High-hardness water corrosion and scale inhibitor and preparation method thereof

Abstract

The invention relates to the field of industrial water treatment agents, and discloses a high-hardness water corrosion and scale inhibitor and a preparation method thereof. The scale inhibitor comprises the following components in parts by weight: 15-25 parts of an organic phosphonic acid compound; 10 to 20 parts of a polycarboxylic acid polymer; 3-8 parts of zinc salt; 2-5 parts of an azole compound; 5-12 parts of a cosolvent; the total parts by weight are 100; the preparation method comprises the steps of raw material preparation, mixing and dissolving, sequential addition and reaction control, system optimization and finished product preparation. In the scale inhibitor, the organic phosphonic acid and the polycarboxylic acid polymer synergistically inhibit scale, and the zinc salt and the azole compound synergistically inhibit corrosion, so that the scale inhibitor can stably play a role in high-hardness and high-alkalinity water, effectively inhibit corrosion and scaling of equipment, prolong the service life of the equipment and reduce the operation cost; the preparation process is simple, all the components are easy to obtain, the cost is controllable, and industrial production, popularization and application are facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of industrial water treatment agents, more particularly, it relates to a high-hardness water corrosion and scale inhibitor and a preparation method thereof. BACKGROUND

[0002] High-hardness water generally refers to water with a total concentration (in terms of calcium carbonate) of calcium and magnesium ions exceeding 300 mg / L, which is widely present in circulating cooling water systems, boiler heating pipe networks, central air conditioning cooling equipment in the industrial fields of chemical industry, electric power, metallurgy, etc. The calcium and magnesium ions in such water quality are easy to combine with anions such as carbonate and sulfate in water to form insoluble salts such as calcium carbonate and calcium sulfate, which can adhere to the pipe wall of the heat exchanger, the inner wall of the pipeline and the metal surface of the equipment in the form of scale layer. From the actual hazards, fouling can cause a substantial increase in the thermal resistance of the heat exchange interface. According to industry data, when the thickness of the scale layer reaches 1 mm, the heat exchange efficiency can be reduced by 15% to 20%, directly causing an increase in energy consumption; at the same time, the uneven deposition of the scale layer can cause local overheating of the equipment, accelerate the fatigue aging of the metal material, and even cause system pressure abnormalities due to pipeline blockage, thereby causing safety hazards. The corrosion problem is more hidden and far-reaching: the corrosion medium such as dissolved oxygen and chloride ion in high-hardness water can penetrate through the cracks of the scale layer to the metal surface to form a local electrochemical corrosion cell, resulting in local corrosion phenomena such as pitting and crevice corrosion. Statistics show that the corrosion rate of equipment under high-hardness water quality can be 2-3 times that under normal water quality, and the average service life is shortened by 30% to 50%, and the annual loss due to corrosion and fouling accounts for 8% to 12% of the total industrial operating cost. The existing corrosion and scale inhibition technology is difficult to adapt to the harsh water quality conditions of high hardness and high alkalinity (pH≥8.5): although traditional organic phosphonate scale inhibitors (such as ATMP and HEDP) can play a role by chelating calcium and magnesium ions, they are easy to form calcium phosphonate precipitates under high ion concentration, thereby reducing the scale inhibition efficiency; the molecular chain of polycarboxylic acid dispersants (such as PAA and HPMA) is easy to be entangled by high-concentration metal ions, and the dispersion capacity decays significantly, and when the calcium hardness exceeds 500 mg / L, the scale inhibition rate often decreases to below 70%. In terms of corrosion inhibition, single zinc salt corrosion inhibitors are easy to form zinc hydroxide precipitates in high-pH environments, thereby losing corrosion inhibition activity; and azole compounds have limited protective effect on carbon steel, and are difficult to cope with systems with multiple metal materials (such as carbon steel, copper alloy and stainless steel).

[0003] More importantly, the existing composite corrosion and scale inhibitors generally have the problem of insufficient synergy: the chemical antagonism between the scale inhibition component and the corrosion inhibition component may occur (such as the formation of a complex of polycarboxylic acid and zinc ions), resulting in a lower overall performance than when used alone; and when the water quality fluctuates (such as a short-term increase of 200 mg / L in calcium hardness and a fluctuation of ±0.5 in pH), the adaptability of the agent is poor, and the corrosion inhibition rate and the scale inhibition rate fluctuate by 20% to 30%, which cannot meet the needs of long-term stable operation of industrial systems. Therefore, it is an urgent need in the field of industrial water treatment to develop a synergistic corrosion and scale inhibitor that has strong scale inhibition ability and efficient corrosion inhibition performance in high-hardness and high-alkalinity water quality, and has strong adaptability to water quality fluctuations. SUMMARY

[0004] The application aims to provide a corrosion and scale inhibitor suitable for high-hardness water environment, to realize the synergistic inhibition of corrosion and scaling, to focus on solving the technical problems of accelerated scale crystal deposition and intensified electrochemical corrosion in high-hardness water quality, and to provide a chemical agent solution for long-term stable operation of equipment in high-hardness water quality.

[0005] To achieve the above-mentioned application purposes, the application provides a synergistic corrosion and scale inhibitor that has strong scale inhibition ability and efficient corrosion inhibition performance in high-hardness and high-alkalinity water quality, and has strong adaptability to water quality fluctuations.

[0006] In a first aspect, the application provides a high-hardness water corrosion and scale inhibitor, which comprises the following components in parts by weight: organic phosphonic acid compound 15 to 25 parts; polycarboxylic acid polymer 10 to 20 parts; zinc salt 3 to 8 parts; azole compound 2 to 5 parts; cosolvent 5 to 12 parts; deionized water to make up to 100 parts.

[0007] The above technical solution components mainly play the following roles: scale inhibition: the molecular structure of the organic phosphonic acid compound contains multiple phosphonic acid groups (-PO (OH)2), which form stable six-membered ring chelates (stability constant K≥10 8 ) with calcium and magnesium ions, thereby reducing the concentration of free calcium and magnesium ions in water, keeping the ion product (IP) in the solution lower than the solubility product of calcium carbonate (Ksp=4.5×10 -9 ) and calcium sulfate (Ksp=9.1×10 -6 ), and inhibiting the nucleation process of scale crystals from the thermodynamic point of view. At the same time, the phosphonic acid groups can be adsorbed on the active growth points of scale crystals (such as calcium carbonate) through coordination bonds, change the regularity of crystal lattice arrangement, form distorted unstable crystals, and reduce the growth rate of the crystals. As an anionic dispersant, the carboxyl group (-COOH) on the molecular chain of polycarboxylic acid polymer dissociates in water to carry a negative charge, which can be adsorbed on the scale crystal surface by electrostatic attraction, making the absolute value of zeta potential of the crystal surface increase (≥30 mV) and forming a steric hindrance effect. This effect can effectively prevent the collision and agglomeration of adjacent scale crystals, control the crystal particle size below 1 μm, and make it difficult to deposit on the metal surface. More importantly, there is a synergistic effect between organic phosphonic acid and polycarboxylic acid: phosphonic acid chelates can combine with polycarboxylic acid molecular chains through hydrogen bonds, prolonging the residence time of the polymer in water (half-life period extended by 2-3 times), while the steric hindrance effect of polycarboxylic acid can reduce the formation of calcium phosphate deposits. The combination of the two can improve the scale inhibition efficiency by 30%-40% compared to single component, especially for calcium sulfate scale which is easily formed in high hardness water. The long-acting scale inhibition can be achieved by destroying the "ladder expansion" mechanism of crystal growth. Inhibition effect: Zn 2+ dissociated from zinc salt in neutral to weak alkaline environment (pH 6.5-8.5) can combine with hydroxyl (-OH) in water to form Zn (OH)2colloidal particles. These particles are enriched in the anode area of the carbon steel surface (areas with corrosion current density ≥10 μA / cm 2 ) through electrochemical migration, quickly forming a dense zinc oxide (ZnO) protective film with a thickness of about 50-100 nm. The porosity of this film is ≤0.1%, which can effectively block the penetration of dissolved oxygen, chloride ions and other corrosion media in water (permeability coefficient ≤10 -12 cm / s), reducing the corrosion rate of carbon steel from 0.2 mm / a to below 0.02 mm / a. The molecular structure of azole compounds contains a nitrogen heterocycle, which forms a coordination bond with Cu 2+ on the surface of copper alloy through the lone pair of electrons of the ring nitrogen atom, forming a monomolecular adsorption film on the metal surface (coverage ≥95%). This film can significantly increase the corrosion potential of copper alloy (positive shift ≥200 mV), inhibit the cathodic reduction reaction (O2+ 2H2O + 4e - → 4OH - ), and block the dissolution of copper ions (Cu → Cu 2+ + 2e - ), thus kinetically suppressing the occurrence of electrochemical corrosion. The synergistic mechanism of the corrosion inhibition components is embodied in the "complementary coverage" effect of the inorganic protective film formed by zinc salt and the organic adsorption film of azole. The zinc oxide film has excellent protection for iron-based materials such as carbon steel, while the azole film is more targeted for copper alloy. At the same time, the polycarboxylic acid polymer can transport zinc ions and azole molecules to the micro defects (such as scratches and grain boundaries) on the metal surface through adsorption, promote the preferential formation of the protective film in the weak area, and achieve comprehensive protection for multi-material equipment.

[0008] Further, the organic phosphonic acid compound includes one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxyethylidene diphosphonic acid, amino trimethylene phosphonic acid, and diethylene triamine pentamethylene phosphonic acid.

[0009] Further, the polycarboxylic acid polymer includes one or more of acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer, hydrolyzed polymaleic anhydride, polyacrylic acid, and maleic acid-acrylic acid copolymer.

[0010] Further, the zinc salt includes one or more of zinc sulfate, zinc chloride, and zinc nitrate.

[0011] Further, the azole compound includes one or more of benzotriazole, methyl benzotriazole, and mercaptobenzothiazole.

[0012] Further, the cosolvent includes one or more of ethanol, isopropyl alcohol, ethylene glycol, and glycerol.

[0013] Further, the corrosion and scale inhibitor for high-hardness water includes the following components in parts by weight: 2-phosphonobutane-1,2,4-tricarboxylic acid 20 parts; acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer 15 parts; zinc sulfate 5 parts; benzotriazole 3 parts; ethanol 8 parts; deionized water to 100 parts.

[0014] Further, the organic phosphonic acid compound is a sulfonated modified phosphonic acid-based polyaspartic acid, which is prepared by the following steps: Step a, place L-aspartic acid monomers in a reaction container, heat to 160-180°C under nitrogen atmosphere, pre-react for 2-3h, then continue the polycondensation reaction at 190-200°C under vacuum condition with pressure ≤-0.095 MPa for 1.5-2h, to obtain poly succinimide powder, with number average molecular weight Mn controlled at 5000-6500 Da; Step b: Mix the polysuccinimide powder obtained in step a with deionized water at a mass ratio of 1:(6~8), heat to 65~70°C, adjust the pH to 9.3~9.5, and then slowly add sodium 2-aminoethanesulfonate aqueous solution equivalent to 20~25% of the mass of polysuccinimide powder, controlling the dropping rate to 1~2 mL / min. After the dropping is completed, keep the reaction at the temperature for 4~6 hours. Step c: While maintaining the temperature and stirring of the reaction system from step b, slowly add sodium phosphite equivalent to 12-15% of the mass of polysuccinimide powder and formaldehyde aqueous solution equivalent to 6-8% of the mass of polysuccinimide powder, adjust the pH to 4.0-4.5, and carry out the phosphomethylation reaction at 82-86°C for 3-5 hours. After the reactions in steps d and c are completed, the system is cooled to room temperature, the pH is adjusted to 2.5-3.0, and the reaction solution is purified by dialysis for 36-48 hours using a dialysis bag with a molecular weight cutoff of 1000 Da to remove inorganic salts and small molecule impurities. Finally, the dialysis solution is concentrated under vacuum at 55-60℃ and dried under vacuum at 70-80℃ to constant weight. After grinding, sulfonated phosphonic acid-based polyaspartic acid is obtained.

[0015] The aforementioned sulfonated modified phosphonic acid-based polyaspartic acid, through stepwise introduction of sulfonic acid and phosphonic acid groups to modify the molecular structure of polyaspartic acid, significantly improves its applicability and stability in high-hardness, high-alkalinity water. This modified product combines the excellent dispersing and anti-deposition capabilities of sulfonic acid groups with the strong chelating effect of phosphonic acid groups. The two functional groups produce a significant synergistic effect, effectively overcoming the inherent defect of traditional organophosphonic acids that easily form insoluble calcium phosphonate precipitates. When applied to corrosion and scale inhibitors in high-hardness water, it maintains a transparent aqueous solution state even at extremely high calcium ion concentrations, is not easily ineffective due to self-precipitation, and greatly improves the overall scale inhibition rate of high-hardness water corrosion and scale inhibitors, while ensuring the long-lasting and stable corrosion inhibition effect.

[0016] Secondly, this application discloses a method for preparing the high-hardness water corrosion and scale inhibitor as described in any of the first aspects, comprising the following steps: Step 1, Raw material preparation: Weigh each component accurately according to the formula, dry the organophosphonic acid compound, and sieve the polycarboxylic acid polymer; Step 2, Mixing and Dissolving: Add deionized water to the reaction vessel, and add the organophosphonic acid compound at a constant rate while stirring until a homogeneous and clear solution is formed; Step 3, Sequential Addition and Reaction Control: While maintaining stirring and temperature, add the polycarboxylic acid polymer in portions, stirring until fully dissolved; then add the zinc salt and azole compound sequentially, increasing the stirring rate and extending the stirring time to promote the formation of a stable complex structure between zinc ions and azole compound; Step 4, System optimization and finished product preparation: Reduce the stirring rate and add a co-solvent. After stirring and mixing evenly, cool and filter to obtain the high hardness water corrosion and scale inhibitor.

[0017] Furthermore, in step 3, after adding the polycarboxylic acid polymer, the viscosity of the system is controlled at 5-10 mPa·s; after adding the zinc salt and azole compound, the completeness of the complexation reaction is detected by ultraviolet spectrophotometry. In step 4, the particle size distribution of the system is detected by a Malvern laser particle size analyzer, and the finished product must meet the requirement that the particle size distribution D50 ≤ 1 μm; the turbidity of the solution is measured by a turbidity meter, and the finished product must meet the requirement that the turbidity of the solution ≤ 5 NTU.

[0018] In summary, this application has the following beneficial effects: This invention is designed specifically for high-hardness water. Organophosphonic acid and polycarboxylic acid polymers synergistically inhibit scale formation, while zinc salts and azole compounds synergistically inhibit corrosion. It functions stably in high-hardness, high-alkalinity water, effectively suppressing equipment corrosion and scaling, extending equipment lifespan, and reducing operating costs. The preparation process is simple, the components are readily available, and the cost is controllable, facilitating industrial production and widespread application. Detailed Implementation

[0019] The technical solutions and effects of this application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely for explaining the invention and are not intended to limit the invention.

[0020] Example 1 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 15 parts of organophosphonic acid compound (PBTCA), 10 parts of polycarboxylic acid polymer (AA / AMPS), 3 parts of zinc salt (zinc sulfate), 2 parts of azole compound (BTA), 5 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0021] The preparation method of this high-hardness water corrosion and scale inhibitor is as follows: Step 1, Raw material preparation Based on the above mass ratio, use an electronic analytical balance to accurately weigh the organophosphonic acid compound, polycarboxylic acid polymer, zinc salt, azole compound, cosolvent, and deionized water. All raw materials need to be pretreated. The organophosphonic acid compound needs to be dried at 40℃±2℃ for 2 hours to remove free moisture, and the polycarboxylic acid polymer needs to be passed through a 200-mesh sieve to remove mechanical impurities. Step 2, Mix and dissolve Add the calculated amount of deionized water to a 150L stainless steel reactor (equipped with a paddle stirrer, temperature sensor, and reflux condenser). Turn on the stirring system and set the stirring speed to 100~200 r / min (dynamically adjusted according to the material viscosity: 150~200 r / min when the initial water volume is small, and reduced to 100~150 r / min after the water volume is replenished). Simultaneously, control the temperature of the reaction system at 25℃±3℃ using a constant temperature water bath. Use a peristaltic pump (flow rate 50~100 mL / min) to uniformly inject the organophosphonic acid compound into the reactor and continue stirring for 10~15 min. During this period, monitor the dispersion of the solution in real time using a laser particle size analyzer (particle size distribution RSD≤5%) until a homogeneous and clear liquid is formed, confirming that there are no solid particles remaining. Step 3, add the reaction control ingredients sequentially. Maintaining a stable stirring rate and temperature, add the polycarboxylate polymer in three batches (3 min apart) through a solid feeding funnel to avoid local agglomeration. Continue stirring for 15-20 min, monitoring the system viscosity using a rotational viscometer (controlled at 5-10 mPa·s) to ensure the polymer molecular chains are fully extended. Subsequently, add the zinc salt (at a uniform rate of 5 g / min) and the azole compound (dissolved in 5% ethanol solution and added dropwise), increasing the stirring rate to 180-200 r / min and extending the stirring time to 20-30 min to promote the formation of a stable complex structure between zinc ions and the azole compound. Detect the completeness of the complexation reaction using a UV spectrophotometer (280 nm wavelength) (the reaction is considered complete when the absorbance remains stable for more than 3 min). Step 4, System Optimization and Finished Product Preparation Reduce the stirring speed to 120-150 r / min, and slowly add the co-solvent through a separatory funnel (dropping rate 2-3 mL / s). After stirring for 10-15 min, use a Malvern laser particle size analyzer to detect the particle size distribution of the system (D50 ≤ 1 μm), and measure the turbidity of the solution using a turbidimeter (≤ 5 NTU). Finally, turn off the heating device and allow it to cool naturally to room temperature (25℃ ± 2℃). Filter the solution through a 0.45 μm microporous membrane to remove trace amounts of insoluble matter, obtaining a uniform and transparent high-hardness water corrosion and scale inhibitor product. Package the product in a polyethylene plastic drum and store it away from light.

[0022] Tests showed that, in high-hardness water (calcium hardness 600 mg / L), at 40°C and with a reagent concentration of 20 mg / L, the corrosion inhibition rate of carbon steel was 90%, and the scale inhibition rate of calcium carbonate was 95%.

[0023] Example 2 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 20 parts of organophosphonic acid compound (PBTCA), 15 parts of polycarboxylic acid polymer (AA / AMPS), 5 parts of zinc salt (zinc sulfate), 3 parts of azole compound (BTA), 8 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0024] The preparation method is the same as in Example 1.

[0025] Tests showed that, in high-hardness water (calcium hardness 800 mg / L), at 50°C and with a reagent concentration of 35 mg / L, the corrosion inhibition rate of carbon steel was 93%, and the scale inhibition rate of calcium carbonate was 97%.

[0026] Example 3 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 25 parts of organophosphonic acid compound (PBTCA), 20 parts of polycarboxylic acid polymer (AA / AMPS), 8 parts of zinc salt (zinc sulfate), 5 parts of azole compound (BTA), 12 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0027] The preparation method is the same as in Example 1.

[0028] Tests showed that, in high-hardness water (calcium hardness 1000 mg / L), at 60°C and with a reagent concentration of 50 mg / L, the carbon steel corrosion inhibition rate was 95% and the calcium carbonate scale inhibition rate was 98%.

[0029] Example 4 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 18 parts of organophosphonic acid compound (PBTCA), 12 parts of polycarboxylic acid polymer (AA / AMPS), 4 parts of zinc salt (zinc sulfate), 2.5 parts of azole compound (BTA), 6 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0030] Except for step 4, where the stirring rate is controlled at 120 r / min and the pH of the system is adjusted to 6.5 with 0.05 mol / L sodium hydroxide solution during the mixing process to obtain the corrosion and scale inhibitor, the rest of the preparation method is the same as in Example 1.

[0031] Tests showed that under conditions of high hardness water (calcium hardness 700 mg / L), 45℃, and reagent concentration of 25 mg / L, the corrosion inhibition rate of carbon steel was 91%, the scale inhibition rate of calcium carbonate was 96%, and the scale inhibition rate of calcium sulfate reached 92% (tested according to GB / T 16632-2008 method).

[0032] Example 5 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 22 parts of organophosphonic acid compound (PBTCA), 18 parts of polycarboxylic acid polymer (AA / AMPS), 6 parts of zinc salt (zinc sulfate), 4 parts of azole compound (BTA), 10 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0033] Except for step 4, where the stirring rate is set to 180 r / min, the system temperature is maintained at 30℃±2℃ during preparation, and the total stirring time is extended to 90 min, the rest of the preparation methods are the same as in Example 1.

[0034] Tests showed that, in a high-hardness water environment (calcium hardness 900 mg / L), at 55°C and with a reagent concentration of 40 mg / L, the corrosion inhibition rate for carbon steel was 94%, the scale inhibition rate for calcium carbonate was 97.5%, and the corrosion inhibition rate for copper alloys (referring to the method in GB / T 10123-2021) reached 90%.

[0035] Example 6 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 16 parts of organophosphonic acid compound (PBTCA), 14 parts of polycarboxylic acid polymer (AA / AMPS), 3.5 parts of zinc salt (zinc sulfate), 3 parts of azole compound (BTA), 7 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0036] Except for step 4, where the stirring rate is 140 r / min, 0.5 parts of sodium citrate (as an auxiliary chelating agent) are added during the preparation process, and the mixture is filtered after thorough mixing, the rest of the preparation method is the same as in Example 1.

[0037] Tests showed that, in high-hardness water (calcium hardness 650 mg / L, magnesium hardness 300 mg / L), at 42°C and a reagent concentration of 28 mg / L, the carbon steel corrosion inhibition rate was 92%, the calcium carbonate scale inhibition rate was 95.5%, and no stratification occurred after the solution stood for 72 hours (stability test passed).

[0038] Example 7 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 23 parts of organophosphonic acid compound (PBTCA), 16 parts of polycarboxylic acid polymer (AA / AMPS), 7 parts of zinc salt (zinc sulfate), 4.5 parts of azole compound (BTA), 9 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0039] Except for step 4, where the stirring rate is controlled at 160 r / min and the temperature is increased in a stepwise manner (25℃→35℃→25℃) during mixing to promote component dissolution, the rest of the preparation method is the same as in Example 1.

[0040] Tests showed that under conditions of high hardness water (calcium hardness 950 mg / L, pH 8.2), 58℃, and a reagent concentration of 45 mg / L, the corrosion inhibition rate of carbon steel was 94.5%, the scale inhibition rate of calcium carbonate was 98%, and after a 30-day dynamic simulation test (circulating water system), the increase in scale thickness on the pipe wall was ≤0.02 mm.

[0041] Example 8 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 17 parts of organophosphonic acid compound (PBTCA), 13 parts of polycarboxylic acid polymer (AA / AMPS), 5 parts of zinc salt (zinc sulfate), 3.5 parts of azole compound (BTA), 8 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0042] Except for step 4, where the stirring rate is 130 r / min and the pH of the system is adjusted to 7.5 after preparation, the rest of the preparation method is the same as in Example 1.

[0043] Tests showed that in high-hardness water (calcium hardness 750 mg / L, chloride ion content 100 mg / L), at 48℃ and a reagent concentration of 32 mg / L, the corrosion inhibition rate of carbon steel was 92.5%, the scale inhibition rate of calcium carbonate was 96%, and the inhibition effect on chloride ion-induced pitting corrosion was significant (pitting depth ≤ 5 μm).

[0044] Example 9 A high-hardness water corrosion and scale inhibitor, the raw materials used in its preparation include: 15 parts of organophosphonic acid compound (sulfonated modified phosphonic acid polyaspartic acid), 10 parts of polycarboxylic acid polymer (AA / AMPS), 3 parts of zinc salt (zinc sulfate), 2 parts of azole compound (BTA), 5 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0045] The preparation method is the same as in Example 1.

[0046] The preparation method of sulfonated modified phosphonic acid polyaspartic acid is as follows: 100 g of L-aspartic acid was weighed and placed in a 500 mL three-necked flask, and nitrogen gas was introduced to purge air. The oil bath temperature was raised to 180 °C, and the reaction was stirred at this temperature for 3 hours. Subsequently, the vacuum pump was turned on, and the system vacuum was reduced to -0.097 MPa, while the temperature was raised to 200 °C, and the reaction was continued for 2 hours. After the reaction was completed, polysuccinimide powder was obtained, and its number average molecular weight (Mn) was determined by GPC to be 6500 Da.

[0047] Take 20g of the above-mentioned polysuccinimide powder and add it to 160g of deionized water in a 500mL reaction flask, stirring to form a suspension. Heat to 70℃ and adjust the pH to 9.5 by adding 10% NaOH solution dropwise. Slowly add 50mL of an aqueous solution containing 5g of sodium 2-aminoethanesulfonate using a constant pressure dropping funnel, controlling the dropping rate at 1.5 mL / min. After the addition is complete, maintain the reaction at 70℃ and pH 9.5 for 6 hours.

[0048] Subsequently, 3g of sodium phosphite and 4.3g of 37% formaldehyde aqueous solution were added to the system, and the pH of the reaction system was adjusted to 4.0 with 20% dilute sulfuric acid. The temperature was raised to 85℃, and the reaction was continued under these conditions for 5 hours.

[0049] After the reaction was complete, the mixture was cooled to room temperature, and the pH of the system was adjusted back to 2.8 using 30% NaOH solution. All the reaction solution was placed in a dialysis bag (MWCO: 1000 Da) and dialyzed under running deionized water for 2 days. The dialysate was transferred to a rotary evaporator and concentrated under reduced pressure at 60°C to 1 / 5 of its original volume. It was then transferred to a petri dish and dried in a vacuum drying oven at 80°C for 24 hours. The dried pale yellow transparent solid was ground and passed through a 200-mesh sieve to obtain 28.5 g of sulfonated phosphonic acid-based polyaspartic acid, with a yield of 28.5% and a purity of 98%.

[0050] Tests showed that, in high-hardness water (calcium hardness 600 mg / L), at 40°C and with a reagent concentration of 20 mg / L, the corrosion inhibition rate of carbon steel was 94%, and the scale inhibition rate of calcium carbonate was 97%.

[0051] Comparative Example 1 Weigh out 20 parts of hydroxyethylidene diphosphonic acid, 15 parts of polyacrylic acid, 5 parts of zinc sulfate, 3 parts of benzotriazole, and 8 parts of ethanol, and add deionized water to make up to 100 parts. Prepare a corrosion and scale inhibitor according to the preparation method described in Example 1.

[0052] Tests showed that under conditions of high hardness water (calcium hardness 800 mg / L), 50℃, and a reagent concentration of 35 mg / L, the corrosion inhibition rate of carbon steel was 85%, and the scale inhibition rate of calcium carbonate was 78%.

[0053] Comparative Example 2 Weigh out 20 parts of PBTCA, 15 parts of AA / AMPS, and 8 parts of ethanol, and add deionized water to make up to 100 parts. Prepare a scale inhibitor according to the preparation method described in Example 1.

[0054] Tests showed that under conditions of high hardness water (calcium hardness 800 mg / L, chloride ion content 50 mg / L), 50℃, and reagent concentration 35 mg / L, calcium carbonate achieved a scale inhibition rate of 96%, but its corrosion inhibition rate for carbon steel was only 65%, and it had virtually no corrosion inhibition effect on copper alloys.

[0055] Comparative Example 3 15 parts of polyaspartic acid (number average molecular weight ~6500 Da), 10 parts of polycarboxylic acid polymer (AA / AMPS), 3 parts of zinc salt (zinc sulfate), 2 parts of azole compound (BTA), 5 parts of cosolvent (ethanol), and deionized water to make up to 100 parts.

[0056] The preparation method is the same as in Example 1.

[0057] Tests showed that, in high-hardness water (calcium hardness 600 mg / L), at 40°C and with a reagent concentration of 20 mg / L, the corrosion inhibition rate of carbon steel was 84%, and the scale inhibition rate of calcium carbonate was 85%.

[0058] In summary, this invention is designed specifically for high-hardness water. Organophosphonic acid and polycarboxylic acid polymers synergistically inhibit scale formation, while zinc salts and azole compounds synergistically inhibit corrosion. It can function stably in high-hardness, high-alkalinity water, effectively suppressing equipment corrosion and scaling, extending equipment lifespan, and reducing operating costs. The preparation process is simple, the components are readily available, and the cost is controllable, facilitating industrial production and widespread application.

[0059] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-hardness water corrosion and scale inhibitor, characterized in that, The components include the following parts by weight: 15-25 parts of organophosphonic acid compound; 10-20 parts of polycarboxylate polymer; 3 to 8 parts zinc salt; 2-5 parts of azole compounds; 5-12 parts of co-solvent; Add deionized water to bring the total to 100 parts.

2. The high hardness water corrosion and scale inhibitor according to claim 1, characterized in that, The organophosphonic acid compounds include one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxyethylidene diphosphonic acid, aminotrimethylphosphonic acid, and diethylenetriaminepentamethylidene phosphonic acid.

3. The high hardness water corrosion and scale inhibitor according to claim 1, characterized in that, The polycarboxylic acid polymers include one or more of acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer, hydrolyzed polymaleic anhydride, polyacrylic acid, and maleic acid-acrylic acid copolymer.

4. The high hardness water corrosion and scale inhibitor according to claim 1, characterized in that, The zinc salt includes one or more of zinc sulfate, zinc chloride, and zinc nitrate.

5. The high hardness water corrosion and scale inhibitor according to claim 1, characterized in that, The azole compounds include one or more of benzotriazole, methylbenzotriazole, and mercaptobenzothiazole.

6. The high hardness water corrosion and scale inhibitor according to claim 1, characterized in that, The co-solvent includes one or more of ethanol, isopropanol, ethylene glycol, and glycerol.

7. The high hardness water corrosion and scale inhibitor according to claim 1, characterized in that, The components include the following parts by weight: 20 parts of 2-phosphonobutane-1,2,4-tricarboxylic acid; 15 parts of acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer; 5 parts zinc sulfate; 3 parts of benzotriazole; 8 parts ethanol; Add deionized water to bring the total to 100 parts.

8. The high hardness water corrosion and scale inhibitor according to claim 1, characterized in that, The organophosphonic acid compound is sulfonated modified phosphonic acid-based polyaspartic acid, which is prepared by the following steps: Step a: Place L-aspartic acid monomer in a reaction vessel, heat to 160~180°C under a nitrogen atmosphere, pre-react for 2~3 hours, and then continue the polycondensation reaction at 190~200°C for 1.5~2 hours under a vacuum condition of pressure ≤ -0.095 MPa to obtain polysuccinimide powder with a number average molecular weight Mn controlled at 5000~6500 Da; Step b: Mix the polysuccinimide powder obtained in step a with deionized water at a mass ratio of 1:(6~8), heat to 65~70°C, adjust the pH to 9.3~9.5, and then slowly add sodium 2-aminoethanesulfonate aqueous solution equivalent to 20~25% of the mass of polysuccinimide powder, controlling the dropping rate to 1~2 mL / min. After the dropping is completed, keep the reaction at the temperature for 4~6 hours. Step c: While maintaining the temperature and stirring of the reaction system from step b, slowly add sodium phosphite equivalent to 12-15% of the mass of polysuccinimide powder and formaldehyde aqueous solution equivalent to 6-8% of the mass of polysuccinimide powder, adjust the pH to 4.0-4.5, and carry out the phosphomethylation reaction at 82-86°C for 3-5 hours. After the reactions in steps d and c are completed, the system is cooled to room temperature, the pH is adjusted to 2.5-3.0, and the reaction solution is purified by dialysis for 36-48 hours using a dialysis bag with a molecular weight cutoff of 1000 Da to remove inorganic salts and small molecule impurities. Finally, the dialysis solution is concentrated under vacuum at 55-60℃ and dried under vacuum at 70-80℃ to constant weight. After grinding, sulfonated phosphonic acid-based polyaspartic acid is obtained.

9. The method for preparing the high hardness water corrosion and scale inhibitor according to any one of claims 1-8, characterized in that, Includes the following steps: Step 1, Raw material preparation: Weigh each component accurately according to the formula, dry the organophosphonic acid compound, and sieve the polycarboxylic acid polymer; Step 2, Mixing and Dissolving: Add deionized water to the reaction vessel, and add the organophosphonic acid compound at a constant rate while stirring until a homogeneous and clear solution is formed; Step 3, Sequential Addition and Reaction Control: While maintaining stirring and temperature, add the polycarboxylic acid polymer in portions, stirring until fully dissolved; then add the zinc salt and azole compound sequentially, increasing the stirring rate and extending the stirring time to promote the formation of a stable complex structure between zinc ions and azole compound; Step 4, System optimization and finished product preparation: Reduce the stirring rate and add a co-solvent. After stirring and mixing evenly, cool and filter to obtain the high hardness water corrosion and scale inhibitor.

10. The method for preparing the high hardness water corrosion and scale inhibitor according to claim 9, characterized in that, In step 3, after adding the polycarboxylic acid polymer, the viscosity of the system is controlled at 5-10 mPa·s; after adding the zinc salt and azole compound, the completeness of the complexation reaction is detected by ultraviolet spectrophotometry. In step 4, the particle size distribution of the system is detected by a Malvern laser particle size analyzer, and the finished product must meet the requirement that the particle size distribution D50 ≤ 1 μm; the turbidity of the solution is measured by a turbidity meter, and the finished product must meet the requirement that the turbidity of the solution ≤ 5 NTU.