Method for preparing basic magnesium sulfate microspheres at normal temperature

Abstract

The invention discloses a method for preparing basic magnesium sulfate microspheres at normal temperature, which comprises the following steps: taking magnesium sulfate heptahydrate, tartaric acid and ammonia water as raw materials, adding the ammonia water into a magnesium sulfate solution containing tartaric acid to form magnesium sulfate sol, carrying out solid-liquid separation on the magnesium sulfate solution, washing, and drying the obtained solid to obtain the magnesium sulfate microspheres. The preparation method of the basic magnesium oxysulfate microspheres provided by the invention is simple and relatively mild in conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic chemistry, and particularly relates to a method for preparing basic magnesium sulfate microspheres at room temperature. Background Art

[0002] Magnesium sulfate whiskers have a general structure, expressed as xMgSO4·yMg(OH)2·zH2O. They appear as a white powder, with needle- or fan-shaped whiskers under a scanning electron microscope. Common types include 513, 512, and 123. They possess high strength, low density, and a high elastic modulus, providing reinforcement, stiffness enhancement, and flame retardancy. They are typically produced by direct hydrothermal synthesis using MgSO4 and ammonia (or NaOH) as raw materials, or by a two-step process using MgCl2, MgSO4, and ammonia (or NaOH) as raw materials. "Research Progress on the Preparation and Modification of Magnesium Sulfate Whiskers," by Gao Chuanhui, Ocean University of China, describes a one-step hydrothermal synthesis of magnesium sulfate whiskers at 190°C using MgCl2, MgSO4, and ammonia as raw materials. The whiskers are fibrous, with a fan-shaped shape at one end. The whiskers have a diameter of 0.5 to 2 μm and an aspect ratio of 50 to 200. Patent CN115821392A discloses a method for preparing monodisperse basic magnesium sulfate whiskers, which uses magnesium sulfate and activated magnesium oxide as raw materials and undergoes a hydrothermal reaction at 160-220°C for 4-10 hours. By adjusting the temperature and reaction time of the hydrothermal reaction, the whisker size can be adjusted within a range of 0.5-3 microns in width and 20-100 microns in length. Chinese patent application CN115896916A discloses a method for preparing basic magnesium sulfate whiskers and a method for preparing the same, which uses magnesium sulfate heptahydrate and magnesium hydroxide as raw materials, and undergoes a temperature reaction while stirring in a reactor with distilled water. After constant temperature, the whiskers are subjected to ultrasonication and centrifugal dehydration to produce fibrous basic magnesium sulfate whiskers. Patent CN108034991B discloses a method for preparing type 311 basic magnesium sulfate whiskers, which uses magnesium sulfate heptahydrate and magnesium hydroxide as raw materials, and undergoes a hydrothermal reaction, washing, and drying to obtain type 311 basic magnesium sulfate whiskers.

[0003] Spherical particles are usually used in paints and coatings to enhance the flexibility and adhesion of paints and coatings, are easy to disperse, and have good thixotropy. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method for preparing basic magnesium sulfate microspheres at room temperature using magnesium sulfate heptahydrate and ammonia water as main raw materials, comprising the following steps: Step 1, heating and stirring a magnesium sulfate solution formed by magnesium sulfate heptahydrate and tartaric acid to mix uniformly to obtain a reaction solution; Step 2: After the reaction solution is cooled to room temperature, aqueous ammonia is added dropwise to the stirred reaction solution, and the reaction is carried out at room temperature to obtain a reaction suspension; Step 3: Place the suspension obtained in step 2 into a centrifuge to separate the solid and liquid; Step 4: Wash and dry the solid obtained in step 3 to obtain basic magnesium sulfate microspheres.

[0005] Preferably, the content of magnesium sulfate in the magnesium sulfate solution in step 1 is 25wt%, and the mass ratio of magnesium sulfate solution to tartaric acid is 100:0.5-2.

[0006] Preferably, the concentration of the ammonia water in the step 2 is 15 wt %, and the mass ratio of the ammonia water, tartaric acid and magnesium sulfate solution is 10-20:0.5-2:100.

[0007] Preferably, the stirring reaction in step 2 is carried out for 2 to 6 hours at a rotation speed of 30 to 60 rpm.

[0008] Preferably, the rotation speed of the three centrifuges in the steps is 3000 r / min and the time is 5 min.

[0009] Preferably, the drying temperature in step 4 is 30-60° C., and the drying time is 24 hours.

[0010] Compared with the prior art, the present invention has the following beneficial effects: the basic magnesium oxysulfide microspheres prepared by the present invention are simple to prepare, under mild conditions, easy to produce in large quantities, and have good flexibility and adhesion.

[0011] The participation of biomass or organic polymers in the process of spherulite formation is a necessary condition. The admixture used in the present invention is biomass. In the initial stage of the reaction, magnesium sulfate heptahydrate, tartaric acid and water are aggregated into particles. The Mg in the particles is 2+ The hydrolysis process forms nanocrystals wrapped in organic macromolecules, which then aggregate to form microspheres with rough surfaces. As the reaction time increases, the density of these microspheres gradually increases, their surfaces become smoother, and the internal needle-like building blocks are arranged along the radius of the sphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is the X-ray diffraction pattern of the basic magnesium sulfate microspheres of the present invention, wherein ad represents the X-ray diffraction patterns of the basic magnesium sulfate microspheres in Example 1, Example 2, Example 3, and Example 4, respectively.

[0013] Figure 2 1 and 2 are scanning electron micrographs of the basic magnesium sulfate microspheres of the present invention, wherein ad represent scanning electron micrographs of the basic magnesium sulfate microspheres in Example 1, Example 2, Example 3, and Example 4, respectively.

[0014] Figure 3 These are the performance test data of the coating prepared from the basic magnesium sulfate microspheres obtained in Examples 1 to 4. DETAILED DESCRIPTION

[0015] The present invention will now be further described with reference to the accompanying drawings and specific embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0016] Example 1 This embodiment discloses a method for preparing basic magnesium sulfate microspheres at room temperature, comprising the following steps: 1. Prepare 800 g of 25% magnesium sulfate aqueous solution, add 4 g of tartaric acid to the magnesium sulfate solution, and heat and stir until the mixture is uniform; 2. Add 80g of 15% ammonia water dropwise to the stirring magnesium oxysulfide solution and let it stand at room temperature until a white sol appears; 3. Place the white sol in a centrifuge and centrifuge at 3000 r / min for 5 minutes. Wash the obtained white solid with deionized water and dry it in a drying oven at 40°C for 24 hours to obtain basic magnesium oxysulfide microspheres.

[0017] The X-ray diffraction patterns and scanning electron microscopy images of the prepared microsphere products are as follows: Figure 1 The middle curve a and Figure 2 As shown in a.

[0018] Example 2 This embodiment discloses a method for preparing basic magnesium sulfate microspheres at room temperature, comprising the following steps: 1. Prepare 800 g of 25% magnesium sulfate aqueous solution, add 8 g of tartaric acid to the magnesium sulfate solution, and heat and stir until the mixture is uniform; 2. Add 80g of 15% ammonia water dropwise to the stirring magnesium oxysulfide solution and let it stand at room temperature until a white sol appears; 3. Place the white sol in a centrifuge and centrifuge at 3000 r / min for 5 minutes. Wash the obtained white solid with deionized water and dry it in a drying oven at 40°C for 24 hours to obtain basic magnesium oxysulfide microspheres.

[0019] The X-ray diffraction patterns and scanning electron microscopy images of the prepared microsphere products are as follows: Figure 1 The middle curve b and Figure 2 As shown in b.

[0020] Example 3 This embodiment discloses a method for preparing basic magnesium sulfate microspheres at room temperature, comprising the following steps: 1. Prepare 800 g of 25% magnesium sulfate aqueous solution, add 12 g of tartaric acid to the magnesium sulfate solution, and heat and stir until the mixture is uniform; 2. Add 80g of 15% ammonia water dropwise to the stirring magnesium oxysulfide solution and let it stand at room temperature until a white sol appears; 3. Place the white sol in a centrifuge and centrifuge at 3000 r / min for 5 minutes. Wash the obtained white solid with deionized water and dry it in a drying oven at 40°C for 24 hours to obtain basic magnesium oxysulfide microspheres.

[0021] The X-ray diffraction patterns and scanning electron microscopy images of the prepared microsphere products are as follows: Figure 1 The middle curve c and Figure 2 As shown in c.

[0022] Example 4 This embodiment discloses a method for preparing basic magnesium sulfate microspheres at room temperature, comprising the following steps: 1. Prepare 800 g of 25% magnesium sulfate aqueous solution, add 16 g of tartaric acid to the magnesium sulfate solution, and heat and stir until the mixture is uniform; 2. Add 80g of 15% ammonia water dropwise to the stirring magnesium oxysulfide solution and let it stand at room temperature until a white sol appears; 3. Place the white sol in a centrifuge and centrifuge at 3000 r / min for 5 minutes. Wash the obtained white solid with deionized water and dry it in a drying oven at 40°C for 24 hours to obtain basic magnesium oxysulfide microspheres.

[0023] The X-ray diffraction patterns and scanning electron microscopy images of the prepared microsphere products are as follows: Figure 1 The middle curve d and Figure 2 As shown in d.

[0024] The present embodiments 1 to 4 are applied to cement waterproof coatings, and the cement indicators are tested as follows: Figure 3 As shown. Coating 5 is a polymer cement waterproof coating, comprising an epoxy resin emulsion, a dispersant, a defoamer, a fungicide, and water; Coating 1 is a coating 5 to which 5% by mass of basic magnesium sulfate microspheres prepared in Example 1 are added; Coating 2 is a coating 5 to which 5% by mass of basic magnesium sulfate microspheres prepared in Example 2 are added; Coating 3 is a coating 5 to which 5% by mass of basic magnesium sulfate microspheres prepared in Example 3 are added; and Coating 4 is a coating 5 to which 5% by mass of basic magnesium sulfate microspheres prepared in Example 4 are added.

[0025] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing basic magnesium sulfate microspheres at room temperature, characterized in that: The steps of the method include: Step 1: adding deionized water to magnesium sulfate heptahydrate to form a magnesium sulfate solution; Step 2: adding tartaric acid to the magnesium sulfate solution, heating and stirring to mix uniformly to obtain a reaction solution; Step 3: Cool the magnesium sulfate solution to room temperature, slowly add aqueous ammonia to the stirred reaction solution, and react at room temperature to obtain a reaction suspension; Step 4: separating the reaction suspension obtained in step 3 into solid and liquid, washing and drying the solid obtained after separation to obtain basic magnesium sulfate microspheres.

2. The preparation method according to claim 1, wherein: The content of magnesium sulfate in the magnesium sulfate solution is 10-25 wt %.

3. The preparation method according to claim 1, wherein: The mass ratio of the magnesium sulfate solution to tartaric acid is 100:0.5-2.

4. The preparation method according to claim 1, wherein: The concentration of the ammonia water is 10-15 wt %.

5. The preparation method according to claim 1, wherein: The mass ratio of ammonia water, tartaric acid and magnesium sulfate solution in the mixed reaction system is 10-20:0.5-2:

100.

6. The preparation method according to claim 1, characterized in that: The mixed system is stirred and reacted for 2 to 6 hours, and then the obtained emulsion is filtered and washed.

7. The preparation method according to claim 1, characterized in that: When using a centrifuge for solid-liquid separation, the speed is 1000~3000r / min and the time is 5~10min.

8. The preparation method according to claim 1, characterized in that: Water is used for washing, the drying temperature is 30-60°C, and the drying time is 12-24 hours.

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