determination of Surface Tension of Surfactants," specifies the determination of surface tension in Examples 1-6 and Comparative Examples 1-7. pH values ​​were measured using a 10.0 g / L sample aqueous solution at 25.0 ± 0.5 °C. Density was measured using the original sample solution at 20.0 ± 0.5 °C using a density bottle. Limiting viscosity was determined using an Ubbelohde viscometer with four concentration series (0.10 g / dL, 0.20 g / dL, 0.30 g / dL, and 0.40 g / dL) prepared using a 1.0 mol / L sodium chloride aqueous solution as the solvent. These concentrations were measured at 30.0 ± 0.1 °C and extrapolated to zero concentration. Surface tension was determined using a 1.0 g / L sample aqueous solution at 25.0 ± 0.5 °C using the platinum ring method.

[0053] Corrosion inhibition performance: Tested according to GB / T 18175-2014 "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotary Plating Method". The test piece was an A3 carbon steel plate, 50mm × 25mm × 2mm in size, with a surface area of ​​28cm². 2 The test pieces were successively polished with 400-grit, 800-grit, and 1200-grit sandpaper, rinsed with deionized water, degreased with anhydrous ethanol, dried, and weighed to 0.1 mg. For each group, 800 mL of artificially prepared water was used, the pH adjusted to 8.50±0.05, and the sample stock solution was added at 45±1℃ to achieve a reagent dosage of 60 mg / L. A rotating plate corrosion tester was used at a speed of 75 r / min for 72 hours. After the test, rust was removed, cleaned, dried, and re-weighed according to the method specified in GB / T 18175-2014. The corrosion inhibition rate was calculated using the formula: Corrosion inhibition rate = (Corrosion rate of blank group - Corrosion rate of treated group) / Corrosion rate of blank group × 100%.

[0054] Scale inhibition performance: The scale inhibition performance of water treatment agents was determined according to GB / T 16632-2019, "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Carbonate Deposition Method". A 500mL Erlenmeyer flask was used, and artificially prepared water was added to achieve a calcium ion concentration of 240 mg / L and a bicarbonate concentration of 732 mg / L in the test solution. Sample stock solution was added to bring the reagent dosage to 60 mg / L. After thorough mixing, the solution was placed in a constant temperature water bath at 80±1℃ and allowed to stand for 10 hours. After the reaction, the solution was cooled to 25℃, filtered to remove the deposits, and the residual calcium ion concentration in the filtrate was determined using a standard solution of disodium ethylenediaminetetraacetate. The scale inhibition rate was calculated according to the formula in GB / T 16632-2019.

[0055] Performance control of slime-forming bacteria: The test was conducted according to GB / T 14643.1-2009 "Determination of Bacteria and Algae in Industrial Circulating Cooling Water - Part 1: Determination of Slime-forming Bacteria - Plate Counting Method". Industrial circulating cooling water samples were taken from the field and pre-cultured at 30℃ for 24 hours to prepare an initial slime-forming bacteria count of approximately 1.0 × 10⁻⁶. 5 CFU / mL working bacterial solution. Take 99.92 mL of working bacterial solution for each group into a 250 mL sterile Erlenmeyer flask, add 0.08 mL of sample stock solution to make the final sample addition amount 80 mg / L, and incubate at 30℃ and 120 r / min for 24 h. Take a sample and determine the number of remaining mucus-forming bacteria by plate counting method. At the same time, hang a cleaned, dried and weighed polytetrafluoroethylene (PTFE) hanging strip in each Erlenmeyer flask, and record the adhesion on the surface of the hanging strip after 24 h.

[0056] Evaluation of the dynamic circulating cooling water operation effect: The evaluation was conducted according to GB / T 39296-2020 "Evaluation of the Operation Effect of Circulating Cooling Water Treatment - Monitoring Method for Heat Exchangers". A small-scale laboratory dynamic circulating cooling water device was used, with an effective system volume of 60L, a concentration ratio of 3.0, a test tube inlet flow rate of 1.8 m³ / h, a saturated steam temperature in the heat exchange chamber controlled at 100±2℃, an initial inlet and outlet water temperature difference of 10±1℃, a flow velocity in the plate holder not less than 0.3 m / s, and a pressure drop monitoring tube flow rate of 1.1 m³ / h. The system operated continuously for 30 days. During the experiment, the inlet and outlet temperatures of the test tubes, flow rate, steam temperature, and pressure difference were recorded every 12 hours. The heat transfer coefficient reduction rate, deposit mass, pressure difference increase, and dynamic corrosion rate were calculated according to the method in GB / T 39296-2020.

[0057] The test results are shown in Table 1.

[0058] Table 1 Performance Test Results

[0059] As can be seen from Table 1, this application achieves a significant synergistic effect in corrosion inhibition, scale inhibition, and bactericidal properties by orderly introducing tertiary amine side chains, benzyl quaternary ammonium units, dodecyl quaternary ammonium units, and carboxymethyl betaine units onto the same polyaspartic acid backbone.

[0060] Compared to Example 1, Comparative Example 1, due to excessive ring-opening in step two, resulted in a significant reduction in the sites that could subsequently hydrolyze into carboxylic acid units. Although some cation sites were retained, the corrosion inhibition rate and scale inhibition rate decreased to 84.6% and 82.9%, respectively, and the 30-day dynamic deposit mass increased to 13.9 mg / cm³. 2 This indicates that an excessively high degree of ring opening can disrupt the balance between the main chain carboxylic acid sites and adsorption film formation.

[0061] Comparative Examples 2 and 3, which used simultaneous and reverse feeding respectively, showed corrosion inhibition rates of only 88.9% and 87.6%, and 24h slime-forming bacteria counts of 2900 CFU / mL and 1900 CFU / mL, respectively. This indicates that when benzyl quaternary ammonium and dodecyl quaternary ammonium are constructed in the order of benzylation followed by long-chain quaternization, it is more beneficial to balance aqueous phase dispersibility, interfacial adsorption, and bactericidal contact efficiency.

[0062] Comparative Example 4, after hydrolysis and subsequent quaternization, maintained a scale inhibition rate of 92.1% due to the large number of carboxylic acid units, but its corrosion inhibition rate was only 86.1%, and the decrease rate of dynamic heat transfer coefficient and the increase rate of dynamic pressure difference reached 12.9% and 6.1 kPa, respectively. This indicates that constructing a bilevel hydrophobic quaternary ammonium site first and then hydrolyzing the remaining imide site is more conducive to forming a stable and dense interfacial protective layer.

[0063] In Comparative Example 5, without the introduction of carboxymethyl betaine sites, the surface tension increased to 46.5 mN / m, and the dynamic sediment mass and 24-hour slime-forming bacteria count were 10.7 mg / cm³. 2 The concentration of 3300 CFU / mL indicates that betaine-type internal salt sites play an important role in improving the hydration and dispersion capacity of the outer layer and inhibiting the adhesion of slime.

[0064] Comparative Examples 6 and 7 lack benzyl quaternary ammonium units or dodecyl quaternary ammonium units, respectively. Although the former still has a certain film-destructive effect on bacteria, its corrosion inhibition film formation and dispersion stability are insufficient. Although the latter maintains a certain scale inhibition ability, its bactericidal performance is significantly weakened. This further illustrates that the adsorption of aromatic quaternary ammonium, long-chain hydrophobic contact and betaine hydration dispersion are not simply superimposed, but have a synergistic effect of 1+1>2.

[0065] Among the various embodiments, Example 3 exhibited the best overall balance, with corrosion inhibition rate and scale inhibition rate reaching 94.7% and 96.8%, respectively. The number of slime-forming bacteria decreased to 290 CFU / mL after 24 hours, and the dynamic corrosion rate was only 0.034 mm / a. Example 5, due to a further increase in betaine sites, demonstrated the best dynamic operational stability, with its dynamic heat transfer coefficient decrease rate, dynamic deposit mass, and dynamic pressure difference increase being as low as 7.4%, 6.8 mg / cm³, and 6.8 mg / cm³, respectively. 2 And 3.5 kPa. The above results show that this application achieves synergistic matching of carboxylic acid complexation sites, quaternary ammonium bactericidal sites, hydrophobic contact sites, and hydration dispersion sites on the polyaspartic acid backbone, thereby achieving excellent corrosion and scale inhibition performance at a dosage of 60 mg / L and efficient control of slime-forming bacteria at a dosage of 80 mg / L, combining the advantages of static evaluation and 30-day dynamic cyclic evaluation.

[0066] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A corrosion inhibitor, scale inhibitor, and bactericide, characterized in that, The invention includes polyaspartic acid derivatives with polyaspartic acid as the backbone; based on the mass fractions of the raw materials used to prepare the polyaspartic acid derivatives, taking 20 parts of L-aspartic acid as a reference, the raw materials include 4.0-5.3 parts of 3-dimethylaminopropylamine, 1.1-1.9 parts of benzyl chloride, 3.0-4.4 parts of 1-bromododecane and 1.7-2.8 parts of sodium chloroacetate; the polyaspartic acid derivatives are prepared by polysuccinimide obtained by polycondensation of L-aspartic acid, followed by ring-opening reaction with 3-dimethylaminopropylamine, then reacting sequentially with benzyl chloride and 1-bromododecane, followed by alkaline hydrolysis and then reaction with sodium chloroacetate.

2. The corrosion inhibitor, scale inhibitor, and bactericide according to claim 1, characterized in that, The corrosion inhibitor, scale inhibitor, and bactericide is an aqueous solution.

3. The corrosion inhibitor, scale inhibitor, and bactericide according to claim 2, characterized in that, The solid content of the corrosion inhibitor, scale inhibitor, and bactericide is 26.8wt%-29.0wt%.

4. The corrosion inhibitor, scale inhibitor, and bactericide according to claim 1, characterized in that, Based on the mass fraction of the raw materials used to prepare the polyaspartic acid derivative, taking 20 parts of L-aspartic acid as a baseline, the raw materials also include 1.6-2.4 parts of phosphoric acid with a mass fraction of 85% and 4.0-4.6 parts of sodium hydroxide.

5. A method for preparing a corrosion-inhibiting, scale-inhibiting, and bactericidal agent according to any one of claims 1-4, characterized in that, Includes the following steps: (1) L-aspartic acid and phosphoric acid were mixed and polycondensed to obtain polysuccinimide intermediate; (2) React the polysuccinimide intermediate with 3-dimethylaminopropylamine to obtain a polysuccinimide intermediate with tertiary amine side chain modification; (3) The tertiary amine side chain modified polysuccinimide intermediate is reacted sequentially with benzyl chloride and 1-bromododecane to obtain a bipara hydrophobic quaternized intermediate; (4) After adding sodium hydroxide aqueous solution to the bi-stage hydrophobic quaternization intermediate for alkaline hydrolysis, it reacts with sodium chloroacetate and is then dialyzed and concentrated to obtain a corrosion inhibitor, scale inhibitor and bactericide.

6. The method for preparing the corrosion inhibitor, scale inhibitor, and bactericide according to claim 5, characterized in that, In step (1), L-aspartic acid and phosphoric acid are stirred and heated to 148-152°C under nitrogen protection and kept at that temperature for 15-25 min. Then, the temperature is raised to 178-182°C, and the system pressure is reduced to 30-35 kPa within 30 min before the reaction continues for 2.5-3.5 h.

7. The preparation method of the corrosion inhibitor, scale inhibitor, and bactericide according to claim 5, characterized in that, In step (2), the reaction temperature is 54-58℃ and the time is 2.5-3.5h.

8. The method for preparing the corrosion inhibitor, scale inhibitor, and bactericide according to claim 5, characterized in that, In step (3), the reaction temperature of the tertiary amine side-chain modified polysuccinimide intermediate with benzyl chloride is 68-72℃ and the reaction time is 2-2.5h, and the reaction temperature with 1-bromododecane is 86-90℃ and the reaction time is 5-7h.

9. The method for preparing the corrosion inhibitor, scale inhibitor, and bactericide according to claim 5, characterized in that, In step (4), the alkaline hydrolysis temperature is 44-46℃ and the time is 2.5-3.5h; the reaction temperature with sodium chloroacetate is 70-74℃ and the time is 4-6h.

10. The method for preparing the corrosion inhibitor, scale inhibitor, and bactericide according to claim 5, characterized in that, In step (4), dialysis and concentration are performed as follows: some of the mixed solvent is removed under reduced pressure at 48-52℃, the concentrate is placed in a dialysis bag with a molecular weight cutoff of 1000, and dialysis is performed with deionized water for 36-48 hours. The dialysis solution is replaced every 8 hours, and the concentration is performed under reduced pressure after dialysis.

Images