Preparation method and application of fly ash-based ceramic catalytic membrane

Abstract

The invention discloses a preparation method and application of a fly ash-based ceramic catalytic membrane, and belongs to the field of water treatment application. Fly ash is used as a raw material, according to the components of the fly ash, the melting characteristic of the fly ash is accurately regulated and controlled by adding a fusing inhibitor and / or a fluxing agent in a specific proportion into the fly ash, and then the blended fly ash powder is mixed with water, a pore forming agent and a binding agent in proportion to prepare uniform plastic pug; a ceramic precursor film is prepared through extrusion forming, and after drying, the fly ash-based ceramic film is prepared through high-temperature sintering in an air atmosphere. The fluxing component selected in the fly ash-based ceramic catalytic membrane has catalytic activity, regulation and control of the sintering temperature of the ceramic membrane can be achieved, the prepared fly ash-based ceramic catalytic membrane has catalytic performance and a membrane separation function, integrated coupling of the membrane separation function and the advanced oxidation function is achieved, and the fly ash-based ceramic catalytic membrane can be used for deep removal of organic pollutants in water.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of water treatment, and particularly relates to a preparation method of a fly ash-based ceramic catalytic membrane and application of the fly ash-based ceramic catalytic membrane in catalytic water treatment. BACKGROUND

[0002] Coal is the second largest source of fossil fuel in the world today. Although the world has set carbon emission standards to call for emission reduction, the combustion of fossil fuels is inevitable due to the increasing demand for energy. The coal combustion process (thermal power generation, coal gasification) produces a large amount of solid waste-fly ash (Al2O3, Fe2O3, SiO2, CaO, MgO and SiO2) with complex components, and the resource utilization of fly ash has been an important issue to be solved in the fields of environmental engineering and material science.

[0003] The current mainstream disposal methods such as landfill and road construction not only occupy a large amount of land resources, but also are difficult to realize high value-added utilization of fly ash, resulting in resource waste. The preparation of ceramic membranes from fly ash is a feasible method for resource utilization of fly ash. However, the components of fly ash are significantly different in different regions due to the influence of coal sources, combustion conditions and other factors, and this complexity leads to difficulties in controlling the sintering temperature during the preparation of ceramic membranes. In addition, the traditional physical membrane separation has a trade-off relationship between "flux-removal efficiency", and at the same time, it also faces the problem of membrane pollution, which limits the further popularization and application of traditional membrane separation technology in the field of organic wastewater deep treatment. SUMMARY

[0004] To solve the problems in the prior art, the application provides a preparation method and application of a fly ash-based ceramic catalytic membrane. The application uses fly ash as raw material, adjusts the melting temperature of fly ash by adding refractory components (such as Al2O3, TiO2 and ZrO2) and / or fluxing components (such as Fe2O3, MnO2, CuO and Co3O4) with catalytic activity according to the ash component composition of fly ash, so as to accurately control the ash melting characteristics of fly ash, thereby controlling the sintering temperature of the fly ash-based ceramic membrane. At the same time, the catalytic activity of the fluxing component is used to strengthen the catalytic activity of the ceramic membrane, which not only realizes the control of the sintering temperature of the ceramic membrane, but also enables the prepared fly ash-based ceramic catalytic membrane to have both catalytic performance and membrane separation function, so as to realize the integration and coupling of membrane separation and catalytic oxidation, and be used for the deep removal of organic pollutants in water. The preparation method is simple in process and easy to operate. The application aims to provide a fly ash-based ceramic catalytic membrane which is low in cost and can be used for removing organic pollutants in water.

[0005] The technical scheme of the application is as follows: A preparation method of a fly ash-based ceramic catalytic membrane, which is specifically performed according to the following steps: (1) Mixing: fly ash, fluxing component and / or anti-fluxing component and water are mixed in a certain mass ratio to prepare a mixture, which is treated by wet ball milling to prepare a stable slurry, and then dried, crushed and sieved to obtain a uniform powder.

[0006] (2) Forming: the powder obtained in step (1) is mixed with a pore-forming agent, a forming agent and water in a certain proportion, and then the mixture is formed into a mud, which is sealed and aged, extruded and dried at room temperature to obtain a precursor film.

[0007] (3) Sintering: the dried precursor film obtained in step (2) is placed in a muffle furnace and sintered at high temperature in an air atmosphere to obtain a fly ash-based ceramic catalytic membrane.

[0008] Further, in step (1), the wet ball milling treatment is carried out at room temperature for 2-24 h; the drying is carried out at 60-120 ℃ for 2-5 h; the crushing time is 5-20 min; and the sieving is carried out by selecting a screen with a mesh size of 100 mesh or less. The specific steps of mixing are as follows: the mixture of fly ash, fluxing component or anti-fluxing component and water is ball milled at room temperature for 2-24 h to form a stable suspension slurry, which is then dried at 60-120 ℃ for 2-5 h, crushed for 5-20 min, and finally sieved by selecting a screen with a mesh size of 100 mesh or less.

[0009] Preferably, the anti-fluxing component is one or more of alumina, titanium oxide and zirconium oxide; and the fluxing component is one or more of catalytically active iron oxide, manganese dioxide, copper oxide and tricobalt tetraoxide. The fly ash is obtained from a coal-fired power plant or a coal gasification plant, and the main components are alumina, iron oxide, calcium oxide, magnesium oxide and silicon dioxide, wherein the mass fraction of alumina is 15-55%, the mass fraction of iron oxide is 3-15%, the mass fraction of calcium oxide is 2-15%, the mass fraction of magnesium oxide is 0.1-5%, and the mass fraction of silicon dioxide is 15-60%, and the total mass fraction of the main components is less than 100%.

[0010] Preferably, in step (1), the ash melting temperature is adjusted by adding fluxing or anti-fluxing components according to the composition of the fly ash. The mass ratio of fly ash to fluxing component is 100:1-30, and the further preferred range is 1-15; the mass ratio of fly ash to anti-fluxing component is 100:1-30, and the further preferred range is 1-15; and the mass ratio of the total amount of fly ash, fluxing component and / or anti-fluxing component to water is 100:120-150.

[0011] Further, in step (2), the time for the mud practice is 30-60 min; the time for aging is 24-72 h, and further preferably in the range of 24-56 h. The specific steps for molding are as follows: the powder, pore-forming agent, molding agent and water are mixed to form a uniform and plastic mud in 30-60 min at room temperature, and then the mud is aged for 24-72 h, extruded and dried at room temperature to obtain the precursor film.

[0012] Preferably, in step (2), the pore-forming agent is one or more of polyvinyl alcohol, polyvinyl butyral, polystyrene, styrene-acrylonitrile copolymer particles, and the size range is 1-50 µm. The molding agent is one or more of carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose, hydroxyethyl cellulose.

[0013] Preferably, in step (2), the mass ratio of the components in the mud is: powder: pore-forming agent = 100: 5-20, powder: molding agent = 100: 5-30, and powder: water = 100: 20-40, and further preferably in the range of powder: pore-forming agent = 100: 5-15, powder: molding agent = 100: 15-30, and powder: water = 100: 25-40.

[0014] Further, in step (3), the specific process for sintering is: sintering in an air atmosphere, the heating rate is 1-6 ℃ / min, the sintering final temperature is 800-1300 ℃, and further preferably in the range of 1000-1200 ℃, and the temperature is kept constant for 0.0.5-5 h, and further preferably in the range of 2-4 h, and then naturally cooled to room temperature to obtain the fly ash-based ceramic catalytic membrane.

[0015] The application also provides a fly ash-based ceramic catalytic membrane prepared by the above method, and the outer diameter of the precursor film is 3 mm-40 mm and the wall thickness is 0.5 mm-10 mm.

[0016] The application also provides the application of the above fly ash-based ceramic catalytic membrane in water purification, which can be used for the purification of water bodies containing organic pollutants; for example, for the treatment of wastewater containing organic pollutants such as bisphenol A, azo organic matter (such as methyl orange, congo red, etc.), rhodamine B dye, phenol, etc. The fly ash-based ceramic catalytic membrane is used as a catalyst to remove organic pollutants in wastewater by activating one or more of H2O2 (hydrogen peroxide), PMS (peroxymonosulfate), PDS (peroxodisulfate), O3 (ozone), etc.

[0017] The application has the following beneficial effects: The fly ash-based ceramic catalytic membrane provided by the application has the advantages of simple preparation process, high preparation efficiency, low economic cost, and the like, and is conducive to expanding production.

[0018] The fly ash-based ceramic catalytic membrane has high catalytic activity, strong thermal stability, and high strength, and enables resource utilization of fly ash, and has great application prospects in the field of purification of water polluted by organic pollutants. DETAILED DESCRIPTION

[0019] The application is further described below in conjunction with examples. The examples are only used to illustrate the application and are not used to limit the scope of the application. In the following examples, the experimental methods not specified in the specific conditions are generally carried out according to the conventional conditions in the field or according to the conditions recommended by the manufacturers; the raw materials, reagents, and the like used, if not specifically stated, are all raw materials and reagents that can be obtained through commercial channels according to the conventional market; any non-essential change made by a person skilled in the art on the basis of the application, i.e., replacement, is within the scope of protection claimed by the application.

[0020] Example 1 (1) Preparation of the fly ash-based ceramic catalytic membrane At room temperature, 3.84 g of Fe2O3 was added to 100 g of fly ash (main components: Al2O331.15%, Fe2O35.56%, CaO 5.13%, MgO 0.81%, SiO249.83%) to adjust the component ratio of the fly ash, and fly ash with an adjusted component ratio was obtained; 100 g of the fly ash with the adjusted component ratio and 120 g of water were mixed and ball milled for 12 h to form a stable suspension slurry, which was transferred to a drying box and dried at 80 ℃ for 5 h; then the dried slurry was put into a pulverizer and pulverized for 10 min, and finally sieved under a 100-mesh screen; 100 g of the sieved powder, 10 g of polyvinyl alcohol (average particle size 10 µm), 20 g of carboxymethyl cellulose, and 30 g of water were put into a pug mill and mixed for 45 min to form a uniform and plastic mud, which was then aged for 24 h; finally, the aged mud was put into a molding machine, and a precursor membrane was extruded and dried at room temperature; the dried fly ash-based ceramic precursor membrane was sintered at a rate of 5 ℃ / min to 1200 ℃ in an air atmosphere for 0.5 h, and finally naturally cooled to room temperature to obtain a fly ash-based ceramic catalytic membrane.

[0021] (2) Application of the fly ash-based ceramic catalytic membrane in water purification The prepared fly ash-based ceramic catalytic membrane with a length of 6 cm, a wall thickness of 2 mm, and an outer diameter of 8 mm was placed in a 1L container to degrade 50 ppm rhodamine B dye using H2O2. Under the conditions of room temperature, H2O2 = 0.2 g / L, and flow rate = 0.4 mL / min, the removal rate of rhodamine B was 85.8% at 5 min and 97.7% at 30 min, and the removal rate remained basically unchanged for the subsequent 1.5 h.

[0022] Example 2 (1) Preparation of fly ash-based ceramic catalytic membrane At room temperature, 5.47 g of MnO2 was added to 100 g of fly ash (main components accounted for: Al2O3 34.10%, Fe2O3 3.41%, CaO 3.41%, MgO 0.35%, SiO2 54.33%), and the component ratio of the fly ash was adjusted to obtain adjusted fly ash. After mixing 100 g of the adjusted fly ash with 150 g of water, the mixture was ball milled for 10 h to form a stable suspension slurry, which was then transferred to a drying box and dried at 100°C for 3.5 h. The dried slurry was then pulverized in a pulverizer for 20 min and sieved through a 200 mesh screen. The sieved 100 g of powder, 15 g of polyvinyl alcohol (average particle size 15 µm), 25 g of carboxymethyl cellulose, and 40 g of water were mixed in a pug mill for 60 min to form a uniform and plastic mud. After aging for 36 h, the aged mud was placed in a molding machine to extrude a precursor membrane, which was then dried at room temperature. The dried fly ash-based ceramic precursor membrane was sintered at 1100°C for 3 h at a rate of 5°C / min in an air atmosphere, and then naturally cooled to room temperature to obtain a fly ash-based ceramic catalytic membrane.

[0023] (2) Application of fly ash-based ceramic catalytic membrane in water purification The prepared fly ash-based ceramic catalytic membrane with a length of 6 cm, a wall thickness of 2.5 mm, and an outer diameter of 9 mm was placed in a 1L container to degrade 40 ppm bisphenol A using PDS. Under the conditions of room temperature, PDS = 0.2 g / L, and flow rate = 0.4 mL / min, the removal rate of bisphenol A was about 82.6% at 5 min, and then the removal rate further increased, reaching about 94.8% at 2 h.

[0024] Example 3 (1) Preparation of fly ash-based ceramic catalytic membrane At room temperature, 2.34 g of TiO2 and 5.36 g of CuO were added to 100 g of fly ash (main components: Al2O3 52.99%, Fe2O3 4.84%, CaO 14.51%, MgO 0.67%, SiO2 19.77%) to adjust the component ratio of the fly ash, and the fly ash with adjusted component ratio was obtained. 100 g of the fly ash with adjusted component ratio and 130 g of water were mixed and ball milled for 20 h to form a stable suspension slurry, which was then transferred to a drying box and dried at 120°C for 3 h. The dried slurry was then put into a pulverizer and pulverized for 15 min, and finally sieved through a 200 mesh screen. 100 g of the sieved powder, 5 g of polyvinyl alcohol (particle size 23 µm), 30 g of carboxymethyl cellulose, and 35 g of water were mixed in a pug mill for 60 min to form a uniform and plastic clay, which was then aged for 48 h. Finally, the aged clay was put into a molding machine to extrude a precursor film, which was dried at room temperature. The dried fly ash-based ceramic precursor film was sintered at a rate of 5°C / min to 1300°C for 2 h in an air atmosphere, and finally naturally cooled to room temperature to obtain a fly ash-based ceramic catalytic membrane.

[0025] (2) Application of fly ash-based ceramic catalytic membrane in water purification The prepared fly ash-based ceramic catalytic membrane with a length of 6 cm, a wall thickness of 5 mm, and an outer diameter of 20 mm was placed in a 1 L container, and a 60 ppm phenol solution was degraded using PMS. Under the conditions of room temperature, PMS = 0.2 g / L, and flow rate = 0.4 mL / min, the removal rate of phenol was about 79.2% at 5 min, and then the removal rate further increased, reaching about 88.4% at 30 min, and about 96.5% at 2 h.

Claims

1. A method of making a fly ash-based ceramic catalytic membrane, characterized by: The preparation method comprises the following steps: (1) mixing: mixing fly ash, fluxing components and / or refractory components and water to prepare a mixture, and then preparing a stable slurry through wet ball milling treatment, and then drying, crushing and sieving to obtain a uniform powder; (2) forming: mixing the mixed powder obtained in step (1) with a pore-forming agent, a forming agent and water in a certain proportion, and then forming a mud through mud kneading, and then sealing and aging the mud, and then extruding and drying at room temperature to obtain a precursor film; (3) sintering: placing the precursor film obtained in step (2) in a muffle furnace, and then sintering at a high temperature in an air atmosphere to obtain a fly ash-based ceramic catalytic membrane.

2. A method of preparing a fly ash based ceramic catalytic membrane according to claim 1, characterized in that: In step (1), the wet ball milling treatment is carried out at room temperature for 2-24 h; the drying is carried out at 60-120 ℃ for 2-5 h; the crushing time is 5-20 min; and the sieving is carried out through a screen with a mesh size of 100 or less.

3. The method of claim 1, wherein the fly ash-based ceramic catalytic membrane is prepared by the steps of: In step (1), the refractory components are one or more of alumina, titania and zirconia; and the fluxing components are one or more of iron oxide, manganese dioxide, copper oxide and tricobalt tetroxide. ​ The fly ash is obtained from a coal-fired power plant or a coal gasification plant, and mainly comprises alumina, iron oxide, calcium oxide, magnesium oxide and silicon dioxide, wherein the mass fraction of the alumina is 15-55%, the mass fraction of the iron oxide is 3-15%, the mass fraction of the calcium oxide is 2-15%, the mass fraction of the magnesium oxide is 0.1-5%, and the mass fraction of the silicon dioxide is 15-60%.

4. The method of claim 1, wherein the fly ash-based ceramic catalytic membrane is prepared by the steps of: In step (1), the mass ratio of the fly ash to the fluxing components is 100:1-30, the mass ratio of the fly ash to the refractory components is 100:1-30, and the mass ratio of the total amount of the fly ash, the fluxing components and / or the refractory components to water is 100:120-150. ​ 5. The method for preparing a fly ash-based ceramic catalytic membrane according to claim 1, characterized in that: In step (2), the mud kneading time is 30-60 min, and the aging time is 24-72 h.

6. The method of claim 1, wherein: In step (2), the pore-forming agent is one or more of polyvinyl alcohol, polyvinyl butyral, polystyrene and styrene-acrylonitrile copolymer particles, and the size of the pore-forming agent is 1-50 µm; The forming agent is one or more of carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, ethyl cellulose and hydroxyethyl cellulose; In the mud, the mass ratio of the powder to the pore-forming agent is 100:5-20, the mass ratio of the powder to the forming agent is 100:5-30, and the mass ratio of the powder to water is 100:20-40.

7. The method for preparing a fly ash-based ceramic catalytic membrane according to claim 1, characterized in that: In step (3), the sintering process is as follows: sintering in an air atmosphere, the heating rate is 1-6 ℃ / min, the sintering final temperature is 800-1300 ℃, and the temperature is kept constant at the sintering final temperature for 0.5-5 h, and then the sintering product is naturally cooled to room temperature to obtain the fly ash-based ceramic catalytic membrane.

8. A fly ash-based ceramic catalytic membrane, characterized by: The fly ash-based ceramic catalytic membrane is prepared by the method of any one of claims 1-7.

9. The fly ash-based ceramic catalytic membrane of claim 8 is used for water purification.

10. Use according to claim 9, characterized in that: The fly ash-based ceramic catalytic membrane is used as a catalyst to activate one or more of H2O2, PMS, PDS and O3 to remove organic pollutants in wastewater.