Al2O3-ZrO2-SiC composite ceramic membrane as well as preparation method and application thereof
By preparing Al2O3-ZrO2-SiC composite ceramic membranes with gradient pore sizes, the problems of low TOC removal rate, high iron ion loss rate and frequent membrane clogging in existing technologies have been solved, achieving efficient treatment of iron-containing waste acid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-13
AI Technical Summary
Existing membrane separation methods struggle to simultaneously achieve high TOC removal rates, low iron ion loss rates, and prevent membrane fouling when treating iron-containing waste acid.
An Al2O3-ZrO2-SiC composite ceramic membrane was prepared by controlling the particle size and material composition to create a transition layer and a core layer with gradient pore size. Combined with the use of nano-tungsten carbide, an Al2O3-ZrO2-SiC composite ceramic membrane was formed.
It achieved high TOC removal rate, low iron ion loss rate, and effectively reduced membrane pore clogging, thus extending the membrane's service life.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of wastewater treatment technology, and more specifically, relates to an Al2O3-ZrO2-SiC composite ceramic membrane, its preparation method, and its application. Background Technology
[0002] With the rapid development of industries such as steel and metal processing, the large amount of iron-containing waste acid generated during surface treatment processes such as pickling steel plates has become a significant source of industrial wastewater. Iron-containing waste acid, as an industrial wastewater with high resource value, contains iron, which is a valuable raw material for preparing iron salt products such as water treatment agents (e.g., polyferric chloride, polyferric sulfate). Currently, one of the mainstream processes for resource utilization is oxidation (e.g., using oxygen or hydrogen peroxide in the presence of catalysts such as nitrite) to remove Fe... 2+ Oxidized to Fe 3+ Ultimately, iron is transformed into high-value-added iron-based water purification products.
[0003] However, iron-containing waste acid has an extremely complex composition. Besides high concentrations of iron ions and free acid, it also commonly contains various organic pollutants, the content of which is usually characterized by total organic carbon (TOC), ranging from tens of milligrams per liter to thousands of milligrams per liter. This TOC in iron-containing waste acid severely interferes with the aforementioned oxidation process of iron ions: firstly, organic matter can encapsulate iron ions or form complexes with them, leading to a decrease in iron ion recovery rate and product purity; secondly, organic matter volatilized into the gas phase during the reaction may react with oxygen, posing a potential safety risk of fire or even explosion under certain conditions (such as static electricity generated by friction). Therefore, it is essential to effectively pretreat iron-containing waste acid to reduce its TOC content before it enters core resource recovery units such as catalytic oxidation.
[0004] Against this backdrop, existing technologies have proposed using membrane separation methods, specifically filtration pretreatment of iron-containing waste acid to reduce its TOC content. For example, a Chinese patent for a resource-based treatment method of iron-zinc-containing waste acid employs a 300μm pore size membrane for filtration pretreatment before catalytic oxidation. However, the pore size of the membrane used in this existing technology is too large, resulting in limited TOC retention. Conversely, using a smaller pore size to improve TOC retention leads to easy pore clogging, resulting in frequent backwashing cycles and a shortened membrane lifespan. Summary of the Invention
[0005] To address the challenges of existing membrane separation methods for treating TOC in iron-containing waste acid, which struggle to achieve a high TOC removal rate, a low iron ion loss rate, and minimal membrane fouling, this invention provides an Al2O3-ZrO2-SiC composite ceramic membrane. Using this Al2O3-ZrO2-SiC composite ceramic membrane to filter iron-containing waste acid not only results in a high TOC removal rate and a low iron ion loss rate, but also maintains a low membrane fouling rate even after prolonged operation.
[0006] The above-mentioned objective of this invention is achieved through the following technical solution: S1. Mix Al2O3-ZrO2 composite powder, pore-forming agent, binder and solvent to obtain transition layer slurry; S2. Mix Al2O3-ZrO2-SiC composite powder, nano-tungsten carbide, pore-forming agent, binder and solvent to obtain core layer slurry; S3. The transition layer slurry described in step S1 is sequentially coated onto the surface of the support, and the transition layer slurry described in step S1 is dried to form a transition layer. Then the core layer slurry described in step S2 is coated onto the support, and the core layer slurry described in step S2 is dried to form a core layer. Finally, the support is sintered to obtain an Al2O3-ZrO2-SiC composite ceramic film. The average particle size of the Al2O3-ZrO2 composite powder in step S1 is 0.4~0.6μm; the Al2O3-ZrO2 composite powder contains 70~85wt% Al2O3 and 15~30wt% ZrO2; The average particle size of the Al2O3-ZrO2-SiC composite powder in step S2 is 0.08~0.12μm; the Al2O3-ZrO2-SiC composite powder contains 60~75wt% Al2O3, 15~30wt% ZrO2, and 10~30wt% SiC.
[0007] It should be noted that: This invention uses Al2O3-ZrO2 composite powder with specific components as the main component, and controls the particle size of the Al2O3-ZrO2 composite powder within a specific range. Combined with a binder and a pore-forming agent, a transition layer slurry for the composite ceramic membrane is prepared. Simultaneously, using Al2O3-ZrO2-SiC composite powder with specific components as the main component, and controlling the particle size of the Al2O3-ZrO2-SiC composite powder within a specific range, combined with nano-tungsten carbide, a binder, and a pore-forming agent, a core layer slurry for the composite ceramic membrane is prepared. Using the above-mentioned transition layer slurry and core layer slurry, an Al2O3-ZrO2-SiC composite ceramic membrane with a transition layer and a core layer is prepared.
[0008] The introduction of ZrO2, SiC, and nano-tungsten carbide can improve the adsorption performance of the membrane material surface. At the same time, none of the above materials will interact with iron ions, thereby improving the TOC removal efficiency of the Al2O3-ZrO2-SiC composite ceramic membrane. In addition, controlling the particle size of Al2O3-ZrO2 composite powder and Al2O3-ZrO2-SiC composite powder within a specific range can enable the resulting composite ceramic membrane to form a gradient pore size, which can reduce membrane pore blockage during operation while maintaining a high TOC removal rate and a low iron ion loss rate.
[0009] Preferably, the pore size in the transition layer is 50~100nm; the pore size in the core layer is 10~20nm.
[0010] Preferably, the Al2O3-ZrO2 composite powder in step S1 is prepared by ball milling and mixing the components, and then calcining at 1000~1200℃ for 1.8~3h to obtain the Al2O3-ZrO2 composite powder.
[0011] Preferably, the pore-forming agent in step S1 and the pore-forming agent in step S2 are independently at least one of polyethylene glycol, starch, and polymethyl methacrylate microspheres.
[0012] Preferably, the adhesive in step S1 and the adhesive in step S2 are independently at least one of sodium carboxymethyl cellulose, methyl cellulose, and polyvinyl alcohol.
[0013] Preferably, the solvent in step S1 and the solvent in step S2 are independently at least one of water and ethanol.
[0014] Preferably, the mass ratio of Al2O3-ZrO2 composite powder, pore-forming agent and binder in step S1 is 1:(0.15~0.35):(0.05~0.15).
[0015] Preferably, the Al2O3-ZrO2-SiC composite powder prepared in step S2 is prepared by ball milling and mixing the components, followed by calcination at 1000-1200℃ for 1.8-3 hours to obtain the Al2O3-ZrO2-SiC composite powder.
[0016] Preferably, the mass ratio of Al2O3-ZrO2-SiC composite powder, nano-tungsten carbide, pore-forming agent and binder in step S2 is 1:(0.02~0.1):(0.15~0.35):(0.05~0.15).
[0017] Preferably, the average particle size of the nano-tungsten carbide in step S2 is 50~100nm.
[0018] Preferably, the support in step S3 is one of a ceramic support, a titanium support, a nickel support, an aluminum support, or a stainless steel support.
[0019] This invention also protects an Al2O3-ZrO2-SiC composite ceramic film, which is prepared by the above-described method.
[0020] This invention also protects the application of the above-mentioned Al2O3-ZrO2-SiC composite ceramic membrane in the treatment of iron-containing waste acid.
[0021] This invention also protects a method for treating TOC in iron-containing waste acid, comprising the following steps: using the above-mentioned Al2O3-ZrO2-SiC composite ceramic membrane to perform cross-flow filtration treatment on the iron-containing waste acid; During the cross-flow filtration process, the iron-containing waste acid passes successively through the transition layer and core layer of the Al2O3-ZrO2-SiC composite ceramic membrane.
[0022] During the cross-flow filtration process, iron-containing waste acid first passes through the transition layer for filtration. Impurities larger than the pore size of the transition layer are directly intercepted without contacting the core layer, thus effectively reducing the clogging of the core layer. Impurities with sizes between the pore sizes of the transition layer and the core layer are intercepted by the core layer with smaller pore sizes after entering the membrane through the transition side.
[0023] Preferably, the TOC content in the iron-containing waste acid is ≤3000mg / L, and the iron content is ≤900mg / L.
[0024] Preferably, before the cross-flow filtration, the process further includes a step of pre-treating the iron-containing waste acid to remove larger insoluble particles; pre-removing larger insoluble particles from the iron-containing waste acid can reduce the load on the Al2O3-ZrO2-SiC composite ceramic membrane during subsequent filtration and extend its service life.
[0025] More preferably, the pretreatment method is precipitation or primary filtration, or a combination of both.
[0026] More preferably, the filter membrane used in the primary filtration has a pore size of 0.1~1μm.
[0027] Preferably, during the cross-flow filtration process, the pressure is 0.1~0.5MPa and the flow rate of the iron-containing waste acid is 0.5~1.5m / s.
[0028] Preferably, after the cross-flow filtration, the process further includes a backwashing step of the Al2O3-ZrO2-SiC composite ceramic membrane.
[0029] More preferably, the backwash solution has a pH of 1 to 2 and contains 0.5 wt% sodium persulfate.
[0030] More preferably, the backwashing pressure is 0.8~1.2MPa and the pulse frequency is 1~3Hz.
[0031] Compared with the prior art, the beneficial effects of the present invention are: This invention provides an Al2O3-ZrO2-SiC composite ceramic membrane, the membrane material of which is an Al2O3-ZrO2-SiC composite system doped with nano-tungsten carbide, and has a transition layer and a core layer with different pore sizes. When using this Al2O3-ZrO2-SiC composite ceramic membrane to filter iron-containing waste acid, it not only has a high TOC removal efficiency and a low iron ion loss rate, but also the membrane pores are not easily blocked, and it can maintain a low membrane clogging rate even after a long period of operation. Detailed Implementation
[0032] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.
[0033] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.
[0034] Example 1 This embodiment provides a method for preparing an Al2O3-ZrO2-SiC composite ceramic film, the steps of which are as follows: (1) 100g of Al2O3-ZrO2 composite powder with an average particle size of 0.5μm (self-made, preparation method as follows: Al2O3 powder (reagent grade, Aladdin, the same below) and ZrO2 powder (reagent grade, Aladdin, the same below) with a mass ratio of 85:15 were calcined at 1100℃ for 2h, and the product was ball-milled for 6h (zirconia balls, ball-to-material ratio 10:1, water medium, mass ratio of mixed powder to water 2:1, ball mill speed 300rpm) to obtain Al2O3-ZrO2 composite powder) was mixed with 18g of pore-forming agent polyethylene glycol, 8g of binder polyvinyl alcohol and 300g of deionized water, and ball-milled to disperse to form a uniform slurry, which is the transition layer slurry; (2) 100g of Al2O3-ZrO2-SiC composite powder with an average particle size of 0.1μm (self-made, preparation method as follows: Al2O3 powder, ZrO2 powder and SiC powder (reagent grade, Aladdin, the same below) with a mass ratio of 75:15:10 were calcined at 1100℃ for 2h, and the product was ball-milled for 16h (zirconia balls, ball-to-material ratio 8:1, water medium, mixed powder and water mass ratio 2:1, ball mill speed 300rpm) to obtain Al2O3-ZrO2-SiC composite powder), 5g of nano tungsten carbide (average particle size of 75nm, the same below), 20g of pore-forming agent starch, 10g of binder sodium carboxymethyl cellulose and 330g of deionized water were mixed, ball-milled and dispersed to form a uniform slurry, which is the core layer slurry; (3) A transition layer slurry was coated on the α-Al2O3 porous ceramic support and dried to form a transition layer with a thickness of 30 μm. Subsequently, a core layer slurry was coated on the surface of the transition layer and dried to form a core layer with a thickness of 10 μm, thus obtaining the coated film preform. The coated film preform was placed in a high-temperature furnace and sintered at 1000℃ for 2 hours to obtain the Al2O3-ZrO2-SiC composite ceramic film.
[0035] Example 2 This embodiment provides a method for preparing an Al2O3-ZrO2-SiC composite ceramic film, which differs from Example 1 in that: In step (1), the average particle size of the Al2O3-ZrO2 composite powder is 0.4 μm (the ball milling time during the preparation of Al2O3-ZrO2 composite powder is 8 h).
[0036] Example 3 This embodiment provides a method for preparing an Al2O3-ZrO2-SiC composite ceramic film, which differs from Example 1 in that: In step (2), the average particle size of the Al2O3-ZrO2-SiC composite powder is 0.08 μm (the ball milling time during the preparation of the Al2O3-ZrO2-SiC composite powder is 24 h).
[0037] Example 4 This embodiment provides a method for preparing an Al2O3-ZrO2-SiC composite ceramic film, which differs from Example 1 in that: In step (1), the mass ratio of Al2O3 powder to ZrO2 powder is 70:30 during the preparation of Al2O3-ZrO2 composite powder, the amount of pore-forming agent polyethylene glycol is 20g, the amount of binder polyvinyl alcohol is 10g, and the amount of deionized water is 310g. In step (2), the mass ratio of Al2O3 powder, ZrO2 powder and SiC powder in the preparation of Al2O3-ZrO2-SiC composite powder is 60:20:20, the amount of nano tungsten carbide is 7g, the amount of pore-forming agent starch is 22g, and the amount of binder sodium carboxymethyl cellulose is 11g.
[0038] Comparative Example 1 This comparative example provides a method for preparing an Al2O3-ZrO2-SiC composite ceramic film, which differs from Example 1 in that: In step (2), the average particle size of the Al2O3-ZrO2-SiC composite powder is 0.5 μm (the ball milling time during the preparation of the Al2O3-ZrO2-SiC composite powder is 8 h).
[0039] Comparative Example 2 This comparative example provides a method for preparing an Al2O3-ZrO2-SiC composite ceramic film, which differs from Example 1 in that: In step (1), the average particle size of the Al2O3-ZrO2 composite powder is 0.1 μm (the ball milling time during the preparation of Al2O3-ZrO2 composite powder is 16 h).
[0040] Comparative Example 3 This comparative example provides a method for preparing an Al2O3-SiC composite ceramic film, which differs from Example 1 in that: In step (1), the Al2O3-ZrO2 composite powder is replaced with an equal amount of Al2O3 powder with an average particle size of 0.5μm; In step (2), the Al2O3-ZrO2-SiC composite powder is replaced with an equal mass of Al2O3-SiC composite powder with an average particle size of 0.1μm (self-made, the preparation method is as follows: Al2O3 powder and SiC powder with a mass ratio of 88:12 are calcined at 1100℃ for 2h, and the product is ball-milled for 16h (zirconia balls, ball-to-material ratio 8:1, water medium, mixed powder to water mass ratio 2:1, ball mill speed 300rpm).
[0041] Comparative Example 4 This comparative example provides a method for preparing an Al2O3-ZrO2 composite ceramic membrane, which differs from Example 1 in that: In step (2), the Al2O3-ZrO2-SiC composite powder is replaced with an equal mass of Al2O3-ZrO2 composite powder with an average particle size of 0.1μm (self-made, the preparation method is as follows: Al2O3 powder and ZrO2 powder with a mass ratio of 83.3:16.7 are calcined at 1100℃ for 2h, and the product is ball-milled for 16h (zirconia balls, ball-to-material ratio 8:1, water medium, mixed powder to water mass ratio 2:1, ball mill speed 300rpm).
[0042] Comparative Example 5 This comparative example provides a method for preparing an Al2O3-ZrO2-SiC composite ceramic film. The difference from Example 1 is that nano-tungsten carbide is not added in step (2).
[0043] Performance testing The information on iron-containing waste acid used in this invention is shown in Table 1.
[0044] Table 1 Information on iron-containing waste acid used in this invention
[0045] In this invention, the TOC determination method for iron-containing waste acid and filtrate is as follows: the determination is performed using a Shimadzu TOC-VCPH analyzer in accordance with standard method HJ 501-2009.
[0046] In this invention, the TOC removal rate is calculated as follows: TOC removal rate = [1 - (TOC content in filtrate / TOC content in iron-containing waste acid)] × 100%.
[0047] In this invention, the method for determining iron ions in iron-containing waste acid and filtrate is as follows: Based on GB / T 11911-1989, the method uses the ortho-... Spectrophotometric determination of phenanthroline.
[0048] In this invention, the iron ion loss rate is calculated as follows: iron ion loss rate = 1 - (filtrate mass × filtrate iron ion mass fraction) / (iron-containing waste acid mass × iron-containing waste acid iron ion mass fraction).
[0049] In this invention, the method for measuring the pore blockage rate of the composite ceramic membrane is as follows: according to HY / T 063-2002, the permeation flux is tested.
[0050] The composite ceramic membranes prepared in the various embodiments and comparative examples were used to filter iron-containing waste acid, and the process is as follows: (1) The iron-containing waste acid was subjected to primary filtration (bag filter, 300 mesh) to remove larger particles of impurities and suspended solids, and the waste acid was pretreated; the TOC content of the pretreated waste acid was 2510 mg / L and the iron ion content was 5.8%; (2) The pretreated waste acid was filtered through the composite ceramic membranes of each embodiment or comparative example, and the filtration method was cross-flow filtration. The waste acid passed through the transition layer and the core layer of the composite ceramic membrane in sequence, and the filtration pressure was controlled at 0.5 MPa, and the flow rate of the iron-containing waste acid was 1.0 m / s.
[0051] (3) After 24 hours of filtration, stop filtration; collect all filtrate from the start to the end of operation, and take samples to test the TOC content and iron ion content; measure the membrane pore blockage rate of the composite ceramic membrane after the end of operation.
[0052] The data on TOC removal rate, iron ion loss rate, and membrane pore blockage rate for each embodiment and comparative example are shown in Table 2.
[0053] Table 2. TOC removal rate, iron ion loss rate, and membrane pore blockage rate for each embodiment and comparative example.
[0054] Comparing the TOC removal rate, iron ion loss rate, and membrane pore blockage rate of the iron-containing waste acid in each embodiment and comparative example, it can be found that the composite ceramic membranes prepared in Examples 1 to 4 all have a TOC removal rate of over 89%, an iron ion loss rate of less than 2.4%, and a membrane pore blockage rate of less than 7.2% after 24 hours of operation. This indicates that the Al2O3-ZrO2-SiC composite ceramic membrane of the present invention has a good TOC removal effect and low iron ion loss when applied to the treatment of iron-containing waste acid, and the membrane pores are also less prone to blockage.
[0055] The Al2O3-ZrO2-SiC composite powder used in Comparative Example 1 had an excessively large particle size, resulting in an excessively large pore size in the core layer of the composite ceramic membrane, leading to a poor TOC removal rate. The Al2O3-ZrO2 composite powder used in Comparative Example 2 had an excessively small particle size, resulting in an excessively small pore size in the transition layer of the composite ceramic membrane, a high iron ion loss rate, and easy clogging of the composite ceramic membrane. The composite ceramic membrane in Comparative Example 3 did not contain ZrO2, the composite ceramic membrane in Comparative Example 4 did not contain SiC, and the core layer of the composite ceramic membrane in Comparative Example 5 did not contain nano-tungsten carbide. As a result, the composite ceramic membranes in the above comparative examples had poor TOC removal rates, high iron ion loss rates, and were also prone to pore clogging.
[0056] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing an Al2O3-ZrO2-SiC composite ceramic membrane, characterized in that, Includes the following steps: S1. Mix Al2O3-ZrO2 composite powder, pore-forming agent, binder and solvent to obtain transition layer slurry; S2. Mix Al2O3-ZrO2-SiC composite powder, nano-tungsten carbide, pore-forming agent, binder and solvent to obtain core layer slurry; S3. The transition layer slurry described in step S1 is sequentially coated onto the surface of the support, and the transition layer slurry described in step S1 is dried to form a transition layer. Then the core layer slurry described in step S2 is coated onto the support, and the core layer slurry described in step S2 is dried to form a core layer. Finally, the support is sintered to obtain an Al2O3-ZrO2-SiC composite ceramic film. The average particle size of the Al2O3-ZrO2 composite powder in step S1 is 0.4~0.6μm; the Al2O3-ZrO2 composite powder contains 70~85wt% Al2O3 and 15~30wt% ZrO2; The average particle size of the Al2O3-ZrO2-SiC composite powder in step S2 is 0.08~0.12μm; the Al2O3-ZrO2-SiC composite powder contains 60~75wt% Al2O3, 15~30wt% ZrO2, and 10~30wt% SiC.
2. The preparation method according to claim 1, characterized in that, The pore-forming agent in step S1 and the pore-forming agent in step S2 are independently at least one of polyethylene glycol, starch, and polymethyl methacrylate microspheres.
3. The preparation method according to claim 1, characterized in that, The adhesive in step S1 and the adhesive in step S2 are independently at least one of sodium carboxymethyl cellulose, methyl cellulose, and polyvinyl alcohol.
4. The preparation method according to claim 1, characterized in that, The mass ratio of Al2O3-ZrO2 composite powder, pore-forming agent and binder in step S1 is 1:(0.15~0.35):(0.05~0.15).
5. The preparation method according to claim 1, characterized in that, The mass ratio of Al2O3-ZrO2-SiC composite powder, nano-tungsten carbide, pore-forming agent and binder in step S2 is 1:(0.02~0.1):(0.15~0.35):(0.05~0.15).
6. The preparation method according to claim 1, characterized in that, The thickness of the transition layer is 25~35μm, and the thickness of the core layer is 8~12μm.
7. An Al2O3-ZrO2-SiC composite ceramic membrane, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 6.
8. The application of the Al2O3-ZrO2-SiC composite ceramic membrane according to claim 7 in the treatment of iron-containing waste acid.
9. A method for treating TOC in iron-containing waste acid, characterized in that, The process includes the following steps: using the Al2O3-ZrO2-SiC composite ceramic membrane described in claim 7 to perform cross-flow filtration treatment on iron-containing waste acid; During the cross-flow filtration process, the iron-containing waste acid passes successively through the transition layer and core layer of the Al2O3-ZrO2-SiC composite ceramic membrane.
10. The method for treating TOC in iron-containing waste acid according to claim 9, characterized in that, During the cross-flow filtration process, the pressure is 0.1~0.5MPa and the flow rate of the iron-containing waste acid is 0.5~1.5m / s.