A preparation method of a ceramic membrane based on endogenous pore forming and catalysis of algal-containing sludge

Abstract

The present application belongs to the field of environmental functional materials and water treatment technology, and aims to provide a preparation method of ceramic membrane based on endogenous pore forming and catalysis of sludge containing algae. The method comprises the following steps: taking dewatered sludge of water supply plant in algae outbreak period of water source, drying, ball milling and sieving to obtain sludge powder; soaking and washing after using organic acid with complexing ability as heavy metal removal agent, pre-carbonization treatment, dry pressing into embryo, sintering into membrane sheet; primary activation treatment in weak oxidizing strong acid, washing and heating treatment for secondary activation to obtain ultrafiltration ceramic membrane product. The method is simple in operation steps, easy to implement and green and environmental protection; the prepared ceramic membrane has good separation performance and high mechanical strength, can catalyze oxidizing agent commonly used in water treatment while filtering, and free radicals are generated by decomposition to degrade organic matter; or catalyze common cleaning agent sodium hypochlorite during membrane cleaning to generate free radicals to strengthen the cleaning effect.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials and water treatment technology, specifically relating to a method for preparing a ceramic membrane with catalytic function using endogenous components (algae, manganese oxides, aluminum salt flocs) in algae-containing sludge from water plants, applicable to scenarios such as drinking water purification and medical wastewater treatment. Background Technology

[0002] Coupling membrane separation with catalytic oxidation is a cutting-edge technology in water treatment. Separation membranes with both catalytic and filtration functions can efficiently remove pollutants from water while simultaneously achieving self-cleaning of the fouled membrane, making them a current research hotspot in the field of water treatment. Traditional ceramic membranes use pure-phase inorganic materials such as kaolin, Al2O3, TiO2, ZrO2, and SiO2 as raw materials, resulting in high costs and a lack of catalytic function. If catalytic function is required, an additional catalyst must be loaded, complicating the process.

[0003] Algal blooms in water sources during certain seasons are a common problem faced by many water treatment plants that use lakes and reservoirs as their water source. During algal blooms, water treatment plants typically add permanganate at the intake to enhance algae removal, odor control, and control algal toxins. Therefore, the sludge from these plants at this time contains algae, manganese oxides, and other components in addition to the aforementioned substances. This presents a significant challenge for subsequent sludge disposal. Using traditional landfill methods to treat this sludge can easily lead to the release of algal toxins and the leakage of manganese ions. Therefore, the disposal of algae-containing sludge from water treatment plants is a pressing issue that the water supply industry urgently needs to address.

[0004] Therefore, the present invention aims to propose a new solution to address the above-mentioned problems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing ceramic membranes based on endogenous pore formation and catalysis of algae-containing sludge.

[0006] To solve the technical problem, the solution of the present invention is:

[0007] A method for preparing an ultrafiltration ceramic membrane with both catalytic and filtration functions is provided, comprising the following steps:

[0008] (1) Take dewatered sludge from the water supply plant during the algae bloom period, and dry, ball mill and screen it to obtain sludge powder;

[0009] (2) Use organic acids with complexing ability as heavy metal removal agents to soak the sludge powder; then wash it with deionized water and air dry it naturally.

[0010] (3) Pre-carbonize the air-dried sludge powder in an anaerobic atmosphere;

[0011] (4) The pre-carbonized sludge powder is dry-pressed to prepare sludge embryos;

[0012] (5) The sludge green embryo is heated and sintered to form a membrane;

[0013] (6) Place the sintered membrane in a weak oxidizing strong acid and perform preliminary activation treatment by circulating filtration; then switch to circulating filtration with deionized water, rinse until the conductivity remains unchanged, and then air dry at room temperature.

[0014] (7) The air-dried membrane is heated under vacuum conditions to perform secondary activation, thereby obtaining the ultrafiltration ceramic membrane product.

[0015] As a preferred embodiment of the present invention, in step (1), the organic matter content of the sludge is 35% to 50%; the drying temperature is 105 to 120°C and the drying time is ≥24h; the particle size range of the sludge powder obtained by ball milling and sieving is 6.5 to 10μm.

[0016] As a preferred embodiment of the present invention, in step (2), the organic acid is citric acid or oxalic acid with a mass concentration of 5.5% to 10%, and the soaking time is 24 to 36 hours.

[0017] As a preferred embodiment of the present invention, in step (3), nitrogen or helium is continuously introduced into the tube furnace to form an oxygen-free atmosphere; the temperature of the pre-carbonization treatment is 350-450°C and the time is 3-5 hours.

[0018] As a preferred embodiment of the present invention, in step (4), the pressure is controlled to be 20-25 MPa during the dry pressing process.

[0019] As a preferred embodiment of the present invention, in step (5), a heating controller is used to perform programmed heating, with a heating rate of 5 to 15°C / min, a sintering temperature of 1000 to 1200°C, and a sintering time of 1.5 to 2 hours.

[0020] As a preferred embodiment of the present invention, in step (6), the strong acid used for preliminary activation is hydrochloric acid with a concentration of 0.1 to 0.2 mol / L, and the activation treatment time is 3 to 4 hours.

[0021] As a preferred embodiment of the present invention, in step (7), the temperature during the secondary activation is 250-400°C and the activation time is 2-2.5h.

[0022] This invention further provides a method for water treatment using an ultrafiltration ceramic membrane prepared by the aforementioned method. The method involves using the ultrafiltration ceramic membrane as a filter element in a filtration device or purification apparatus; introducing drinking water, sewage, or wastewater to be treated into the filtration device or purification apparatus, allowing the water to pass through the ultrafiltration ceramic membrane for filtration while ensuring a contact time of at least 8 seconds during actual filtration; and simultaneously intercepting particulate pollutants using the micropores on the ultrafiltration ceramic membrane while catalytically decomposing oxidant pollutants in the water.

[0023] As a preferred embodiment of the present invention, the oxidant pollutant refers to a residual oxidant used in water treatment, specifically any one or more of the following: sodium hypochlorite, chlorine dioxide, chloramine, ozone, hydrogen peroxide, persulfate, perdisulfate, peracetic acid, sodium percarbonate, permanganate, and ferrate.

[0024] Description of the invention principle:

[0025] 1. Compared to sewage treatment plant sludge, water supply plant sludge has a relatively simple and stable composition, mainly containing minerals such as alumina, iron oxide, and calcium oxide, as well as a certain proportion of organic matter, water, and ash. Most water supply plants dewater the sludge and landfill it as waste, or simply recycle it as a coagulant to produce building materials such as expanded clay and ceramic bricks. However, these applications do not fully realize the high-value-added resource utilization of sludge. The applicant's research team, through long-term in-depth research, discovered that the composition of water supply plant sludge is quite similar to the raw material requirements for preparing ceramic membranes. Using water supply plant sludge as a raw material for ceramic membranes is a very beneficial and highly feasible attempt.

[0026] 2. The present invention proposes innovative ideas from the following aspects: (1) Raw material utilization innovation: The sludge from the water plant during the algae bloom period is used directly without the need for external additives (skeleton material, pore-forming agent, etc.), and the cost is significantly reduced compared with traditional ceramic membranes. (2) Intrinsic function innovation: Algae in the sludge are pre-carbonized under nitrogen protection at 300℃ to form microporous precursors (their high-temperature calcination and gasification leave uniform pores); the iron, manganese and aluminum components in the sludge are protected by reducing carbon during the high-temperature sintering process, which can reduce the oxygen coordination degree of metal elements and improve the catalytic activity of the ceramic membrane; Fe2O3, Al2O3 and other oxides and manganese ions and oxides are sintered at high temperature to form a spinel structure, which can significantly improve the mechanical strength of the ceramic membrane. (3) Process innovation: The low-temperature-high-temperature-vacuum low-temperature heat treatment process is adopted, combined with acid washing to enhance the active sites. (4) Functional innovation of finished membrane material: The ceramic membrane prepared by the present invention has both ultrafiltration filtration performance (average pore size <100nm) and catalytic performance.

[0027] In light of the bottleneck problems in the treatment of algae-containing sludge from water treatment plants and innovative ideas for ceramic membrane preparation, this invention proposes a method for preparing ultrafiltration ceramic membranes with both catalytic and filtration functions using inexpensive algae-containing sludge from water treatment plants. Micropores (porosity 45%-50%) generated by algal carbonization are utilized to replace external pore-forming agents; Mn oxides in the sludge act as catalysts, catalyzing the generation of active free radicals from conventional water treatment oxidants such as hypochlorite, chlorine dioxide, and ozone; aluminum salt flocs and manganese oxide ions form a spinel structure (MnAl2O4), improving the membrane's compressive strength.

[0028] 3. The key differences between this invention and the prior art are: (1) When using sludge to prepare ceramic membranes, the prior art usually only considers filtration performance as the core indicator, while the product of this invention has both catalytic and filtration performance; (2) In order to ensure that the structural strength of the product meets the requirements, the prior art usually requires the addition of auxiliary materials such as kaolin, clay, and organic pore-forming agents (wood chips, starch, etc.) in the preparation process in addition to the sludge itself; the present invention does not require the addition of any materials in addition to the sludge itself, and relies entirely on the precise and ingenious control of the preparation process to achieve the required function; (3) The existing catalytic membrane technology completely relies on exogenous catalysts, and the added catalytic components are often precious metals, which are costly. The present invention ingeniously utilizes the role of iron, manganese and aluminum components in sludge in the high-temperature sintering process to improve the catalytic activity of the ceramic membrane without the need to add any precious metal catalysts.

[0029] Compared with the prior art, the technical advantages of the present invention are:

[0030] 1. The method for preparing the inorganic catalytic filtration ceramic membrane provided by this invention has simple operation steps, is easy to implement, and is green and environmentally friendly;

[0031] 2. The ceramic membrane prepared by this invention has good separation performance and high mechanical strength. It can catalyze common water treatment oxidants while filtering, and decompose them to generate free radicals for degrading organic matter; or catalyze common cleaning agent sodium hypochlorite during membrane cleaning to generate free radicals, thereby enhancing the cleaning effect.

[0032] 3. This invention solves the problems of high cost and high energy consumption in current ceramic membrane preparation technology, and can effectively solve the problem of difficult sludge treatment in water plants during algal blooms. Attached Figure Description

[0033] Figure 1 This is a pore size distribution diagram of the ceramic membrane obtained by the present invention;

[0034] Figure 2 This is a diagram showing the catalytic performance of the ceramic membrane prepared according to the present invention. Detailed Implementation

[0035] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0036] Part One: Implementation Scheme of the Invention

[0037] The present invention discloses a method for preparing an ultrafiltration ceramic membrane with both catalytic and filtration functions, comprising the following steps:

[0038] (1) Take dewatered sludge from the water supply plant during the algal bloom period, and dry, ball mill and screen it to obtain sludge powder; the organic matter content of the sludge is 35% to 50%; the drying temperature is 105 to 120℃ and the drying time is ≥24h; the particle size of the sludge powder obtained by ball milling and screening is 6.5 to 10μm.

[0039] The sludge is selected from dewatered sludge from water supply plants during algal blooms. The carbonization of the algae creates micropores, replacing external pore-forming agents. The sludge is treated to ensure the removal of both free and bound water. After drying, the sludge is ball-milled and sieved to control the particle size of the powder, ensuring that the prepared ceramic membrane maintains a suitable pore size while also possessing good porosity and permeability.

[0040] (2) Use organic acids with complexing ability as heavy metal removal agents to soak the sludge powder; then wash it with deionized water and air dry it naturally; the organic acid is citric acid or oxalic acid with a mass concentration of 5.5% to 10% and the soaking time is 24 to 36 hours.

[0041] To avoid the impact of heavy metal impurities on catalytic activity, milder organic acids such as citric acid and oxalic acid are used to remove harmful heavy metals such as Pb and Cd, which can reduce corrosion of raw materials. By controlling the concentration of organic acids and the soaking time, the corrosion of raw materials can be minimized while achieving a good removal effect of harmful heavy metals.

[0042] (3) In an oxygen-free atmosphere, the air-dried sludge powder is pre-carbonized; nitrogen or helium is continuously introduced into the tube furnace to form an oxygen-free atmosphere; the temperature of the pre-carbonization treatment is 350-450℃ and the time is 3-5h.

[0043] The pre-carbonization process is carried out under anaerobic conditions by continuously introducing an inert protective gas. The temperature and time of the pre-carbonization treatment are controlled to retain the organic skeleton of the algae and remove volatiles, thereby enhancing the stability of the overall structure during subsequent sintering.

[0044] (4) The pre-carbonized sludge powder is dry-pressed to form sludge embryos; the pressure is controlled at 20-25 MPa during the dry-pressing process.

[0045] The pre-carbonized sludge powder is dry-pressed into a blank, and the pressure during dry pressing is controlled to ensure porosity and reduce cracks that may occur during the subsequent high-temperature sintering process.

[0046] (5) The sludge green embryo is heated and sintered to form a membrane; the heating controller is used to perform programmed heating, with a heating rate of 5-15℃ / min, a sintering temperature of 1000-1200℃, and a sintering time of 1.5-2h.

[0047] The green body produced by dry pressing needs to be sintered. During the sintering process, by reasonably controlling the heating rate, sintering temperature and time, a ceramic film with high strength can be obtained.

[0048] (6) Place the sintered membrane in a weak oxidizing strong acid and perform preliminary activation treatment by circulating filtration; then switch to circulating filtration with deionized water, rinse until the conductivity remains unchanged, and then air dry at room temperature.

[0049] When initially activating the ceramic membrane, a weak oxidizing strong acid is used, such as hydrochloric acid with a concentration of 0.1–0.2 mol / L, and the activation time is 3–4 hours.

[0050] (7) The air-dried membrane is heated under vacuum conditions to perform secondary activation, thereby obtaining the ultrafiltration ceramic membrane product.

[0051] Secondary activation under vacuum conditions can generate more oxygen vacancies (characterized by the ratio of lattice oxygen to adsorbed oxygen determined by X-ray energy dispersive spectroscopy). The temperature for secondary activation is 250–400 °C, and the activation time is 2–2.5 h.

[0052] Part Two: Specific Embodiments and Comparative Examples

[0053] Example 1

[0054] (1) Dewatered sludge from a water supply plant in Jinhua City during an algal bloom was selected. The organic matter content of the sludge was 45%. After drying at 105℃ for 24 hours, the sludge was crushed in a ball mill and then screened by a mechanical vibrating screen to obtain sludge powder with a particle size of 1340-2000 mesh (6.5-10μm) for subsequent preparation of ceramic membranes.

[0055] (2) Take the sludge powder obtained in step (1), soak it in 7.5% citric acid as a heavy metal removal agent for 30 hours, then wash it with deionized water until the conductivity remains unchanged and air dry it at room temperature.

[0056] (3) Place the sludge powder from step (2) into a tubular furnace and maintain an oxygen-free atmosphere by continuously purging nitrogen. Set the heating temperature of the tubular furnace to 400℃ and the heating time to 4 hours. After heating, maintain nitrogen protection until it cools to room temperature.

[0057] (4) Take the sludge powder from step (3) and place it in a tablet press. The pressure of the tablet press is controlled at 20 MPa for 10 minutes and then the pressure is gradually released to obtain the molded green embryo.

[0058] (5) Take the shaped green blank from step (4) into a muffle furnace, set the program to heat up at a rate of 10℃ / min until it reaches 1000℃, keep it at this temperature for 1.5 hours, and then gradually cool it down to room temperature;

[0059] (6) Take the sintered membrane from step (5), circulate and filter it with a 0.1 mol / L dilute hydrochloric acid solution, and activate it for 4 hours. Then circulate and filter it with deionized water until the conductivity is zero, and then let it air dry naturally.

[0060] (7) Place the activated ceramic membrane from step (6) in a vacuum drying oven and perform vacuum thermal activation at 300°C for 2 hours to finally obtain a shaped ceramic membrane with catalytic function. The average pore size was measured to be 65–92 nm, and the product belongs to ultrafiltration membrane.

[0061] Example 2:

[0062] (1) Dewatered sludge from a water supply plant in Huzhou City during an algal bloom was selected. The organic matter content of the sludge was 35%. After drying at 120℃ for 30 hours, the sludge was crushed in a ball mill and then screened by a mechanical vibrating screen to obtain sludge powder with a particle size of 1340-2000 mesh (6.5-10μm) for subsequent preparation of ceramic membranes.

[0063] (2) Take the sludge powder obtained in step (1), soak it in 5.5% citric acid as a heavy metal removal agent for 24 hours, then wash it with deionized water until the conductivity remains unchanged and air dry it at room temperature.

[0064] (3) Place the sludge powder from step (2) into a tube furnace and maintain an oxygen-free atmosphere by continuously passing helium gas through it. Set the heating temperature of the tube furnace to 350°C and the heating time to 3 hours. After heating, maintain nitrogen protection until it cools to room temperature.

[0065] (4) Take the sludge powder from step (3) and place it in a tablet press. The pressure of the tablet press is controlled at 23 MPa for 10 minutes and then the pressure is gradually released to obtain the molded green embryo.

[0066] (5) Take the shaped green blank from step (4) into a muffle furnace, set the program to heat up at a rate of 5℃ / min until it reaches 1100℃, keep it at this temperature for 1.8 hours, and then gradually cool it down to room temperature;

[0067] (6) Take the sintered membrane from step (5), circulate and filter it with a 0.15 mol / L dilute hydrochloric acid solution, and activate it for 3 hours. Then circulate and filter it with deionized water until the conductivity is zero, and then let it air dry naturally.

[0068] (7) Place the activated ceramic membrane from step (6) in a vacuum drying oven and perform vacuum thermal activation at 250°C for 2.5 hours to finally obtain a shaped ceramic membrane with catalytic function. The average pore size was measured to be 40–75 nm, and the product belongs to ultrafiltration membrane.

[0069] Example 3:

[0070] (1) Dewatered sludge from a water supply plant in Jiaxing City during an algal bloom was selected. The sludge contained 50% organic matter. After drying at 110℃ for 36 hours, the sludge was crushed in a ball mill and then screened through a mechanical vibrating screen to obtain sludge powder with a particle size of 1340-2000 mesh (6.5-10μm) for subsequent preparation of ceramic membranes.

[0071] (2) Take the sludge powder obtained in step (1), soak it in 10% citric acid as a heavy metal removal agent for 36 hours, then wash it with deionized water until the conductivity remains unchanged and air dry it at room temperature.

[0072] (3) Place the sludge powder from step (2) into a tubular furnace and maintain an oxygen-free atmosphere by continuously purging nitrogen. Set the heating temperature of the tubular furnace to 450°C and the heating time to 5 hours. After heating, maintain nitrogen protection until it cools to room temperature.

[0073] (4) Take the sludge powder from step (3) and place it in a tablet press. The pressure of the tablet press is controlled at 20 MPa for 10 minutes and then the pressure is gradually released to obtain the molded green embryo.

[0074] (5) Take the shaped green blank from step (4) into a muffle furnace, set the program to heat up at a rate of 15℃ / min until it reaches 1200℃, keep it at this temperature for 2 hours, and then gradually cool it down to room temperature.

[0075] (6) Take the sintered membrane from step (5), circulate and filter it with a 0.2 mol / L dilute hydrochloric acid solution, and activate it for 3.5 hours. Then circulate and filter it with deionized water until the conductivity is zero, and then let it air dry naturally.

[0076] (7) Place the activated ceramic membrane from step (6) in a vacuum drying oven and perform vacuum thermal activation at 400℃ for 2 hours to finally obtain a shaped ceramic membrane with catalytic function. The average pore size was measured to be 45-82 nm, and the product belongs to ultrafiltration membrane.

[0077] Example 4

[0078] (1) Dewatered sludge from a water supply plant in Jinhua City during an algal bloom was selected. The organic matter content of the sludge was 45%. After drying at 105℃ for 24 hours, the sludge was crushed in a ball mill and then screened by a mechanical vibrating screen to obtain sludge powder with a particle size of 1340-2000 mesh (6.5-10μm) for subsequent preparation of ceramic membranes.

[0079] (2) Take the sludge powder obtained in step (1), soak it in 7.5% oxalic acid as a heavy metal removal agent for 30 hours, then wash it with deionized water until the conductivity remains unchanged and air dry it at room temperature.

[0080] (3) Place the sludge powder from step (2) into a tubular furnace and maintain an oxygen-free atmosphere by continuously purging nitrogen. Set the heating temperature of the tubular furnace to 400℃ and the heating time to 4 hours. After heating, maintain nitrogen protection until it cools to room temperature.

[0081] (4) Take the sludge powder from step (3) and place it in a tablet press. The pressure of the tablet press is controlled at 25 MPa for 10 minutes and then the pressure is gradually released to obtain the molded green embryo.

[0082] (5) Take the shaped green blank from step (4) into a muffle furnace, set the program to heat up at a rate of 10℃ / min until it reaches 1000℃, keep it at this temperature for 1.5 hours, and then gradually cool it down to room temperature;

[0083] (6) Take the sintered membrane from step (5), circulate and filter it with a 0.1 mol / L dilute hydrochloric acid solution, and activate it for 4 hours. Then circulate and filter it with deionized water until the conductivity is zero, and then let it air dry naturally.

[0084] (7) The activated ceramic membrane from step (6) was placed in a vacuum drying oven and vacuum-activated at 300°C for 2.2 hours to finally obtain a shaped ceramic membrane with catalytic function. The average pore size was measured to be 65–92 nm, and the product belongs to ultrafiltration membrane.

[0085] Comparative Example 1

[0086] The ceramic membrane product was prepared by referring to the protocol described in the journal article "Desalination and Water Treatment" (https: / / www.sciencedirect.com / science / article / pii / S1944398624138908).

[0087] The main difference from the present invention is that the raw materials used in this comparative example are pure γ-Al2O3 and α-Al2O3, carboxymethyl cellulose (CMC, Merck) as a polymer binder, and polyvinyl alcohol (PVA, Merck) as a drying chemical control additive. The average pore size is 20.3 nm, and it has almost no catalytic oxidation ability.

[0088] Comparative Example 2

[0089] A ceramic membrane product was prepared by referring to the scheme described in patent document CN202411458234.0.

[0090] The main difference from the present invention is that the raw materials used in this comparative example are aluminum-containing sludge from a water treatment plant, corn starch, sawdust, coal powder, and polystyrene. The resulting ceramic membrane has the function of catalyzing the degradation of organic matter methylene blue by hydrogen peroxide, but its catalytic oxidation function is weak (methylene blue is degraded by more than 70% in 10s under the condition of ~2mol / L hydrogen peroxide). Therefore, it mainly utilizes the weak catalytic function of the ceramic membrane for self-cleaning, focusing on the filtration function and lacking catalytic oxidation function.

[0091] The raw material used in this invention is aluminum-containing sludge from a water treatment plant during an algal bloom, with no other additives. The product of this invention is an ultrafiltration ceramic membrane (pore size ~60nm) that combines filtration and catalytic oxidation, and exhibits excellent catalytic performance; at 1.34×10⁻⁶... - 4 In the presence of sodium hypochlorite at a concentration of mol / L, a contact time of 8 seconds is sufficient to degrade ≥20% of carbamazepine, an organic compound that is difficult to degrade with conventional oxidants.

[0092] Comparative Example 3

[0093] We purchased ultrafiltration ceramic membrane products, model FCM-25, from a manufacturer in Nanjing.

[0094] The main difference from the present invention is that this product is an ultrafiltration ceramic membrane prepared using pure Al2O3 as raw material, and the pore-forming agent and other additives are unknown. This product only has filtration function and does not have catalytic oxidation function.

[0095] Part Three: Product Testing and Results Analysis

[0096] This invention uses carbamazepine, a common recalcitrant organic compound in water and wastewater treatment, as a model for testing catalytic performance. The concentration of carbamazepine is determined using high-performance liquid chromatography (HPLC). Sodium hypochlorite (10 mg / L), the most commonly used oxidant in ceramic membrane treatment processes, is used as the oxidant, and the reaction time simulates the actual contact time of filtration at 8 seconds.

[0097] Oxidation treatment can treat almost all industrial wastewater, and is particularly suitable for treating organic matter in wastewater that is difficult to biodegrade, such as most pesticides and insecticides, phenols, cyanides, and substances that cause color and odor. Commonly used oxidants in water treatment include potassium ferrate, potassium permanganate, peracetic acid, chlorine dioxide, potassium persulfate, potassium persulfate, hydrogen peroxide, potassium percarbonate, chloramine, and sodium hypochlorite. However, these oxidants themselves will leave residues in the water and are also considered pollutants, requiring further treatment. Figure 2The figure shows the catalytic degradation performance of the ceramic membrane prepared in Example 1 against various oxidizing agents. As can be seen from the figure, the ceramic membrane of the present invention has a significant removal capacity for various oxidizing agents; when using the ceramic membrane of the present invention, the removal rate of carbamazepine is significantly higher than that under the condition of oxidation alone (oxidant directly contacts carbamazepine for oxidation, without the participation of the ceramic membrane).

[0098] The ceramic membranes obtained in Example 1 and Comparative Examples 1-3 were subjected to porosity, pore size distribution, and catalytic performance tests. Porosity and pore size distribution were analyzed using a high-performance fully automated mercury porosimeter. The performance test results of the examples and comparative examples are shown in Table 1.

[0099] Table 1

[0100]

[0101] The test data above show that the ceramic membrane prepared by this invention has good filtration performance, and its pore size meets the requirements of ultrafiltration accuracy; at the same time, it has good catalytic oxidation performance in removing trace amounts of harmful organic matter in water, with a first-order reaction rate constant of ~10. -2 s -1 In comparison, the products prepared by existing technologies have almost no catalytic oxidation performance compared to the present invention.

[0102] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a ceramic membrane based on endogenous pore creation and catalysis of sludge containing algae, characterized by, The method comprises the following steps: (1) taking the dewatered sludge of a water supply plant at the outbreak period of an algae in a water source, the sludge containing iron, manganese and aluminum components; the sludge is treated by drying, ball milling and screening to obtain sludge powder; (2) soaking the sludge powder with an organic acid having complexing ability as a heavy metal removal agent; the organic acid is citric acid or oxalic acid with a mass concentration of 5.5%-10%, and the soaking time is 24-36 h; then the sludge powder is washed with deionized water and naturally air-dried; (3) pre-carbonizing the air-dried sludge powder in an oxygen-free atmosphere; the pre-carbonizing temperature is 350-450 ℃, and the time is 3-5 h; (4) forming the pre-carbonized sludge powder into a sludge green body in a dry pressing manner; (5) sintering the sludge green body after being heated to obtain a membrane sheet; (6) placing the sintered membrane sheet in a weakly oxidizing strong acid for preliminary activation treatment by circulating filtration; the strong acid is hydrochloric acid with a concentration of 0.1-0.2 mol / L; then the membrane sheet is washed with deionized water by circulating filtration until the conductivity is constant, and then the membrane sheet is taken out and air-dried at room temperature; (7) heating the air-dried membrane sheet under vacuum conditions for secondary activation at 250-400 ℃ to obtain an ultrafiltration ceramic membrane product.

2. The method of claim 1, wherein, In the step (1), the organic matter content in the sludge is 35%-50%; the drying temperature is 105-120 ℃, and the drying time is ≥24 h; the sludge powder obtained by ball milling and screening has a particle size range of 6.5-10 μm.

3. The method of claim 1, wherein, In the step (3), nitrogen or helium is continuously introduced into a tube furnace to form an oxygen-free atmosphere.

4. The method of claim 1, wherein, In the step (4), the pressure is controlled to be 20-25 Mpa during the dry pressing forming.

5. The method of claim 1, wherein, In the step (5), a heating controller is used for programmed heating, the heating rate is 5-15 ℃ / min, the sintering temperature is 1000-1200 ℃, and the sintering time is 1.5-2 h.

6. The method of claim 1, wherein, In the step (6), the activation treatment time is 3-4 h.

7. The method of claim 1, wherein, In the step (7), the secondary activation time is 2-2.5 h.

8. A method for water treatment using the ultrafiltration ceramic membrane obtained by the method according to any one of claims 1 to 7, characterized in that, The ultrafiltration ceramic membrane is used as a filter device or a filter of a purification device; drinking water, sewage or wastewater to be treated is introduced into the filter device or the purification device, the water flows through the ultrafiltration ceramic membrane and the contact time during actual filtration is ensured to be at least 8 seconds; while the micropores on the ultrafiltration ceramic membrane intercept particulate pollutants, the oxidant pollutants in the water are catalytically decomposed.

9. The method of claim 8, wherein, The oxidant pollutants refer to residual oxidants used for water treatment, and are specifically any one or more of the following: sodium hypochlorite, chlorine dioxide, chloramine, ozone, hydrogen peroxide, monopersulfate, peroxymonosulfate, peroxyacetic acid, sodium percarbonate, permanganate and ferrate.

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