Modified red mud as well as preparation method and application thereof

Abstract

The invention provides modified red mud as well as a preparation method and application thereof, and belongs to the technical field of resource reutilization. Red mud, stearic acid and a solvent are mixed for a modification reaction, and a modified product is obtained; the mass ratio of the red mud to the stearic acid is 1: (3-4); the time of the modification reaction is 12 to 24 hours; and washing the modified product to remove unreacted stearic acid to obtain the modified red mud. Chemical elements in the red mud are effectively utilized, aluminate in the red mud and stearic acid are subjected to a modification reaction to form a hydrophobic membrane, and the mass ratio of the red mud to the stearic acid and the time of the modification reaction are combined and limited, so that the water contact angle of the obtained modified red mud is larger than 140 degrees, the problem that the hydrophilicity of the red mud is stubborn is thoroughly overcome, and the service life of the red mud is prolonged. Therefore, the composite material can be used as a high-performance functional filler to be applied to the fields of waterproofing, anticorrosive coatings and oil stain adsorption, and high-value rise of resources is realized.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and in particular to a modified red mud, its preparation method, and its application. Background Technology

[0002] Red mud is a highly alkaline industrial solid waste generated during alumina production. Breakthroughs in its surface modification technology have significantly expanded its application areas, enabling waste-to-waste treatment and resource utilization. Modified red mud can be applied in multiple fields, from water treatment to marine engineering, covering environmental protection, energy, and construction.

[0003] Most red mud is simply treated and then stored in open-air dams near alumina plants. This not only occupies a large amount of land but also incurs high land acquisition fees and dam construction costs for relevant entities. Furthermore, the transportation and storage processes generate dust, sand, and other pollutants, causing serious environmental pollution and posing significant safety hazards such as red mud leaks. Currently, most red mud resource utilization methods use it as an inert admixture, failing to effectively utilize its chemical components, such as its use as an inert admixture in cement, road base material, or in the production of unfired bricks. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a modified red mud, its preparation method, and its application. The modification method of this invention can improve the hydrophobicity of red mud.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing modified red mud, comprising the following steps: Red mud, stearic acid, and solvent are mixed and subjected to a modification reaction to obtain a modified product; the mass ratio of red mud to stearic acid is 1:3~4; the modification reaction time is 12~24h. The modified product is washed to remove unreacted stearic acid, yielding the modified red mud.

[0006] Preferably, the mass ratio of red mud to stearic acid is 1:3.6.

[0007] Preferably, the red mud has a particle size of <100μm.

[0008] Preferably, the solvent includes anhydrous ethanol.

[0009] Preferably, the ratio of the total mass of the red mud and stearic acid to the amount of solvent is 4~5g:50mL.

[0010] Preferably, the temperature of the modification reaction is 60°C.

[0011] Preferably, the detergent used for washing includes anhydrous ethanol.

[0012] Preferably, the washing is performed 3 to 5 times.

[0013] The present invention also provides a modified red mud prepared by the preparation method described above, wherein the water contact angle of the modified red mud is >140°.

[0014] This invention also provides the application of the modified red mud described in the above technical solution in the fields of waterproofing, anti-corrosion coatings, and oil stain adsorption.

[0015] This invention provides a method for preparing modified red mud, comprising the following steps: mixing red mud, stearic acid and solvent to carry out a modification reaction to obtain a modified product; the mass ratio of red mud to stearic acid is 1:3~4; the modification reaction time is 12~24h; and washing the modified product to remove unreacted stearic acid to obtain the modified red mud.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention effectively utilizes the chemical elements in red mud, and modifies the red mud by reacting aluminates with stearic acid to form a hydrophobic film. The reaction principle is as follows: Figure 1 As shown: 3C 17 H 35 COOH + Na[Al(OH)4]→(C 17 H 35 COO)3Al↓+ NaOH + H2O, By controlling the mass ratio of red mud to stearic acid and the reaction time, the resulting modified red mud achieves a water contact angle >140°, completely overcoming the persistent hydrophilicity problem of red mud. This allows it to be used as a high-performance functional filler in waterproofing, anti-corrosion coatings, and oil adsorption, achieving a high-value leap in resource utilization. The superior superhydrophobic properties demonstrate the low-cost and high-efficiency nature of the modification process (compared to existing technologies or high-temperature and complex modification processes), providing an industrialization technology path with clear performance indicators (water contact angle) for the large-scale, high-value-added utilization of red mud. Furthermore, the modification method of this invention uses a single organic acid to modify red mud, resulting in a simple modification process and significant cost advantages.

[0017] This invention also provides modified red mud prepared by the preparation method described above. The advantages of the modified red mud are as follows: Dust suppression: Surface hydrophobicity can effectively reduce the water absorption of red mud particles, reduce their tendency to generate dust after drying, and improve the storage and transportation environment.

[0018] Reduced environmental risks: The hydrophobic membrane formed can block direct and rapid contact between internal alkaline substances and water, which helps to slow down the rate and intensity of alkaline leachate production. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the modified reaction principle described in this invention; Figure 2 This is a flowchart of the preparation of modified red mud in Example 1; Figure 3 The image shows the water contact angle test result of the modified red mud prepared in Example 1. Figure 4 The actual hydrophobic effect of the modified red mud prepared in Example 1 is shown. Detailed Implementation

[0020] This invention provides a method for preparing modified red mud, comprising the following steps: Red mud, stearic acid, and solvent are mixed and subjected to a modification reaction to obtain a modified product; the mass ratio of red mud to stearic acid is 1:3~4; the modification reaction time is 12~24h. The modified product is washed to remove unreacted stearic acid, yielding the modified red mud.

[0021] Unless otherwise specified, all raw materials used in this invention are commercially available products in the field.

[0022] This invention involves mixing red mud, stearic acid, and a solvent to undergo a modification reaction, yielding a modified product. The mass ratio of red mud to stearic acid is 1:3-4. The modification reaction time is 12-24 hours. During the modification reaction, the aluminate in the red mud reacts with stearic acid to form a hydrophobic film. By limiting the mass ratio of red mud to stearic acid and the modification reaction time, the water contact angle of the obtained modified red mud is >140°, completely overcoming the persistent problem of red mud's hydrophilicity. This allows it to be used as a high-performance functional filler in waterproofing, anti-corrosion coatings, and oil adsorption, achieving a high-value leap in resource utilization.

[0023] In this invention, the preferred mass ratio of red mud to stearic acid is 1:3.6.

[0024] In this invention, the particle size of the red mud is preferably <100μm.

[0025] In this invention, the solvent preferably includes anhydrous ethanol.

[0026] In this invention, the preferred ratio of the total mass of the red mud and stearic acid to the amount of solvent is 4-5 g: 50 mL, specifically 4.6 g: 50 mL.

[0027] In this invention, the preferred temperature for the modification reaction is 60°C.

[0028] In this invention, the red mud is preferably dried and ground, passed through a 200-mesh sieve (particle size <100 μm), and then mixed with stearic acid and a solvent to carry out the modification reaction.

[0029] After obtaining the modified product, the present invention washes the modified product to remove unreacted stearic acid, thereby obtaining the modified red mud.

[0030] In this invention, the detergent used for washing preferably includes anhydrous ethanol.

[0031] In this invention, the washing is preferably performed 3 to 5 times, specifically 3, 4 or 5 times.

[0032] In this invention, the unreacted stearic acid is preferably used again for red mud modification.

[0033] After the washing is completed, the present invention preferably washes the material 3 to 5 times with deionized water, then dries it at 60°C for 6 to 24 hours, and then grinds it into powder to obtain the modified red mud.

[0034] The present invention also provides modified red mud prepared by the preparation method described above, wherein the water contact angle of the modified red mud is >140°, specifically 140.78°, 141.49° or 147.50°.

[0035] This invention also provides the application of the modified red mud described in the above technical solution in the fields of waterproofing, anti-corrosion coatings, and oil stain adsorption.

[0036] The present invention does not impose any special limitation on the specific method of application, and any method known to those skilled in the art can be used.

[0037] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] Example 1 Figure 2 This is a flowchart of the preparation of modified red mud in Example 1.

[0039] First, the red mud was dried and ground. 1g of red mud (particle size <100μm) that had passed through a 200-mesh sieve was mixed with 3.6g of stearic acid. Then, the mixture was mixed with an alcohol solution (anhydrous ethanol) at a ratio of 4.6g:50mL. The mixture was stirred at 60℃ for 24 hours to carry out the modification reaction. The mixture was then washed five times with anhydrous ethanol, yielding 2g of stearic acid (56% of the original stearic acid mass), which could be used again for red mud modification. The modified red mud was then washed five times with deionized water, dried at 60℃ for 24 hours, and then ground into powder to obtain 1.4g of modified red mud with hydrophobic properties.

[0040] Figure 3 The image shows the water contact angle test result of the modified red mud prepared in Example 1.

[0041] Figure 4 The actual hydrophobic effect of the modified red mud prepared in Example 1 is shown.

[0042] The differences in preparation process parameters between the other embodiments and comparative examples and Example 1 are shown in Table 1. The water contact angles of the modified red mud obtained in each embodiment and comparative example are shown in Table 1. It can be seen that the present invention successfully transforms red mud into a strongly hydrophobic / near-superhydrophobic material with a contact angle >140° through one-step organic acid surface modification, completely overcoming the stubborn problem of red mud's hydrophilicity, enabling it to be used as a high-performance functional filler in high-end waterproof / anti-corrosion coatings, polymer composite materials, and oil adsorbents, achieving a high-value leap in resource utilization. The intuitive superhydrophobic properties verify the low cost and high efficiency of the modification process (compared to high-temperature / complex processes). It provides an industrialization technology path with clear performance indicators (water contact angle) for the large-scale, high-value-added utilization of red mud.

[0043] Table 1. Preparation process parameters and water contact angles of the examples and comparative examples.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing modified red mud, characterized in that, Includes the following steps: Red mud, stearic acid, and solvent were mixed and subjected to a modification reaction to obtain the modified product; The mass ratio of red mud to stearic acid is 1:3~4; the modification reaction time is 12~24h; The modified product is washed to remove unreacted stearic acid, yielding the modified red mud.

2. The preparation method according to claim 1, characterized in that, The mass ratio of red mud to stearic acid is 1:3.

6.

3. The preparation method according to claim 1, characterized in that, The red mud has a particle size of <100μm.

4. The preparation method according to claim 1, characterized in that, The solvent includes anhydrous ethanol.

5. The preparation method according to claim 1 or 4, characterized in that, The ratio of the total mass of the red mud and stearic acid to the amount of solvent is 4~5g:50mL.

6. The preparation method according to claim 1, characterized in that, The temperature of the modification reaction is 60°C.

7. The preparation method according to claim 1, characterized in that, The detergent used in the washing process includes anhydrous ethanol.

8. The preparation method according to claim 1 or 7, characterized in that, The washing process is repeated 3 to 5 times.

9. The modified red mud prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The modified red mud has a water contact angle >140°.

10. The application of the modified red mud according to claim 9 in the fields of waterproofing, anti-corrosion coatings, and oil adsorption.

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