阅读说明：本技术 一种海工钢筋混凝土靶向阻锈剂及其制备方法和应用 (Marine reinforced concrete targeted rust inhibitor and preparation method and application thereof ) 是由 李伟华 张文辉 陈梦竹 郑海兵 于 2021-09-08 设计创作，主要内容包括：本发明属于建筑材料技术领域,具体涉及一种海工钢筋混凝土靶向阻锈剂及其制备方法和应用,本发明的海工钢筋混凝土靶向阻锈剂为表面负载银离子的插层亚硝酸根的钙铝型层状双金属氢氧化物,该靶向阻锈剂基于层状双金属氢氧化物的层间离子可交换特性及银离子特异性识别氯离子的特性制备得到,在靶向固化渗透侵入的氯离子的同时可以释放出具有阻锈作用的亚硝酸根,对钢筋达到一种双重保护的作用,且与水泥水化产物同质异构,对混凝土基体无副作用,防腐性能优异。(The invention belongs to the technical field of building materials, and particularly relates to a maritime reinforced concrete targeted rust inhibitor, and a preparation method and application thereof.)

1. The maritime work reinforced concrete target rust inhibitor is characterized by being intercalated nitrite layered double hydroxide with Ag loaded on the surface.

2. The marine reinforced concrete targeted rust inhibitor according to claim 1, wherein the layered double hydroxide is calcium-aluminum type hydrotalcite.

3. The application of the maritime reinforced concrete targeted rust inhibitor of claim 1 or 2 in the protection of ocean engineering reinforced concrete.

4. The preparation method of the marine reinforced concrete targeted rust inhibitor as claimed in claim 2, characterized by comprising the following steps:

s1, respectively dissolving sodium carbonate, calcium hydroxide, sodium metaaluminate, silver nitrate and sodium nitrite in boiling water to obtain a solution I, a solution II, a solution III, a solution IV and a solution V;

s2, combining the solution I, the solution II and the solution III, adjusting the PH to obtain a reaction solution VI, and stirring the reaction solution VI;

s3, carrying out hydrothermal reaction on the stirred reaction solution VI, carrying out suction filtration and washing after the reaction to obtain a filter cake, and drying and grinding the filter cake to obtain Ca-LDH;

s4, roasting the Ca-LDH obtained in the step S3 to obtain Ca-LDO;

s5, dissolving Ca-LDO into the solution IV, adjusting the pH value, stirring, carrying out suction filtration washing and drying to obtain Ag/Ca-LDO;

s6, dissolving Ag/Ca-LDO in the solution V, stirring at room temperature for 24-48h, and performing suction filtration, washing and drying to obtain the marine reinforced concrete targeted rust inhibitor.

5. The method according to claim 3, wherein in step S1, the concentration of solution I is 0.2-0.5mol/L, the concentration of solution II is 1-3mol/L, the concentration of solution III is 0.25-1.5mol/L, the concentration of solution IV is 0.1-0.5mol/L, and the concentration of solution V is 0.5-2.0 mol/L.

6. The method according to claim 3, wherein in step S2, the volume ratio of solution I to solution II to solution III is 2:1: 1.

7. The preparation method according to claim 3, wherein in the step S3, the hydrothermal reaction is carried out at 80-120 ℃ for 24-48 h.

8. The method according to claim 3, wherein in step S4, the baking is performed at 500-900 ℃ for 3-6 h.

9. The method according to claim 3, wherein in step S5, the ratio of Ca-LDO to solution IV is (0.5-1.0) g: 40 mL.

10. The method according to claim 3, wherein in step S6, the ratio of Ag/Ca-LDO to solution V is (0.5-1.5) g: 200 mL.

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a maritime reinforced concrete targeted rust inhibitor, and a preparation method and application thereof.

Background

China has abundant ocean resources, and is a marine big country since ancient times. However, in the process of ocean construction, it is important to solve the problem of reinforcing steel bar corrosion of bridges, ships, ocean resource development platforms and the like. The chloride ions causing the corrosion of the reinforced concrete are free chloride ions (accounting for 88 percent of the total amount of corrosive anions in the seawater), and the inherent anticorrosive passive film of the steel is damaged by the chloride ions, so that the corrosion rate is at least 1000 times higher than the original corrosion rate of 0.1 mu m/a. Therefore, if the problem of chloride ion corrosion in the reinforced concrete structure can be effectively solved, the method has very important significance for prolonging the service life of the concrete structure, meeting social requirements and promoting economic development.

Layered Double Hydroxides (also called LDHs or hydrotalcite materials) are novel multifunctional two-dimensional nano materials, the main structure of the Layered Double Hydroxides is composed of two metal Hydroxides, the Layered Double Hydroxides have excellent performances such as interlaminar ion exchangeability and structure memory effect, and are isomerous with hydration products (AFm phase) of cement, and the Layered Double Hydroxides have good compatibility with cement matrixes, so that the Layered Double Hydroxides are widely used in reinforced concrete structures. However, in the interior of concrete, OH is present^-、SO₄ ^2-Etc. with Cl^-Competitive adsorption of anions results in the inability of conventional LDHs to specifically recognize chloride ions. Although organic rust inhibitors which adsorb chloride ions are also available on the market at present, the organic rust inhibitors lose their effect due to degradation of the cement during hydration. If the LDHs material is combined with the rust inhibitor by a certain method, the specific recognition of chloride ions and the dual rust inhibition effect are expected to be achieved. Therefore, there is a need to develop a process for organically combining the LDHs material with the rust inhibitor to prepare a novel marine reinforced concrete targeted rust inhibitor.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a preparation method of a marine reinforced concrete targeted rust inhibitor, the prepared targeted rust inhibitor can specifically identify chloride ions, has higher chlorine fixing performance even in a complex environment with multiple anions of concrete coexisting, can slowly release nitrite anions with a rust inhibiting effect while solidifying the chloride ions, can effectively avoid the advanced release of the rust inhibitor, has a double protection effect on delaying the reinforcement corrosion of the concrete, and can be widely applied to the protection of the marine engineering reinforced concrete.

In order to achieve the purpose, the invention adopts the technical scheme that:

the invention provides a maritime reinforced concrete targeted rust inhibitor which is an intercalated nitrite layered double hydroxide with Ag loaded on the surface.

Preferably, the layered double hydroxide is calcium-aluminum type hydrotalcite.

Preferably, the maritime reinforced concrete targeted rust inhibitor is applied to the protection of maritime engineering reinforced concrete.

Furthermore, the maritime reinforced concrete targeted rust inhibitor is internally doped in the reinforced concrete.

The invention also provides a preparation method of the marine reinforced concrete targeted rust inhibitor, which comprises the following steps:

s1, respectively dissolving sodium carbonate, calcium hydroxide, sodium metaaluminate, silver nitrate and sodium nitrite in boiling water to obtain a solution I, a solution II, a solution III, a solution IV and a solution V;

s2, combining the solution I, the solution II and the solution III, adjusting the PH to obtain a reaction solution VI, and stirring the reaction solution VI;

s3, carrying out hydrothermal reaction on the stirred reaction solution VI, carrying out suction filtration and washing after the reaction to obtain a filter cake, and drying and grinding the filter cake to obtain Ca-LDH;

s4, roasting the Ca-LDH obtained in the step S3 to obtain Ca-LDO;

s5, dissolving Ca-LDO into the solution IV, adjusting the pH value, stirring, carrying out suction filtration washing and drying to obtain Ag/Ca-LDO;

s6, dissolving Ag/Ca-LDO in the solution V, stirring at room temperature for 24-48h, and performing suction filtration, washing and drying to obtain the marine reinforced concrete targeted rust inhibitor.

According to the intercalation calcium-aluminum nitrite type layered double hydroxide with the Ag loaded on the surface, which is prepared by the method, on one hand, based on the structure memory effect of the layered double hydroxide, anions for specifically recognizing chloride ions are loaded on a layer plate, and the rust inhibitor is loaded between layers in an intercalation reconstruction mode, so that the loss of the rust inhibitor is effectively avoided while the chloride ions are solidified in a targeted manner; on the other hand, on the basis of the interlayer anion exchangeability of the layered double hydroxide, nitrate radicals with the rust resistance effect can be released while harmful chloride ions are adsorbed, double protection on steel bars in concrete is achieved, the corrosion resistance is excellent, the structure is isomeric with a cement hydration product, no side effect is generated on a concrete matrix, and the layered double hydroxide can be used as an internally-doped marine reinforced concrete targeted rust inhibitor, and the application prospect is very wide.

Preferably, in step S1, the concentration of solution I is 0.2-0.5mol/L, the concentration of solution II is 1-3mol/L, the concentration of solution III is 0.25-1.5mol/L, the concentration of solution IV is 0.1-0.5mol/L, and the concentration of solution V is 0.5-2.0 mol/L. Specifically, the concentration of the solution I is 0.25mol/L, the concentration of the solution II is 2.10mol/L, the concentration of the solution III is 1.36mol/L, the concentration of the solution IV is 0.1mol/L, and the concentration of the solution V is 0.41 mol/L.

Preferably, in step S2, the volume ratio of the solution I, the solution II and the solution III is 2:1: 1.

Preferably, in the step S3, the hydrothermal reaction is carried out for 24h-48h at the temperature of 80-120 ℃. Specifically, the hydrothermal reaction is carried out for 24 hours at 120 ℃.

Preferably, in step S4, the calcination is carried out at 500-900 ℃ for 3-6 h. Specifically, the roasting is carried out for 3 hours at 900 ℃.

Preferably, in step S5, the ratio of Ca-LDO to solution iv is (0.5-1.0) g: 40 mL. Specifically, the feed-liquid ratio of the Ca-LDO to the solution IV is 1.0 g: 40 mL.

Preferably, in step S6, the ratio of Ag/Ca-LDO to solution v is (0.5-1.5) g: 200 mL. Specifically, the material-liquid ratio of the Ag/Ca-LDO to the solution V is 1.0 g: 200 mL.

Preferably, the pH is adjusted to 12-13 in step S2 and to 9-10 in step S5. Specifically, the PH is adjusted to 12 in step S2, and the PH is adjusted to 9 in step S5.

Preferably, the stirring treatment in the step S2 is stirring at room temperature for 0.5-2 h; the stirring treatment of the step S5 is stirring for 24 to 48 hours at the temperature of between 45 and 55 ℃. Specifically, the stirring treatment in the step S2 is stirring at room temperature for 1 hour; the stirring treatment in the step S5 is stirring at 50 ℃ for 24 h.

Preferably, in steps S3, S5 and S6, the suction filtration washing is performed by first washing with water and then washing with ethanol three times.

Preferably, in step S3, the grinding is to 200 mesh size.

Preferably, the drying is 50 ℃ vacuum drying for 48h in step S3, 50 ℃ vacuum drying for 24h in step S5, and 45 ℃ vacuum drying for 48h in step S6.

Compared with the prior art, the invention has the beneficial effects that:

the maritime work reinforced concrete target rust inhibitor is a layered double hydroxide of intercalation nitrite with Ag loaded on the surface, can release the nitrite as the rust inhibitor to inhibit the corrosion of steel bars in concrete while adsorbing chloride ions in a targeted manner, plays a role in double protection, and cannot lose the rust inhibitor loaded between layers due to the hydration process of cement. The targeted rust inhibitor has excellent corrosion resistance in a complex environment with coexistence of multiple anions of concrete, is isomerous with a cement hydration product, does not generate side effect on the performance of a cement matrix, has wide application and has higher economic and social benefits.

Drawings

FIG. 1 shows Ag/Ca-NO prepared in example 1₂XRD patterns of LDH and the Ag/Ca-LDO prepared in comparative example 1;

FIG. 2 shows Ag/Ca-NO prepared in example 1₂An LDH chloride ion isothermal equilibrium adsorption curve diagram;

FIG. 3 is an electrochemical impedance spectrum of each set of steel bars at the immersion age of 48h (a1 is an electrochemical impedance spectrum Nyquist diagram, and a2 is an electrochemical impedance spectrum Bode diagram).

Detailed Description

The following further describes the embodiments of the present invention. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The experimental procedures in the following examples were carried out by conventional methods unless otherwise specified, and the test materials used in the following examples were commercially available by conventional methods unless otherwise specified.

Example 1 preparation of Marine reinforced concrete Targeted Corrosion inhibitor

The maritime work reinforced concrete targeted rust inhibitor is an intercalated nitrite layered double hydroxide with Ag loaded on the surface, namely Ag/Ca-NO₂An LDH, the preparation method of which comprises the steps of:

(1) preparation of calcium-aluminum layered double hydroxide Ca-LDO in roasted state

1) Weighing 2.65g of sodium carbonate, dissolving in 100mL of boiled distilled water, and carrying out ultrasonic treatment for 5min to obtain a solution I; weighing 7.78g of calcium hydroxide, dissolving in 50mL of boiled distilled water, and carrying out ultrasonic treatment for 5min to obtain a solution II; weighing 5.56g of sodium metaaluminate, dissolving in 50mL of boiled distilled water, and carrying out ultrasonic treatment for 5min to obtain a solution III;

2) uniformly mixing the solutions I, II and III, dropwise adding 2mol/L sodium hydroxide solution to adjust the pH value to 12 to obtain a reaction solution VI, and stirring the reaction solution VI at room temperature (1800r/min) for 1 h;

3) transferring the stirred reaction solution VI into a reaction kettle, carrying out hydrothermal reaction in an oven at 120 ℃ for 24 hours, carrying out suction filtration with deionized water for three times, and carrying out suction filtration and washing with absolute ethyl alcohol for three times to obtain a filter cake; drying the filter cake in a vacuum environment at 50 ℃ for 48h, grinding the dried product to 200 meshes to obtain Ca-LDH (also called Ca-CO)₃LDH)。

4) And (3) placing the ground Ca-LDH powder in a muffle furnace at 900 ℃ for roasting for 3h to prepare roasted layered double hydroxide which is recorded as Ca-LDO.

(2) Preparation of baked layered double hydroxide Ag/Ca-LDO with Ag loaded on surface

1) Weighing 1.7g of silver nitrate, dissolving the silver nitrate in 100mL of boiled distilled water, and carrying out ultrasonic treatment for 5min to obtain a solution IV;

2) adding 1g of Ca-LDO prepared in the step (1) into 40mL of solution IV, titrating the pH to 9 with ammonia water, stirring in a constant-temperature water bath at 50 ℃ (1800r/min) for 24h, sequentially performing suction filtration and washing with deionized water for three times, performing suction filtration and washing with absolute ethyl alcohol for three times, and drying the obtained product in a vacuum oven at 50 ℃ for 24h to obtain solid powder Ag/Ca-LDO.

(3) Preparing intercalation nitrite layered double hydroxide Ag/Ca-NO with Ag loaded on surface₂ LDH

1) Weighing 6.9g of sodium nitrite, dissolving in 200mL of boiled distilled water, and carrying out ultrasonic treatment for 5min to obtain a solution V;

2) adding 1g of Ag/Ca-LDO prepared in the step (2) into 200mL of solution V, stirring at room temperature (1800r/min) for 24h, performing suction filtration with deionized water for three times, performing suction filtration and washing with absolute ethyl alcohol for three times, and performing vacuum drying on the obtained product in an oven at 45 ℃ for 48h to obtain solid powder Ag/Ca-NO₂ LDH。

Example 2 preparation of Marine reinforced concrete Targeted Corrosion inhibitor

The specific preparation method is the same as that of example 1. The difference is that in the second step 2) of (3), 1g of Ag/Ca-LDO prepared in the step 2 is added into the solution V, stirred at room temperature (1800r/min) for 48h, then is filtered and filtered with deionized water for three times, is filtered and washed with absolute ethyl alcohol for three times, and the obtained product is dried in a 45 ℃ oven in vacuum for 48h to obtain solid powder Ag/Ca-NO₂ LDH。

Example 3 preparation of Marine reinforced concrete Targeted Corrosion inhibitor

The specific preparation method is the same as that of example 1. Except that in the first step 1) of (3), 13.8g of sodium nitrite was added.

Comparative example 1 preparation of Ag-Supported calcined calcium-aluminum layered double hydroxide Ag/Ca-LDO

The preparation method was the same as in steps (1) to (2) of example 1.

Comparative example 2Ca-NO₂Preparation of LDH double metal hydroxides

23.62g of Ca (NO) was weighed out separately₃)₂·4H₂O, 18.75g of AlNO₃·9H₂Dissolving O in boiling 200mL distilled water, and performing ultrasonic treatment for 5min to obtain solution A. 13.8g of NaNO are weighed out₂12g of NaOH was dissolved in 100mL of boiled distilled water and sonicated for 5min to obtain solution B. Mixing the solution A and the solution B, stirring for 24h at room temperature, performing suction filtration with deionized water for three times, performing suction filtration and washing with absolute ethyl alcohol for three times, and performing vacuum drying on the obtained product in a 45 ℃ oven for 48h to obtain solid powder Ca-NO₂LDH。

Experimental example 1XRD analysis

Intercalation nitrite layered double hydroxide Ag/Ca-NO for releasing Ag loaded on surface₂LDH Structure, Ag/Ca-NO prepared in example 1₂The LDH and the Ag/Ca-LDO prepared in comparative example 1 were subjected to XRD analysis, and compared with the preparation of the precursor Ca-CO₃LDH and Ca-NO₂LDH (comparative example 2) was compared. As can be seen from FIG. 1, Ag/Ca-LDO and Ag/Ca-NO₂LDH has obvious Ag characteristic diffraction peak, which indicates that Ag ions are successfully loaded. Significant Ca-NO appeared in example 1 compared to Ag/Ca-LDO₂The LDH characteristic diffraction peak of the LDH structure shows that the intercalation nitrite layered double-metal hydroxide Ag/Ca-NO with Ag loaded on the surface is successfully prepared based on the structure memory effect of the Ag/Ca-LDO₂ LDH。

Experimental example 2 analysis of ability to bind chloride ion

Sodium chloride was added to simulated concrete pore liquid (saturated calcium hydroxide solution at pH 12.5) at different concentrations, 5, 10, 20, 40 and 80mmol/L respectively. Then, 0.5g of Ag/Ca-NO from examples 1 to 3 was added to each solution₂LDH and the Ag/Ca-LDO of comparative example 1, having a volume of 50mL, were then charged into a sealed bottle having a capacity of about 100mL, and stirring was continued for 24h, which was fitted using the Langmuir model and the Freundlich model.

As shown in the chloride ion isothermal equilibrium adsorption curve of FIG. 2, the measured experimental data are more matched with the Langmuir model, and the Ag/Ca-NO in example 1 is obtained by fitting₂The saturated adsorption capacity of LDH to chloride ions in simulated concrete pore liquid is 4.207mmol/g, and the example2 Ag/Ca-NO₂The saturated adsorption capacity of LDH to chloride ions in simulated concrete pore liquid is 4.103mmol/g, and Ag/Ca-NO in example 3₂The saturated adsorption capacity of LDH on chloride ions in the simulated concrete pore liquid is 4.089mmol/g, while the saturated adsorption capacity of Ag/Ca-LDO prepared in the comparative example 1 on chloride ions in the simulated concrete pore liquid is 4.59 mmol/g. Ag/Ca-NO compared to comparative example 1₂The LDH has little reduction of chloride ion consolidation capability, but still has good chlorine-fixing performance.

Experimental example 3 electrochemical analysis

Adding 3.5 wt% of NaCl solution into simulated concrete pore liquid (saturated calcium hydroxide solution with the pH value of 12.5), uniformly stirring to obtain electrolyte to simulate the corrosion of chloride salt in seawater, and taking 100mL of electrolyte for later use. The Ag/Ca-NO prepared in example 1 was added to the electrolyte in an amount of 1g/L₂LDH (noted as Ag/Ca-NO)₂LDH group) and Ag/Ca-LDOs prepared in comparative example 1 (noted as Ag/Ca-LDO group), with a simulated concrete pore solution (electrolyte) without any rust inhibitor incorporated as a control group. Q235 carbon steel (f10mm × 5mm) was pretreated before corrosion experiments: firstly, carrying out ultrasonic treatment on the copper-clad laminate by using absolute ethyl alcohol to remove impurities on the surface, and welding a copper wire on one surface of the copper-clad laminate after drying; then sealing the PVC pipe in epoxy resin, after the epoxy resin is completely cured, polishing the exposed surface with sand paper (400-3000 mesh) and cleaning with absolute ethyl alcohol, immersing the PVC pipe in blank simulated concrete pore solution for passivation for 14 days, and respectively immersing the passivated Q235 carbon steel in Ag/Ca-NO₂The LDH group, the Ag/Ca-LDO group and the control group are soaked for 48 hours. And finally, performing an electrochemical impedance test by using a CHI660E electrochemical workstation, wherein the test system is a three-electrode system (steel bars are used as working electrodes, a platinum sheet is used as an auxiliary electrode, and a saturated calomel electrode is used as a reference electrode).

FIG. 3 is an electrochemical impedance spectrogram of Q235 carbon steel of each group after soaking for 48h, wherein a1 is an electrochemical impedance spectrum Nyquist diagram, a2 is an electrochemical impedance spectrum Bode diagram, the Nyquist diagram consisting of an impedance imaginary part and a real part in the electrochemical impedance spectrum can judge the corrosion performance of the steel bar through the capacitive arc radius, and the capacitive arc radiusThe larger the steel bar, the more corrosion resistant the steel bar; and the Bode diagram can analyze the corrosion condition of the steel bars through phase angles, and the larger the phase angle is, the less the steel bars are corroded. As can be seen from FIG. 3, the control group had a relatively small arc radius and phase angle, indicating that the steel bar was in Cl condition without the rust inhibitor^-Corrosion occurs rapidly and the polarization resistance decreases rapidly. After the Ag/Ca-LDO prepared in the comparative example 1 is doped, the volume-resistance arc radius of the steel bar is increased to a certain extent compared with that of a control group; and incorporated into the Ag/Ca-NO prepared in example 1₂After LDH, the capacitive arc resistance radius and the phase angle of the steel bar are far larger than those of a control group and an Ag/Ca-LDO group, which shows that the calcium-aluminum layered double hydroxide of the intercalation nitrite with Ag loaded on the surface, prepared by the invention, can obviously improve the corrosion resistance of the steel bar, and the protection effect is far better than that of the Ag/Ca-LDO.

It can be seen from the above experimental examples that the maritime work reinforced concrete targeted rust inhibitor is a layered double hydroxide of intercalation nitrite with Ag loaded on the surface, and based on the interlayer ion exchangeable characteristic of the layered double hydroxide and the characteristic of silver ion specificity recognition of chloride ions, the invention releases nitrite with rust inhibiting effect while the chloride ions invaded by targeted solidification and permeation, thereby achieving a double protection effect on the reinforced steel bar.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.