High-dispersion three-dimensional nano-hybrid targeted rust-inhibiting material and preparation method thereof

Abstract

The invention provides a high-dispersion three-dimensional nano-hybrid targeted rust-inhibiting material and a preparation method thereof, and belongs to the technical field of rust-inhibiting materials. The preparation method comprises the following steps: mixing a divalent metal salt and a trivalent metal salt in a solvent, adding a surfactant and a sodium hydroxide solution, and carrying out a co-precipitation reaction and a hydrothermal reaction to obtain LDH nano-microspheres; and mixing the LDH nano-microspheres with a corrosion inhibitor solution, and carrying out an intercalation reaction to obtain the corrosion-inhibiting material. The high-dispersion three-dimensional nano-hybrid anti-corrosion material has a strong targeted adsorption effect on chloride ions, invasion of an erosion medium is inhibited from the source, anti-corrosion molecules are slowly released while the chloride ions are adsorbed, and the anti-corrosion molecules are migrated to the surface of a steel bar to be adsorbed to form a protective film layer, so that the dual anti-corrosion effect on the steel bar is achieved.

Description

Technical Field

[0001] This invention relates to the field of rust-inhibiting materials technology, and in particular to a highly dispersed three-dimensional nano-hybrid targeted rust-inhibiting material and its preparation method. Background Technology

[0002] Steel corrosion is one of the main causes of insufficient durability in reinforced concrete structures. Adopting appropriate anti-corrosion measures is an effective means to improve the durability of reinforced concrete structures and ensure their service life. Steel corrosion inhibitors are widely used due to their ease of application and cost-effectiveness. However, conventional corrosion inhibitors, such as nitrite-based and amino alcohol-based inhibitors, have environmental problems or are prone to leakage, leading to insufficient long-term effectiveness. Furthermore, corrosion inhibitors often have side effects on the concrete matrix, affecting the physical and mechanical properties of the concrete. Using a suitable carrier to load the corrosion-inhibiting molecules can not only achieve effective utilization of the corrosion inhibitor but also solve its negative impact on the concrete matrix.

[0003] Layered double hydroxides (LDHs), as inorganic materials, share similar structures and properties with cement hydration products. They exhibit high thermal stability and compatibility with concrete, making them excellent carriers for rust-inhibiting molecules. Their interlayer anion exchange effect enables the adsorption of chloride ions and the release of rust inhibitors as needed, thus addressing the problems of poor compatibility and insufficient long-term rust inhibition of conventional rust inhibitors with concrete. However, as nanoscale materials, LDHs also suffer from easy aggregation and poor redispersibility. Their layered structure has a large number of -OH groups on its surface, resulting in high surface energy and a tendency to form hydrogen bonds, leading to soft agglomeration. This, in turn, leads to hard agglomeration through condensation, exacerbating the aggregation problem. Agglomeration prevents the full exposure of LDHs' adsorption active sites, significantly reducing chloride ion adsorption performance and hindering the achievement of expected rust-inhibiting properties. Furthermore, the high specific surface area of ​​LDH nanoparticles results in high water absorption, significantly reducing the workability of concrete. Therefore, to maintain workability, it is necessary to increase the water-cement ratio or use water-reducing agents, which reduces the basic properties of concrete or increases costs. Therefore, improving the self-dispersibility of LDHs and enhancing their chloride ion adsorption performance is of great significance for the development of LDH-supported rust inhibitors. Summary of the Invention

[0004] The purpose of this invention is to provide a highly dispersed three-dimensional nano-hybrid targeted rust inhibitor and its preparation method, so as to solve the problems of poor dispersion of layered double hydroxides and poor chloride ion adsorption performance in the prior art.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a highly dispersed three-dimensional nano-hybrid targeted corrosion inhibitor, comprising the following steps:

[0007] (1) mixing divalent metal salt and trivalent metal salt in solvent, adding surfactant and sodium hydroxide solution to carry out coprecipitation reaction and hydrothermal reaction, obtaining LDH nanometer microspheres;

[0008] (2) mixing LDH nanometer microspheres and rust inhibitor solution to carry out intercalation reaction, obtaining rust inhibitor material.

[0009] As preferred, in step (1), the divalent metal salt comprises calcium salt, magnesium salt or zinc salt; the trivalent metal salt comprises aluminum salt or iron salt; the molar ratio of divalent metal ion in the divalent metal salt to trivalent metal ion in the trivalent metal salt is 2-4:1.

[0010] As preferred, in step (1), the solvent is ethylene glycol, propylene glycol or triethylene glycol; the mass-volume ratio of the divalent metal salt to solvent is 0.5-1.0 g:30-50 mL.

[0011] As preferred, in step (1), the mass ratio of the divalent metal salt to surfactant is 0.5-1.0:0.4-1.6; the surfactant comprises sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium stearate or alkyl ether carboxylate.

[0012] As preferred, in step (1), the mass ratio of sodium hydroxide in the sodium hydroxide solution to the divalent metal salt is 0.2-0.4:0.5-1.0.

[0013] As preferred, in step (1), the temperature of the hydrothermal reaction is 150-170℃, and the time of the hydrothermal reaction is 20-28h.

[0014] As preferred, in step (2), the mass-volume ratio of the LDH nanometer microspheres to rust inhibitor solution is 3-6 g:80-120 mL; the mass concentration of the rust inhibitor solution is 10-20%.

[0015] As preferred, in step (2), the intercalation reaction is carried out in inert atmosphere, the temperature of the intercalation reaction is 22±2℃, and the time of the intercalation reaction is 10-14h.

[0016] As preferred, in step (2), the pH value is adjusted to 9-11 after the intercalation reaction.

[0017] The application also provides a rust inhibitor material prepared by the method for preparing high-dispersed three-dimensional nanometer hybrid targeted rust inhibitor material.

[0018] The application has the following advantages:

[0019] The application solves the core problem of easy agglomeration of LDH load type rust inhibitor by using surface active molecule modification and three-dimensional spherical structure, improves the working performance of concrete, fully exposes the surface active adsorption site by the advantage of high specific surface area of three-dimensional spherical structure, improves the saturated adsorption amount of corrosion source chloride ion and the load amount of rust inhibitor molecule, and greatly improves the corrosion resistance of steel bar. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a preparation flowchart of the nano hybrid targeted rust inhibitor material of the application;

[0021] Figure 2 It is an X-ray diffraction pattern of Ca / Al-LDH prepared in Example 1;

[0022] Figure 3 It is an SEM and EDS pattern of LDH nanospheres prepared in Example 1, Example 2 and Example 3, wherein a is Example 1, b and c are Example 2, d is Example 3, and e is an EDX spectrum;

[0023] Figure 4 It is the action mechanism of the nano hybrid targeted rust inhibitor material of the application;

[0024] Figure 5 It is the test result of cement paste fluidity, wherein a is a blank group, and b is an experimental group;

[0025] Figure 6 It is a rust resistance performance test N yquist Figure, equivalent circuit diagram and R p Calculation result. DETAILED DESCRIPTION

[0026] The application provides a preparation method of high dispersion three-dimensional nano hybrid targeted rust inhibitor material, comprising the following steps:

[0027] (1) mixing divalent metal salt and trivalent metal salt in a solvent, adding a surfactant and sodium hydroxide solution, and then performing co-precipitation reaction and hydrothermal reaction to obtain LDH nanospheres;

[0028] (2) mixing the LDH nanospheres and a rust inhibitor solution, and then performing intercalation reaction to obtain a rust inhibitor material.

[0029] In the application, in step (1), the divalent metal salt comprises calcium salt, magnesium salt or zinc salt; the trivalent metal salt comprises aluminum salt or iron salt; and the molar ratio of divalent metal ions in the divalent metal salt to trivalent metal ions in the trivalent metal salt is 2-4:1, and can be 2:1, 3:1 or 4:1.

[0030] In the present application, the calcium salt is preferably calcium nitrate tetrahydrate; and the aluminum salt is preferably aluminum nitrate nonahydrate.

[0031] In the present application, in step (1), the solvent is ethylene glycol, propylene glycol or triethylene glycol; the mass-volume ratio of the divalent metal salt and the solvent is 0.5-1.0 g:30-50 mL, preferably 0.6-0.9 g:35-45 mL, and further preferably 0.708-0.8 g:40 mL.

[0032] In the present application, the mixing of the divalent metal salt and the trivalent metal salt in the solvent is preferably carried out by first adding the surfactant and then adding a sodium hydroxide solution, which is preferably a sodium hydroxide ethylene glycol solution.

[0033] In the present application, in step (1), the mass ratio of the divalent metal salt and the surfactant is 0.5-1.0:0.4-1.6, and can be specifically 0.708:0.4, 0.708:1.2, 0.708:1.6; and the surfactant comprises sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium stearate or alkyl ether carboxylate.

[0034] In the present application, in step (1), the mass ratio of sodium hydroxide in the sodium hydroxide solution and the divalent metal salt is 0.2-0.4:0.5-1.0, preferably 0.25-0.35:0.6-0.9, and further preferably 0.30-0.32:0.708-0.8.

[0035] In the present application, in step (1), the temperature of the hydrothermal reaction is 150-170℃, preferably 155-165℃, and further preferably 160℃, and the time of the hydrothermal reaction is 20-28 h, preferably 22-26 h, and further preferably 24 h.

[0036] In the present application, in step (2), the mass-volume ratio of the LDH nanomicrosphere and the rust inhibitor solution is 3-6 g:80-120 mL, preferably 4-5 g:90-110 mL, and further preferably 4-5 g:100 mL; and the mass concentration of the rust inhibitor solution is 10-20%, and can be specifically 10%, 12%, 15%, 18%, 20%.

[0037] In the present application, the type of the rust inhibitor is not particularly limited, and any rust inhibitor meeting the requirements in the art can be used. The rust inhibitor in the rust inhibitor solution of the present application comprises an organic rust inhibitor or an inorganic rust inhibitor, wherein the organic rust inhibitor can be one or more of sodium tartrate, sodium glutamate and sodium benzoate, and the inorganic rust inhibitor can be sodium nitrate and / or sodium molybdate.

[0038] In the present application, in step (2), the intercalation reaction is carried out in an inert atmosphere, the temperature of the intercalation reaction is 22±2℃, the time of the intercalation reaction is 10-14h, preferably 11-13h, and further preferably 12h.

[0039] In the present application, in step (2), the pH value is adjusted to 9-11 after the intercalation reaction.

[0040] The present application also provides a rust-proof material prepared by the method for preparing the high-dispersed three-dimensional nano-hybrid targeted rust-proof material.

[0041] The technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0042] Example 1

[0043] 0.708g of Ca(NO3)2·4H2O and 0.563g of Al(NO3)3·9H2O were dissolved in 40mL of ethylene glycol under stirring, then 0.4g of sodium dodecyl sulfate was added, and continuous stirring was carried out until complete dissolution, to obtain a mixed solution. In another flask, 0.32g of NaOH was dissolved in 20mL of ethylene glycol. The sodium hydroxide solution was added to the above mixed solution, and co-precipitation was carried out under vigorous stirring. Then the mixture was transferred to an autoclave, sealed, heated to 160℃, and hydrothermally reacted for 24h. The precipitate was collected, washed thoroughly with deionized water and ethanol, and dried at 60℃ for 12h, to obtain white powder-shaped LDH nanospheres, denoted as Ca / Al-LDH.

[0044] 4g of Ca / Al-LDH was placed in 100mL of a sodium tartrate solution (mass concentration of 15%), and continuously stirred under magnetic stirring at a temperature of 22℃ in a nitrogen atmosphere (to avoid contact with carbon dioxide) for 12h. The pH value was adjusted to 10 with a 1mol / L sodium hydroxide solution, and the high-dispersed three-dimensional nano-hybrid targeted rust-proof material was obtained after filtration, washing and drying.

[0045] Example 2

[0046] The difference from Example 1 is that the addition amount of sodium dodecyl sulfate is 1.2g, and other conditions are the same.

[0047] Example 3

[0048] The difference from Example 1 is that the addition amount of sodium dodecyl sulfate is 1.6g, and other conditions are the same.

[0049] The X-ray diffraction pattern of Ca / Al-LDH prepared in Example 1 was collected by an XRD diffractometer, with a scanning step of 0.02° and a scanning range of 3°-80°, and the result is as shown inFigure 2 As shown in the figure, Figure 2 It can be seen that the spectrum of Ca / Al-LDH presents a representative high crystalline layered structure, but compared with the standard diffraction pattern of Ca / Al-LDH, the XRD result of Ca / Al-LDH of Example 1 is affected by the presence of sulfur oxide impurities in the structure.

[0050] Figure 3 The SEM and EDS images of the LDH nanospheres prepared for Example 1, Example 2 and Example 3, test conditions: Zeiss SUPRA55, acceleration voltage 20kV, energy dispersive x-ray spectroscopy EDS. From Figure 3 It can be seen that the LDH nanospheres are irregular solid spherical intercalation sheets, with a particle size of 3-13μm, and a small number of irregular calcium-containing oxides on the surface. With the increase of the addition amount of sodium dodecyl sulfate, the dispersibility of the LDH nanospheres is better, and the particle size of the microspheres is also increased. From Figure 3 e can be seen that calcium is uniformly distributed in the entire shell of the microsphere, and the distribution of oxygen, calcium, sulfur and sodium elements is consistent with the results of the total elemental distribution spectrum.

[0051] Figure 4 The mechanism of the nano-hybrid targeted rust inhibitor material of the application is that chloride ions penetrate into the concrete, a small part of which is combined with cement hydration products C-S-H and the like through physical and chemical methods to delay the penetration rate and reduce the chloride ion diffusion coefficient, and the remaining part is ion exchanged with the flower-like LDH nanospheres, the chloride ions are adsorbed between the layers of the LDH nanospheres, and at the same time, the interlayer loaded anion rust inhibitor molecules are released, realizing the targeted adsorption of chloride ions, making the chloride ions lose the erosion activity "inactivation", inhibiting the intrusion of the erosion medium from the source, and slowly releasing the rust inhibitor molecules while adsorbing the chloride ions and migrating to the surface of the steel bar to form a protective film layer, playing a protective role for the steel bar and improving the chloride ion critical concentration value.

[0052] Although the dispersibility of the rust inhibitor material is better as the amount of surfactant increases, the cost is high when the amount is large, so in actual production, the amount of 1.2g is used to prepare the rust inhibitor material.

[0053] Performance test:

[0054] (1) Influence on the working performance of concrete

[0055] The cement paste fluidity was tested by adding the rust inhibitor material prepared in Example 2 (addition amount of 0.5%, and the test results are shown in Figure 5 As shown by the results, the cement paste fluidity is greatly increased from 10cm to 16.5cm after adding the rust inhibitor material, significantly improving the fluidity and working performance of the cement paste.

[0056] (2) Rust inhibition performance

[0057] Carbon steel coupons were encapsulated with epoxy resin, and the exposed working surface was 10 mm in diameter and 78.5 mm in area 2 The exposed surface of the steel coupons was first polished with different grades of SiC paper, then polished with diamond polishing agent (1.0 μm), and then cleaned with deionized water and anhydrous ethanol. A saturated solution of Ca(OH)2was prepared using deionized water to simulate the chemical environment inside the concrete. Subsequently, the coupons were immersed in SCP for 3 days to promote the formation of a stable passivation film on the surface of the steel bars. Subsequently, a saturated Ca(OH)2solution with a mass fraction of 3.5% NaCl was used as a blank group of corrosive solution, and a solution containing 3.5% NaCl and the corrosion inhibitor of Example 2 was used as a corrosion inhibitor group, wherein the amount of the corrosion inhibitor added was 0.1% and 0.5%, respectively, and were named LDH-01 and LDH-05. The samples pre-passivated for 3 days were exposed to these solutions, respectively, to test the corrosion inhibition behavior of the corrosion inhibitor. An electrochemical workstation was used to perform electrochemical tests using a three-electrode cell device. The working electrode was Q235 carbon steel. A saturated calomel electrode (SCE) and a platinum electrode were used as the reference electrode and the counter electrode, respectively. After 3 days, electrochemical impedance spectroscopy (EIS) tests were performed before the addition of each group of corrosion inhibitors and NaCl, and 24 hours after the addition of the inhibitors and NaCl. The EIS results were measured at a potential of 10 mV using a frequency range of 10 5 to 10 -2 Hz. Finally, the results of the EIS were fitted with a proposed equivalent circuit (EEC) using ZSimpWin software, and the N yquist figure, equivalent circuit diagram, and R p calculation results are shown in Figure 6 Table 1.

[0058] Table 1 EIS test fitting results

[0059]

[0060] The protective performance of the corrosion inhibitor was characterized by electrochemical impedance spectroscopy (EIS), Figure 6 Nyquist plots of carbon steel electrodes and carbon steel electrodes with different concentrations of corrosion inhibitors in simulated corrosive media are shown. The Nyquist plots of all systems exhibit a single capacitive arc feature, indicating that the corrosion process is controlled by the charge transfer step. As the concentration of the corrosion inhibitor increases, the capacitive arc radius increases significantly, especially at the optimal concentration of 0.5%, indicating that the interface charge transfer resistance is significantly enhanced, and the corrosion inhibitor effectively inhibits the electrochemical reaction at the metal / electrolyte interface.

[0061] The EIS data were fitted using the equivalent circuit model shown in Figure 6 , where Rs R is the solution resistance d R is the film resistance, Q is a constant phase element CPE, R2 is the charge transfer resistance p = R d + R2). The fitting results (Table 1) show that:

[0062] The charge transfer resistance R p : blank group R p is only 111710 Ω·cm 2 While adding 0.5% of the rust inhibitor, R p is greatly improved to 1285000 Ω·cm 2 , an increase of more than 10 times. R p The sharp increase directly proves that the rust inhibitor molecules form a dense adsorption layer on the metal surface, which significantly hinders the anodic dissolution and cathodic reduction processes of the corrosion reaction.

[0063] Corrosion inhibition efficiency calculation: based on R p The rust inhibition efficiency is calculated, and the efficiency under the optimal concentration is as high as 98%, indicating that the rust inhibitor has excellent corrosion inhibition capacity.

[0064] In summary, the EIS data and the equivalent circuit fitting results are consistent, which shows that the rust inhibitor forms a high barrier layer on the steel surface through strong adsorption, significantly improves the interface impedance and reduces the double-layer capacitance, thereby effectively delaying the corrosion process of the metal matrix.

[0065] The above is only the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a highly dispersed three-dimensional nano-hybrid targeted rust inhibitor, characterized in that, Includes the following steps: (1) A divalent metal salt and a trivalent metal salt were mixed in a solvent, and a surfactant and sodium hydroxide solution were added. After co-precipitation and hydrothermal reaction, LDH nanospheres were obtained. (2) After mixing LDH nanospheres and rust inhibitor solution, an intercalation reaction is carried out to obtain rust inhibitor material.

2. The method for preparing the highly dispersed three-dimensional nano-hybrid targeted rust inhibitory material according to claim 1, characterized in that, In step (1), the divalent metal salt contains calcium salt, magnesium salt or zinc salt; the trivalent metal salt contains aluminum salt or iron salt; the molar ratio of the divalent metal ions in the divalent metal salt to the trivalent metal ions in the trivalent metal salt is 2 to 4:

1.

3. The method for preparing the highly dispersed three-dimensional nano-hybrid targeted rust inhibitory material according to claim 1 or 2, characterized in that, In step (1), the solvent is ethylene glycol, propylene glycol or triethylene glycol; the mass-volume ratio of the divalent metal salt to the solvent is 0.5-1.0 g: 30-50 mL.

4. The method for preparing the highly dispersed three-dimensional nano-hybrid targeted rust inhibitory material according to claim 3, characterized in that, In step (1), the mass ratio of the divalent metal salt to the surfactant is 0.5-1.0:0.4-1.6; the surfactant comprises sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium stearate or alkyl ether carboxylates.

5. The method for preparing the highly dispersed three-dimensional nano-hybrid targeted rust inhibitory material according to claim 1, 2, or 4, characterized in that, In step (1), the mass ratio of sodium hydroxide to divalent metal salt in the sodium hydroxide solution is 0.2-0.4:0.5-1.

0.

6. The method for preparing the highly dispersed three-dimensional nano-hybrid targeted rust inhibitory material according to claim 5, characterized in that, In step (1), the temperature of the hydrothermal reaction is 150-170℃ and the time of the hydrothermal reaction is 20-28h.

7. The method for preparing the highly dispersed three-dimensional nano-hybrid targeted rust inhibitory material according to claim 4 or 6, characterized in that, In step (2), the mass-to-volume ratio of the LDH nanospheres to the rust inhibitor solution is 3-6 g: 80-120 mL; the mass concentration of the rust inhibitor solution is 10-20%.

8. The method for preparing the highly dispersed three-dimensional nano-hybrid targeted rust inhibitory material according to claim 7, characterized in that, In step (2), the intercalation reaction is carried out in an inert atmosphere, the temperature of the intercalation reaction is 22±2℃, and the time of the intercalation reaction is 10~14h.

9. The method for preparing the highly dispersed three-dimensional nano-hybrid targeted rust inhibitory material according to claim 6 or 8, characterized in that, In step (2), the pH value is adjusted to 9-11 after the intercalation reaction.

10. The rust-inhibiting material prepared by the method of any one of claims 1 to 9 for preparing the highly dispersed three-dimensional nano-hybrid targeted rust-inhibiting material.

Images