A method for preparing mesoporous magnesium silicate from magnesite

Abstract

A method for preparing mesoporous magnesium silicate from magnesite belongs to the field of mineral processing technology. The steps are as follows: (1) using heavy magnesium water and water glass obtained by hydrating and carbonizing magnesite as raw materials and deionized water as solvent to prepare magnesium bicarbonate solution and sodium silicate solution; adding the sodium silicate solution dropwise to the magnesium bicarbonate solution and stirring to obtain a reaction solution; (2) using sodium hydroxide as solute and deionized water as solvent to prepare sodium hydroxide solution, and adding it dropwise to the above reaction solution to obtain a magnesium silicate precursor solution; (3) placing the magnesium silicate precursor solution in a reactor for reaction to obtain a suspension containing a white precipitate; (4) separating the above suspension into solid and liquid, washing, and obtaining a filter cake; drying and grinding in a mortar to obtain mesoporous magnesium silicate. The mesoporous magnesium silicate prepared by the method of the present invention has the advantages of high purity, complex micro-nanostructure, abundant adsorption active sites, large specific surface area, and strong adsorption.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing, and particularly relates to a method for preparing mesoporous magnesium silicate using magnesite as a raw material. Background Art

[0002] Due to the development of mining, metallurgy, pesticides, fertilizers, and electronic device manufacturing, large amounts of industrial wastewater are discharged directly into water bodies, causing serious heavy metal pollution. Heavy metals are difficult to degrade naturally and can accumulate in the body through biomagnification. Excessive intake of heavy metals can pose a certain risk to human health.

[0003] Magnesium silicate is a highly dispersible material. Due to its excellent chemical stability, high specific surface area, continuous pores, excellent adsorption properties, and simple regeneration, it is widely used in edible oil decolorization, wastewater treatment, drug delivery, polyether refining, and radioactive material storage. Magnesium silicate can be directly used for the adsorption of heavy metals and organic molecules in wastewater. It is also widely used in polymer, catalyst, carbon nanofiber templates, ceramic production, and atmospheric CO2 adsorption. Due to its large specific surface area, numerous internal through-pores, and excellent physical and chemical stability, magnesium silicate is widely used in synthetic templates and as a template material. Due to its high whiteness and adhesive properties, it is also used in candy polishing glazes, gum dusting powders, and rice coatings. Because the chemical elements in magnesium silicate are harmless to the human body, and magnesium is even an essential metal, magnesium silicate is even permitted as table salt. Complex magnesium silicate is widely used in building exterior wall insulation.

[0004] my country boasts abundant magnesite resources, accounting for approximately a quarter of the world's reserves, with proven reserves reaching 3.1 billion tons, primarily distributed in Liaoning and Shandong. Magnesite is primarily used in the production of dead-burned magnesia, light-burned magnesia, magnesia sand, and magnesium products, as well as in the metallurgical sector for refractory materials, accounting for approximately 90% of total magnesite consumption. In recent years, the decline in demand for refractory materials has led to a corresponding decline in demand for magnesite. Therefore, the preparation of magnesium-based materials using magnesite as a raw material has become a new direction for the efficient and high-value utilization of my country's magnesite resources. Currently, magnesium silicate is primarily prepared using chemical reagents, and existing preparations of high-surface-area mesoporous magnesium silicate often incorporate foaming agents and templates, resulting in high production costs and difficulties in industrial production. Using natural magnesite as a raw material and preparing high-surface-area mesoporous magnesium silicate without additives offers the advantages of widely available raw materials, low production costs, and high added value. This approach could potentially enable efficient and high-value utilization of my country's magnesite resources, but research remains limited. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a method for preparing mesoporous magnesium silicate from magnesite. The method uses heavy magnesium water obtained by hydrating and carbonizing magnesite as a magnesium source and water glass as a silicon source. Under additive-free conditions, the method controls the raw material concentration, reaction temperature, reaction pH, hydrothermal temperature, and hydrothermal time to prepare porous granular accumulation, porous flower ball shape, and porous network mixed magnesium silicate; after calcination and activation, a mesoporous magnesium silicate with a large specific surface area and high surface activity is obtained. The porous network and flower ball mixed magnesium silicate prepared by this method has the advantages of high purity, complex micro-nanostructure, abundant adsorption active sites, large specific surface area, controllable pore structure, and excellent adsorption performance. It plays an important role in the fields of heavy metal ion adsorption, frying oil treatment, and radioactive material adsorption.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing mesoporous magnesium silicate from magnesite, comprising the following steps:

[0008] (1) Using heavy magnesium water and water glass obtained by hydration and carbonization of magnesite as raw materials and deionized water as solvent, the heavy magnesium water is configured into a magnesium bicarbonate solution, and the water glass is configured into a sodium silicate solution; the sodium silicate solution is slowly added dropwise to the magnesium bicarbonate solution, and stirred and mixed to obtain a reaction solution;

[0009] (2) preparing a sodium hydroxide solution using sodium hydroxide as a solute and deionized water as a solvent, and then dropwise adding the sodium hydroxide solution to the above reaction solution to obtain a magnesium silicate precursor solution;

[0010] (3) placing the magnesium silicate precursor solution in a reaction vessel to react and obtain a suspension containing a white precipitate;

[0011] (4) separating the suspension containing the white precipitate from the solid-liquid phase, washing the suspension to obtain a filter cake; drying the filter cake, and then grinding the filter cake to obtain mesoporous magnesium silicate;

[0012] The mesoporous magnesium silicate has an adjustable morphology and is a granular stacked mesoporous magnesium silicate or a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate.

[0013] The preparation method of the granular stacked mesoporous magnesium silicate comprises the following steps: in step (1), the concentration of the magnesium bicarbonate solution is 0.2-0.5 mol / L, and the concentration of the sodium silicate solution is 0.3-1.2 mol / L; the dropping temperature is 60-80°C, the molar ratio of sodium silicate to magnesium bicarbonate in the solution is (1-3):1, the dropping rate is 1.5 mL / min-2 mL / min; the stirring rate is 60-200 rpm, and the stirring time is 0.5-1 h;

[0014] In the step (2), the concentration of the sodium hydroxide solution is 1 to 3 mol / L, and the pH value of the magnesium silicate precursor solution is 8 to 12;

[0015] In the step (3), the reaction temperature is 150-190° C. and the reaction time is 8-48 hours;

[0016] In the step (4), the solid-liquid separation is preferably performed by suction filtration, the drying temperature is 60 to 90° C., and the drying time is 12 to 48 hours.

[0017] The preparation method of the porous flower ball-shaped and porous network-shaped mixed mesoporous magnesium silicate, in step (1), the concentration of the magnesium bicarbonate solution is 0.2-0.5 mol / L; the concentration of the sodium silicate solution is 0.3-0.6 mol / L; the temperature of the dropwise addition is 60-80°C, the molar ratio of sodium silicate to magnesium bicarbonate is (1-2):1, the dropwise addition rate is 1.5 mL / min-2 mL / min; the stirring rate is 60-200 rpm, and the stirring time is 0.5-1 h;

[0018] In the step (2), the concentration of the sodium hydroxide solution is 1 to 3 mol / L, and the pH value of the magnesium silicate precursor solution is 9 to 10;

[0019] In the step (3), the reaction temperature is 130-150° C. and the reaction time is 8-24 h;

[0020] In the step (4), the solid-liquid separation is preferably performed by suction filtration; the drying temperature is 60 to 90° C., and the drying time is 12 to 48 hours.

[0021] The present invention provides a mesoporous magnesium silicate, which is prepared by the above-mentioned preparation method and has a granular accumulation morphology, a particle diameter of 50 to 100 nm, a pore size of 8 to 15 nm, and a specific surface area of 200 to 300 m 2 / g.

[0022] The present invention provides a mesoporous magnesium silicate, which is prepared by the above-mentioned preparation method, and has a morphology of a mixture of porous flower balls and porous networks, wherein the diameter of the porous flower balls is 100-150 nm, the pore size of the porous networks is 15-20 nm, the average pore size is 8-20 nm, and the specific surface area is 400-600 m 2 / g.

[0023] The present invention provides a method for preparing mesoporous magnesium silicate from magnesite, which has the following beneficial effects:

[0024] The present invention is a kind of using mineral as raw material, which improves the upper limit of the specific surface area that magnesium silicate can prepare in the absence of additives, and can be granular, porous flower ball-shaped and porous mesh-shaped regulation and control during the preparation process, increasing the application scene of magnesite, adjusting the production plan in combination with market needs, achieving the effect of one input and multiple product outputs, and can bring more competitiveness to enterprises. The present invention has the advantages of simple operation, easy control of process, mild conditions, and easy implementation. The mesoporous magnesium silicate prepared using the method of the present invention has the advantages of high purity, complex micro-nano structure, rich adsorption active sites, large specific surface area, and strong adsorption, and plays an important role in the fields of edible oil decolorization, sewage treatment, drug carriers, polyether refining, and radioactive material sealing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD pattern of the granular stacked mesoporous magnesium silicate prepared in Example 1;

[0026] Figure 2 This is a nitrogen adsorption-desorption curve of the granular stacked mesoporous magnesium silicate prepared in Example 1;

[0027] Figure 3 This is the pore size distribution diagram of the granular mesoporous magnesium silicate prepared in Example 1;

[0028] Figure 4 This is the SEM image of the granular stacked mesoporous magnesium silicate prepared in Example 1;

[0029] Figure 5 This is the SEM image of the granular stacked mesoporous magnesium silicate prepared in Example 2;

[0030] Figure 6 This is the SEM image of the granular stacked mesoporous magnesium silicate prepared in Example 3;

[0031] Figure 7 The XRD pattern of the mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate prepared in Example 4;

[0032] Figure 8 This is a nitrogen adsorption-desorption curve of the mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate prepared in Example 4;

[0033] Figure 9 This is the pore size distribution diagram of the mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate prepared in Example 4;

[0034] Figure 10 and Figure 11 This is the SEM image of the mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate prepared in Example 4;

[0035] Figure 12 This is the SEM image of the mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate prepared in Example 5;

[0036] Figure 13 This is the SEM image of the mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate prepared in Example 6;

[0037] Figure 14 This is the SEM spectrum of the mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate prepared in Example 7. DETAILED DESCRIPTION

[0038] The following provides specific embodiments of the method for preparing morphology-controlled mesoporous magnesium silicate from magnesite of the present invention, which are granular stacked mesoporous magnesium silicate, porous flower ball-shaped mesoporous magnesium silicate and porous network mixed mesoporous magnesium silicate.

[0039] The instruments used in the embodiments of the present invention are as follows:

[0040]

[0041]

[0042] Example 1

[0043] A method for preparing granular stacked mesoporous magnesium silicate, the specific steps are as follows:

[0044] (1) Using heavy magnesium water obtained by hydration and carbonization of magnesite and water glass as raw materials and deionized water as solvent, a 0.2 mol / L magnesium bicarbonate solution and a 0.3 mol / L sodium silicate solution were prepared; at 80°C, the sodium silicate solution was added dropwise to the magnesium bicarbonate solution at a rate of 1.5 mL / min, with the molar ratio of sodium silicate to magnesium bicarbonate in the solution being 3:1; the mixture was stirred at a rate of 100 rpm for 0.5 h to obtain a reaction solution;

[0045] (2) using sodium hydroxide as a solute and deionized water as a solvent to prepare a 1 mol / L sodium hydroxide solution, and then adding the sodium hydroxide solution dropwise to the above reaction solution to obtain a magnesium silicate precursor solution with a pH value of 10;

[0046] (3) placing the magnesium silicate precursor solution in a hydrothermal reactor with a polytetrafluoroethylene liner to react at a temperature of 190° C. for 8 h to obtain a suspension containing a white precipitate;

[0047] (4) The suspension containing the white precipitate is filtered and washed to obtain a filter cake; the filter cake is dried at 60° C. for 20 h, and then ground in a mortar to obtain granular stacked mesoporous magnesium silicate.

[0048] The prepared granular stacked mesoporous magnesium silicate was analyzed: its XRD pattern is shown in Figure 1 , pore structure analysis see Figure 2 and Figure 3 , the sample SEM spectrum is shown in Figure 4 .

[0049] Figure 1 It can be seen that the diffraction peaks of the samples prepared under the above conditions all correspond to the standard characteristic peaks of Mg3Si2O5(OH)4 (JCPDS22-1157), and there are no other impurity peaks, indicating that the obtained product is magnesium silicate.

[0050] Figure 2 It can be seen that the adsorption isotherms of the products all conform to the type IV isotherm, the hysteresis loops are all closed at P / P0=0.2 and the hysteresis loops belong to the H4 type. The magnesium silicate contains slit pores, micropores and smaller mesopores.

[0051] Figure 3 It can be seen that the sample prepared under the above conditions is mesoporous magnesium silicate with an average pore diameter of 12.56 nm and a specific surface area of 252.2 m 2 / g.

[0052] Figure 4 It can be seen that the sample prepared under the above conditions is composed of granular stacked mesoporous magnesium silicate, with an average particle diameter of 80 nm and a large number of pores on the surface.

[0053] Example 2

[0054] A method for preparing granular stacked mesoporous magnesium silicate, the specific steps are as follows:

[0055] (1) Using heavy magnesium water obtained by hydration and carbonization of magnesite and water glass as raw materials and deionized water as solvent, a 0.2 mol / L magnesium bicarbonate solution and a 0.3 mol / L sodium silicate solution were prepared; at 60°C, the sodium silicate solution was added dropwise to the magnesium bicarbonate solution at a rate of 2 mL / min, the molar ratio of sodium silicate to magnesium bicarbonate in the solution was 1.5:1, and the mixture was stirred at a rate of 110 rpm for 0.5 h to obtain a reaction solution;

[0056] (2) using sodium hydroxide as a solute and deionized water as a solvent to prepare a 1 mol / L sodium hydroxide solution, and then adding the sodium hydroxide solution dropwise to the above reaction solution to obtain a magnesium silicate precursor solution with a pH value of 10;

[0057] (3) placing the magnesium silicate precursor solution in a hydrothermal reactor with a polytetrafluoroethylene liner to react at a temperature of 170° C. for 8 h to obtain a suspension containing a white precipitate;

[0058] (4) The suspension containing the white precipitate is filtered and washed to obtain a filter cake; the filter cake is dried at 60° C. for 22 h, and then ground in a mortar to obtain granular stacked mesoporous magnesium silicate.

[0059] The prepared granular stacked mesoporous magnesium silicate was analyzed: its SEM spectrum is shown in Figure 5 The figure shows that the product is composed of stacked particles with an average particle diameter of 50nm, a pore size of 10nm, and a specific surface area of 281.5m 2 / g.

[0060] Example 3

[0061] A method for preparing granular stacked mesoporous magnesium silicate, the specific steps are as follows:

[0062] (1) Using heavy magnesium water obtained by hydration and carbonization of magnesite and water glass as raw materials and deionized water as solvent, a 0.3 mol / L magnesium bicarbonate solution and a 0.6 mol / L sodium silicate solution were prepared; at 70°C, the sodium silicate solution was added dropwise to the magnesium bicarbonate solution at a rate of 1.7 mL / min, with the molar ratio of sodium silicate to magnesium bicarbonate in the solution being 3:1, and the mixture was stirred at a rate of 110 rpm for 0.5 h to obtain a reaction solution;

[0063] (2) using sodium hydroxide as a solute and deionized water as a solvent to prepare a 3 mol / L sodium hydroxide solution, and then adding the sodium hydroxide solution dropwise to the above reaction solution to obtain a magnesium silicate precursor solution with a pH value of 9;

[0064] (3) placing the magnesium silicate precursor solution in a hydrothermal reactor with a polytetrafluoroethylene liner to react at a temperature of 170° C. for 8 h to obtain a suspension containing a white precipitate;

[0065] (4) The suspension containing the white precipitate is filtered and washed to obtain a filter cake; the filter cake is dried at 60° C. for 22 h, and then ground in a mortar to obtain granular stacked mesoporous magnesium silicate.

[0066] The prepared granular stacked mesoporous magnesium silicate was analyzed: its SEM spectrum is shown in Figure 6 The figure shows that the product is composed of granular stacks with an average diameter of 50nm, an average pore size of 12nm, and a specific surface area of 240.7m 2 / g.

[0067] Example 4

[0068] A method for preparing a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate, the specific steps are as follows:

[0069] (1) Using heavy magnesium water obtained by hydration and carbonization of magnesite and water glass as raw materials and deionized water as solvent, a 0.2 mol / L magnesium bicarbonate solution and a 0.3 mol / L sodium silicate solution were prepared; at 70°C, the sodium silicate solution was added dropwise to the magnesium bicarbonate solution at a rate of 1.8 mL / min, with the molar ratio of sodium silicate to magnesium bicarbonate in the solution being 1.5:1; the mixture was stirred at a rate of 120 rpm for 0.5 h to obtain a reaction solution;

[0070] (2) using sodium hydroxide as a solute and deionized water as a solvent to prepare a 3 mol / L sodium hydroxide solution, and then adding the sodium hydroxide solution dropwise to the above reaction solution to obtain a magnesium silicate precursor solution with a pH value of 9;

[0071] (3) placing the magnesium silicate precursor solution in a hydrothermal reactor with a polytetrafluoroethylene liner to react at a temperature of 150° C. for 8 h to obtain a suspension containing a white precipitate;

[0072] (4) The suspension containing the white precipitate is filtered and washed to obtain a filter cake; the filter cake is dried at 80° C. for 22 h, and then ground in a mortar to obtain a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate.

[0073] The prepared porous flower ball and porous network mixed mesoporous magnesium silicate was analyzed: its XRD pattern is shown in Figure 7 , pore structure analysis see Figure 8 and Figure 9 , SEM images are shown in Figure 10 and Figure 11 .

[0074] Figure 7 It can be seen that the diffraction peaks of the samples prepared under the above conditions all correspond to the standard characteristic peaks of Mg3Si2O5(OH)4 (JCPDS22-1157), and there are no other impurity peaks, indicating that the obtained product is magnesium silicate.

[0075] Figure 8 It can be seen that the adsorption isotherms of the products all conform to the type IV isotherm, the hysteresis loops are all closed at P / P0=0.2 and the hysteresis loops belong to the H4 type. The magnesium silicate contains slit pores, micropores and smaller mesopores.

[0076] Figure 9 It can be seen that the sample prepared under the above conditions is mesoporous magnesium silicate with an average pore diameter of 14.04 nm and a specific surface area of 539.9 m 2 / g.

[0077] Figure 10 and Figure 11It can be seen that the sample prepared under the above conditions is composed of mesoporous magnesium silicate mixed with porous flower balls and porous networks, the average pore size of the porous network is 15 nm, and the average diameter of the porous flower balls is 100 nm.

[0078] Example 5

[0079] A method for preparing a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate, the specific steps are as follows:

[0080] (1) Using heavy magnesium water and water glass obtained by hydration and carbonization of magnesite as raw materials and deionized water as solvent, a 0.2 mol / L magnesium bicarbonate solution and a 0.3 mol / L sodium silicate solution were prepared; at 70°C, the sodium silicate solution was added dropwise to the magnesium bicarbonate solution at a rate of 2 mL / min, the molar ratio of sodium silicate to magnesium bicarbonate in the solution was 1.5:1, and the mixture was stirred at a rate of 120 rpm for 0.5 h to obtain a reaction solution.

[0081] (2) Using sodium hydroxide as a solute and deionized water as a solvent, a 3 mol / L sodium hydroxide solution was prepared, and then the sodium hydroxide solution was added dropwise to the above reaction solution to obtain a magnesium silicate precursor solution with a pH value of 10.

[0082] (3) The magnesium silicate precursor solution was placed in a hydrothermal autoclave with a polytetrafluoroethylene liner for reaction at a temperature of 150° C. for 12 h to obtain a suspension containing a white precipitate.

[0083] (4) The suspension containing the white precipitate is filtered and washed to obtain a filter cake; the filter cake is dried at 60° C. for 22 h, and then ground in a mortar to obtain a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate.

[0084] The prepared porous flower ball and porous network mixed mesoporous magnesium silicate was analyzed: SEM spectrum is shown in Figure 12 .

[0085] Figure 12 It can be seen that the sample prepared under the above conditions is composed of a mixture of porous flower balls with an average diameter of 110nm and porous networks with an average pore size of 15nm. The specific surface area is 547.38m 2 / g.

[0086] Example 6

[0087] A method for preparing a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate, the specific steps are as follows:

[0088] (1) Using heavy magnesium water and water glass obtained by hydration and carbonization of magnesite as raw materials and deionized water as solvent, a 0.4 mol / L magnesium bicarbonate solution and a 0.3 mol / L sodium silicate solution were prepared; at 70°C, the sodium silicate solution was added dropwise to the magnesium bicarbonate solution at a rate of 1.5 mL / min, the molar ratio of sodium silicate to magnesium bicarbonate in the solution was 1.5:1, and the mixture was stirred at a rate of 120 rpm for 0.5 h to obtain a reaction solution.

[0089] (2) Using sodium hydroxide as a solute and deionized water as a solvent, a 1 mol / L sodium hydroxide solution was prepared, and then the sodium hydroxide solution was added dropwise to the above reaction solution to obtain a magnesium silicate precursor solution with a pH value of 9.

[0090] (3) The magnesium silicate precursor solution was placed in a hydrothermal autoclave with a polytetrafluoroethylene liner for reaction at a temperature of 130° C. for 12 h to obtain a suspension containing a white precipitate.

[0091] (4) The suspension containing the white precipitate is filtered and washed to obtain a filter cake; the filter cake is dried at 60° C. for 20 h, and then ground in a mortar to obtain a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate.

[0092] The prepared porous flower ball and porous network mixed mesoporous magnesium silicate was analyzed: SEM spectrum is shown in Figure 13 .

[0093] Figure 13 It can be seen that the sample prepared under the above conditions is composed of a mixture of porous flower balls and porous network mesoporous magnesium silicate. The average pore size of the porous network is 20nm, the average diameter of the porous flower balls is 120nm, and the specific surface area is 592.2m 2 / g.

[0094] Example 7

[0095] A method for preparing a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate, the specific steps are as follows:

[0096] (1) Using heavy magnesium water obtained by hydration and carbonization of magnesite and water glass as raw materials and deionized water as solvent, a 0.2 mol / L magnesium bicarbonate solution and a 0.3 mol / L sodium silicate solution were prepared; at 70°C, the sodium silicate solution was added dropwise to the magnesium bicarbonate solution at a rate of 1.9 mL / min, the molar ratio of sodium silicate to magnesium bicarbonate in the solution was 2:1, and the mixture was stirred at a rate of 100 rpm for 0.5 h to mix uniformly, thereby obtaining a reaction solution.

[0097] (2) Using sodium hydroxide as a solute and deionized water as a solvent, a 1 mol / L sodium hydroxide solution was prepared, and then the sodium hydroxide solution was added dropwise to the above reaction solution to obtain a magnesium silicate precursor solution with a pH value of 9.

[0098] (3) The magnesium silicate precursor solution was placed in a hydrothermal autoclave with a polytetrafluoroethylene liner for reaction at a temperature of 130° C. for 8 h to obtain a suspension containing a white precipitate.

[0099] (4) The suspension containing the white precipitate is filtered and washed to obtain a filter cake; the filter cake is dried at 60° C. for 24 hours, and then ground in a mortar to obtain a mixed porous flower ball-shaped and porous network-shaped mesoporous magnesium silicate.

[0100] The prepared porous flower ball and porous network mixed mesoporous magnesium silicate was analyzed: SEM spectrum is shown in Figure 14 .

[0101] Figure 14 It can be seen that the sample prepared under the above conditions is composed of a mixture of porous flower balls and porous network mesoporous magnesium silicate. The average pore size of the porous network is 20nm, the average diameter of the porous flower balls is 150nm, and the specific surface area is 472.3m 2 / g.

Claims

1. A method for preparing mesoporous magnesium silicate from magnesite, characterized in that: The following steps are involved: (1) Using heavy magnesium water and water glass obtained by hydration and carbonization of magnesite as raw materials, deionized water as solvent to prepare heavy magnesium water into magnesium bicarbonate solution, and water glass into sodium silicate solution; at a temperature of 60-80° C., the sodium silicate solution is dropwise added to the magnesium bicarbonate solution, and the mixture is stirred and mixed to obtain a reaction solution; (2) preparing a sodium hydroxide solution using sodium hydroxide as a solute and deionized water as a solvent, and then adding the sodium hydroxide solution dropwise to the above reaction solution to obtain a magnesium silicate precursor solution; (3) placing the magnesium silicate precursor solution in a reaction vessel to react and obtain a suspension containing a white precipitate; The reaction temperature is 130-150° C., and the reaction time is 8-24 hours; (4) separating the suspension containing the white precipitate into solid and liquid, washing, and obtaining a filter cake; drying and grinding the filter cake to obtain mesoporous magnesium silicate; The mesoporous magnesium silicate is a mixture of porous flower balls and porous meshes, the porous flower balls have a diameter of 100-150 nm, the porous meshes have a pore size of 15-20 nm, the average pore size is 8-20 nm, and the specific surface area is 400-600 m 2 / g.

2. The method for preparing mesoporous magnesium silicate from magnesite according to claim 1, characterized in that: In the step (1), the concentration of the magnesium bicarbonate solution is 0.2-0.5 mol / L; the concentration of the sodium silicate solution is 0.3-0.6 mol / L; the temperature of the dropwise addition is 60-80°C, the molar ratio of sodium silicate to magnesium bicarbonate in the solution is (1-2):1, the dropwise addition rate is 1.5 mL / min-2 mL / min; the stirring rate is 60-200 rpm, and the stirring time is 0.5-1 h.

3. The method for preparing mesoporous magnesium silicate from magnesite according to claim 1, characterized in that: In the step (2), the concentration of the sodium hydroxide solution is 1-3 mol / L, and the pH value of the magnesium silicate precursor solution is 9-10.

4. The method for preparing mesoporous magnesium silicate from magnesite according to claim 1, characterized in that: In the step (4), the solid-liquid separation is performed by suction filtration; the drying temperature is 60-90° C., and the drying time is 12-48 hours.

Images