CN108585001B

CN108585001B - Layered double metal hydroxide LDH-CO3-SO42-Preparation method and application of whisker

Info

Publication number: CN108585001B
Application number: CN201810276489.3A
Authority: CN
Inventors: 吴健松
Original assignee: Lingnan Normal University
Current assignee: Lingnan Normal University
Priority date: 2018-03-30
Filing date: 2018-03-30
Publication date: 2020-05-05
Anticipated expiration: 2038-03-30
Also published as: CN108585001A

Abstract

The invention discloses a layered double metal hydroxide LDH-CO₃‑SO₄ ^2‑A preparation method and application of the whisker. The preparation method comprises the following steps: s1, preparing MgCO₃Solution with Al₂(SO₄)₃Mixing the solution, and adding alkali to adjust the pH value of the mixed solution to 7.40; s2, adding 1.40-1.60 mol/LNa into the mixed solution of S1₂CO₃The solution is evaporated and crystallized until the pH value of the system is 8.0, the system pH is detected every 8.7-9.3 h in the evaporation process, alkali is added to increase the pH value of the system by 0.05, and the precipitate is filtered and washed to obtain the layered double hydroxide LDH-CO₃‑SO₄ ^2‑Whisker of the chemical formula Mg₆A_l2(OH)₁₄CO₃SO₄·4H₂And O. The preparation method of the invention forms LDH-CO with special appearance, composition and crystal structure by controlling the feeding ratio, the pH value of the reaction system, the reaction temperature and the reaction time₃‑SO₄ ^2‑The preparation method of the whisker is simple, environment-friendly, efficient and energy-saving, and the obtained LDH-CO₃‑SO₄ ^2‑The whisker can be widely applied to toughening and reinforcing materials, catalytic materials, flame retardant materials and adsorption materials.

Description

Layered double metal hydroxide LDH-CO3-SO42-Preparation method and application of whisker

Technical Field

The invention belongs to the field of layered double-metal hydroxide materials, and particularly relates to layered double-metal hydroxide LDH-CO₃-SO₄ ^2-A preparation method and application of the whisker.

Background

Layered Double Hydroxides (LDH) are a general name of Hydrotalcite (HT) and Hydrotalcite-Like Compounds (HTlc), are important inorganic functional materials, have the functions of catalysis, adsorption, flame retardance and the Like, and are environment-friendly multifunctional inorganic materials. The most typical LDH is Mg₆Al₂(OH)₁₆CO₃.4H₂O, also known as magnesium aluminum hydrotalcite if the Mg in the magnesium aluminum hydrotalcite²⁺、A1³⁺Or CO₃ ^2-The ion is replaced by other ion to obtain hydrotalcite-like compound (HTLc).

The formula of HTLc is:

(wherein M is²⁺Is a divalent metal ion, such as Mg2+, Ni2+, Co2+, Zn2+, Cu2+ and the like; m³⁺Being trivalent metal ions, e.g. Al³⁺、Cr³⁺、Fe³⁺、Sc³⁺Etc.; a is an interlayer anion, e.g. CO₃ ^2-、NO^3-、 Cl^-、SO₄ ^2-、PO₄ ^3-、C₆H₄(COO)₂ ^2-Etc.; m is the number of interlayer bound water). By

The sheet layers formed are called metal sheet layers and are composed of

The resulting layer is referred to as an anionic layer and this layered structure is shown in figure 1.

For LDH compounds, studies at home and abroad have mainly focused on the substitution of divalent cations in metal sheet layers, such as the substitution of magnesium ions for copper ions or cobalt ions, and the substitution of anions for organic biomolecules such as amino acids, have also been devised. Intercalated LDH composite materials containing copper, cobalt, nickel, organic acid, polyacid and the like are designed by Beijing university of chemical industry, a plurality of scholars study LDH preparation technology abroad, and LDH is used as a catalyst to synthesize a plurality of important organic compounds and inorganic compounds which are used as fire retardants, adsorbents and the like. But to date, for the preparation of LDH-CO₃-SO₄ ^2-Whiskers cannot be reported or searched, few reports can be found for preparing LDH into whisker shapes, most of the preparation routes of LDH are prepared by using certain whiskers (such as magnesium hydroxide whiskers) as precursors, and the preparation technical routes are long and high in cost.

Therefore, the development of a simple and easy whisker-shaped LDH compound has great research significance and application value.

Disclosure of Invention

The invention aims to overcome the defects of long technical route, high preparation cost and the like of preparing whisker-shaped LDH compounds in the prior art, and provides a layered double-metal hydroxide LDH-CO₃-SO₄ ^2-A preparation method of the whisker.

Another object of the present invention is to provide a process for the preparation thereofLDH-CO of₃-SO₄ ^2-A whisker.

It is another object of the present invention to provide the layered double hydroxide LDH-CO mentioned above₃-SO₄ ^2-The crystal whisker is applied to preparing toughening and reinforcing materials, catalytic materials, flame-retardant materials or adsorbing materials.

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

layered double metal hydroxide LDH-CO₃-SO₄ ^2-The preparation method of the whisker comprises the following steps:

s1, preparing MgCO₃Solution with Al₂(SO₄)₃Mixing the solutions, adding base to adjust pH of the mixed solution to 7.40, wherein Mg²⁺The concentration is 2.10-2.70 mol/L, and Al is in³⁺The concentration is 0.50-0.70 mol/L, CO₃ ^2-With SO₄ ^2-In a molar ratio of 1: 1;

s2, adding 1.40-1.60 mol/LNa into the mixed solution of S1₂CO₃The solution is evaporated and crystallized until the pH value of the system is 8.0, the system pH is detected every 8.7-9.3 h in the evaporation process, alkali is added to increase the pH value of the system by 0.05, and the precipitate is filtered and washed to obtain the layered double hydroxide LDH-CO₃-SO₄ ^2-Whisker of the chemical formula Mg₆A_l2(OH)₁₄CO₃SO₄·4H₂O。

The inventor unexpectedly discovers that the charge ratio, the pH value of a reaction system, the reaction temperature, the reaction time and the like given in the preparation process can be applied to the prepared LDH-CO₃-SO₄ ^2-The morphology, composition and crystal structure of the whiskers have great influence, so that the layered double metal hydroxide LDH-CO can be obtained under the specific preparation conditions of the invention₃-SO₄ ^2-A whisker.

Preferably, S1Mg²⁺Concentration of 2.40mol/L, Al³⁺The concentration was 0.80 mol/L.

For the purposes of low energy consumption, clean and environment-friendly preparation of the layer of the inventionDouble metal hydroxide like CO₃-SO₄ ^2-The whisker is evaporated under the condition of wind blowing and sun drying, and the evaporation condition is as follows: the temperature of the solution is 5-45 ℃, and the surface air speed of the solution is 3-5 m/s.

The Qinghai salt lake area has abundant solar energy resources and wind energy resources, the temperature is 4-45 ℃ throughout the year, the wind speed is 3-5 m/S, the S2 reaction system can be placed in the open place of the Qinghai salt lake area, the slow evaporation of water is realized by utilizing natural solar energy and wind energy resources, the energy is saved, and the green chemical industry is realized.

Preferably, the MgCO of S1₃Solution with Al₂(SO₄)₃The mixed solution of the solution is prepared from salt lake bitter bittern. More preferably, the salt lake bittern is Qinghai salt lake bittern.

A great amount of bittern is available in Qinghai salt lake (such as Lithocarpus koenigii, Theaca salt lake bittern or Kaerfeng salt lake), and is used for preparing LDH-CO₃-SO₄ ^2-The whisker is an excellent natural resource. However, the resources cannot be scientifically and highly utilized all the time, but are left unused all the time, which wastes salt lake resources, causes serious salinization of soil around the salt lake and withering of plants, damages the ecological environment of the salt lake and brings difficulty to the resource exploitation of the salt field in the future. Fully utilizes high-quality Mg in the salt lake bittern²⁺And Al³⁺As a process for preparing LDH-CO₃-SO₄ ^2-The raw material source of the crystal whisker can utilize high-quality resources of the salt lake to realize high-value utilization, and protect the ecological environment of the salt lake and is beneficial to the development of salt field resources.

Layered double hydroxide LDH-CO prepared by the method₃-SO₄ ^2-Whisker of which the chemical formula is Mg₆A_l2(OH)₁₄CO₃SO₄·4H₂O。

LDH-CO of the invention₃-SO₄ ^2-The whisker not only has the functions of catalysis, flame retardance and adsorption of an LDH compound, but also has larger specific surface area and interlaminar ion exchangeability, and also has the toughness of the whiskerThe reinforcing function has pore diameter adjustable modification, and is an environment-friendly multifunctional inorganic material.

The layered double hydroxide LDH-CO described above₃-SO₄ ^2-The application of the whisker in preparing toughening reinforcing materials, catalytic materials, flame-retardant materials or adsorbing materials is also within the protection scope of the invention.

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

the invention provides a layered double metal hydroxide LDH-CO₃-SO₄ ^2-Whiskers, LDH-CO₃-SO₄ ^2-The whisker compound not only has the functions of catalysis, flame retardance and adsorption of the LDH compound, but also has the functions of toughening and reinforcing of the whisker, has adjustable and denatured pore diameter, and is an environment-friendly multifunctional inorganic material. The preparation process of the compound forms LDH-CO with special appearance, composition and crystal structure by controlling the feeding ratio, the pH value of a reaction system, the reaction temperature and the reaction time₃-SO₄ ^2-The whisker and the preparation method are simple, environmentally-friendly, efficient and energy-saving, and the obtained LDH-CO₃-SO₄ ^2-The crystal whisker can be widely applied to toughening and reinforcing materials, catalytic materials, flame-retardant materials and adsorbing materials.

Drawings

Fig. 1 is a schematic view of the layered structure of HTLc.

FIG. 2 is a diagram for preparing layered double hydroxide LDH-CO₃-SO₄ ^2-A roadmap of whiskers.

FIG. 3 is the layered double hydroxide LDH-CO prepared in example 1₃-SO₄ ^2-XRD pattern of whiskers.

FIG. 4 is the layered double hydroxide LDH-CO of example 1₃-SO₄ ^2-SEM image of whiskers.

FIG. 5 is a graph of layered double hydroxide LDH-CO prepared in comparative example 1₃-SO₄ ^2-SEM image of whiskers.

Detailed Description

The present invention will be further described with reference to the following examples. These examples are merely representative descriptions of the present invention, but the present invention is not limited thereto. The test methods used in the following examples are all conventional methods unless otherwise specified; the raw materials and reagents used, etc., are all commercially available from conventional sources unless otherwise specified.

Examples 1 to 8

Layered double metal hydroxide LDH-CO₃-SO₄ ^2-A whisker having the chemical formula

Mg₆A_l2(OH)₁₄CO₃SO₄·4H₂O, the preparation method has the flow chart shown in figure 1 and comprises the following steps:

s1, preparing MgCO₃Solution with Al₂(SO₄)₃Mixing the solution, and adding alkali to adjust the pH value of the mixed solution to 7.40;

s2, adding Na into the mixed solution of S1₂CO₃The solution is added until the pH value of the system is 8.0, the evaporation reaction is carried out until the precipitation is complete, the pH value of the system is detected every 8 times in the evaporation process, the alkali is added to increase the pH value of the system by 0.05, and the precipitation is filtered, washed and obtained to obtain the layered double hydroxide LDH-CO₃-SO₄ ^2-A whisker.

Wherein MgCO of examples 1 to 7₃The solution consists of MgCO₃·6H₂Preparation of O, Al₂(SO₄)₃The solution is made of Al₂(SO₄)₃·18H₂Preparing O;

MgCO of example 8₃Solution and Al₂(SO₄)₃The mixed solution of the solution is prepared from the Qinghai salt lake bittern.

The parameters of specific examples are shown in Table 1, wherein Mg in S1²⁺Concentration of A mol/L, Al³⁺The concentration is B mol/L; na in S2₂CO₃The concentration is C mol/L.

TABLE 1

Serial number	A	B	C
				Example 1	2.40	0.60	1.5
Example 2	2.10	0.60	1.5
				Example 3	2.70	0.60	1.50
Example 4	2.40	0.50	1.50
				Example 5	2.40	0.70	1.50
Example 6	2.40	0.60	1.40
				Example 7	2.40	0.60	1.60
Example 8	2.40	0.60	1.5

Comparative examples 1 to 7

The comparative example was conducted in substantially the same manner as in example 1, and the chemical composition was the same as in example 1, and the specific reference values are shown in Table 2.

TABLE 2

Serial number	A	B	C	D
					Comparative example 1	2.40	0.4	1.50	8.0
Comparative example 2	2.40	0.8	1.50	8.0
					Comparative example 3	2.00	0.80	1.50	8.0
Comparative example 4	2.80	0.80	1.50	8.0
					Comparative example 5	2.40	0.80	1.30	8.0
Comparative example 6	2.40	0.80	1.70	8.0
					Comparative example 7	2.40	0.80	1.50	9.0
Comparative example 8	2.40	0.80	1.5 0	7.0

Result detection

(1) And (3) detecting the whisker structure:

the whisker junction prepared in example 1 was examined by X-ray diffraction (XRD) examination.

From the XRD test, it is found that the layered double hydroxide LDH-CO prepared in example 1 is₃-SO₄ ^2-The XRD results of the whiskers are shown in fig. 1. Examples 2 to 5 of the layered double hydroxide LDH-CO prepared₃-SO₄ ^2-The XRD results of the whiskers were the same as in example 1.

As shown in FIG. 1, which is a layered double hydroxide LDH-CO prepared in example 1₃-SO₄ ^2-XRD pattern of whiskers. The diffraction characteristic peak shows that the sample has sharp peak shape, and the position and the intensity of each main diffraction peak show that the substance is LDH-CO with a layered structure₃-SO₄ ^2-As can be seen from the XRD diffraction pattern of the layered double metal hydroxide LDH-CO₃-SO₄ ^2-The compound has a layered structure of LDH (LDH of the layered structure diffracts in the (003) plane with the greatest intensity, followed by the (006) plane and the smallest (009) plane due to the "extinction" effect of the layered compound on XRD I have marked diffraction peaks corresponding to the (003), (006) and (009) planes in the drawing.

(2) Topography detection

The layered duplex metal prepared in example 1 was examined by Scanning Electron Microscopy (SEM)Hydroxide LDH-CO₃-SO₄ ^2-The appearance of the whisker is calculated by biological microscope observation₃-SO₄ ^2-Aspect ratio of the whisker. The aspect ratio structure of the whiskers is shown in Table 3 below, LDH-CO prepared in example 1₃-SO₄ ^2-FIG. 3 shows a scanning electron micrograph of whiskers, the sample having whisker-like shape, LDH-CO prepared in comparative example 1₃-SO₄ ^2-The scanning electron micrograph of the whisker is shown in fig. 4, without the shape of the whisker.

TABLE 3

(3) Composition detection

The results of elemental analysis of the samples are shown in Table 4, and the data in Table 4 show that the samples substantially satisfy n_Mg:n_Al:n_S:n_CWhen oxygen (oxygen content obtained by the subtraction method) and hydrogen are combined together, the chemical formula is assumed to be Mg₆Al₂(OH)₁₄CO₃SO₄·4H₂O。

TABLE 4LDH-CO₃-SO₄ ^2-Results of elemental analysis

(Mg)％	(Al)％	(S)％	(C)％	(H)％	Mg/Al/S/C
						21.59	8.21	4.84	1.83	3.31	0.900:0.304:0.151:0.153

Claims

1. Layered double metal hydroxide LDH-CO₃-SO₄ ^2-The preparation method of the whisker is characterized by comprising the following steps:

s1, preparing MgCO₃Solution with Al₂(SO₄)₃Mixing the solutions, adding base to adjust pH of the mixed solution to 7.40, wherein Mg²⁺Al with a concentration of 2.10-2.70 mol/L³⁺The concentration is 0.50-0.70 mol/L, CO₃ ^2-With SO₄ ^2-In a molar ratio of 1: 1;

s2, adding 1.40-1.60 mol/LNa into the mixed solution of S1₂CO₃The solution is evaporated and crystallized until the pH value of the system is 8.0, the system pH is detected every 8.7-9.3 h in the evaporation process, alkali is added to increase the pH value of the system by 0.05, and the precipitate is filtered and washed to obtain the layered double hydroxide LDH-CO₃-SO₄ ^2-Whisker of the chemical formula Mg₆Al₂(OH)₁₄CO₃SO₄·4H₂And O, the evaporation is carried out under the condition of wind blowing and sun drying, and the evaporation conditions are as follows: the temperature of the solution is 5-45 ℃, and the surface air speed of the solution is 3-5 m/s.

2. The layered double hydroxide LDH-CO of claim 1₃-SO₄ ^2-The preparation method of the whisker is characterized in that Mg in S1²⁺Concentration of 2.40mol/L, Al³⁺The concentration was 0.80 mol/L.

3. The layered double hydroxide LDH-CO of claim 1₃-SO₄ ^2-The preparation method of the whisker is characterized in that the alkali for adjusting the pH is 0.01mol/L sodium hydroxide solution.

4. The layered double hydroxide LDH-CO of claim 1₃-SO₄ ^2-A method for producing a whisker, wherein the MgCO is₃Solution with Al₂(SO₄)₃The mixed solution of the solution is prepared from salt lake bittern.

5. The layered double hydroxide LDH-CO of claim 1₃-SO₄ ^2-The preparation method of the crystal whisker is characterized in that the salt lake bittern is Qinghai salt lake bittern.

6. Layered double hydroxide LDH-CO prepared by the method of any one of claims 1 to 5₃-SO₄ ^2-Whisker of the chemical formula Mg₆Al₂(OH)₁₄CO₃SO₄·4H₂O。

7. The layered double hydroxide LDH-CO of claim 6₃-SO₄ ^2-The crystal whisker is applied to preparing toughening and reinforcing materials, catalytic materials, flame-retardant materials or adsorbing materials.