Corrosion and scale inhibitor suitable for high-salinity water, preparation method and application thereof

Abstract

This invention discloses a corrosion and scale inhibitor suitable for high-salinity water, its preparation method, and its application. The components include nano-SiO2@NH2, organophosphonates, zinc salts, polycarboxylic acid, and nano-SiO2. The nano-SiO2@NH2, organophosphonates, and zinc salts constitute the corrosion inhibitor component in a mass ratio of (0.8~1.2):0.5:(0.3~0.4). The polycarboxylic acid and nano-SiO2 constitute the scale inhibitor component in a total solids content mass ratio of 3:1. The polycarboxylic acid grafting rate in the scale inhibitor component is ≥80%. The corrosion inhibitor component and the scale inhibitor component are compounded in a 1:1 ratio to prepare the finished agent. The preparation method includes preparing the corrosion inhibitor component and adjusting the pH to 3~4, preparing the scale inhibitor component, and compounding the corrosion inhibitor component and the scale inhibitor component to prepare the finished agent. This invention uses nano-SiO2@NH2 to configure corrosion inhibitors and nano-SiO2 to configure scale inhibitors, and strictly mixes each component in steps to achieve a synergistic chemical and physical corrosion and scale inhibition effect. The finished agent has the characteristics of corrosion inhibition rate and CaCO3 inhibition rate of over 95%, MgSiO3 inhibition rate of over 80%, tolerance to high salt environment, high high temperature stability and low biotoxicity.

Description

Technical Field

[0001] This invention belongs to the field of water treatment agents, and specifically relates to a corrosion and scale inhibitor suitable for high salinity, its preparation method, and its application. Background Technology

[0002] In southern regions where groundwater resources are abundant, most boilers use groundwater. However, groundwater has a high content of metallic salts such as calcium, magnesium, and aluminum, as well as chloride ions, resulting in high water hardness. This easily leads to scaling and corrosion in boilers, especially under high temperature and pressure environments, where scaling and corrosion are more severe, directly affecting boiler efficiency and lifespan. Every year, a high percentage of boilers suffer from tube ruptures and drum bulging and burnout due to scaling. In some areas, the average scale thickness can reach 2-8 mm. Since the thermal conductivity of scale is only 1%-1.5% of that of iron, it not only seriously affects the safe operation of boilers but also causes significant fuel waste. For example, 0.5 mm thick scale increases energy consumption by 2%, while 3 mm thick scale can increase energy consumption by 10%, and 8 mm thick scale can even increase energy consumption by 35%.

[0003] Currently, the most commonly used water treatment products on the market are organophosphonates, which inhibit scale and corrosion. Their scale inhibition mechanism mainly involves the complexation of organophosphonates with calcium and magnesium ions in water to form stable complexes. These complexes can remain soluble under different water temperatures and pH conditions. However, when the salinity of the water is high or the concentration is large, these corrosion and scale inhibitors are prone to hydrolysis or oxidative decomposition, leading to the formation of calcium phosphate precipitates and causing scale to reappear in the boiler. This results in boiler users spending money on boiler water treatment products but failing to achieve the desired scale removal or prevention effect. In some cases, it may even further increase the phosphorus content in the water, causing water pollution after discharge and increasing the cost of wastewater treatment for boiler users. Summary of the Invention

[0004] (I) Technical Issues

[0005] The technical problem to be solved by this invention is that existing water treatment products cannot effectively deal with boiler scaling and corrosion caused by high salinity. This invention proposes a novel corrosion and scale inhibitor and its preparation method, aiming to significantly improve boiler operating efficiency and extend service life.

[0006] (II) Technical Solution

[0007] This invention is achieved through the following technical solution:

[0008] This invention proposes a corrosion and scale inhibitor suitable for high-salinity water, comprising nano-SiO2@NH2, organophosphonates, zinc salts, polycarboxylic acid, and nano-SiO2. The corrosion inhibitor is composed of nano-SiO2@NH2, organophosphonates, and zinc salts in a mass ratio of (0.8–1.2):0.5:(0.3–0.4), while the scale inhibitor is composed of polycarboxylic acid and nano-SiO2 in a total solids content mass ratio of 3:1. The polycarboxylic acid grafting rate in the scale inhibitor is ≥80%. The corrosion inhibitor and the scale inhibitor are compounded in a 1:1 ratio to form the finished product.

[0009] Based on the above formulation, a corrosion inhibitor with synergistic corrosion inhibition effect is formed by adding nano-SiO2@NH2 to conventional scale inhibitors such as organophosphonates and zinc salts, and a scale inhibitor with synergistic scale inhibition effect is formed by adding nano-SiO2 to conventional scale inhibitors such as polycarboxylic acid. The finished agent is prepared by secondary compounding of the corrosion inhibitor and scale inhibitor components. It has the advantages of good synergistic effect of each component, is not easy to precipitate, has high dispersion stability, and when applied to high saline water quality, it can form a continuous and dense corrosion inhibitor film on the inner wall of the boiler. It has the advantages of corrosion inhibition rate not greater than 0.03mm / a, corrosion inhibition rate and CaCO3 inhibition rate higher than 95%, MgSiO3 inhibition rate higher than 80%, tolerance to high chlorine environment of 5000mg / L, high high temperature stability, and low biological toxicity.

[0010] Preferably, the organophosphonate is selected from one or more of hydroxyethylidene diphosphonic acid, hydroxyphosphonoacetic acid, ethylenediaminetetramethylenephosphonic acid, and dimethylphenylphosphonate, and the purity of the organophosphonate is ≥98% and the content of active component is ≥50%.

[0011] Preferably, the zinc salt is zinc sulfate with a purity of ≥99.9%.

[0012] Preferably, the polycarboxylic acid is polyacrylic acid or an acrylic acid copolymer, the polycarboxylic acid has a molecular weight of 2000-5000 Da and a solid content of ≥40%, so that the compounded corrosion and scale inhibitor can simultaneously achieve good effects in inhibiting calcium carbonate scale and magnesium silicate scale, thereby improving the applicable water quality range.

[0013] Preferably, the nano-SiO2 in the nano-SiO2@NH2 and the nano-SiO2 in the scale inhibitor component have a particle size of 20-50 nm and a specific surface area of ​​2200 m². 2 / g, surface hydroxyl density is 3-5 per nm 2 This ensures that nano-SiO2 has good dispersibility and provides sufficient adsorption and coordination sites, which is conducive to forming a more stable mixture morphology.

[0014] Preferably, the corrosion and scale inhibitor is further formulated with 1% mercaptobenzothiazole as a synergistic agent. The mercaptobenzothiazole, acting as a synergistic agent, bridges the corrosion-inhibiting and scale-inhibiting components. The mercapto groups are coordinated with zinc and amino ions, and the benzene rings are hydrophobically linked to polycarboxylic acid, forming a stable composite micelle layer resistant to 120°C on the exterior of the corrosion-inhibiting film. This further inhibits scale growth and adhesion, improving the synergistic effect of corrosion and scale inhibition.

[0015] This invention also provides a method for preparing a corrosion and scale inhibitor suitable for high-salinity water, comprising the following steps:

[0016] S1, Raw material pretreatment: The organophosphonate is dissolved and diluted with deionized water to prepare a 30% concentration organophosphonate solution to remove insoluble matter; the polycarboxylic acid is purified to the target molecular weight by dialysis.

[0017] S2, Preparation of corrosion inhibitor components: Prepare the components according to the mass ratio of nano-SiO2@NH2, organophosphonate and zinc salt (0.8~1.2):0.5:(0.3~0.4). First, add zinc salt to organophosphonate solution and premix evenly, then add nano-SiO2@NH2 to form a mixed solution. Place the mixed solution in a constant temperature water bath at 50±2℃ and stir with stirring parameters of 200±10 rpm for 2.0±0.1h. During the stirring process, monitor the pH with an online pH meter and adjust the pH with 10% HNO3 to control the pH at 3.0~4.0 to obtain a homogeneous corrosion inhibitor component solution with a light transmittance ≥95%.

[0018] S3, prepare scale inhibitory components: prepare polycarboxylic acid and nano-SiO2 at a total solid content mass ratio of 3:1, pre-disperse nano-SiO2 in deionized water, adjust the pH to 10 with NaOH, add polycarboxylic acid and place in an ice bath environment of ≤30℃, and perform ultrasonic mixing at 40kHz for 15±1min to obtain a scale inhibitory component solution with a polycarboxylic acid grafting rate ≥80%.

[0019] S4, Compound Activation: The corrosion inhibitor solution is added to the scale inhibitor solution at a flow rate of 5 mL / min and mixed evenly. The mass ratio of the corrosion inhibitor solution to the scale inhibitor solution is 1:1. After mixing, ultrasonic activation is performed. The ultrasonic activation parameters are 20 kHz, 30 ± 1 min, and the temperature during the ultrasonic process is controlled ≤40℃ to obtain a stable composite micelle solution.

[0020] S5, Finished Product Adjustment and Preparation: Adjust the mixed solution obtained in step S4 with 10% NaOH solution, controlling the pH to 7.5–8.5, and adjust the Na+ content in the mixed solution using reverse osmosis or ion exchange. + The final product is obtained by aseptic filling with a content of <0.1mol / L.

[0021] Based on the above preparation method, by using organophosphonates and Zn 2+ The nano-SiO2@NH2 was added in a sequential gradient and mixed in a strictly stepwise manner to prepare the corrosion inhibitor and scale inhibitor components, ensuring that each formed a stable complex. The corrosion inhibitor component was mixed at a pH of 3.0–4.0. After mixing, the overall pH of the agent was adjusted again, and the Na+ content was controlled. + The content is controlled to avoid direct polymerization and precipitation of zinc salt and polycarboxylic acid during the compounding process, and to form a negative potential in the agent to prevent nano-SiO2@NH2 and nano-SiO2 from agglomerating and failing. The corrosion and scale inhibitor prepared by this method has high stability, is resistant to high temperature and high salinity, and is not easily hydrolyzed or oxidized. After use, it can form a continuous and stable corrosion and scale inhibition effect on the inner wall of the boiler.

[0022] Preferably, the method for obtaining nano-SiO2@NH2 in step S2 is as follows: nano-SiO2 is dispersed in deionized water, the pH is adjusted to 4.5±0.2, the temperature is raised to 60℃ and kept constant, a silane coupling agent is added and stirred to mix, so that the nano-SiO2 and the hydrolysis product of the silane coupling agent undergo a condensation reaction to obtain amino-modified SiO2@NH2. The nano-SiO2 surface treated by this step can form a high amino grafting rate, and the generated SiO2@NH2 can increase the corrosion inhibition rate of the agent by about 10%.

[0023] Preferably, in step S3, when pre-dispersing nano-SiO2, 0.1% polyethylene glycol PEG-400 is added as a dispersing aid to improve the pre-dispersion effect of nano-SiO2 and promote the bonding between nano-SiO2 and polycarboxylic acid to form a scale inhibitor solution with a high grafting rate.

[0024] Preferably, in step S4, after the corrosion inhibitor and scale inhibitor are mixed, they are placed in a light-proof environment. First, 1.0 ± 0.05% mercaptobenzothiazole, 9% deionized water, and 0.05% butylated hydroxytoluene by mass percentage are added and mixed, and then ultrasonic activation is performed. This step, by adding mercaptobenzothiazole as a synergistic agent, can further improve the compound stability of the corrosion inhibitor and scale inhibitor, so that the finished agent exists in a high-temperature resistant composite micelle form, which can further enhance the corrosion and scale inhibition effect in high-salt water.

[0025] This invention also provides an application of a corrosion and scale inhibitor suitable for high-salinity boiler water. The dosage of the corrosion and scale inhibitor is determined based on the molar ratio of calcium ions to organophosphonates in the boiler water being ≥1:1.2. Specifically, the content of nano-SiO2@NH2 in the added water is controlled at 15%–25%, and the zinc salt content is adjusted according to the chloride ion content in the water. When the chloride content in the water is 108 mg / L, the zinc salt content is no more than 8%. This dosage control method can form a continuous corrosion-inhibiting film layer on the inner wall of the boiler, maintaining good dispersion stability, preventing precipitation, and resulting in a more durable corrosion and scale inhibition effect.

[0026] (III) Beneficial Effects

[0027] Compared with existing corrosion and scale inhibitors, the corrosion and scale inhibitor of the present invention has the following beneficial effects:

[0028] 1) By adding nano-SiO2@NH2 to conventional scale inhibitors such as organophosphonates and zinc salts to form a corrosion inhibitor component with synergistic corrosion inhibition effect, and by adding nano-SiO2 to conventional scale inhibitors such as polycarboxylic acid to form a scale inhibitor component with synergistic scale inhibition effect, the finished agent is prepared through secondary compounding of the corrosion inhibitor component and the scale inhibitor component. It has the advantages of good synergistic effect of each component, is not easy to precipitate, has high dispersion stability, and when applied to high saline water quality, it can form a continuous and dense corrosion inhibitor film on the inner wall of the boiler. It has the advantages of corrosion inhibition rate not greater than 0.03mm / a, corrosion inhibition rate of over 95%, CaCO3 inhibition rate of over 95%, MgSiO3 inhibition rate of over 80%, tolerance to high chlorine environment of 5000mg / L, high high temperature stability, and low biological toxicity.

[0029] 2) By adding mercaptobenzothiazole as a synergist in the compounding stage, the corrosion inhibitor and scale inhibitor are bridged, forming a stable composite micelle layer that can withstand 120℃ on the outside of the corrosion inhibitor film, further blocking the growth and adhesion of scale, and improving the synergistic effect of corrosion and scale inhibition and high temperature stability.

[0030] 3) By using organophosphonates, Zn 2+ The nano-SiO2@NH2 was added in a sequential gradient and mixed in a strictly stepwise manner to prepare the corrosion inhibitor and scale inhibitor components, ensuring that each formed a stable complex. The corrosion inhibitor component was mixed at a pH of 3.0–4.0. After mixing, the overall pH of the agent was adjusted again, and the Na+ content was controlled. + The content is controlled to avoid direct polymerization and precipitation of zinc salt and polycarboxylic acid during the compounding process, and to form a negative potential in the agent to prevent nano-SiO2@NH2 and nano-SiO2 from agglomerating and failing. The corrosion and scale inhibitor prepared by this method has high stability, is resistant to high temperature and high salinity, and is not easily hydrolyzed or oxidized. After use, it can form a continuous and stable corrosion and scale inhibition effect on the inner wall of the boiler.

[0031] 4) By adjusting the amount of corrosion and scale inhibitor added according to the calcium and chloride ion content of the added water, the effectiveness of the corrosion and scale inhibitor can be guaranteed, and a continuous corrosion-inhibiting film layer can be formed on the inner wall of the boiler, maintaining good dispersion stability, making it less prone to precipitation, and extending the duration of corrosion and scale inhibition.

[0032] The mechanism of action of the corrosion and scale inhibitor of the present invention includes:

[0033] (1) The synergistic corrosion inhibition effect of the corrosion inhibitory components, specifically including:

[0034] a) The silanol groups (-SiOH) on the surface of nano-SiO2@NH2 form Si-O-Fe covalent bonds with the Fe element in the boiler metal matrix, thereby forming a continuous corrosion-inhibiting chemical film on the inner wall of the boiler and achieving the corrosion inhibition effect.

[0035] b) Protonation of some amino groups (-NH2) in nano-SiO2@NH2 to -NH3 + Subsequently, it reacts with the phosphonate (-PO3) of organophosphonate (PBTCA). 2- Electrostatic adsorption forms SiO2@NH3 + -O3P-PBTCA complex enhances the adsorption of organophosphonates to corrosion-inhibiting films;

[0036] c) Chelating free Fe in boiler water using organophosphonates 2+ Mg 2+ Ca 2+ It forms a soluble complex, further increasing the film thickness and achieving a synergistic corrosion inhibition effect;

[0037] d) By controlling the protonation potential ζ of amino groups (-NH2) in nano-SiO2@NH2 to +28mV, Cl in high-salinity boiler water is adsorbed. - Reduce high levels of cl - Risk of pitting corrosion to the boiler's metal substrate;

[0038] e) Some silanol groups (-SiOH) on the surface of nano-SiO2@NH2 react with Zn 2+ The generated Zn(OH)2 is deposited on the surface of nano-SiO2@NH2, which inhibits the reduction of dissolved oxygen in boiler water, thereby inhibiting the cathodic reaction on the boiler metal substrate and further enhancing the corrosion inhibition effect;

[0039] (2) Synergistic scale inhibition effect of scale inhibitory components: The porous structure of the high specific surface area nano-SiO2 surface provides Mg 2+ Ca 2+The adsorption and growth sites of free metal ions are obtained, and the CaCO3 scale nuclei are encapsulated by high molecular weight polycarboxylic acid grafted with nano-SiO2, thereby inhibiting the further growth of scale nuclei and achieving the scale inhibition effect.

[0040] (3) Synergistic corrosion and scale inhibition effects of corrosion inhibitors and scale inhibitors: ungrafted polycarboxylic acid nano-SiO2 and free Zn 2+ The reaction produces [ZnSO3]. + The colloid fills the vacancies in the passivation film, enhances the density and toughness of the passivation film, prevents scale from depositing on the boiler wall surface and forming scale, and further achieves a synergistic corrosion and scale inhibition effect.

[0041] (4) The synergistic effect of mercaptobenzothiazole: the mercapto group coordinates with zinc ions and amino ions, and the benzene ring is hydrophobically connected with polycarboxylic acid, forming a further bridging of corrosion inhibitor and scale inhibitor components. A stable composite micelle layer withstanding 120℃ is formed on the outside of the corrosion inhibitor film, further blocking the growth and adhesion of scale and improving the synergistic effect of corrosion and scale inhibition. Attached Figure Description

[0042] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0044] Example 1

[0045] This embodiment provides a corrosion and scale inhibitor suitable for high-salinity water. Its effective components include nano-SiO2@NH2, organophosphonates, zinc salts, polycarboxylic acid, and nano-SiO2, with the balance being deionized water. The nano-SiO2@NH2, organophosphonates, and zinc salts constitute the corrosion inhibitor component in a mass ratio of (0.8-1.2):0.5:(0.3-0.4), and the polycarboxylic acid and nano-SiO2 constitute the scale inhibitor component in a total solids mass ratio of 3:1. The polycarboxylic acid grafting rate in the scale inhibitor component is ≥80%. The corrosion inhibitor component and the scale inhibitor component are compounded in a 1:1 ratio to form the finished agent.

[0046] The organophosphonate is selected from one or more of hydroxyethylidene diphosphonic acid, hydroxyphosphonoacetic acid, ethylenediaminetetramethylenephosphonic acid, and dimethylphenylphosphonate, and the purity of the organophosphonate is ≥98%, and the content of active component is ≥50%. In this embodiment, hydroxyethylidene diphosphonic acid (HEDP) is preferred. Its molecular structure contains CP bonds, which have good antioxidant properties and can capture free oxygen and other oxidizing components in the water to be treated. At the same time, its molecular weight and structure are more conducive to chelating calcium and magnesium ions, and it has higher scale inhibition and corrosion inhibition synergy.

[0047] The zinc salt used is zinc sulfate with a purity of ≥99.9%.

[0048] The polycarboxylic acid is polyacrylic acid or an acrylic acid copolymer. The polycarboxylic acid has a molecular weight of 2000-5000 Da and a solid content of ≥40%. In this embodiment, polyacrylic acid is preferred because it has a suitable molecular weight. At the same time, its linear structure can adsorb onto the surface of scale-forming nuclei such as calcium carbonate and magnesium silicate and encapsulate the scale-forming nuclei, preventing the growth of the nuclei and thus forming irregular fine particles to achieve the scale inhibition effect.

[0049] The nano-SiO2 in the nano-SiO2@NH2 and the nano-SiO2 in the scale inhibitor component are selected with a particle size of 20-50 nm and a specific surface area of ​​2200 m². 2 / g, surface hydroxyl density is 3-5 per nm 2 This ensures that nano-SiO2 has good dispersibility and provides sufficient adsorption and coordination sites.

[0050] The ratio of corrosion inhibitor and scale inhibitor in the corrosion and scale inhibitor of this embodiment is based on the following:

[0051] (1) Control standard for the amount of nano SiO2@NH2 added in the corrosion inhibitor: When it is less than 0.8 parts, the continuity of the corrosion inhibitor film on the surface of the boiler metal substrate is poor and the corrosion inhibition rate is <85%; when it is greater than 1.2 parts, the dispersibility of the compounded finished agent decreases and the agent exhibits micro-agglomeration (DLS>200nm measured by 600nm spectrophotometry).

[0052] (2) Standard for controlling the amount of zinc salt added in the corrosion inhibitor: When the amount is less than 0.3 parts, the potential shifts to the right by 10mV after compounding, and the dispersion stability of the agent is less than 7 days; when the amount is greater than 0.4 parts, the free Zn + Excessive content, with cl - ZnCl2 microparticles precipitate, and the drug dispersion stability is also less than 7 days;

[0053] The scale inhibitor component ratio control standard is as follows: When the proportion of polycarboxylic acid (taking PAA as an example) is greater than 3 parts, the calcium carbonate scale inhibition rate is greater than 98%, but the magnesium silicate scale inhibition rate is less than 70%. When the proportion of nano-SiO2 is greater than 1 part, the viscosity of the compounded agent increases (Brook-field viscosity > 50 CP), making pumping difficult during agent addition. Specifically, the component ratios of the corrosion and scale inhibitor in this embodiment are as follows:

[0054] Corrosion inhibitor components: 1 part nano-SiO2@NH2 (20% content in the water to be treated); 0.5 part organophosphonate (10% content in the water to be treated); 0.3 part zinc salt (6% content in the water to be treated); the remainder is deionized water.

[0055] Scale inhibitor components: 1.5 parts polycarboxylic acid (30% content in the water to be treated), 0.5 parts nano-SiO2 (10% content in the water to be treated), and the remainder is deionized water;

[0056] Compound formulation: 1 part corrosion inhibitor; 1 part scale inhibitor

[0057] Example 2

[0058] The difference between the component ratios of the corrosion and scale inhibitor in this embodiment and those in Example 1 is as follows:

[0059] The corrosion inhibitor component contains 0.8 parts of nano-SiO2@NH2 (16% of the content in the water to be treated), and the remaining components are the same as in Example 1.

[0060] Example 3

[0061] The difference between the component ratios of the corrosion and scale inhibitor in this embodiment and those in Example 1 is as follows:

[0062] The corrosion inhibitor component contains 1.2 parts of nano-SiO2@NH2 (containing 24% of the water to be treated), and the remaining components are the same as in Example 1.

[0063] Example 4

[0064] The difference between the component ratios of the corrosion and scale inhibitor in this embodiment and those in Example 1 is as follows:

[0065] Based on the formulation of Example 1, 0.05 parts of 1% mercaptobenzothiazole were added, and the rest remained the same as in Example 1.

[0066] Example 5

[0067] This embodiment provides comparative examples 1-4 of the corrosion and scale inhibitors of Examples 1-4:

[0068] Comparative Example 1: No nano-SiO2@NH2 was added to the corrosion inhibitor component, and the other components were the same as in Example 1.

[0069] Comparative Example 2: In the scale inhibitor component, PAA: nano-SiO2 = 2:1, that is, the solid content of nano-SiO2 in the scale inhibitor component is >30%, and the other components are the same as in Example 1.

[0070] Comparative Example 3: In the scale inhibitor component, the ratio of PAA to nano-SiO2 is 4:1, that is, the solid content of PAA in the scale inhibitor component is >75%, and the other components are the same as in Example 1.

[0071] Example 6

[0072] This embodiment provides a method for preparing a corrosion and scale inhibitor suitable for high-salinity water, used to prepare the corrosion and scale inhibitors of Examples 1-4 and Comparative Examples 1-4 of Example 5:

[0073] S1, Raw material pretreatment: The organophosphonate is dissolved and diluted with deionized water to prepare a 30% concentration organophosphonate solution to remove insoluble matter; the polycarboxylic acid is purified to the target molecular weight by dialysis.

[0074] S2, Preparation of corrosion inhibitor components: Prepare the components according to the mass ratio of nano-SiO2@NH2, organophosphonate and zinc salt in Examples 1-4 and Comparative Example 1. First, add zinc salt to the organophosphonate solution and premix evenly, then add nano-SiO2@NH2 to form a mixed solution. Place the mixed solution in a constant temperature water bath at 50±2℃ and stir with stirring parameters of 200±10 rpm for 2.0±0.1 h. During the stirring process, monitor the pH with an online pH meter and adjust the pH with 10% HNO3. The pH is controlled at 3.0-4.0 to obtain a homogeneous corrosion inhibitor component solution with a transmittance ≥95%.

[0075] S3, Prepare scale inhibitory components: Polycarboxylic acid and nano-SiO2 are prepared according to the total solid content mass ratio of Examples 1-4 and Comparative Example 3 / 4. Nano-SiO2 is pre-dispersed in deionized water, and the pH is adjusted to 10 with NaOH. Polycarboxylic acid is added and placed in an ice bath environment at ≤30°C. Ultrasonic mixing is performed at 40kHz for 15±1min to obtain a scale inhibitory component solution with a polycarboxylic acid grafting rate ≥80%.

[0076] S4, Compound Activation: The corrosion inhibitor solution is added to the scale inhibitor solution at a flow rate of 5 mL / min and mixed evenly. The mass ratio of the corrosion inhibitor solution to the scale inhibitor solution is 1:1. After mixing, ultrasonic activation is performed. The ultrasonic activation parameters are 20 kHz, 30 ± 1 min, and the temperature during the ultrasonic process is controlled ≤40℃ to obtain a stable composite micelle solution.

[0077] S5, Finished Product Adjustment and Preparation: Adjust the mixed solution obtained in step S4 with 10% NaOH solution, controlling the pH to 7.5–8.5, and adjust the Na+ content in the mixed solution using reverse osmosis or ion exchange. + The final product is obtained by aseptic filling with a content of <0.1mol / L.

[0078] In step S2, the nano-SiO2@NH2 is obtained by dispersing nano-SiO2 in deionized water, adjusting the pH to 4.5±0.2, heating to 60℃ and maintaining the temperature, adding silane coupling agent and stirring to mix, so that the nano-SiO2 and the hydrolysis product of silane coupling agent undergo a condensation reaction to obtain amino-modified SiO2@NH2.

[0079] Taking KH-550 (γ-aminolactonetriethoxysilane) as an example of a silane coupling agent:

[0080] The condensation reaction between KH-550 hydrolyzed and SiO2 surface-SiOH is as follows:

[0081] SiO2-0H+NH2(CH2)3Si(OC2H5)3→SiO2-0-Si(CH2)3NH2+3C2H5OH

[0082] The chemical formula of SiO2 after modification is: SiO2@NH2 (core structure: SiO2 surface grafted with -(CH2)3NH2)

[0083] Furthermore, in step S3, when pre-dispersing nano-SiO2, 0.1% polyethylene glycol PEG-400 is added as a dispersing aid to improve the pre-dispersion effect of nano-SiO2.

[0084] Furthermore, in preparing the corrosion and scale inhibitor of Example 4, in step S4, after the corrosion inhibitor and scale inhibitor are mixed, they are placed in a light-protected environment. First, 1.0 ± 0.05% mercaptobenzothiazole, 9% deionized water and 0.05% dibutylhydroxytoluene by mass percentage are added and mixed, and then ultrasonic activation is performed.

[0085] The key control process of the preparation method in this embodiment is:

[0086] (1) When preparing corrosion inhibitor components, organic phosphonates and Zn 2+ The nano-SiO2@NH2 was mixed and prepared in a sequential gradient addition order, and the pH was adjusted to 3.0-4.0;

[0087] (2) Strictly configure the corrosion inhibitor and scale inhibitor components in steps so that they each form a stable complex, and then add the corrosion inhibitor to the scale inhibitor to form a compound.

[0088] (3) After the compounding is completed, the overall pH of the drug is adjusted again and the Na+ is controlled. + The concentration is kept below 0.1 mol / L to ensure that the zeta potential of the finished drug is at a stable polarization potential point of -20 mV, thereby guaranteeing the dispersion stability of the finished drug and prolonging the duration of action.

[0089] The changes in ζ-potential during the preparation process are shown in Table 1 below:

[0090] Table 1 Correspondence between Regulatory Factors and Potential Changes

[0091]

[0092] The corrosion and scale inhibitors of Examples 1-4 prepared according to the preparation method of Example 6 and the comparative examples 1-4 were mixed in the experimental water and their performance was tested. The corrosion inhibition rate was tested by rotating carbon steel plates according to GB / T18175-2000, the scale inhibition rate was tested by static scale inhibition according to GB / T16632-2008, and the dispersion stability was detected by HPLC after 30 days of static standing.

[0093] Table 2: Experimental Water Quality Indicators

[0094]

[0095] Table 3: Comparison of Scale Inhibition Effect Tests

[0096] reagents <![CDATA[Calcium carbonate resistance rate (%)]]> <![CDATA[MgSiO3 resistivity (%)]]> Dispersion stability (30 days) Comparative Example 3 92.3 65.2 5% precipitate Example 1 98.1 82.7 Transparent, without sediment Comparative Example 4 98.7 78.4 Increased viscosity

[0097] As can be seen from the comparative data in Table 3, the corrosion and scale inhibitors in Examples 1 to 4 (the above data are the average data of at least 3 tests) have good corrosion and scale inhibition effects.

[0098] Further performance tests were conducted on the corrosion and scale inhibition of Example 1. High-temperature dispersion stability was detected by 48h HPLC. Chloride ion tolerance was tested by rotating the tablet under a simulated high-chlorine environment (5000mg / L). The decrease in corrosion inhibition rate was used as the characterization index. Biotoxicity was tested for fish median lethal dose according to GB / T21761-2011.

[0099] Table 4: Other performance test results of Example 1:

[0100]

[0101]

[0102] As shown in the table above, the corrosion and scale inhibitor of the present invention also has good high-temperature stability, high-salinity tolerance and low biotoxicity, making it suitable for high-salinity treatment and environmentally friendly.

[0103] Example 7

[0104] This embodiment provides an application of a corrosion and scale inhibitor suitable for high-salinity boiler water. The corrosion and scale inhibitor of this invention is added to the boiler water to be treated according to the following method:

[0105] The amount of corrosion and scale inhibitor added is determined based on the molar ratio of calcium ions to organophosphonates (PBTCA) in boiler water ≥ 1:1.2, and the content of nano-SiO2@NH2 in the added water is controlled at 15% to 25%. The zinc salt content is adjusted according to the chloride ion content in the water. When the chloride content in the water is 108 mg / L, the zinc salt content is adjusted to no more than 8%.

[0106] After the addition, carbon steel hanging plates were used to monitor the water body for one month (30 days). The summary results of the actual dosage of corrosion and scale inhibitor and the final corrosion and scale inhibition effect are shown in Table 6.

[0107] Table 5: Dosage and Inhibiting Effect of Corrosion and Scale Inhibitors

[0108]

[0109]

[0110] As shown in the table above, the monitoring results show that the corrosion inhibition rate can reach over 95%, the CaCO3 inhibition rate can reach over 95%, and the MgSiO3 inhibition rate can reach over 80%. Furthermore, no corrosion or scaling was observed on the inner wall of the boiler, and no turbidity or flocculent matter was observed in the water. The corrosion and scale inhibitor in this embodiment has a good corrosion and scale inhibition effect in high-salt water.

[0111] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A corrosion and scale inhibitor suitable for high-salinity water, characterized in that... Its components include nano-SiO2@NH2, organophosphonates, zinc salts, polycarboxylic acid, and nano-SiO2. Among them, nano-SiO2@NH2, organophosphonates, and zinc salts constitute the corrosion inhibitor component in a mass ratio of (0.8~1.2):0.5:(0.3~0.4), and polycarboxylic acid and nano-SiO2 constitute the scale inhibitor component in a total solid content mass ratio of 3:

1. The polycarboxylic acid grafting rate in the scale inhibitor component is ≥80%. The corrosion inhibitor component and the scale inhibitor component are compounded in a 1:1 ratio to form the finished agent. The organophosphonate is selected from one or more of hydroxyethylidene diphosphonic acid, hydroxyphosphonoacetic acid, ethylenediaminetetramethylenephosphonic acid, and dimethylphenylphosphonate, and the purity of the organophosphonate is ≥98% and the content of active component is ≥50%. The polycarboxylic acid is polyacrylic acid or an acrylic acid copolymer, and the polycarboxylic acid has a molecular weight of 2000~5000 Da and a solid content of ≥40%. The zinc salt used is zinc sulfate with a purity of ≥99.9%.

2. The corrosion and scale inhibitor suitable for high-salinity water as described in claim 1, characterized in that: The nano-SiO2 has a particle size of 20-50 nm and a specific surface area of ​​2200 m². 2 / g, surface hydroxyl density is 3~5 per nm 2 .

3. The corrosion and scale inhibitor suitable for high-salinity water as described in claim 1, characterized in that: The corrosion and scale inhibitor is also formulated with 1% by weight of mercaptobenzothiazole as a synergistic agent.

4. A method for preparing a corrosion and scale inhibitor suitable for high-salinity water, used to prepare the corrosion and scale inhibitor suitable for high-salinity water as described in claim 1, characterized in that... Includes the following steps: S1, Raw material pretreatment: The organophosphonate is dissolved and diluted with deionized water to prepare a 30% concentration organophosphonate solution to remove insoluble matter; the polycarboxylic acid is purified to the target molecular weight by dialysis. S2, Preparation of corrosion inhibitor components: Prepare the components according to the mass ratio of nano-SiO2@NH2, organophosphonate and zinc salt (0.8~1.2):0.5:(0.3~0.4). First, add zinc salt to the organophosphonate solution and premix evenly, then add nano-SiO2@NH2 to form a mixed solution. Place the mixed solution in a constant temperature water bath at 50±2℃ and stir with stirring parameters of 200±10 rpm for 2.0±0.1 h. During the stirring process, monitor the pH with an online pH meter and adjust the pH to 3.0~4.0 with 10% HNO3 to obtain a homogeneous corrosion inhibitor component solution with a light transmittance ≥95%. S3, prepare scale inhibitory components: prepare polycarboxylic acid and nano-SiO2 at a total solid content mass ratio of 3:1, pre-disperse nano-SiO2 in deionized water, adjust the pH to 10 with NaOH, add polycarboxylic acid and place in an ice bath environment ≤30℃, and perform ultrasonic mixing at 40kHz for 15±1min to obtain a scale inhibitory component solution with a polycarboxylic acid grafting rate ≥80%. S4, Compound Activation: The corrosion inhibitor solution is added to the scale inhibitor solution at a flow rate of 5 mL / min and mixed evenly. The mass ratio of the corrosion inhibitor solution to the scale inhibitor solution is 1:

1. After mixing, ultrasonic activation is performed. The ultrasonic activation parameters are 20 kHz, 30 ± 1 min, and the temperature during the ultrasonic process is controlled ≤40℃ to obtain a stable composite micelle solution. S5, Finished Product Adjustment and Preparation: Adjust the mixed solution obtained in step S4 with 10% NaOH solution, controlling the pH to 7.5-8.5, and adjust the Na+ content in the mixed solution using reverse osmosis or ion exchange. + The final product is obtained by aseptic filling with a content of <0.1mol / L.

5. The method for preparing a corrosion and scale inhibitor suitable for high-salinity water as described in claim 4, characterized in that, The method for obtaining nano-SiO2@NH2 in step S2 is as follows: nano-SiO2 is dispersed in deionized water, the pH is adjusted to 4.5±0.2, the temperature is raised to 60℃ and kept constant, silane coupling agent is added and stirred to mix, so that nano-SiO2 and the hydrolysis product of silane coupling agent undergo a condensation reaction to obtain amino-modified SiO2@NH2.

6. The method for preparing a corrosion and scale inhibitor suitable for high-salinity water according to claim 4, characterized in that: In step S3, when pre-dispersing nano-SiO2, 0.1% polyethylene glycol PEG-400 is added as a dispersing aid.

7. The method for preparing a corrosion and scale inhibitor suitable for high-salinity water as described in claim 4, characterized in that: In step S4, after the corrosion inhibitor and scale inhibitor are mixed, they are transferred to a light-proof environment. First, 1.0 ± 0.05% mercaptobenzothiazole, 9% deionized water and 0.05% dibutylhydroxytoluene by mass percentage are added and mixed, and then ultrasonic activation is performed.

8. The application of the corrosion and scale inhibitor suitable for high-salinity water as described in claim 1 in high-salinity boiler water, characterized in that, The amount of corrosion and scale inhibitor added is determined based on the molar ratio of calcium ions to organophosphonates in boiler water ≥ 1:1.

2. The content of nano-SiO2@NH2 in the water is controlled at 15%~25%, and the zinc salt content is adjusted according to the chloride ion content in the water. When the chloride content in the water is 108 mg / L, the zinc salt content is not greater than 8%.

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