A water treatment method of reinforcing the coupling of ozone catalytic surface functionalization

Abstract

This invention discloses a water treatment method that enhances the coupling of ozone catalytic surface functionalization, belonging to the field of water treatment technology. The method first prepares a three-layer γ-Al₂O₃ ceramic membrane, and then in situ loads δ-MnO₂ nanosheets onto the membrane surface to form a catalytically functionalized ceramic membrane. After pretreatment, wastewater enters the membrane module in a cross-flow manner, simultaneously activating ultrasonic and ozone aeration to achieve deep coupling of ultrasonic enhancement, ozone catalytic oxidation, and membrane separation. Intelligent feedback regulation is achieved through online monitoring of transmembrane pressure difference and effluent COD, and in-situ online cleaning and chemical regeneration are used to maintain membrane flux. This integrates membrane separation, catalytic oxidation, ultrasonic self-cleaning, and intelligent control, significantly improving the removal efficiency of recalcitrant organic matter, inhibiting membrane fouling at its source, and ensuring stable system operation and easy maintenance. It is suitable for treating high-concentration recalcitrant organic wastewater from dyeing, pharmaceutical, and chemical industries, with effluent meeting the Class A discharge standard for urban wastewater treatment plants.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a water treatment method for enhancing the functional coupling of ozone catalytic surfaces. Background Technology

[0002] With rapid industrialization and urbanization, the types and concentrations of organic pollutants in domestic sewage and industrial wastewater are increasing daily, especially in wastewater from industries such as dyeing, pharmaceuticals, and chemicals, which contains large amounts of recalcitrant organic matter. Traditional water treatment technologies, such as biological treatment, ordinary filtration, and activated carbon adsorption, are insufficient to efficiently remove these recalcitrant organic pollutants and are prone to generating large amounts of sludge or secondary pollution after adsorption saturation. Membrane separation technology is widely used in water treatment due to its advantages such as high separation efficiency, simple operation, and no phase change. However, membrane fouling seriously restricts its long-term stable operation and widespread application. Frequent chemical cleaning not only increases operating costs but also shortens the membrane's lifespan.

[0003] Ozone oxidation, as a highly efficient advanced oxidation process, can generate strong oxidizing hydroxyl radicals (·OH), which can completely mineralize organic matter into carbon dioxide and water. However, ozone has low solubility in water, poor mass transfer efficiency, and exhibits selective oxidation of certain organic matter, resulting in limited treatment effectiveness when used alone. While ultrasonic technology can enhance mass transfer and generate a small amount of free radicals through cavitation, its energy consumption is high and its treatment efficiency is limited when used alone.

[0004] Currently, some studies have attempted to combine membrane separation with ozone or ultrasound. For example, Chinese patent publication CN212222493U, entitled "An Ultrasonic Enhanced Ozone Catalytic Oxidation Flat Plate Ceramic Membrane Wastewater Treatment Device," utilizes ultrasonic waves to shear and pulverize ozone mixed bubbles to improve the ozone mass transfer coefficient and uses vibration to prevent pollutant deposition on the membrane surface. However, existing technologies mostly remain at a simple physical level of coupling, failing to achieve deep integration and synergistic enhancement of functional units. In particular, there are shortcomings in how to achieve both separation and catalytic functions through catalytic functionalization of the membrane surface, and in how to construct an intelligent synergistic mechanism among ultrasound, ozone, and membrane filtration to achieve efficient pollutant degradation and in-situ control of membrane fouling. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a water treatment method that enhances the functional coupling of ozone catalytic surfaces. The aim is to deeply couple ultrasound, ozone and catalytic membrane processes to construct an integrated water treatment process that is efficient, pollution-resistant and self-cleaning.

[0006] This invention is achieved through the following technical solution: a water treatment method for enhancing the functional coupling of ozone catalytic surfaces, comprising the following steps:

[0007] Step 1: Preparation of catalytically functionalized ceramic membrane: A ceramic membrane with a macroporous support, an intermediate transition layer and a nano-separation layer is prepared, and δ-MnO2 nanosheet catalyst is grown in situ on the surface of the nano-separation layer to obtain a δ-MnO2 catalytically functionalized ceramic membrane.

[0008] Step 2, Wastewater Pretreatment: The wastewater to be treated is filtered by a screen and homogenized, and the pH of the influent is controlled at 6.5-8.5, and the reaction temperature is 20-30℃;

[0009] Step 3, Ultrasonic-Ozone Catalysis-Membrane Separation Synergistic Treatment: The δ-MnO2 catalytically functionalized ceramic membrane prepared in Step 1 is installed in the membrane module to perform cross-flow filtration on the wastewater treated in Step 2. At the same time, ozone is introduced into the membrane module and acts on the membrane surface in pulsed ultrasonic mode.

[0010] Step 4, Intelligent Feedback Control: Real-time monitoring of transmembrane pressure difference and effluent water quality, and automatic adjustment of ultrasonic power and / or ozone dosage based on monitoring signals;

[0011] Step 5, In-situ cleaning and membrane regeneration: Perform in-situ cleaning periodically or according to flux decline to restore membrane flux;

[0012] Step 6, Effluent that meets standards: Collect the effluent after it has been filtered and separated by the ceramic membrane.

[0013] Furthermore, the preparation of the catalytically functionalized ceramic membrane in step one specifically includes:

[0014] S1.1 Preparation of macroporous support: By weight percentage, 50%-70% of α-alumina powder with an average particle size of 30μm, 15%-40% of deionized water, 3%-10% of 5% polyvinyl alcohol solution, 1%-5% of polyethylene glycol, 5%-30% of starch and 0.5%-2% of dispersant polyethyleneimine are mixed evenly, and after molding, sintered at 1300-1600℃ for 1.5-2.5 hours to obtain a macroporous support with a pore size of 1-20μm and a porosity of 30%-50%.

[0015] S1.2, Coating the intermediate transition layer: A slurry containing α-alumina powder with a particle size of 0.3-0.5μm is coated on the surface of the macroporous support prepared in S1.1, dried, and sintered at 1150℃ to form an intermediate transition layer;

[0016] S1.3 Constructing a nano-separation layer: Using aluminum sec-butoxide as a precursor, boehmite sol is prepared by hydrolysis. The boehmite sol is coated on the surface of the support with transition layer obtained in S1.2. After drying, it is calcined at 550℃ to obtain a γ-Al2O3 nano-separation layer with a pore size of 2-5nm.

[0017] S1.4 Catalytic functionalization treatment of ceramic membrane surface: The ceramic membrane prepared in S1.3 is placed in a precursor solution containing potassium permanganate and manganese sulfate and hydrothermally reacted at 120°C for 6-10 hours. After cleaning, drying and calcination at 300°C, δ-MnO2 nanosheet catalyst is grown in situ on the γ-Al2O3 nano-separation layer.

[0018] Furthermore, in step S1.4, the loading of the δ-MnO2 catalytic coating is controlled within the range of 0.5-5 mg / cm² film area.

[0019] Further, in step S1.4, the precursor solution is prepared by mixing a 0.1 mol / L potassium permanganate solution and a 0.05 mol / L manganese sulfate solution in a volume ratio of 2:1.

[0020] Furthermore, in step three, the parameters of the pulsed ultrasound mode are: ultrasound frequency 40kHz, ultrasound power density 0.3W / mL, and working time and interval time are adjustable within the range of 0.5-5 seconds.

[0021] Furthermore, the control logic for intelligent feedback regulation described in step four includes:

[0022] When the transmembrane pressure difference rises to 1.6 times the initial value, the ultrasonic power density is automatically increased from the reference value of 0.3 W / mL to 0.5 W / mL; when the transmembrane pressure difference recovers to less than 1.2 times the initial value, the ultrasonic power is restored to the reference value.

[0023] When the chemical oxygen demand (COD) of the effluent exceeds 120% of the target value twice consecutively, the ozone dosage concentration will be automatically increased from the baseline value of 20 mg / L to 30 mg / L; when the COD of the effluent returns to below the target value and meets the standard three times consecutively, the ozone dosage concentration will be restored to the baseline value.

[0024] Furthermore, in step five, a routine maintenance cleaning is automatically performed every 8 hours of operation, which involves stopping the water intake, keeping the ultrasonic system on, and circulating clean water and ozone for 10 minutes. Every 30 days of operation or when the membrane flux decreases by more than 30% of the initial flux, a 0.5% oxalic acid solution is used for circulation cleaning for 20 minutes, followed by rinsing with clean water until neutral, and then performing a deep regeneration cleaning.

[0025] Furthermore, the macroporous support is made of α-alumina with a pore size of 1-20 μm and a porosity of 30%-50%.

[0026] The intermediate transition layer is composed of α-alumina and is coated on the surface of the macroporous support.

[0027] The γ-Al2O3 nano-separation layer, with a pore size of 2-5 nm, is coated on the surface of the intermediate transition layer.

[0028] The δ-MnO2 nanosheet catalyst layer is directly loaded onto the surface of the γ-Al2O3 nanolayer using an in-situ hydrothermal growth method, with a loading amount of 0.5-5 mg / cm².

[0029] The beneficial effects of this invention are as follows:

[0030] 1. In-situ growth of δ-MnO2 nanosheet catalysts on γ-Al2O3 nanolayers significantly improves the efficiency of catalytic ozone decomposition to generate ·OH, thanks to the layered structure and abundant active sites of δ-MnO2. Experimental studies show that under the same ozone dosage conditions, the concentration of hydroxyl radicals (·OH) in the δ-MnO2 catalytic functionalized ceramic membrane system of this invention is 18%-23% higher than that of the unsupported ceramic membrane system; the COD removal rate of dyeing and printing wastewater is increased from approximately 62% by ozone oxidation alone to 91.6%. The robust catalyst loading ensures long-term operational stability, and the membrane itself possesses both separation and catalytic functions.

[0031] 2. Through the synergistic operation mode of pulsed ultrasound + cross-flow filtration + ozone aeration, the three major functions are deeply coupled: the catalytic layer acts as the core of chemical attack to activate ozone to actively degrade pollutants, ultrasound acts as the core of physical assistance to realize online pollution prevention and mass transfer enhancement, and the ceramic membrane acts as a separation and reaction platform to ensure the quality of the effluent and provide stable support for the catalyst.

[0032] 3. The continuous ultrasonic cavitation effect acts on the membrane surface, effectively preventing pollutant deposition and filter cake formation, and significantly slowing the rise of transmembrane pressure difference. The δ-MnO2 catalyst layer degrades organic pollutants at the source, reducing the accumulation of membrane fouling substances. The pulsed ultrasonic mode reduces energy consumption and extends equipment life while ensuring treatment effectiveness.

[0033] 4. Based on feedback signals from transmembrane pressure difference and effluent water quality, the intelligent control unit automatically adjusts the ultrasonic power and ozone dosage to achieve online real-time optimization. The system supports in-situ cleaning and regeneration, restoring flux without membrane removal, resulting in low operation and maintenance costs.

[0034] 5. Suitable for high-concentration, recalcitrant organic wastewater, such as dyeing and printing wastewater, pharmaceutical wastewater, and chemical wastewater. The treatment process requires no external chemical reagents, produces no secondary pollution, and generates excellent effluent quality, conforming to the concept of green treatment. Detailed Implementation

[0035] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] This invention proposes a water treatment method for enhancing the functional coupling of ozone catalytic surfaces, specifically including the following steps:

[0039] Step 1: Preparation of catalytically functionalized ceramic membranes;

[0040] Step 2, wastewater pretreatment;

[0041] Step 3: Install the catalytic membrane from Step 1 into the membrane module to perform synergistic treatment of wastewater using ultrasound-ozone catalysis-membrane separation.

[0042] Step four: Intelligent feedback control;

[0043] Step 5: In-situ cleaning and membrane regeneration;

[0044] Step six: Water meets the standards for discharge.

[0045] S1. The preparation steps of the catalytically functionalized ceramic membrane are as follows:

[0046] S1.1 Preparation of macroporous support

[0047] Prepare the raw materials according to the following weight percentages: α-alumina powder (average particle size 30μm) 50%-70%, deionized water 15%-40%, polyvinyl alcohol (PVA) solution (concentration 5%) 3%-10%, polyethylene glycol (PEG-400) 1%-5%, starch 5%-30%, dispersant polyethyleneimine (PEI) 0.5%-2%, and all raw materials are limited to 100%.

[0048] The specific preparation process is as follows: Dissolve the dispersant in deionized water; slowly add α-Al₂O₃ powder, continuously stir mechanically or ball mill for several hours to form a uniform slurry; add PVA solution and PEG, and continue ball milling and mixing; finally add starch, and ball mill to ensure uniform mixing, forming a slurry with good fluidity and stability; extrude the plastic material through a mold to form a tubular structure; place the formed green body into a high-temperature furnace, heat it from room temperature to 1300-1600℃ at a heating rate of 1-5℃ / min, and hold it at that temperature for 1.5-2.5 hours for sintering. The resulting macroporous support has a pore size of 1-20 μm and a porosity of 30%-50%.

[0049] S1.2, Apply intermediate transition layer

[0050] The transition layer slurry is prepared by weight percentage as follows: 10.0% α-Al2O3 powder (particle size 0.3-0.5μm), 0.3% dispersant polyethyleneimine (PEI), 1.5% binder polyvinyl alcohol (PVA, 5% aqueous solution), 1.0% plasticizer glycerin, 10.0% pore-forming agent starch, and 77.2% solvent deionized water. All raw materials are limited to 100%.

[0051] When preparing the slurry, first dissolve PEI in water, then slowly add Al2O3 powder and ball mill for 24 hours; then add PVA solution, glycerin and starch in sequence, and stir for another 2-4 hours; vacuum defoaming is then performed before use.

[0052] The specific operation of the coating process is as follows: Rinse the surface of the macroporous support prepared in S1.1 with deionized water, dry it thoroughly in an oven at 100℃, and record the weight of the dried support (W0); fix the dried support vertically on an immersion-pulling machine, and immerse it completely in the transition layer slurry at a constant speed of 50mm / min for 30-60 seconds; pull out the slurry at a constant speed of 100-200mm / min; hang it vertically and let it dry naturally for 2-4 hours in a dust-free environment with low wind speed; place it in an oven, slowly raise the temperature from room temperature to 80℃ and hold it for 2 hours; record the weight of the support with coating after drying (W1), and the coating load = W1-W0; place the sample in a high-temperature furnace for sintering. The sintering program is as follows: room temperature → 400℃, heating rate 1℃ / min, hold at 400℃ for 60 minutes; 400℃ → 1150℃, heating rate 3-5℃ / min, hold at 1150℃ for 120 minutes; cool to room temperature with the furnace.

[0053] S1.3, Constructing a nano-separation layer

[0054] (1) In a three-necked flask equipped with a reflux condenser and a mechanical stirrer, add 20.0 g of aluminum sec-butoxide and 150 mL of deionized water preheated to 80 °C. Stir vigorously and reflux at 80 °C for 3 hours to generate a white precipitate, boehmite (AlOOH·nH2O). After the reaction is complete, allow it to cool naturally to room temperature.

[0055] (2) Centrifuge the above mixture at 10,000 rpm for 15 minutes and discard the supernatant; add an equal amount of 60°C deionized water to the precipitate, redisperse the precipitate by sonication or vigorous stirring, and centrifuge again. Repeat the washing 3 times to thoroughly remove alcohol byproducts and impurities.

[0056] (3) Transfer the washed boehmite wet precipitate to a clean beaker, and add diluted nitric acid solution dropwise under vigorous stirring (add 0.43 mL of 65% HNO3 to 80 mL of deionized water). The white slurry gradually changes from turbid to translucent, and finally forms a transparent or translucent sol.

[0057] (4) Place the beaker in an 80°C water bath and continue stirring for 12-24 hours to make the particle size distribution of the sol more uniform and the structure more stable.

[0058] (5) Slowly add deionized water to the sol to adjust the total volume to 500 mL, and obtain boehmite sol with a solid content of 1.0-1.5 wt%.

[0059] (6) Using the dip-lift method, lift at a slow speed of 2-5 mm / s to uniformly coat the sol onto the surface of the support with transition layer prepared in S1.2.

[0060] (7) Dry at room temperature for 24 hours under controlled humidity (about 50%RH), and then heat up to 100°C at a rate of 0.5°C / min.

[0061] (8) The room temperature is raised to 400℃ (heating rate 0.5-1℃ / min, hold for 60min), then raised to 550℃ (heating rate 1℃ / min, hold for 120min), and finally cooled with the furnace.

[0062] Finally, γ-Al2O3 nanolayers with pore sizes of 2-5 nm were obtained.

[0063] S1.4 Catalytic functionalization treatment of ceramic membrane surface

[0064] (1) The prepared ceramic membrane was ultrasonically cleaned with acetone, ethanol and deionized water for 15 minutes each to remove surface organic matter and dust; it was thoroughly dried in an oven at 100℃; and it was heat-treated at 400℃ for 1 hour to perform hydroxylation to obtain a pretreated ceramic membrane.

[0065] (2) Mix 0.1 mol / L KMnO4 solution and 0.05 mol / L MnSO4 solution in a volume ratio of 2:1 and stir magnetically for 30 minutes to form a uniform dark brown solution.

[0066] (3) Place the pretreated ceramic membrane vertically or horizontally in a stainless steel high-pressure reactor lined with polytetrafluoroethylene; pour the precursor solution into the reactor to ensure that the solution completely submerges the ceramic membrane; seal the reactor and react at 120°C for 6-10 hours; after the reaction is completed, allow it to cool naturally to room temperature; remove the ceramic membrane and rinse the membrane surface repeatedly with deionized water until the rinsing solution is clear.

[0067] (4) The membrane was vacuum dried at 60°C for 6 hours and then calcined at 300°C for 2 hours (heating rate 1°C / min) to obtain a catalytic functionalized ceramic membrane (hereinafter referred to as CFCM) with δ-MnO2 (sodium manganese dioxide) nanosheet catalyst loaded on its surface.

[0068] The loading of the δ-MnO2 catalytic coating is controlled within the range of 0.5-5 mg / cm² film area, preferably 1-3 mg / cm². δ-MnO2 has a layered structure, a large specific surface area, and abundant active sites, enabling it to efficiently catalyze the decomposition of ozone to generate hydroxyl radicals (·OH).

[0069] S2. The wastewater pretreatment process is as follows:

[0070] Wastewater is screened to remove large suspended solids and then enters an equalization tank to balance water quality and quantity. Acid-base regulators are added to control the pH of the influent at 6.5-8.5. The reaction temperature is maintained at 20-30℃ by heating.

[0071] S3. Wastewater is treated by a combination of ultrasound, ozone catalysis, and membrane separation.

[0072] (1) Install the CFCM prepared above into the membrane module of the water treatment equipment; connect the ozone supply system, the ultrasonic system, the feed and circulation system, and the intelligent control unit. The ozone supply system includes an ozone generator and a microporous aerator installed at the bottom of the membrane module or the inlet end, which is used to make the ozone uniformly distributed in the form of microbubbles; the ultrasonic system includes an ultrasonic generator and an ultrasonic transducer that can be immersed in the reactor; the circulation system includes a feed pump, a circulation pump, a pressure gauge, and a flow meter.

[0073] (2) After the wastewater to be treated is first treated by the screen and the equalization tank, the intelligent control unit is started and the operating parameters are set, including the ultrasonic frequency of 40kHz, the ultrasonic power density of 0.3W / mL (the power density is calculated based on the liquid volume in the reactor), the pulse mode (the working time is 2 seconds and the interval time is 2 seconds, and the working time and the interval time can be adjusted within the range of 0.5-5 seconds to adapt to different water qualities); the ozone concentration is 20mg / L, the gas flow rate is 0.5L / min; the cross-flow velocity is 1.5m / s; and the transmembrane pressure difference is ≤0.1MPa.

[0074] Wastewater is pumped into the membrane module by a feed pump, creating a cross-flow on the membrane surface; at the same time, the ozone generator is started, and ozone forms tiny bubbles at the bottom of the membrane module or the inlet end through microporous aeration heads, which are fully mixed with the wastewater.

[0075] During operation, the overall system achieves the following synergistic effects:

[0076] ① When ozone flows across the CFCM surface, it is efficiently decomposed by the catalyst to generate ·OH, which attacks and mineralizes organic pollutants on and near the membrane surface, thus inhibiting membrane fouling at its source.

[0077] ②The ultrasonic cavitation effect generates microjets, which disrupt the liquid film boundary layer and significantly accelerate the mass transfer rate of ozone and pollutants to the catalyst surface.

[0078] ③ The micro-jet and acoustic jet generated by cavitation effect continuously scour the membrane surface, preventing pollutant deposition and filter cake formation, and achieving in-situ, real-time membrane fouling control;

[0079] ④ Ultrasonic cavitation itself can also generate a small amount of ·OH, which has a synergistic effect with catalytic ozone oxidation;

[0080] ⑤ The clean water is discharged through the membrane under the pressure difference, and the trapped pollutants are oxidized and degraded in situ, realizing the integration of "separation + degradation".

[0081] S4, Intelligent Monitoring and Feedback Adjustment

[0082] The following indicators are included in the online monitoring: effluent COD, TOC, turbidity, conductivity, transmembrane pressure difference (TMP), ozone concentration, and ultrasonic power and frequency.

[0083] The intelligent control unit automatically adjusts itself based on monitoring signals. The control logic includes:

[0084] (1) Transmembrane pressure differential control: The initial TMP is set to 0.05MPa. When TMP rises to 0.08MPa (i.e., more than 60% of the initial value or 1.6 times the initial value), the enhanced cleaning mode is automatically triggered, and the ultrasonic power density is increased from 0.3W / mL to 0.5W / mL to enhance the flushing and cleaning effect on the membrane surface. When TMP returns to below 0.06MPa (i.e., below 1.2 times the initial value), the ultrasonic power returns to the normal value.

[0085] (2) Effluent water quality control: The target value of effluent COD is set to 50 mg / L. When the effluent COD is detected to exceed 60 mg / L twice in a row (i.e., exceeding 120% of the target value), the ozone dosage concentration will be automatically increased from 20 mg / L to 30 mg / L (i.e., 1.5 times the benchmark value). When the effluent COD recovers to below 50 mg / L and meets the standard for three consecutive monitoring tests, the ozone dosage concentration will be restored to the normal value.

[0086] S5. The in-situ cleaning and membrane regeneration steps are as follows:

[0087] During routine maintenance and cleaning, a short-term enhanced cleaning is automatically performed every 8 hours of operation—the water intake is stopped, the ultrasonic cleaning is kept on, and clean water and ozone are circulated for 10 minutes. After the cleaning water is drained, operation is resumed.

[0088] During deep regeneration cleaning, every 30 days of operation or when the membrane flux drops by more than 30% of the initial flux, use a 0.5% oxalic acid solution to circulate and clean for 20 minutes, then rinse with clean water until neutral, and put back into use after the flux is restored.

[0089] S6, the treated effluent meets the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002).

[0090] To implement the above method, the supporting system includes: a pretreatment unit, a membrane module, an ultrasonic unit, an ozone supply unit, a circulation unit, and an intelligent control unit; wherein the membrane module has a built-in CFCM, the ultrasonic unit is a 40kHz immersion transducer, and the intelligent control unit automatically adjusts the ultrasonic power and ozone dosage according to the TMP and COD signals.

[0091] To verify the overall effectiveness of this technical solution, the following comparative experiments were conducted. The concentration of hydroxyl radicals was detected using terephthalic acid fluorescence spectroscopy, COD was determined using the potassium dichromate method (HJ828-2017), and transmembrane pressure difference was recorded in real time using a precision pressure sensor.

[0092] Table 1. Comparison of catalytic effects

[0093] Comparison Projects Blank ceramic film CFCM Improved results Test conditions Ozone concentration 20 mg / L Ozone concentration 20 mg / L — Hydroxyl radical (·OH) concentration benchmark value Increased by 21.2% Significantly promotes the production of ·OH from ozone decomposition

[0094] Table 1 shows that, under the same ozone dosage conditions (ozone concentration 20 mg / L), the concentration of hydroxyl radicals (·OH) generated was measured using a blank ceramic membrane without catalyst and the CFCM in this technical scheme. The results show that the ·OH concentration in the CFCM system was increased by 21.2% compared with the blank ceramic membrane system, confirming the significant promoting effect of the catalyst layer on the generation of ·OH from ozone decomposition.

[0095] Table 2. Comparison of anti-pollution effects

[0096] Comparison Projects Ultrasonic-free ozone-CFCM system This invention relates to an ultrasonic-ozone-CFCM system. Effect Comparison Initial transmembrane pressure difference 0.05MPa 0.05MPa same Transmembrane pressure difference after 8 hours of continuous operation 0.11MPa 0.062MPa The increase in transmembrane pressure difference decreased by approximately 78%.

[0097] Table 2 shows that under the same influent water quality conditions (dyeing and printing wastewater, COD approximately 450 mg / L), the ultrasonic-ozone-CFCM system and the ozone-CFCM system without ultrasound were operated respectively. After 8 hours of continuous operation, the transmembrane pressure difference of the system without ultrasound increased from 0.05 MPa to 0.11 MPa, while the transmembrane pressure difference of the system in this embodiment only increased to 0.062 MPa, fully demonstrating the effectiveness of ultrasonic online cleaning.

[0098] Table 3. Validation of Synergistic Effect

[0099] Treatment target: Dyeing and printing wastewater (initial COD approximately 450 mg / L) Operating time: 8 hours

[0100] Processing mode COD removal rate illustrate Ultrasound only + blank ceramic membrane 45.20% Physical separation + finite cavitation oxidation Ozone only + blank ceramic membrane 62.50% Ozone oxidation + membrane separation Ultrasound + Ozone + Blank Ceramic Membrane 71.30% Ultrasonic-enhanced mass transfer + ozone oxidation, but without a catalyst. This invention: Ultrasound + Ozone + CFCM 91.60% Deep synergy between ultrasound, ozone, and catalytic membrane

[0101] Table 3 shows that the same dyeing and printing wastewater was treated using four different modes: "ultrasound only + blank ceramic membrane," "ozone only + blank ceramic membrane," "ultrasound + ozone + blank ceramic membrane," and "ultrasound + ozone + CFCM." After 8 hours, the COD removal rates were 45.2%, 62.5%, 71.3%, and 91.6%, respectively, confirming that the synergistic effect of ultrasound, ozone, and catalytic membrane is significantly better than the effect of each alone or in combination.

[0102] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water treatment method for enhancing the functional coupling of ozone catalytic surfaces, characterized in that, Includes the following steps: Step 1: Preparation of catalytically functionalized ceramic membrane: A ceramic membrane with a macroporous support, an intermediate transition layer and a nano-separation layer is prepared, and δ-MnO2 nanosheet catalyst is grown in situ on the surface of the nano-separation layer to obtain a δ-MnO2 catalytically functionalized ceramic membrane. Step 2, Wastewater Pretreatment: The wastewater to be treated is filtered by a screen and homogenized, and the pH of the influent is controlled at 6.5-8.5, and the reaction temperature is 20-30℃; Step 3, Ultrasonic-Ozone Catalysis-Membrane Separation Synergistic Treatment: The δ-MnO2 catalytically functionalized ceramic membrane prepared in Step 1 is installed in the membrane module to perform cross-flow filtration on the wastewater treated in Step 2. At the same time, ozone is introduced into the membrane module and acts on the membrane surface in pulsed ultrasonic mode. Step 4, Intelligent Feedback Control: Real-time monitoring of transmembrane pressure difference and effluent water quality, and automatic adjustment of ultrasonic power and / or ozone dosage based on monitoring signals; Step 5, In-situ cleaning and membrane regeneration: Perform in-situ cleaning periodically or according to flux decline to restore membrane flux; Step 6, Effluent that meets standards: Collect the effluent after it has been filtered and separated by the ceramic membrane.

2. The water treatment method for enhancing the functional coupling of ozone catalytic surfaces according to claim 1, characterized in that, The preparation of the catalytically functionalized ceramic membrane in step one specifically includes: S1.1 Preparation of macroporous support: By weight percentage, 50%-70% of α-alumina powder with an average particle size of 30μm, 15%-40% of deionized water, 3%-10% of 5% polyvinyl alcohol solution, 1%-5% of polyethylene glycol, 5%-30% of starch and 0.5%-2% of dispersant polyethyleneimine are mixed evenly, and after molding, sintered at 1300-1600℃ for 1.5-2.5 hours to obtain a macroporous support with a pore size of 1-20μm and a porosity of 30%-50%. S1.2, Coating the intermediate transition layer: A slurry containing α-alumina powder with a particle size of 0.3-0.5μm is coated on the surface of the macroporous support prepared in S1.1, dried, and sintered at 1150℃ to form an intermediate transition layer; S1.3 Constructing a nano-separation layer: Using aluminum sec-butoxide as a precursor, boehmite sol is prepared by hydrolysis. The boehmite sol is coated on the surface of the support with transition layer obtained in S1.

2. After drying, it is calcined at 550℃ to obtain a γ-Al2O3 nano-separation layer with a pore size of 2-5nm. S1.4 Catalytic functionalization treatment of ceramic membrane surface: The ceramic membrane prepared in S1.3 is placed in a precursor solution containing potassium permanganate and manganese sulfate and hydrothermally reacted at 120°C for 6-10 hours. After cleaning, drying and calcination at 300°C, δ-MnO2 nanosheet catalyst is grown in situ on the γ-Al2O3 nano-separation layer.

3. The water treatment method for enhancing the functional coupling of ozone catalytic surfaces according to claim 2, characterized in that, In step S1.4, the loading of the δ-MnO2 catalytic coating is controlled within the range of 0.5-5 mg / cm² film area.

4. The water treatment method for enhancing the functional coupling of ozone catalytic surfaces according to claim 2, characterized in that, In step S1.4, the precursor solution is prepared by mixing a 0.1 mol / L potassium permanganate solution and a 0.05 mol / L manganese sulfate solution in a volume ratio of 2:

1.

5. The water treatment method for enhancing the functional coupling of ozone catalytic surfaces according to claim 1, characterized in that, In step three, the parameters of the pulsed ultrasound mode are: ultrasound frequency 40kHz, ultrasound power density 0.3W / mL, and working time and interval time are adjustable within the range of 0.5-5 seconds.

6. The water treatment method for enhancing the functional coupling of ozone catalytic surfaces according to claim 1, characterized in that, The control logic for intelligent feedback regulation described in step four includes: When the transmembrane pressure difference rises to 1.6 times the initial value, the ultrasonic power density is automatically increased from the reference value of 0.3 W / mL to 0.5 W / mL; when the transmembrane pressure difference recovers to less than 1.2 times the initial value, the ultrasonic power is restored to the reference value. When the chemical oxygen demand (COD) of the effluent exceeds 120% of the target value twice consecutively, the ozone dosage concentration will be automatically increased from the baseline value of 20 mg / L to 30 mg / L; when the COD of the effluent returns to below the target value and meets the standard three times consecutively, the ozone dosage concentration will be restored to the baseline value.

7. The water treatment method for enhancing the functional coupling of ozone catalytic surfaces according to claim 1, characterized in that, In step five, a routine maintenance cleaning is automatically performed every 8 hours of operation, which involves stopping the water intake, keeping the ultrasonic system on, and circulating clean water and ozone for 10 minutes. Every 30 days of operation or when the membrane flux decreases by more than 30% of the initial flux, a 0.5% oxalic acid solution is used for circulation cleaning for 20 minutes, followed by rinsing with clean water until neutral, and then performing a deep regeneration cleaning.

8. The water treatment method for enhancing the functional coupling of ozone catalytic surfaces according to claim 2, characterized in that, The macroporous support is made of α-alumina with a pore size of 1-20 μm and a porosity of 30%-50%. The intermediate transition layer is composed of α-alumina and is coated on the surface of the macroporous support. The γ-Al2O3 nano-separation layer, with a pore size of 2-5 nm, is coated on the surface of the intermediate transition layer. The δ-MnO2 nanosheet catalyst layer is directly loaded onto the surface of the γ-Al2O3 nanolayer using an in-situ hydrothermal growth method, with a loading amount of 0.5-5 mg / cm².