Asymmetric ceramic membrane raw material, preparation method and asymmetric ceramic membrane

Abstract

The invention relates to a ceramic membrane, in particular to an asymmetric ceramic membrane raw material, a preparation method and an asymmetric ceramic membrane. Raw materials of the asymmetric ceramic membrane comprise a support body raw material, a middle layer raw material and a separation layer raw material, the support body is prepared from the following raw materials in parts by mass: 100 parts of inorganic ceramic, 5-10 parts of a sintering aid, 2-5 parts of PVA (Polyvinyl Acetate) and 75-100 parts of water; the middle layer is prepared from the following raw materials in parts by mass: 100 parts of emery powder, 4-10 parts of a sintering aid, 2-5 parts of PVA (Polyvinyl Acetate) and 80-120 parts of water; the separation layer is prepared from the following raw materials in parts by mass: 100 parts of inorganic ceramic, 0-10 parts of a sintering aid, 2-5 parts of PVA (Polyvinyl Acetate) and 100-200 parts of water. The asymmetric ceramic membrane provided by the invention is prepared by adopting a method of layered material distribution, one-time pressurization and one-time sintering, and the cost is low.

Description

Technical Field

[0001] The invention relates to a ceramic membrane, in particular to an asymmetric ceramic membrane raw material, a preparation method and an asymmetric ceramic membrane. Background Art

[0002] Ceramic membrane is a kind of inorganic membrane, belonging to the solid membrane material in membrane separation technology. It is mainly made of inorganic ceramic materials such as aluminum oxide, zirconium oxide, titanium oxide and silicon oxide of different specifications as the support body, and is made by surface coating and high-temperature firing. Ceramic membrane has good chemical stability, acid resistance, alkali resistance and organic solvent resistance; high mechanical strength, can be reverse flushed; strong anti-microbial ability; high temperature resistance; narrow pore size distribution, high separation efficiency and other advantages. It has been widely used in the fields of food industry, bioengineering, environmental engineering, chemical industry, petrochemical industry, metallurgical industry, etc.

[0003] Ceramic membranes usually have a three-layer structure (support layer, intermediate layer and separation layer) with an asymmetrical distribution. Therefore, during the preparation of ceramic membranes, it is necessary to first prepare the support, then process the support, then prepare the intermediate layer on the surface of the support, and finally prepare the separation layer on the surface of the support. The preparation process is complicated, which greatly increases the preparation cost of the membrane material. The high cost of membrane materials also limits their application range. Summary of the invention

[0004] In order to solve the above-mentioned problem of high preparation cost, the present invention provides an asymmetric ceramic membrane raw material, and the specific technical solution is as follows:

[0005] A raw material for an asymmetric ceramic membrane, including a support material, an intermediate layer material and a separation layer material;

[0006] The support body raw materials include the following raw materials in parts by mass: 100 parts of inorganic ceramics, 5-10 parts of sintering aids, 2-5 parts of PVA, and 75-100 parts of water; the intermediate layer raw materials include the following raw materials in parts by mass: 100 parts of inorganic ceramics, 4-10 parts of sintering aids, 2-5 parts of PVA, and 80-120 parts of water; the separation layer raw materials include the following raw materials in parts by mass: 100 parts of inorganic ceramics, 0-10 parts of sintering aids, 2-5 parts of PVA, and 100-200 parts of water.

[0007] A method for preparing an asymmetric ceramic membrane comprises the following steps:

[0008] Step 1, preparing raw materials for the support, the intermediate layer and the separation layer;

[0009] Step 2: arranging the support body raw material, the intermediate layer raw material and the separation layer raw material in the mold in sequence, and then pressing and molding them to obtain a ceramic membrane green body;

[0010] Step three, firing the ceramic membrane blank in a high-temperature kiln to obtain an asymmetric ceramic membrane;

[0011] Step 4: Process the asymmetric ceramic membrane according to requirements.

[0012] Preferably, when arranging the raw materials, first adjust the mold cavity depth, use the mold cavity depth to control the thickness of the support body, arrange the support body raw material in the mold cavity, and scrape and remove excess raw material; then adjust the mold cavity depth by a hydraulic press to leave space in the mold cavity for laying the middle layer raw material; after laying the middle layer raw material, scrape and remove excess raw material; then adjust the mold cavity depth by a hydraulic press to leave space in the mold cavity for laying the separation layer raw material; after laying the separation layer raw material, scrape and remove excess raw material.

[0013] Preferably, the preparation of the support material comprises the following steps:

[0014] 100 parts of inorganic ceramic raw materials are used as aggregates, and 5-10 parts of sintering aids, 2-5 parts of PVA and 75-100 parts of water are added; ball milling is performed in a ball mill for 4-12 hours, and the slurry is passed through a 200-mesh sieve and then spray granulated, and then passed through a 60-80-mesh sieve to prepare a support body raw material.

[0015] Preferably, the preparation of the intermediate layer raw material includes the following steps:

[0016] 100 parts of inorganic ceramic raw materials are used as aggregates, and 4-10 parts of sintering aids, 2-5 parts of PVA and 80-120 parts of water are added; the slurry is ball-milled in a ball mill for 8-24 hours, and the slurry is spray-granulated after passing through a 200-mesh sieve, and then passed through an 80-mesh sieve to prepare an intermediate layer raw material;

[0017] Preferably, the preparation of the separation layer raw material includes the following steps:

[0018] 100 parts of inorganic ceramic raw materials are used as aggregates, and 0-10 parts of sintering aids, 2-5 parts of PVA and 100-200 parts of water are added; the slurry is ball-milled in a ball mill for 24 hours, and the slurry is spray-granulated after passing through a 200-mesh sieve, and is made into a separation layer raw material after passing through an 80-100-mesh sieve.

[0019] Preferably, the pressure during the compression molding is 20 to 100 MPa, and the holding time is 30 to 60 seconds.

[0020] Preferably, the sintering temperature is 1350-1700° C., and the holding time is 3-6 hours.

[0021] An asymmetric ceramic membrane is made by using the above-mentioned method for preparing an asymmetric ceramic membrane.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The asymmetric ceramic membrane provided by the present invention is prepared by a method of layered fabrication, one-time pressurization and one-time sintering, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of the present invention;

[0025] Figure 2 This is a flow chart for the preparation of existing asymmetric ceramic membranes. DETAILED DESCRIPTION

[0026] The present invention will be further described with reference to the accompanying drawings.

[0027] Embodiment 1

[0028] like Figure 1 As shown, a preparation method of an alumina ceramic membrane for a microbubble generator includes the following steps:

[0029] Raw material preparation:

[0030] Preparation of support material: 100 parts of corundum powder (D50 = 28 μm) as aggregate, 5 parts of feldspar, 3 parts of calcium carbonate, 2 parts of talc, 2 parts of PVA and 75 parts of water; ball milling in a ball mill for 6 hours, spray granulation after the slurry is sieved through a 200-mesh sieve, and sieved through a 60-mesh sieve to prepare the support material;

[0031] Preparation of intermediate layer raw material: 100 parts of corundum powder (D50 = 10 μm) as aggregate, 5 parts of feldspar, 3 parts of calcium carbonate, 2 parts of talc, 2 parts of PVA and 80 parts of water; ball milling in a ball mill for 10 hours, spray granulation after the slurry is sieved through a 200-mesh sieve, and sieved through an 80-mesh sieve to prepare the intermediate layer raw material;

[0032] Preparation of separation layer raw material: 100 parts of corundum powder (D50 = 3 μm) as aggregate, 5 parts of feldspar, 3 parts of calcium carbonate, 2 parts of talc, 2 parts of PVA and 100 parts of water; ball milling in a ball mill for 24 hours, spray granulation after the slurry is sieved through a 200-mesh sieve, and sieved through an 80-mesh sieve to prepare the separation layer raw material;

[0033] Molding process:

[0034] Laying, control the cavity depth of the support layer according to design requirements, lay the support material, scrape and remove excess material; increase the cavity depth according to the designed thickness of the middle layer, lay the middle layer material, scrape and remove excess material; increase the cavity depth according to the designed thickness of the separation layer, lay the separation layer material, scrape and remove excess material.

[0035] Pressurize with a hydraulic press, with a molding pressure of 20 MPa and hold the pressure for 30 seconds.

[0036] Firing:

[0037] The ceramic membrane blank is placed in a kiln and fired at 1350°C for 5 hours to produce an alumina ceramic membrane material.

[0038] Processing:

[0039] The product is processed according to the product drawings to produce an alumina ceramic membrane with a filtration accuracy of about 1μm.

[0040] Embodiment 2

[0041] like Figure 1 As shown, a silicon carbide ceramic membrane for wastewater filtration is prepared.

[0042] First is the preparation of raw materials:

[0043] Prepare the support raw material, take 100 parts of silicon carbide powder (D50 = 20 μm) as aggregate, add 6 parts of aluminum oxide, 4 parts of yttrium oxide, 5 parts of PVA and 100 parts of water, ball mill in a ball mill for 4 hours, spray granulate the slurry after passing through a 200-mesh sieve, and pass through a 60-mesh sieve to prepare the support raw material;

[0044] The intermediate layer raw material is prepared by using 100 parts of corundum powder (D50 = 7 μm) as aggregate, adding 6 parts of alumina, 4 parts of yttrium oxide, 5 parts of PVA and 120 parts of water, and ball milling in a ball mill for 8 hours. The slurry is sieved through a 200-mesh sieve and then spray granulated, and sieved through an 80-mesh sieve to prepare the intermediate layer raw material;

[0045] Preparation of separation layer raw material: 100 parts of corundum powder (D50 = 1.5 μm) as aggregate, 6 parts of aluminum oxide, 4 parts of yttrium oxide, 5 parts of PVA and 130 parts of water, ball milling in a ball mill for 24 hours, spray granulation after the slurry is sieved through a 200-mesh sieve, and sieved through an 80-mesh sieve to prepare the separation layer raw material;

[0046] Molding process:

[0047] Laying, control the cavity depth of the support layer according to design requirements, lay the support material, scrape and remove excess material; increase the cavity depth according to the designed thickness of the middle layer, lay the middle layer material, scrape and remove excess material; increase the cavity depth according to the designed thickness of the separation layer, lay the separation layer material, scrape and remove excess material.

[0048] Pressurize with a hydraulic press, with a molding pressure of 100 MPa and holding pressure for 50 seconds.

[0049] Firing:

[0050] The ceramic membrane blank is placed in a vacuum kiln and kept at 1700°C for 6 hours to produce a silicon carbide ceramic membrane material.

[0051] Processing:

[0052] The product is processed according to the product drawings to produce a silicon carbide ceramic membrane with a filtration accuracy of about 500nm.

[0053] Embodiment 3

[0054] like Figure 1 As shown, a preparation of an alumina-titania ceramic composite membrane.

[0055] Prepare the support material by using 100 parts of corundum powder (D50=5 μm) as aggregate, adding 3 parts of feldspar, 1 part of calcium carbonate, 1 part of talc, 2 parts of PVA and 100 parts of water; ball milling for 12 hours in a ball mill, spray granulation after the slurry is passed through a 200-mesh sieve, and then passed through an 80-mesh sieve to prepare the support material;

[0056] The intermediate layer raw material is prepared by using 100 parts of corundum powder (D50 = 1 μm) as aggregate, adding 2 parts of feldspar, 1 part of calcium carbonate, 1 part of talc, 2 parts of PVA and 120 parts of water; ball milling is performed in a ball mill for 24 hours, and the slurry is passed through a 200-mesh sieve and then spray granulated, and then passed through an 80-mesh sieve to prepare the intermediate layer raw material;

[0057] The separation layer raw material is prepared by using 100 parts of titanium oxide powder (D50=300nm) as aggregate, adding 2 parts of PVA and 200 parts of water; ball milling is performed in a ball mill for 24 hours, and the slurry is passed through a 200-mesh sieve and then spray granulated, and then passed through a 100-mesh sieve to prepare the separation layer raw material;

[0058] Molding process:

[0059] Laying, control the cavity depth of the support layer according to design requirements, lay the support material, scrape and remove excess material; increase the cavity depth according to the designed thickness of the middle layer, lay the middle layer material, scrape and remove excess material; increase the cavity depth according to the designed thickness of the separation layer, lay the separation layer material, scrape and remove excess material.

[0060] Pressurize with a hydraulic press, the molding pressure is 60MPa, and the pressure is maintained for 60S.

[0061] Firing:

[0062] The ceramic membrane blank is placed in a kiln and fired at 1400°C for 3 hours to produce an alumina-titanium dioxide ceramic composite membrane material.

[0063] Processing:

[0064] The product is processed according to the product drawings to produce an alumina ceramic membrane with a filtration accuracy of about 100nm.

[0065] It is prepared by "one-shot molding method" and has an asymmetric structure. The support body, middle layer (transition layer) and separation layer are formed in one shot by "dry pressing" or "semi-dry pressing". It is mainly used in the filtration of wastewater and aeration treatment of wastewater in the field of environmental protection. The ceramic membrane preparation process includes one-shot molding of the support body, middle layer and separation layer (first evenly arranging the support body raw materials in the mold, then arranging the middle layer raw materials, lightly pressing, arranging the separation layer raw materials, and finally pressurizing), and preparing the ceramic membrane material through sintering.

[0066] The preparation process is simple, which solves the problem of high cost caused by multiple coatings, multiple firings and support body processing of ceramic membrane materials, reduces the application cost, and increases the application of ceramic membranes in the field of water treatment.

[0067] The prepared ceramic membrane is "formed in one go", which solves the problem that traditional ceramic membrane preparation requires multiple coatings and multiple firings, resulting in high costs and limiting its scope of application.

[0068] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the protection scope of the claims of the present invention.

Claims

1. A raw material for an asymmetric ceramic membrane, characterized in that: It includes support material, intermediate layer material and separation layer material; The support material includes the following materials in parts by mass: 100 parts of inorganic ceramics, 5-10 parts of sintering aids, 2-5 parts of PVA, 75-100 parts of water; The intermediate layer raw materials include the following raw materials in parts by mass: 100 parts of inorganic ceramics, 4-10 parts of sintering aids, 2-5 parts of PVA, 80-120 parts of water; The separation layer raw materials include the following raw materials in parts by mass: 100 parts of inorganic ceramics, 0-10 parts of sintering aid, 2-5 parts of PVA, and 100-200 parts of water.

2. A method for preparing an asymmetric ceramic membrane, characterized in that: The following steps are involved: Step 1, preparing raw materials for the support, the intermediate layer and the separation layer; Step 2: arranging the support body raw material, the intermediate layer raw material and the separation layer raw material in the mold in sequence, and then pressing and molding them to obtain a ceramic membrane green body; Step three, firing the ceramic membrane blank in a high-temperature kiln to obtain an asymmetric ceramic membrane; Step 4: Process the asymmetric ceramic membrane according to requirements.

3. The method for preparing an asymmetric ceramic membrane according to claim 2, characterized in that: The preparation of the support material comprises the following steps: 100 parts of inorganic ceramic raw materials are used as aggregates, and 5-10 parts of sintering aids, 2-5 parts of PVA and 75-100 parts of water are added; ball milling is performed in a ball mill for 4-12 hours, and the slurry is passed through a 200-mesh sieve and then spray granulated, and then passed through a 60-80-mesh sieve to prepare a support body raw material.

4. The method for preparing an asymmetric ceramic membrane according to claim 2, characterized in that: The preparation of the intermediate layer raw material comprises the following steps: 100 parts of inorganic ceramic raw materials are used as aggregates, and 4-10 parts of sintering aids, 2-5 parts of PVA and 80-120 parts of water are added; the slurry is ball milled in a ball mill for 8-24 hours, and the slurry is spray granulated after passing through a 200-mesh sieve, and then passed through an 80-mesh sieve to prepare an intermediate layer raw material.

5. The method for preparing an asymmetric ceramic membrane according to claim 2, characterized in that: The preparation of the separation layer raw material comprises the following steps: 100 parts of inorganic ceramic raw materials are used as aggregates, and 0-10 parts of sintering aids, 2-5 parts of PVA and 100-200 parts of water are added; the slurry is ball-milled in a ball mill for 24 hours, and the slurry is spray-granulated after passing through a 200-mesh sieve, and is made into a separation layer raw material after passing through an 80-100-mesh sieve.

6. The method for preparing an asymmetric ceramic membrane according to claim 2, characterized in that: The pressure during the compression molding is 20-100 MPa, and the pressure holding time is 30-60 seconds.

7. The method for preparing an asymmetric ceramic membrane according to claim 2, characterized in that: The sintering temperature is 1350-1700° C., and the heat preservation time is 3-6 hours.

8. The method for preparing an asymmetric ceramic membrane according to claim 2, characterized in that: When arranging the raw materials, first adjust the depth of the mold cavity, use the depth of the mold cavity to control the thickness of the support body, arrange the support body raw materials in the mold cavity, and scrape and remove the excess raw materials; The depth of the mold cavity is then adjusted by a hydraulic press to leave space in the mold cavity for the middle layer of raw materials; After the middle layer of material is smoothed, remove the excess material; The depth of the mold cavity is then adjusted by a hydraulic press to leave space in the mold cavity for laying the separation layer material. After laying the separation layer material, the excess material is scraped off and removed.

9. An asymmetric ceramic membrane, characterized in that: The asymmetric ceramic membrane is prepared by the method for preparing the asymmetric ceramic membrane according to claim 2.

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