CN114314686A - A kind of one-pot preparation method of LDH micro-nano colloidal coating solution - Google Patents

Abstract

The invention relates to a one-pot preparation method of LDH micro-nano colloid coating liquid, belonging to the technical field of nano material preparation. Preparation M²⁺‑M³⁺The method comprises the following steps of taking a salt solution as a solution A, taking an ammonia-ammonium chloride buffer solution as a solution B, taking concentrated ammonia water as a solution C, placing the solution B in a sealed penicillin bottle, placing the solution B in a constant-temperature metal bath vibration pot, injecting the solution A and the solution B into a special penicillin bottle for reaction at a certain temperature and a certain rotating speed by using an injection pump, standing, aging, centrifugally washing, drying, dispersing into a salt and acid mixed solution, and blowing and vibrating by nitrogen to obtain the free-carbon oxygen-free LDH micro-nano colloidal plating solution. The preparation method of the invention actively isolates carbon and oxygen, and the prepared LDH colloidal plating solution has high purity, regular appearance structure and extreme high purityWide application prospect.

Description

A kind of one-pot preparation method of LDH micro-nano colloidal coating solution

Technical field:

The invention relates to a one-pot preparation method of LDH micro-nano colloidal coating solution in a carbon-free oxygen-free atmosphere, and belongs to the technical field of nano material preparation.

Background technique:

Micro-nano colloidal coatings are widely used in catalyst materials, ceramic materials, medical materials and protective materials due to their relatively high strength and excellent corrosion resistance. Low-dimensional, small-scale, functionalized micro-nanostructured colloidal surface layers can significantly change the organization of materials and endow materials with new properties. In the application of reaction catalysis, layered double metal hydroxide (LDH) is a good inorganic functional material, which has rich physicochemical properties due to its special structure and function. Nowadays, LDH plating solution involves medicine, catalysis, flame retardant and many other fields. In particular, the surface effect and volume effect of the micro-nano colloidal material of the catalyst coating determine the good catalytic activity and selectivity of the catalytic reaction. However, due to the influence of preparation conditions, especially the oxidation of carbon dioxide and oxygen, good performance cannot be obtained. Nowadays, most LDH preparations require passive removal of the influence of carbon dioxide and oxygen, and the treatment process is rather cumbersome or neglected.

For example, Chinese patent document CN101759213B discloses a method for preparing layered double metal hydroxide from metal powder, the method utilizes divalent metal powder or its hydroxide, trivalent metal powder or its hydroxide, soluble salt and dehydration Ionized water is configured into a hydrothermal solution in a certain proportion. Then, the solution is placed in a hydrothermal kettle, and the hydrothermal reaction is carried out in a standing state, and the product is separated and washed with water, and then dried to obtain a layered double metal hydroxide. For another example, Chinese patent document CN106334524B discloses a preparation method and application of a core-shell structure layered double metal hydroxide composite particle. The method comprises the following steps: (1) performing a hydrothermal reaction on a glucose solution, and the obtained solid Washing, drying, grinding to obtain carbon microspheres; (2) mixing magnesium chloride and aluminum chloride into deionized water to dissolve, adding dilute ammonia water dropwise in the mixed solution, standing for crystallization, and then filtering the crystallized product with suction , washing, and peptizing the filter cake to convert it into a sol; (3) dispersing the carbon microspheres in methanol to obtain solution A; dispersing the product obtained in step (2) in methanol to obtain colloidal solution B; dispersing solution A Mixing with solution B, the obtained product is centrifuged, dried and ground to obtain layered double metal hydroxide composite particles of core-shell structure, which are used to remove 2,4-dichlorophenoxyacetic acid in water. For another example, Chinese patent document CN107583471B discloses a layered double metal hydroxide composite nanofiltration membrane and a preparation method thereof. The method first modifies the base membrane to generate a polydopamine functional layer, and then forms a polydopamine functional layer on the surface of the polydopamine modified membrane. The double metal hydroxide functional skin layer was constructed in situ to obtain a composite nanofiltration membrane.

插层的LDH纯度往往较差，层间阴离子不纯，容易导致所制得的材料形貌结构不规则。因此，提供纯度更好，结晶度更高，相貌结构更加规则的LDH，并且制备过程简单高效，具有重要意义。为此，提出本发明。However, none of the above methods carried out the preparation of layered double metal hydroxides in a closed environment, and finally did not consider the influence of _CO2 in the air. obtained non-

The purity of intercalated LDH is often poor, and the interlayer anions are impure, which easily leads to irregular morphology and structure of the prepared materials. Therefore, it is of great significance to provide LDH with better purity, higher crystallinity, and more regular appearance and structure, and the preparation process is simple and efficient. To this end, the present invention is proposed.

Invention content:

In view of the deficiencies of the prior art, the present invention provides a method for preparing a one-pot carbon-free oxygen-free LDH micro-nano colloidal plating solution with simple preparation process, low cost, environmental friendliness and high purity. The preparation process of the invention is simple and efficient, carbon and oxygen are actively isolated, and the prepared LDH colloid plating solution has high purity, regular morphology and structure, low cost and environmental friendliness, and has very wide application prospects.

The technical scheme of the present invention is as follows:

A one-pot preparation method of LDH micro-nano colloidal coating liquid, comprising the following steps:

(1) under oxygen-free carbon dioxide and nitrogen protection, the preparation M ²⁺ -M ³⁺ salt solution is A liquid, ammonia-ammonium chloride buffer solution is B liquid, and concentrated ammonia water is C liquid;

(2) Add liquid A and liquid C to liquid B at the same time under the protection of oxygen-free carbon dioxide and nitrogen, and leave to stand for aging after the reaction; the product is centrifuged, washed and dried to obtain a carbonate-free LDH solid; the LDH solid is dispersed into the mixed solution of acid and salt, and shake to obtain the carbon-free oxygen-free LDH micro-nano colloid plating solution.

According to the present invention, preferably, in step (1), the pH of liquid A is 1-2, and the molar ratio of M ²⁺ : M ³⁺ is (2-5): 1, preferably 3: 1; ²⁺ salt and trivalent M ³⁺ salt are dissolved in deionized water that has been acidified and boiled and decarbonated to prepare liquid A;

Preferably, the divalent M ²⁺ is Mg ²⁺ , Co ²⁺ , Ni ²⁺ , Mn ²⁺ or Cu ²⁺ , and the trivalent M ³⁺ is Al ³⁺ or Fe ³⁺ ;

Cl^-或

不能为

Preferably, the anions of the divalent M ²⁺ salt and the trivalent M ³⁺ salt are

Cl ^- or

cannot be

According to the present invention, preferably, the pH value of liquid B in step (1) is 11-13, and a further preferred configuration process is:

Dissolve the solid ammonium chloride in boiled deionized water to obtain a saturated ammonium chloride solution, add the saturated ammonium chloride solution to 25% to 28% concentrated ammonia water, and adjust the pH to 11-13 to obtain ammonia-chlorine ammonium chloride buffer solution.

According to the present invention, preferably, in the process of adding liquid A and liquid C to liquid B at the same time in step (2), it is carried out under constant temperature and stirring conditions. The rotational speed is 500-850r/min, most preferably 800r/min.

According to the present invention, preferably, the volume ratio of liquid A, liquid B and liquid C in step (2) is 1:(1-3):(1-2), most preferably 1:1:1.4;

Preferably, the reaction time is 0.5-2h.

According to the present invention, preferably, the aging temperature in step (2) is 60-80°C, most preferably 70°C; preferably, the aging time is 20-30h.

According to the present invention, preferably, the product in step (2) is centrifuged and washed 3-4 times with absolute ethanol, and dried at 80-100° C. for 8-12 hours.

Cl^-或

盐的阳离子为Na⁺；According to the present invention, preferably, the anion of acid and salt in step (2) is

Cl ^- or

The cation of the salt is Na ⁺ ;

Preferably, after the LDH solid is dispersed in the mixed solution of acid and salt, it is purged with nitrogen gas several times;

Preferably, the shaking time is 10-15h.

其中M²⁺代表二价金属阳离子，M³⁺代表三价金属阳离子，A^n-为层间阴离子，n＝1、2或3，比如有机和无机离子及络合离子，层间阴离子不同，LDH的层间距不同。在x值在0.17-0.33之间时，能得到结构完整的LDH。The chemical formula of the layered double metal hydroxide (LDH) prepared by the present invention is:

Wherein M ²⁺ represents divalent metal cation, M ³⁺ represents trivalent metal cation, An- is interlayer anion, ⁿ =1, 2 or 3, such as organic and inorganic ions and complex ions, interlayer anions are different, The layer spacing of LDH is different. When the value of x is between 0.17 and 0.33, a structurally complete LDH can be obtained.

According to the present invention, a one-pot preparation method of LDH micro-nano colloidal coating solution, a preferred embodiment, includes the following steps:

Liquid A: prepare a M ²⁺ -M ³⁺ salt solution with a pH of 1-2, dissolve divalent M ²⁺ salt and trivalent M ³⁺ salt in deionized water acidified and boiled and decarbonated, keep M ²⁺ : M ³⁺ molar ratio is (2-5): 1;

Liquid B: prepare ammonia-ammonium chloride buffer solution, dissolve 33 g of ammonium chloride solid in 100 ml of boiled deionized water to obtain a saturated ammonium chloride solution with pH=4.46, add the saturated ammonium chloride solution to 25%～28 % concentrated ammonia water, adjust the pH value to 11-13 to obtain ammonia-ammonium chloride buffer solution;

Liquid C: 25% to 28% concentrated ammonia water;

(1) Use a vacuum pump to pump the sealed vial to a negative pressure of 0.07MPa, then purge with nitrogen, repeat three times and evacuate to a negative pressure of 0.07MPa again, to ensure that it is free of oxygen and carbon dioxide, and place liquid B in this sealed vial. Nitrogen protection, placed in a constant temperature metal bath shaking pot, at 70 ° C and 800 r/min speed, slowly inject liquid A and liquid C into a sealed vial with a syringe pump at the same time, and configure a mixed solution, liquid A, liquid B and The volume ratio of liquid C is 1:1:1.4;

(2) After the injection of liquid A and liquid C, keep the rotating speed for 1 hour, then adjust the rotating speed to 0 r/min, and age at a constant temperature of 70 °C for 24 hours in a standing state;

(3) Centrifuge the product, wash it with absolute ethanol for 3-4 times, and dry it at 80-100° C. for 8-12 hours to obtain a carbonate-free LDH solid;

(4) Disperse the prepared LDH into 1 mol/L sodium salt and 3.3 mmol/L acid solution, purge with nitrogen for several times, and shake at room temperature for 12 h to obtain a carbon-free oxygen-free LDH micro-nano colloidal coating solution .

The beneficial effects of the present invention are as follows:

影响实验。相比较传统方法，工艺简单，隔绝空气制备的LDH层间阴离子更纯，LDH结晶度更高，形貌更加规则。1. The inventor of the present invention found that the reason for the impure product obtained by the existing method is that the existing method neglects the influence of oxygen and carbon dioxide in the air. Therefore, in the whole process of the preparation of the present invention, under nitrogen protection conditions, the oxidation of O ₂ in the air, the dissolution of CO ₂ in water, and the generation of

influence experiments. Compared with the traditional method, the process is simple, the LDH interlayer anions prepared by isolating air are purer, the LDH crystallinity is higher, and the morphology is more regular.

2. The whole synthesis process of the carbon-free oxygen-free LDH micro-nano colloidal coating solution of the present invention is carried out in a closed environment (eg vial), and the one-pot synthesis is more efficient, cheap and environmentally friendly.

3. The present invention can also control the material morphology and size of LDH by controlling the metal ion concentration, reaction temperature, reaction time and other conditions. The whole process is non-corrosive to equipment and does not pollute the environment, and is suitable for industrial production.

Description of drawings:

FIG. 1 is a schematic flow chart of the optimal preparation method of the present invention.

FIG. 2 is a photograph of the appearance of the carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution with NO ₃ ^- as the interlayer anion from Example 1. FIG.

Fig. 3 is a photo of Tyndall phenomenon of carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution obtained in Example 1 with the interlayer anion of NO ₃ ^- irradiated with a light beam.

FIG. 4 is a SEM photograph of the carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution obtained in Example 1, in which the interlayer anion is NO ₃ ^- .

FIG. 5 is a photo of the appearance of the carbon-free oxygen-free Fe/Fe-LDH micro-nano colloidal coating solution obtained in Example 2 with the interlayer anion being Cl ^- .

FIG. 6 is a photo of Tyndall phenomenon of carbon-free oxygen-free Fe/Fe-LDH micro-nano colloidal coating solution obtained in Example 2 by irradiating the interlayer anion with Cl ^- with a light beam.

FIG. 7 is a SEM photograph of the carbon-free oxygen-free Fe/Fe-LDH micro-nano colloidal coating solution obtained in Example 2 with the interlayer anion being Cl ^- .

的离碳无氧型Co/Al-LDH微纳米胶体镀层液的外观照片。Figure 8 shows that the interlayer anions in Example 3 are

The appearance photo of the carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution.

的离碳无氧型Co/Al-LDH微纳米胶体镀层液的丁达尔现象照片。Figure 9 shows that the interlayer anion obtained in Example 3 by beam irradiation is:

The photo of Tyndall phenomenon of carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution.

的离碳无氧型Co/Al-LDH微纳米胶体镀层液的SEM照片。Figure 10 shows that the interlayer anion obtained in Example 3 is

SEM image of the carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution.

层间阴离子为NO^3-的Mn/Al-LDH纳米悬浮液的外观照片。Figure 11 is the embodiment 4 without

Photograph of the appearance of the Mn/Al-LDH nanosuspension with NO ^3- as the interlayer anion.

层间阴离子为NO^3-的Mn/Al-LDH纳米悬浮液的丁达尔现象照片。Fig. 12 is the result of irradiating Example 4 with a light beam without

Photograph of Tyndall phenomenon of Mn/Al-LDH nanosuspensions with NO ^3- as the interlayer anion.

层间阴离子为NO^3-的Mn/Al-LDH纳米悬浮液的SEM照片。Figure 13 is the non-

SEM image of the Mn/Al-LDH nanosuspension with NO ^3- as the interlayer anion.

的Mn/Al-LDH微纳米胶体镀层液的外观照片。Figure 14 shows that the interlayer anions from Comparative Example 1 are

Appearance photo of the Mn/Al-LDH micro-nano colloidal coating solution.

的Mn/Al-LDH微纳米胶体镀层液的丁达尔现象照片。Figure 15 shows the interlayer anion obtained by irradiating the comparative example 1 with a beam of

Photo of Tyndall phenomenon of Mn/Al-LDH micro-nano colloidal coating solution.

的Mn/Al-LDH微纳米胶体镀层液的SEM照片。Figure 16 shows that the interlayer anion obtained in Comparative Example 1 is

SEM images of the Mn/Al-LDH micro-nano colloidal coating solution.

FIG. 17 is the XRD diffraction pattern of each sample tested in the test example.

Detailed ways:

The present invention will be further described below with reference to the embodiments and the accompanying drawings, but is not limited thereto.

Example 1:

Accurately weigh Co(NO ₃ ) ₂ ·6H ₂ O and Al(NO ₃ ) ₃ ·9H ₂ O according to the stoichiometric ratio, boil the cooled deionized water and acidify to pH=2 with nitric acid, and configure as Co ²⁺ : Al ³⁺ =3:1, Co-Al salt solution with total metal ion concentration of 0.1mol/l is used as A solution. Dissolve 33 g of solid ammonium chloride in 100 ml of boiled deionized water, add saturated ammonium chloride solution to 25% to 28% concentrated ammonia water, adjust the pH to 12, and obtain ammonia-ammonium chloride buffer solution as B solution . A certain amount of 25% to 28% concentrated ammonia water is used as liquid C.

的离碳无氧型Co/Al-LDH微纳米胶体镀层液。Seal a clean 20ml vial, purge the bottle with nitrogen several times, add liquid B, place it in a constant temperature metal bath shaking pot, set the temperature to 70°C, and rotate the speed to 800r/min. Install liquid A and liquid C on the syringe pump, connect the vial to slowly inject into liquid B, and the volume ratio of liquid A, liquid B and liquid C is 1:1:1.4. After the injection, keep the speed of reaction for 1h, then adjust the speed to 0r/min, and keep the temperature unchanged. After aging at a constant temperature for 24h in a standing state, put the vial into a centrifuge (6000r/min) for centrifugation, and use anhydrous Wash with ethanol 3-4 times and dry at 80°C for 12h. Add 20ml of 1mol sodium nitrate and 3.3mmol nitric acid solution to the solid in the vial, purge with nitrogen for several times, shake at room temperature for 12h, and obtain the interlayer anion as

The carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution.

The photo of the appearance of the carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution with the interlayer anion as NO ₃ ^- obtained in this example is shown in FIG. 2 .

The carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution obtained in this example with an interlayer anion of NO ₃ ^- is irradiated with a light beam, and the photo of the phenomenon is shown in FIG. 3 . It can be seen from Figure 3 that the Co/Al-LDH coating solution has obvious Tyndall effect, which proves its colloidal properties.

Figure 4 shows the SEM photograph of the carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution obtained in this example with an interlayer anion of NO ₃ ^- . It can be seen from Figure 4 that the particles are well dispersed, and most of them have a hydrotalcite-like layered structure, and the particle size and shape have a certain dispersibility.

Example 2:

Accurately weigh FeCl ₂ ·2H ₂ O and FeCl ₃ ·6H ₂ O according to the stoichiometric ratio, boil the cooled deionized water and acidify to pH=1 with nitric acid, and configure Fe ²⁺ : Fe ³⁺ =3:1, total A Fe-Fe salt solution with a metal ion concentration of 0.01 mol/l was used as the A solution. Dissolve 33 g of solid ammonium chloride in 100 ml of boiled deionized water, add saturated ammonium chloride solution to 25% to 28% concentrated ammonia water, adjust the pH to 13, and obtain ammonia-ammonium chloride buffer solution as liquid B . A certain amount of 25% to 28% concentrated ammonia water is used as liquid C.

Seal a clean 20ml vial, purge the bottle with nitrogen several times, add liquid B, place it in a constant temperature metal bath shaking pot, set the temperature to 70°C, and rotate the speed to 800r/min. Install liquid A and liquid C on the syringe pump, connect the vial to slowly inject into liquid B, and the volume ratio of liquid A, liquid B and liquid C is 1:1:1.4. After the injection, keep the speed of reaction for 1h, then adjust the speed to 0r/min, and keep the temperature unchanged. After aging at a constant temperature for 24h in a standing state, put the vial into a centrifuge (6000r/min) for centrifugation, and use anhydrous Wash with ethanol 3-4 times and dry at 80°C for 12h. Add 20 ml of 1 mol sodium chloride and 3.3 mmol of hydrochloric acid solution to the solid in the vial, purge with nitrogen for several times, and shake at room temperature for 12 h to obtain a carbon-free oxygen-free Fe/Fe whose interlayer anion is Cl ^- -LDH micro-nano colloidal coating solution.

The photo of the appearance of the carbon-free oxygen-free Fe/Fe-LDH micro-nano colloidal coating solution with the interlayer anion as Cl ^- obtained in this example is shown in FIG. 5 .

The carbon-free oxygen-free Fe/Fe-LDH micro-nano colloidal coating solution obtained in this example with the interlayer anion as Cl ^- is irradiated with a light beam, and the photo of the phenomenon is shown in FIG. 6 . It can be seen from Figure 6 that the Fe/Fe-LDH coating solution has obvious Tyndall effect, which proves its colloidal properties.

Figure 7 shows the SEM photograph of the carbon-free oxygen-free Fe/Fe-LDH micro-nano colloidal coating solution obtained in this example with the interlayer anion being Cl ^- . It can be seen from Figure 7 that the particles are well dispersed, and most of them have a hydrotalcite-like layered structure, and the particle size and shape have a certain dispersibility.

Example 3:

Accurately weigh CoSO ₄ ·7H ₂ O and Al ₂ (SO ₄ ) ₃ ·18H ₂ O according to the stoichiometric ratio, boil cooled deionized water and acidify to pH=2 with sulfuric acid, and configure Co ²⁺ : Al ³⁺ = 3:1, Co-Al salt solution with total metal ion concentration of 0.05mol/l was used as A solution. Dissolve 33 g of solid ammonium chloride in 100 ml of boiled deionized water, add saturated ammonium chloride solution to 25% to 28% concentrated ammonia water, adjust the pH to 12, and obtain ammonia-ammonium chloride buffer solution as B solution . A certain amount of 25% to 28% concentrated ammonia water is used as liquid C.

的离碳无氧型Co/Al-LDH微纳米胶体镀层液。Seal a clean 20ml vial, purge the bottle with nitrogen several times, add liquid B, place it in a constant temperature metal bath shaking pot, set the temperature to 70°C, and rotate the speed to 800r/min. Install liquid A and liquid C on the syringe pump, connect the vial to slowly inject into liquid B, and the volume ratio of liquid A, liquid B and liquid C is 1:1:1.4. After the injection, keep the speed of reaction for 1h, then adjust the speed to 0r/min, and keep the temperature unchanged. After aging at a constant temperature for 24h in a standing state, put the vial into a centrifuge (6000r/min) for centrifugation, and use anhydrous Wash with ethanol 3-4 times and dry at 80°C for 12h. Add 20ml of 1mol sodium sulfate and 3.3mmol sulfuric acid solution to the solid in the vial, purge with nitrogen for several times, shake at room temperature for 12h, and obtain the interlayer anion as

The carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution.

的离碳无氧型Co/Al-LDH微纳米胶体镀层液的外观照片如图8所示。The interlayer anion obtained in this example is

The photo of the appearance of the carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution is shown in Figure 8.

的离碳无氧型Co/Al-LDH微纳米胶体镀层液，现象照片如图9所示。由图9可知Co/Al-LDH镀层液有明显的的丁达尔效应，证明了它的胶体特性。The interlayer anion obtained by irradiating this example with a light beam is

The carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution, the photo of the phenomenon is shown in Figure 9. It can be seen from Figure 9 that the Co/Al-LDH coating solution has obvious Tyndall effect, which proves its colloidal properties.

的离碳无氧型Co/Al-LDH微纳米胶体镀层液的SEM照片如图10所示。由图10可知颗粒分散良好，大都呈现类水滑石的层状结构，颗粒大小形状呈一定分散性。The interlayer anion obtained in this example is

The SEM photo of the carbon-free oxygen-free Co/Al-LDH micro-nano colloidal coating solution is shown in Figure 10. It can be seen from Figure 10 that the particles are well dispersed, and most of them have a hydrotalcite-like layered structure, and the particle size and shape have a certain dispersibility.

Example 4:

Accurately weigh Mn(NO ₃ ) ₂ ·4H ₂ O and Al(NO ₃ ) ₃ ·9H ₂ O according to the stoichiometric ratio, boil the cooled deionized water and acidify to pH=2 with nitric acid, and configure as Mn ²⁺ : Al ³⁺ =3:1, the Mn-Al salt solution with the total metal ion concentration of 0.01mol/l is used as the A solution. Dissolve 33 g of solid ammonium chloride in 100 ml of boiled deionized water, add saturated ammonium chloride solution to 25% to 28% concentrated ammonia water, adjust the pH to 13, and obtain ammonia-ammonium chloride buffer solution as liquid B . A certain amount of 25% to 28% concentrated ammonia water is used as liquid C.

层间阴离子为NO^3-的Mn/Al-LDH纳米悬浮液。Seal a clean 20ml vial, purge the bottle with nitrogen several times, add liquid B, place it in a constant temperature metal bath shaking pot, set the temperature to 70°C, and rotate the speed to 800r/min. Install liquid A and liquid C on the syringe pump, connect the vial to slowly inject into liquid B, and the volume ratio of liquid A, liquid B and liquid C is 1:1:1.4. After the injection, keep the speed of reaction for 1h, then adjust the speed to 0r/min, and keep the temperature unchanged. After aging at a constant temperature for 24h in a standing state, put the vial into a centrifuge (6000r/min) for centrifugation, and use anhydrous Wash with ethanol 3-4 times and dry at 80°C for 12h. Add 20 ml of 1 mol sodium nitrate and 3.3 mmol of nitric acid solution to the solid in the vial, purge with nitrogen for several times, and shake at room temperature for 12 h to obtain no

The interlayer anion is Mn/Al ^- LDH nanosuspension of NO3-.

层间阴离子为NO^3-的Mn/Al-LDH纳米悬浮液的外观照片如图11所示。None obtained in this example

The photo of the appearance of the Mn/Al-LDH nanosuspension whose interlayer anion is NO ^3- is shown in Fig. 11 .

层间阴离子为NO^3-的Mn/Al-LDH纳米悬浮液，现象照片如图12所示。由图12可知镀层液有明显的的丁达尔效应，证明了它的胶体特性。irradiated with light beams obtained in this example

The Mn/Al-LDH nanosuspension in which the interlayer anion is NO ^3- is shown in Figure 12. It can be seen from Figure 12 that the coating solution has obvious Tyndall effect, which proves its colloidal properties.

层间阴离子为NO^3-的Mn/Al-LDH纳米悬浮液的SEM照片如图13所示。由图13可知颗粒分散良好，大都呈现类水滑石的层状结构，颗粒大小形状呈一定分散性。且得到的层状结构更大。None obtained in this example

The SEM images of the Mn/Al-LDH nanosuspensions with the interlayer anion of NO ^3- are shown in Figure 13. It can be seen from Fig. 13 that the particles are well dispersed, and most of them have a hydrotalcite-like layered structure, and the particle size and shape have a certain dispersibility. And the resulting layered structure is larger.

Comparative Example 1

As described in Example 1, the difference is:

的Co/Al-LDH微纳米胶体镀层液。The whole process is carried out in air without nitrogen protection. The interlayer anion is obtained as

Co/Al-LDH micro-nano colloidal coating solution.

Figure 14 shows the appearance photo of the Co/Al-LDH micro-nano colloidal coating solution with the interlayer anion of NO ^- ₃ obtained in this comparative example.

The Co/Al-LDH micro-nano colloidal coating solution with NO ₃ ^- as the interlayer anion obtained in this comparative example was irradiated with a light beam, and the photo of the phenomenon is shown in FIG. 15 . It can be seen from Figure 15 that this method can also obtain a more obvious Tyndall effect, which has colloidal properties.

Figure 16 shows the SEM photograph of the Co/Al-LDH micro-nano colloidal coating solution with the interlayer anion of NO ₃ ^- obtained in this comparative example. It can be seen from Figure 16 that the layered structure of the prepared LDH is not obvious, tends to be a rod-like structure, and has a small particle size.

It can be seen that the product obtained without the protection of nitrogen does not have a good layered structure and has many impurities.

Test example

The purity of the products of Example 1 and Comparative Example 1 was tested, and the XRD diffraction patterns were shown in FIG. 17 .

It can be seen from the XRD diffraction pattern results in Figure 17 that the characteristic diffraction peaks of hydrotalcite (003), (006), (012), (015), (018), (110), (118) appear in the sample. Example The sample has good crystallinity, strong diffraction intensity and sharp peak shape. However, in Comparative Example 1, the peak shape diffraction intensity was weak and the peak shape was slow, indicating that the crystallinity of the Comparative Example was poor. It further illustrates that the product obtained by the present invention has good crystallinity and higher purity.

Claims (10)

1. A one-pot preparation method of LDH micro-nano colloid coating liquid comprises the following steps:

(1) preparing M under the protection of oxygen-free carbon dioxide-free nitrogen²⁺-M³⁺The salt solution is solution A, the ammonia-ammonium chloride buffer solution is solution B, and the strong ammonia water is solution C;

(2) under the protection of oxygen-free carbon dioxide and nitrogen, simultaneously adding the solution A and the solution C into the solution B, standing and aging after reaction; centrifuging, washing and drying the product to obtain a carbonate-free LDH solid; dispersing the LDH solid into a mixed solution of acid and salt, and oscillating to obtain the carbon-free and oxygen-free LDH micro-nano colloidal plating solution.

2. The one-pot preparation method of the LDH micro-nano colloid coating solution according to claim 1, wherein in the step (1), the pH of the solution A is 1-2, and M is²⁺∶M³⁺The molar ratio is (2-5) to 1;

preferably, divalent M is²⁺Salts and trivalent M³⁺Dissolving salt in acidified deionized water, boiling and decarbonizing to obtain solution A.

3. The one-pot preparation method of the LDH micro-nano colloid coating solution as claimed in claim 1, wherein in the step (1), divalent M is used²⁺Is Mg²⁺、Co²⁺、Ni²⁺、Mn²⁺Or Cu²⁺Trivalent M³⁺Is Al³⁺Or Fe³⁺；

Preferably, divalent M²⁺Salts and trivalent M³⁺The anion of the salt is

Cl^-Or

Can not be

4. The one-pot preparation method of the LDH micro-nano colloid plating solution as claimed in claim 1, wherein the pH value of the solution B in the step (1) is 11-13.

5. The one-pot preparation method of the LDH micro-nano colloid plating solution according to claim 1, wherein the preparation process of the solution B in the step (1) is as follows:

dissolving the ammonium chloride solid in boiled deionized water to obtain a saturated ammonium chloride solution, adding the saturated ammonium chloride solution into 25-28% concentrated ammonia water, and adjusting the pH value to 11-13 to obtain an ammonia-ammonium chloride buffer solution.

6. The one-pot preparation method of the LDH micro-nano colloid plating solution as claimed in claim 1, wherein the step (2) is performed under the conditions of constant temperature and stirring in the process of simultaneously adding the solution A and the solution C into the solution B, the constant temperature is 25-80 ℃, and the stirring speed is 500-850 r/min.

7. The one-pot preparation method of the LDH micro-nano colloid coating solution in claim 1, wherein the volume ratio of the solution A to the solution B to the solution C in the step (2) is 1: 1-3: 1-2;

preferably, the reaction time is 0.5 to 2 hours.

8. The one-pot preparation method of the LDH micro-nano colloid plating solution as claimed in claim 1, wherein the aging temperature in the step (2) is 60-80 ℃; preferably, the aging time is 20-30 h.

9. The one-pot preparation method of the LDH micro-nano colloid plating solution as claimed in claim 1, wherein the product obtained in step (2) is centrifuged, washed with absolute ethanol for 3-4 times, and dried at 80-100 ℃ for 8-12 h.

10. The one-pot preparation method of the LDH micro-nano colloid coating solution as claimed in claim 1, wherein the anion of the acid and salt in the step (2) is

Cl^-Or

The cation of the salt is Na⁺；

Preferably, the LDH solid is dispersed in the mixed solution of the acid and the salt and then is purged by nitrogen for a plurality of times;

preferably, the shaking time is 10-15 h.

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