A silicon-aluminum-based α-iron oxide ceramic membrane for solid waste, its preparation method and application

Abstract

This invention proposes a solid waste silica-alumina-based α-iron oxide ceramic membrane, its preparation method, and its application, belonging to the technical field of wastewater purification and waste resource utilization. The solid waste silica-alumina-based α-iron oxide ceramic membrane of this invention comprises a solid waste silica-alumina-based ceramic membrane and an α-Fe₂O₃ sol coated on the surface of the solid waste silica-alumina-based ceramic membrane. The raw materials for the solid waste silica-alumina-based ceramic membrane include gold mine tailings, electroplating sludge, wheat bran, alumina, and silicon dioxide. The solid waste silica-alumina-based α-iron oxide ceramic membrane is obtained by coating the solid waste silica-alumina-based ceramic membrane with α-Fe₂O₃ sol, drying, and then calcining. This invention realizes the resource reuse of solid waste, reduces production costs, saves energy, and improves the oil repellency rate of the ceramic membrane by loading hydrophilic α-Fe₂O₃ onto the ceramic membrane substrate, achieving efficient treatment of high-concentration oily emulsion wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater purification and waste resource utilization technology, and particularly relates to a silicon-aluminum-based α-iron oxide ceramic membrane for solid waste, its preparation method and application. Background Technology

[0002] Oily wastewater is generated during equipment cleaning and machine lubrication processes in industries such as chemical manufacturing, pharmaceuticals, metal smelting, and food processing. Oily wastewater entering water sources can cause the death of organisms, and entering the soil can severely impact soil ecology. Conventional treatment methods include gravity separation, centrifugal separation, flocculation sedimentation, coarse granulation, and air flotation, all of which utilize different water treatment equipment to remove or reduce the content of harmful substances in oily wastewater.

[0003] Membrane separation technology is considered a 21st-century water treatment technology and is a general term encompassing a large category of technologies. It mainly includes microfiltration, ultrafiltration, nanofiltration, and reverse osmosis. These membrane separation products all utilize the interception capabilities of specially manufactured porous materials to physically remove impurities of a certain particle size from water. Among membrane separation products, inorganic ceramic membranes possess advantages such as high temperature resistance, high mechanical strength, excellent impact resistance, chemical corrosion resistance, long lifespan, and environmental friendliness, making them an ideal water treatment material. Currently, the main components of commercial inorganic ceramic membranes include zirconium oxide, alumina, silicon dioxide, titanium dioxide, and silicon carbide. Due to the scarcity of reagents and the complexity of the sintering process, the market share of commercial ceramics is not high. Therefore, developing low-cost and high-efficiency ceramic membranes is extremely important. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a silicon-aluminum-based α-iron oxide ceramic membrane for solid waste, its preparation method, and its application, thereby solving the problems of cumbersome operation, high cost, and difficulty in large-scale production and application of the existing technology for treating oily emulsion wastewater.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions of the present invention:

[0007] A solid waste silicon-aluminum-based α-iron oxide ceramic membrane (solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane) includes a solid waste silicon-aluminum-based ceramic membrane and an α-Fe2O3 sol coated on one side surface of the solid waste silicon-aluminum-based ceramic membrane;

[0008] The amount of α-Fe₂O₃ sol coated on the surface of the silicon-aluminum-based ceramic membrane of the solid waste is 0.1-0.3 mL·cm⁻¹. -2 Preferably 0.15 mL·cm -2 ;

[0009] The raw materials for the solid waste silicon-aluminum-based ceramic membrane include gold mine tailings, electroplating sludge, wheat bran, aluminum oxide, and silicon dioxide.

[0010] Furthermore, the mass ratio of the gold mine tailings to the electroplating sludge is (0-3):(3-0), wherein the amounts of both the gold mine tailings and the electroplating sludge are not zero.

[0011] The bran accounts for 2% of the total mass of the solid waste silicon-aluminum-based ceramic membrane raw material;

[0012] The aluminum oxide accounts for 9% of the total mass of the silicon-aluminum-based ceramic membrane raw material from solid waste;

[0013] The silica accounts for 4% of the total mass of the silicon-aluminum-based ceramic membrane raw material from solid waste.

[0014] The second technical solution of the present invention:

[0015] A method for preparing a silicon-aluminum-based α-iron oxide ceramic membrane for solid waste involves coating one side of the solid waste silicon-aluminum-based ceramic membrane with α-Fe2O3 sol, drying it, and then calcining it to obtain the solid waste silicon-aluminum-based α-iron oxide ceramic membrane.

[0016] Furthermore, the drying temperature is 60-80℃, and the drying time is 6-12 hours.

[0017] Furthermore, the calcination is carried out by heating to 500°C at a heating rate of 5°C / min in an air atmosphere, holding at that temperature for 120 minutes, and then cooling to room temperature.

[0018] Furthermore, the method for preparing the solid waste silicon-aluminum-based ceramic membrane includes the following steps:

[0019] Gold mine tailings, electroplating sludge, wheat bran, alumina and silica raw materials are crushed and then mixed and ball-milled to obtain ceramic membrane powder. The ceramic membrane powder is then pressed and calcined to obtain the solid waste silicon-alumina-based ceramic membrane.

[0020] Furthermore, in the preparation process of the silicon-aluminum-based ceramic membrane for solid waste, the raw material is pulverized by grinding the raw material and then passing it through a 100-mesh molecular sieve.

[0021] Furthermore, in the preparation process of the silicon-aluminum-based ceramic membrane for solid waste, the ball milling is performed at a rotation speed of 330-380 r / min for 18-24 hours.

[0022] Furthermore, in the preparation process of the silicon-aluminum-based ceramic membrane for solid waste, the pressing is performed at 5-8 MPa.

[0023] Furthermore, in the preparation process of the solid waste silicon-aluminum-based ceramic membrane, the calcination is carried out in an air atmosphere and is divided into three stages: the first stage: heating to 200°C at a heating rate of 5°C / min and holding for 40 minutes; the second stage: heating to 600°C at a heating rate of 2°C / min and holding for 60 minutes; the third stage: heating to 950-1100°C at a heating rate of 3°C / min and holding for 150 minutes.

[0024] Furthermore, in the preparation process of the solid waste silicon-aluminum-based ceramic membrane, after the raw materials are crushed and then mixed and ball-milled, the process also includes drying, grinding, and sieving steps. The drying is carried out at 60-80℃ for 12-14 hours, and the sieving is carried out through a 100-mesh sieve.

[0025] Furthermore, in the preparation process of the solid waste silicon-aluminum-based ceramic membrane, the calcination process also includes a cooling treatment step, wherein the cooling treatment involves reducing the temperature to 500°C at a cooling rate of 4°C / minute and then naturally cooling it to room temperature.

[0026] Furthermore, the preparation method of the α-Fe2O3 sol includes the following steps:

[0027] Aluminum isopropoxide was ground into powder, water was added and refluxed and stirred, then ferric nitrate was added and heated, and nitric acid solution was added and refluxed and stirred again to obtain the α-Fe2O3 sol.

[0028] Furthermore, in the preparation process of α-Fe2O3 sol, the molar ratio of aluminum isopropoxide to water is 1:100, the mass ratio of aluminum isopropoxide to ferric nitrate is 5:1, and the molar ratio of aluminum isopropoxide to nitric acid solution is 25:6.

[0029] Furthermore, in the preparation of α-Fe2O3 sol, the temperature of the water is 84°C.

[0030] Furthermore, in the preparation of α-Fe2O3 sol, water was added and refluxed for 120 minutes, then ferric nitrate was added and the temperature was raised to 90°C. After 30 minutes, nitric acid solution was added, and the mixture was refluxed and stirred at 90°C for another 24 hours.

[0031] The third technical solution of the present invention:

[0032] The application of the aforementioned solid waste silicon-aluminum-based α-iron oxide ceramic membrane in the treatment of oily emulsion wastewater.

[0033] Compared with the prior art, the present invention has the following advantages and technical effects:

[0034] (1) In oil-water emulsions, oil mainly exists in the form of tiny oil droplets. When passing through the ceramic membrane surface of the present invention, most oil droplets with a particle size larger than the pore size of the ceramic membrane surface will be blocked and adsorbed on one side of the ceramic membrane. Water molecules permeate from the oil-water side to the other side under osmotic pressure. The α-iron oxide loaded on the ceramic membrane of the present invention has better hydrophilic and oleophobic properties under the premise of blocking the pore size of the ceramic membrane surface, making it easier for water molecules to pass through the ceramic membrane, thus making it more difficult for oil droplets to adhere to the ceramic membrane surface.

[0035] (2) This invention proposes a ceramic membrane that uses gold mine tailings and electroplating sludge as the main raw materials and is sintered at low temperature, realizing the reuse of solid waste resources, reducing production costs and saving energy. Furthermore, the hydrophilic α-Fe2O3 loaded on the ceramic membrane substrate improves the oil repellency of the ceramic membrane. This invention adopts a simple preparation method of dry pressing and low temperature sintering, and achieves efficient treatment of high-concentration (2000ppm) oily emulsion wastewater at a relatively low sintering temperature (950-1100℃). Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 The image shows the surface SEM image of the solid waste silicon-aluminum-based ceramic membrane prepared in step (1) of Example 1.

[0038] Figure 2 The image shows a surface SEM image of the silicon-aluminum-based α-Fe2O3 ceramic membrane for solid waste prepared in Example 1.

[0039] Figure 3 The images show the process of filtering an oil-in-water emulsion using a silicon-aluminum based α-Fe2O3 ceramic membrane prepared in Example 1, with the left side showing the process before filtration and the right side showing the process after filtration.

[0040] Figure 4 The graph shows the oil-water separation efficiency of the silicon-aluminum-based ceramic membranes for solid waste prepared in Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0045] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0046] This invention provides a solid waste silicon-aluminum-based α-iron oxide ceramic membrane (solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane), comprising a solid waste silicon-aluminum-based ceramic membrane and an α-Fe2O3 sol coated on one side surface of the solid waste silicon-aluminum-based ceramic membrane;

[0047] The amount of α-Fe₂O₃ sol coated on the surface of the silicon-aluminum-based ceramic membrane of the solid waste is 0.1-0.3 mL·cm⁻¹. -2 As an example, in this embodiment of the invention, the coating amount is 0.15 mL·cm. -2 ;

[0048] The raw materials for the solid waste silicon-aluminum-based ceramic membrane include gold mine tailings, electroplating sludge, wheat bran, aluminum oxide, and silicon dioxide.

[0049] In a preferred embodiment of the present invention, the mass ratio of gold mine tailings to electroplating sludge is (0-3):(3-0), wherein the amounts of both gold mine tailings and electroplating sludge are not zero; the bran accounts for 2% of the total mass of the solid waste silicon-aluminum-based ceramic membrane raw material; the alumina accounts for 9% of the total mass of the solid waste silicon-aluminum-based ceramic membrane raw material; and the silica accounts for 4% of the total mass of the solid waste silicon-aluminum-based ceramic membrane raw material. As an example, in embodiments of the present invention, the mass ratio of gold mine tailings to electroplating sludge is 1:1, 1:2, and 2:1.

[0050] This invention also proposes a method for preparing the solid waste silicon-aluminum-based α-iron oxide ceramic membrane, wherein α-Fe2O3 sol is coated on one side of the solid waste silicon-aluminum-based ceramic membrane, and after drying, it is calcined to obtain the solid waste silicon-aluminum-based α-iron oxide ceramic membrane.

[0051] In a preferred embodiment of the present invention, the drying temperature is 60-80°C and the drying time is 6-12 hours; as an example, in an embodiment of the present invention, the drying temperature is 80°C and the drying time is 8 hours.

[0052] In a preferred embodiment of the present invention, the calcination is performed by heating to 500°C at a heating rate of 5°C / min in an air atmosphere, holding at that temperature for 120 minutes, and then cooling to room temperature.

[0053] In a preferred embodiment of the present invention, the method for preparing the silicon-aluminum-based ceramic membrane for solid waste includes the following steps:

[0054] Gold mine tailings, electroplating sludge, wheat bran, alumina and silica raw materials are crushed and then mixed and ball-milled to obtain ceramic membrane powder. The ceramic membrane powder is then pressed and calcined to obtain the solid waste silicon-alumina-based ceramic membrane.

[0055] The raw material crushing process involves grinding the raw material and then passing it through a 100-mesh molecular sieve; the ball milling process involves ball milling at a speed of 330-380 rpm for 12-18 hours; the pressing process involves pressing at 5-8 MPa; and the calcination process is carried out in an air atmosphere and consists of three stages: the first stage involves heating to 200°C at a heating rate of 5°C / min and holding for 40 minutes; the second stage involves heating to 600°C at a heating rate of 2°C / min and holding for 60 minutes; and the third stage involves heating to 950-1000°C at a heating rate of 3°C / min. The temperature is 100℃ and held for 150 minutes. As an example, in this embodiment of the invention, the ball milling is performed at a speed of 387 rpm for 18 hours; the pressing is performed at 6 MPa; the calcination is carried out in an air atmosphere and is divided into three stages: the first stage: heating to 200℃ at a heating rate of 5℃ / min and holding for 40 minutes; the second stage: heating to 600℃ at a heating rate of 2℃ / min and holding for 60 minutes; the third stage: heating to 1050℃ at a heating rate of 3℃ / min and holding for 150 minutes.

[0056] In a preferred embodiment of the present invention, the preparation process of the solid waste silicon-aluminum-based ceramic membrane includes the steps of drying, grinding, and sieving after the raw materials are crushed, mixed and ball-milled. The drying is carried out at 60-80°C for 12-14 hours, and the sieving is carried out through a 100-mesh sieve. As an example, in an embodiment of the present invention, the drying is carried out at 80°C for 12 hours.

[0057] In a preferred embodiment of the present invention, the preparation process of the solid waste silicon-aluminum-based ceramic membrane includes a cooling treatment step after calcination. The cooling treatment involves reducing the temperature to 500°C at a cooling rate of 4°C / minute and then allowing it to cool naturally to room temperature.

[0058] In a preferred embodiment of the present invention, the preparation method of the α-Fe2O3 sol includes the following steps:

[0059] Aluminum isopropoxide was ground into powder, water was added and refluxed with stirring, then ferric nitrate was added and the temperature was raised, followed by the addition of nitric acid solution and continued reflux with stirring to obtain the α-Fe2O3 sol. Further, in the preparation of the α-Fe2O3 sol, the molar ratio of aluminum isopropoxide to water was 1:100, the mass ratio of aluminum isopropoxide to ferric nitrate was 5:1, and the molar ratio of aluminum isopropoxide to nitric acid solution was 25:6; the water temperature was 84°C; water was added and refluxed with stirring for 120 minutes, then ferric nitrate was added and the temperature was raised to 90°C, followed by the addition of nitric acid solution after 30 minutes, and the mixture was refluxed with stirring at 90°C for 24 hours.

[0060] In this embodiment of the invention, room temperature refers to "25±2℃".

[0061] All raw materials used in the embodiments of this invention were obtained through commercial purchase.

[0062] In the gold mine tailings used in this embodiment of the invention, the main minerals contained, by mass percentage, are quartz 44.6%, gypsum 13.2%, orthoclase 16%, and pyrite 26.2%.

[0063] In the electroplating sludge used in this embodiment of the invention, the main minerals contained, by mass percentage, are 68.3% quartz and 31.7% albite.

[0064] The technical solution of the present invention will be further illustrated by the following embodiments.

[0065] Example 1

[0066] (1) Preparation of silicon-aluminum-based ceramic membranes from solid waste

[0067] Gold mine tailings and electroplating sludge were dried to constant weight and dehydrated in a drying oven, then crushed, ground and sieved through a 100-mesh stainless steel screen for later use; bran was ground and crushed and sieved through a 100-mesh stainless steel screen for later use; aluminum oxide and silicon dioxide were ground and crushed and sieved through a 100-mesh stainless steel screen for later use.

[0068] Weigh the raw materials according to the following mass ratios: the mass ratio of gold mine tailings and electroplating sludge is 1:1; wheat bran accounts for 2% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials; aluminum oxide accounts for 9% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials; and silicon dioxide accounts for 4% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials.

[0069] The crushed gold ore tailings, electroplating sludge, bran, alumina and silica were mixed and ball-milled in a grinding media with ethanol as the medium for 18 hours. The speed of the planetary ball mill was set to 360 rpm. After the mixture was uniformly mixed, it was taken out and washed with anhydrous ethanol and collected. Then it was dried in an oven at 80°C for 12 hours and passed through a 100-mesh sieve to obtain ceramic film powder.

[0070] The obtained ceramic membrane powder was placed in a mold (Φ=40mm) and pressed into a ceramic membrane preform with a diameter of 40mm and a thickness of 1.5-1.6mm under a pressure of 6MPa. The ceramic membrane preform was then calcined in air atmosphere in three stages: the first stage was to heat to 200℃ at a heating rate of 5℃ / min and hold for 40 minutes; the second stage was to heat to 600℃ at a heating rate of 2℃ / min and hold for 60 minutes; the third stage was to heat to 1050℃ at a heating rate of 3℃ / min and hold for 150 minutes. After calcination, the temperature was lowered to 500℃ at a cooling rate of 4℃ / min and then allowed to cool naturally to room temperature to obtain a silicon-aluminum based ceramic membrane for solid waste.

[0071] (2) Preparation of α-Fe2O3 sol

[0072] 5.1 g of aluminum isopropoxide was ground into powder using an agate mortar and added to a round-bottom flask containing hot water at 84°C. The molar ratio of aluminum isopropoxide to water was 1:100. The mixture was refluxed and stirred at 84°C for 120 minutes. Then, 1.02 g of ferric nitrate was added and the temperature was raised to 90°C. After 30 minutes, 3.34 mL of nitric acid solution (concentration of 1.8 mol / L) was added to complete the gelation step. The mixture was then refluxed and stirred at 90°C for 24 hours to complete the aging process and obtain α-Fe2O3 sol.

[0073] (3) Preparation of silicon-aluminum based α-Fe2O3 ceramic membranes from solid waste

[0074] The solid waste silicon-aluminum-based ceramic membrane prepared in step (1) was washed clean in ultrapure water and dried in a forced-air drying oven. Then, the α-Fe2O3 sol prepared in step (2) was uniformly coated on one side of the dried solid waste silicon-aluminum-based ceramic membrane, with a coating amount of 0.15 mL·cm. -2 Then, it was dried in a drying oven at 80°C for 8 hours. After drying, it was heated to 500°C in air at a heating rate of 5°C / min and held for 120 minutes. Then it was cooled to room temperature to obtain a solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane. The solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane prepared in this embodiment is denoted as CM-C.

[0075] Example 2

[0076] Same as Example 1, except that in step (1), the mass ratio of gold mine tailings and electroplating sludge is 1:2, and the solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane prepared in this example is denoted as CM-B.

[0077] Example 3

[0078] Same as Example 1, except that in step (1), the mass ratio of gold mine tailings and electroplating sludge is 2:1, and the solid waste silicon aluminum-based α-Fe2O3 ceramic membrane prepared in this example is denoted as CM-D.

[0079] Comparative Example 1

[0080] Same as Example 1, except that the preparation of the silicon-aluminum-based ceramic membrane from solid waste in step (1) is different, and it does not contain electroplating sludge, specifically:

[0081] After drying the gold tailings to constant weight and dehydration in a drying oven, they are taken out, crushed and ground, and then sieved through a 100-mesh stainless steel screen for later use; bran is ground and crushed and then sieved through a 100-mesh stainless steel screen for later use; alumina and silica raw materials are ground and crushed and then sieved through a 100-mesh stainless steel screen for later use.

[0082] Weigh the raw materials according to the following mass ratios: the mass ratio of gold mine tailings and electroplating sludge is 3:0; wheat bran accounts for 2% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials; aluminum oxide accounts for 9% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials; and silicon dioxide accounts for 4% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials.

[0083] The crushed gold ore tailings, bran, alumina and silica raw materials were mixed and ball-milled in a grinding media with ethanol as the medium for 18 hours. The speed of the planetary ball mill was set to 387 r / min. After the mixture was uniformly mixed, the slurry after ball milling was washed with anhydrous ethanol and collected. Then it was dried in an oven at 80℃ for 12 hours and passed through a 100-mesh sieve to obtain ceramic film powder.

[0084] The obtained ceramic membrane powder was placed in a mold (Φ=40mm) and pressed into a ceramic membrane preform with a diameter of 40mm and a thickness of 1.5-1.6mm under a pressure of 6MPa. The ceramic membrane preform was then calcined in air atmosphere in three stages: the first stage was to heat to 200℃ at a heating rate of 5℃ / min and hold for 40 minutes; the second stage was to heat to 600℃ at a heating rate of 2℃ / min and hold for 60 minutes; the third stage was to heat to 1050℃ at a heating rate of 3℃ / min and hold for 150 minutes. After calcination, the temperature was lowered to 500℃ at a cooling rate of 4℃ / min and then allowed to cool naturally to room temperature to obtain a solid waste silicon-aluminum based ceramic membrane. The solid waste silicon-aluminum based ceramic membrane prepared in this comparative example is denoted as CM-E.

[0085] Comparative Example 2

[0086] Same as Example 1, except that the preparation of the silicon-aluminum-based ceramic membrane for solid waste in step (1) is different, and it does not contain gold mine tailings, specifically:

[0087] After the electroplating sludge is dried to constant weight and dehydrated in a drying oven, it is taken out, crushed and ground, and then sieved through a 100-mesh stainless steel screen for later use; the bran is ground and crushed and then sieved through a 100-mesh stainless steel screen for later use; the alumina and silicon dioxide raw materials are ground and crushed and then sieved through a 100-mesh stainless steel screen for later use.

[0088] Weigh the raw materials according to the following mass ratios: the mass ratio of gold mine tailings and electroplating sludge is 0:3; wheat bran accounts for 2% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials; aluminum oxide accounts for 9% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials; and silicon dioxide accounts for 4% of the total mass of solid waste silicon-aluminum-based ceramic membrane raw materials.

[0089] The pulverized electroplating sludge, bran, alumina and silica raw materials were mixed and ball-milled in a grinding media with ethanol as the medium for 18 hours. The speed of the planetary ball mill was set to 387 r / min. After the mixture was uniformly mixed, the slurry after ball milling was washed with anhydrous ethanol and collected. Then it was dried in an oven at 80℃ for 12 hours and passed through a 100-mesh sieve to obtain ceramic film powder.

[0090] The obtained ceramic membrane powder was placed in a mold (Φ=40mm) and pressed into a ceramic membrane preform with a diameter of 40mm and a thickness of 1.5-1.6mm under a pressure of 6MPa. The ceramic membrane preform was then calcined in air atmosphere in three stages: the first stage was to heat to 200℃ at a heating rate of 5℃ / min and hold for 40 minutes; the second stage was to heat to 600℃ at a heating rate of 2℃ / min and hold for 60 minutes; the third stage was to heat to 1050℃ at a heating rate of 3℃ / min and hold for 150 minutes. After calcination, the temperature was lowered to 500℃ at a cooling rate of 4℃ / min and then allowed to cool naturally to room temperature to obtain a solid waste silicon-aluminum based ceramic membrane. The solid waste silicon-aluminum based ceramic membrane prepared in this comparative example is denoted as CM-A.

[0091] Performance testing

[0092] The surface SEM image of the solid waste silicon-aluminum-based ceramic membrane prepared in step (1) of Example 1 is shown below. Figure 1 The surface SEM image of the solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane prepared in Example 1 is shown below. Figure 2 ,from Figure 1 As can be seen, the surface of the silicon-aluminum-based ceramic membrane in solid waste is defect-free and exhibits a porous structure, with obvious sintering necks between particles. Figure 2 As can be seen, coating with α-Fe2O3 sol blocked the large pores of the silicon-aluminum-based ceramic membrane of solid waste and also increased the roughness of the membrane surface.

[0093] The flexural strength of the solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane prepared in Example 1 was tested using the fine ceramic three-point bending method, and the results showed that the strength was ~26.2 MPa.

[0094] Dead-end filtration was performed on the solid waste silica-alumina-based α-Fe2O3 ceramic membrane prepared in Example 1 under an osmotic pressure of 1 bar. Pure water permeated from one side of the ceramic membrane to the other under the same osmotic pressure. The volume of permeated pure water obtained during a 10-minute osmosis test was converted to obtain the pure water flux of the ceramic membrane. The results showed that the pure water permeability of the solid waste silica-alumina-based α-Fe2O3 ceramic membrane prepared in Example 1 was approximately 420 L·m³. -1 ·Hour -1 ·bar -1 The rejection rate of 2000ppm oil-in-water emulsion reached 98.2% under the conditions of 0.5 bar and 0.5 m / s.

[0095] The water-in-oil emulsion permeability test was performed on the solid waste silica-alumina-based α-Fe2O3 ceramic membrane prepared in Example 1. The test method was the same as the pure water permeability test procedure described above. During the experiment, the emulsion first passed through the side coated with α-Fe2O3. Images of the solid waste silica-alumina-based α-Fe2O3 ceramic membrane prepared in Example 1 before and after filtering a 2000 ppm water-in-oil emulsion are shown below. Figure 3 The left side shows the product before filtration, and the right side shows the product after filtration. It can be seen that after filtration through the solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane, the permeate is clear and transparent with almost no oil droplets, proving that the solid waste silicon-aluminum-based α-Fe2O3 ceramic membrane has excellent oil-water separation performance.

[0096] The oil-water separation efficiency graphs of the solid waste silicon-aluminum-based ceramic membranes prepared in Examples 1-3 and Comparative Examples 1-2 are shown in the figure. Figure 4 It can be seen that when the ratio of gold tailings slag to electroplating sludge is 1:1, the solid waste silicon-aluminum ceramic membrane prepared provides a large separation flux while retaining high separation efficiency, which is the preferred solid waste silicon-aluminum ceramic membrane substrate, and α-Fe2O3 is loaded on this basis.

[0097] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A silicon-aluminum-based α-iron oxide ceramic membrane for solid waste, characterized in that, The invention includes a solid waste silicon-aluminum-based ceramic membrane and an α-Fe2O3 sol coated on one side of the solid waste silicon-aluminum-based ceramic membrane; the α-Fe2O3 sol is coated on one side of the solid waste silicon-aluminum-based ceramic membrane, dried, and then calcined to obtain the solid waste silicon-aluminum-based α-iron oxide ceramic membrane. The amount of α-Fe₂O₃ sol coated on the surface of the silicon-aluminum-based ceramic membrane of the solid waste is 0.1-0.3 mL·cm⁻¹. -2 ; The raw materials for the solid waste silicon-aluminum-based ceramic membrane include gold mine tailings, electroplating sludge, wheat bran, aluminum oxide, and silicon dioxide. The preparation method of the α-Fe2O3 sol includes the following steps: Aluminum isopropoxide was ground into powder, water was added and stirred under reflux, then ferric nitrate was added and the mixture was heated, and nitric acid solution was added and stirred under reflux to obtain the α-Fe2O3 sol. The mass ratio of the gold mine tailings to the electroplating sludge is 1:1; The bran accounts for 2% of the total mass of the silicon-aluminum-based ceramic membrane raw material from solid waste; The aluminum oxide accounts for 9% of the total mass of the silicon-aluminum-based ceramic membrane raw material from solid waste; The silica accounts for 4% of the total mass of the silicon-aluminum-based ceramic membrane raw material from solid waste; The method for preparing the silicon-aluminum-based ceramic membrane for solid waste includes the following steps: The solid waste silicon-aluminum-based ceramic membrane raw material is crushed and then mixed and ball-milled to obtain ceramic membrane powder. The ceramic membrane powder is then pressed and calcined to obtain the solid waste silicon-aluminum-based ceramic membrane. The solid waste silicon-aluminum-based ceramic membrane raw material is pulverized by grinding the raw material and then passing it through a 100-mesh molecular sieve; The ball milling was performed at a speed of 360 rpm for 18 hours. The compression was performed at 6 MPa; The calcination is carried out in an air atmosphere and includes: heating to 200°C at a heating rate of 5°C / min and holding for 40 minutes; then heating to 600°C at a heating rate of 2°C / min and holding for 60 minutes; then heating to 1050°C at a heating rate of 3°C / min and holding for 150 minutes.

2. A method for preparing a silicon-aluminum-based α-iron oxide ceramic membrane for solid waste as described in claim 1, characterized in that, α-Fe2O3 sol was coated onto one side of a silicon-aluminum-based ceramic membrane for solid waste, and then dried and calcined to obtain the silicon-aluminum-based α-iron oxide ceramic membrane for solid waste. The preparation method of the α-Fe2O3 sol includes the following steps: Aluminum isopropoxide was ground into powder, water was added and refluxed and stirred, then ferric nitrate was added and heated, and nitric acid solution was added and refluxed and stirred again to obtain the α-Fe2O3 sol.

3. The method for preparing a silicon-aluminum-based α-iron oxide ceramic membrane for solid waste according to claim 2, characterized in that, The drying temperature is 60-80℃, and the time is 6-12 hours; and / or The calcination process involves heating the temperature to 500°C at a rate of 5°C / min in air, holding it at that temperature for 120 minutes, and then cooling it to room temperature.

4. The method for preparing a silicon-aluminum-based α-iron oxide ceramic membrane for solid waste according to claim 2, characterized in that, The molar ratio of aluminum isopropoxide to water is 1:100, the mass ratio of aluminum isopropoxide to ferric nitrate is 5:1, and the molar ratio of aluminum isopropoxide to nitric acid solution is 25:

6.

5. The method for preparing a silicon-aluminum-based α-iron oxide ceramic membrane for solid waste according to claim 2, characterized in that, The temperature of the water is 84°C; Add water and reflux for 120 minutes, then add ferric nitrate and heat to 90°C. After 30 minutes, add nitric acid solution and continue refluxing and stirring at 90°C for 24 hours.

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