A method for modifying a calcium bentonite

Abstract

This invention relates to a method for modifying calcium-based bentonite, comprising the following steps: 1) Sodium modification: Sodium carbonate solution and calcium-based bentonite are placed together in a mill, and the calcium-based bentonite is modified by sodium modification through mixing and milling. Afterwards, it is dried, pulverized, and sieved to obtain a sodium-based bentonite product; 2) Organic modification: Sodium-based bentonite is dissolved in deionized water and stirred at high speed to form a bentonite suspension with a mass concentration of 10%; an alkyl quaternary ammonium salt modifier is dissolved in deionized water to obtain a modifier solution; the modifier solution is added to the suspension under high-speed stirring, with the ratio of modifier solute to suspension solute being 0.05:1~0.2:1; the pH of the system is adjusted to 7~8, and after stirring evenly, it is fed into a microwave reactor. After heating and reacting in a microwave field, it is removed, filtered, washed, dried, pulverized, and sieved to obtain modified bentonite. The entire modification method is simple, efficient, performs well, and saves costs.

Description

Technical Field

[0001] This invention belongs to the field of bentonite modification technology, specifically relating to a method for modifying calcium-based bentonite. Background Technology

[0002] Bentonite's main component is montmorillonite, a 2:1 type layered aluminosilicate. Its basic structure consists of a layer of aluminum-oxygen octahedra sandwiched between two layers of silicon-oxygen tetrahedra, forming layered units with shared oxygen atoms. Each lamellar unit is approximately 1-2 nm thick. Within the tetrahedra and octahedra, high-valence silicon and aluminum ions can be replaced by other low-valence cations (such as K, Na, and Ca), resulting in a negative surface charge. This negative charge is balanced by cations located outside the layered structure. This unique structure determines that bentonite possesses excellent ion exchange capacity and adsorption properties, exhibiting good dispersibility in aqueous solutions as a suspension and gel. Organic bentonite is a high-grade modified clay obtained by replacing the exchangeable cations between montmorillonite layers with organic cations, based on inorganic bentonite. Its most prominent feature is its large interlayer spacing, possessing hydrophobic and oleophilic properties not found in inorganic clays.

[0003] Compared to calcium-based bentonite, sodium-based bentonite has a larger expansion volume and higher cation exchange capacity. This is because the interlayer ions are mainly Na+, the total interlayer charge is not high, the cohesion is weak, and the particles are relatively small. Therefore, calcium-based bentonite needs to be sodium-modified before use to improve its performance and application value. Currently, methods for sodium-modifying calcium-based bentonite include suspension method, extrusion method, stacking method, double helix method, and supercritical treatment method. These methods all have certain drawbacks, such as easy secondary pollution, large equipment size, high cost, and complex post-modification processing and general modification effect. Therefore, it is extremely necessary to provide a rapid modification method for bentonite with a high calcium ion substitution rate, which will help improve the application value and economic value of bentonite. Summary of the Invention

[0004] The purpose of this invention is to provide a simple, efficient, and high-performance method for modifying calcium-based bentonite.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for modifying calcium-based bentonite involves first sodium-modifying the calcium-based bentonite with a sodium-modifying agent through a mixing and rolling process, followed by organic modification with an alkyl quaternary ammonium salt. The method specifically includes the following steps: 1) Sodium modification: Sodium carbonate solution and calcium-based bentonite are put into a mill together and the calcium-based bentonite is modified by sodium modification through mixing and milling. Then, the bentonite is dried, crushed and sieved to obtain sodium-based bentonite product. 2) Organic modification: Sodium-based bentonite was dissolved in deionized water and stirred at high speed to form a bentonite suspension with a mass concentration of 10%; alkyl quaternary ammonium salt modifier was dissolved in deionized water to obtain a modifier solution; the modifier solution was added to the suspension under high-speed stirring, with the ratio of modifier solute to suspension solute being 0.05:1~0.2:1. The pH value of the system was adjusted to 7~8, and after stirring evenly, it was sent to a microwave reactor. After heating and reacting in a microwave field, it was removed, filtered, washed, dried, pulverized and sieved to obtain modified bentonite.

[0006] In step 1), The added sodium carbonate accounts for 2-5% of the mass of calcium-based bentonite; The mixing and grinding time is 20-40 minutes; In step 2), The added alkyl quaternary ammonium salt modifier is selected from one of dodecyltrimethylammonium bromide, tetradecyldimethylbenzylammonium chloride, and hexadecyltrimethylammonium bromide; The mass concentration of the modifier solution is 5-20%; Adjust the pH of the system to 7-8, and then stir for 10 minutes.

[0007] The microwave treatment time is 15-30 minutes, and the microwave heating temperature is 60-90℃. The high-speed stirring speed is 800~1200 rpm; The drying temperature is 80~100℃, and the pulverized and sieved mesh size is 200 mesh.

[0008] The beneficial effects of this invention are: First, calcium-based bentonite is modified by sodium oxidation using a mixing and rolling method. This method is simple to operate, requires minimal equipment, and saves costs. Second, organic modification is performed using a microwave reactor. Microwaves can rapidly activate polar molecules or ions (such as anions and organic cations between montmorillonite layers), directly acting on them to rapidly enhance their activity and facilitate rapid reactions between various reactant ions, thus promoting fast chemical reactions. The entire modification method is simple, efficient, performs well, and saves costs. Specific implementation methods

[0009] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto. Example

[0010] 1) Sodium modification: Weigh 100g of calcium-based bentonite and put it into a mill. Add 34ml of sodium carbonate solution with a mass concentration of 6% and mix for 30min. Then dry the material at 80℃ and crush it through a 200-mesh sieve to obtain sodium-based bentonite.

[0011] 2) Organic modification: Weigh 50g of the above sodium-based bentonite and dissolve it in 450ml of deionized water. Prepare a 10% suspension by stirring at 800 rpm. Weigh 5g of dodecyltrimethylammonium bromide and dissolve it in 45ml of deionized water to obtain a 10% modifier solution. Add the modifier solution to the suspension by stirring at 1200 rpm. Adjust the pH of the system to 7-8. Continue stirring for 10 minutes. Then, transfer the solution to a microwave reactor and heat it to 70℃ in a microwave field. After reacting for 15 minutes, remove the solution, filter and wash it. Dry the filter cake at 100℃ and pulverize it through a 200-mesh sieve to obtain modified bentonite. Example

[0012] 1) Sodium modification: Weigh 100g of calcium-based bentonite and put it into a mill. Add 67ml of sodium carbonate solution with a mass concentration of 6% and mix for 20min. Dry the material at 100℃ and crush it through a 200-mesh sieve to obtain sodium-based bentonite.

[0013] 2) Organic modification: Weigh 50g of the above sodium-based bentonite and dissolve it in 450ml of deionized water. Prepare a 10% suspension by stirring at 1000 rpm. Weigh 2.5g of tetradecyl dimethyl benzyl ammonium chloride and dissolve it in 47.5ml of deionized water to obtain a 5% modifier solution. Add the modifier solution to the suspension by stirring at 1200 rpm, adjust the pH of the system to 7-8, continue stirring for 10 minutes, and then transfer it to a microwave reactor. Heat it to 90℃ in a microwave field and react for 20 minutes. Remove it, filter and wash it. Dry the filter cake at 100℃ and pulverize it through a 200-mesh sieve to obtain modified bentonite. Example

[0014] 1) Sodium modification: Weigh 100g of calcium-based bentonite and put it into a mill. Add 50ml of sodium carbonate solution with a mass concentration of 6% and mix for 30min. Then dry the material at 100℃ and crush it through a 200-mesh sieve to obtain sodium-based bentonite.

[0015] 2) Organic modification: Weigh 50g of the above sodium-based bentonite and dissolve it in 450ml of deionized water. Prepare a 10% suspension by stirring at 800 rpm. Weigh 10g of hexadecyltrimethylammonium bromide and dissolve it in 40ml of deionized water to obtain a 20% modifier solution. Add the modifier solution to the suspension by stirring at 1200 rpm. Adjust the pH of the system to 7-8. Continue stirring for 10 minutes. Then, transfer the solution to a microwave reactor and heat it to 60℃ in a microwave field. After reacting for 20 minutes, remove the solution, filter and wash it. Dry the filter cake at 100℃ and pulverize it through a 200-mesh sieve to obtain modified bentonite. Example

[0016] 1) Sodium modification: Weigh 100g of calcium-based bentonite and put it into a mill. Add 84ml of sodium carbonate solution with a mass concentration of 6% and mix for 40min. Then dry the material at 90℃ and crush it through a 200-mesh sieve to obtain sodium-based bentonite.

[0017] 2) Organic modification: Weigh 50g of the above sodium-based bentonite and dissolve it in 450ml of deionized water. Prepare a 10% suspension by stirring at 1000 rpm. Weigh 7.5g of dodecyltrimethylammonium bromide and dissolve it in 42.5ml of deionized water to obtain a 15% modifier solution. Add the modifier solution to the suspension by stirring at 1200 rpm. Adjust the pH of the system to 7-8. Continue stirring for 10 minutes. Then, transfer the solution to a microwave reactor and heat it to 90℃ in a microwave field. After reacting for 30 minutes, remove the solution, filter and wash it. Dry the filter cake at 80℃ and pulverize it through a 200-mesh sieve to obtain modified bentonite. Example

[0018] 1) Sodium modification: Weigh 100g of calcium-based bentonite and put it into a mill. Add 50ml of sodium carbonate solution with a mass concentration of 6% and mix for 40min. Dry the material at 100℃ and crush it through a 200-mesh sieve to obtain sodium-based bentonite.

[0019] 2) Organic modification: Weigh 50g of the above sodium-based bentonite and dissolve it in 450ml of deionized water. Prepare a 10% suspension by stirring at 1000 rpm. Weigh 7.5g of tetradecyl dimethyl benzyl ammonium chloride and dissolve it in 42.5ml of deionized water to obtain a 15% modifier solution. Add the modifier solution to the suspension by stirring at 1200 rpm, adjust the pH of the system to 7-8, continue stirring for 10 minutes, and then transfer it to a microwave reactor. Heat it to 60℃ in a microwave field and react for 15 minutes. Remove it, filter and wash it. Dry the filter cake at 80℃ and pulverize it through a 200-mesh sieve to obtain modified bentonite. Example

[0020] 1) Sodium modification: Weigh 100g of calcium-based bentonite and put it into a mill. Add 84ml of sodium carbonate solution with a mass concentration of 6%. After mixing and milling for 20min, dry the material at 100℃ and crush it through a 200-mesh sieve to obtain sodium-based bentonite.

[0021] 2) Organic modification: Weigh 50g of the above sodium-based bentonite and dissolve it in 450ml of deionized water. Prepare a 10% suspension by stirring at 1000 rpm. Weigh 10g of hexadecyltrimethylammonium bromide and dissolve it in 40ml of deionized water to obtain a 20% modifier solution. Add the modifier solution to the suspension by stirring at 1200 rpm. Adjust the pH of the system to 7-8. Continue stirring for 10 minutes. Then, transfer the solution to a microwave reactor and heat it to 90℃ in a microwave field. After reacting for 30 minutes, remove the solution, filter and wash it. Dry the filter cake at 100℃ and pulverize it through a 200-mesh sieve to obtain modified bentonite.

[0022] Comparative Example 1 1) Sodium modification: Weigh 100g of calcium-based bentonite and put it into a mill. Add 84ml of sodium carbonate solution with a mass concentration of 6%. After mixing and milling for 40min, dry the material at 100℃ and crush it through a 200-mesh sieve to obtain sodium-based bentonite.

[0023] 2) Organic modification: Weigh 50g of the above sodium-based bentonite and dissolve it in 450ml of deionized water. Prepare a 10% suspension by stirring at 1000 rpm. Weigh 5g of hexadecyltrimethylammonium bromide and dissolve it in 45ml of deionized water to obtain a 10% modifier solution. Add the modifier solution to the suspension by stirring at 1200 rpm, adjust the pH of the system to 7-8, heat to 90℃, react for 2 hours, remove and filter, wash, dry the filter cake at 100℃, and pulverize it through a 200-mesh sieve to obtain modified bentonite.

[0024] The blue absorption and swelling capacity of the modified bentonite were measured according to the method described in national standard GB / T 20973-2020. The specific results are shown in the table below.

[0025] sample <![CDATA[Layer spacing d 001 / nm]]> Blue absorption (g / 100g) Expansion volume (ml / g) Gum value (ml / 15g) Example 1 2.26 32 59 64 Example 2 2.39 36 66 72 Example 3 2.54 37 78 82 Example 4 2.21 29 70 69 Example 5 2.42 33 72 73 Example 6 2.77 42 89 86 Comparative Example 1 1.92 25 43 54

Claims

1. A method for modifying calcium-based bentonite, characterized in that, The calcium-based bentonite is first modified by sodium-based agents through a mixing and rolling process, and then organically modified with alkyl quaternary ammonium salts. The specific steps include: 1) Sodium modification: Sodium carbonate solution and calcium-based bentonite are put into a mill together and the calcium-based bentonite is modified by sodium modification through mixing and milling. Then, the bentonite is dried, crushed and sieved to obtain sodium-based bentonite product. 2) Organic modification: Sodium-based bentonite was dissolved in deionized water and stirred at high speed to form a bentonite suspension with a mass concentration of 10%; an alkyl quaternary ammonium salt modifier was dissolved in deionized water to obtain a modifier solution; the modifier solution was added to the suspension under high-speed stirring, and the ratio of modifier solute to suspension solute was 0.05:1~0.2:1; the pH of the system was adjusted to 7~8, and after stirring evenly, it was sent to a microwave reactor, heated and reacted in a microwave field, and then removed, filtered, washed, dried, pulverized and sieved to obtain modified bentonite.

2. The modification method according to claim 1, characterized in that... In step 1), the mass of sodium carbonate added is 2-5% of the mass of calcium-based bentonite.

3. The modification method according to claim 1, characterized in that... The mixing and grinding time in step 1) is 20~40 minutes.

4. The modification method according to claim 1, characterized in that... The alkyl quaternary ammonium salt modifier added in step 2) is selected from one of dodecyltrimethylammonium bromide, tetradecyldimethylbenzylammonium chloride, and hexadecyltrimethylammonium bromide.

5. The modification method according to claim 1, characterized in that... In step 2), the mass concentration of the modifier solution is 5-20%.

6. The modification method according to claim 1, characterized in that... In step 2), adjust the pH of the system to 7-8, and then stir for 10 minutes.

7. The modification method according to claim 1, characterized in that... In step 2), the microwave treatment time is 15-30 minutes, and the microwave heating temperature is 60-90℃.

8. The modification method according to claim 1, characterized in that... The high-speed stirring speed is 800~1200 rpm.

9. The modification method according to claim 1, characterized in that... The drying temperature is 80~100℃, and the pulverized and sieved mesh size is 200 mesh.