Preparation method and application of functional catalytic membrane for sewage treatment

Abstract

The invention discloses a preparation method and application of a functional catalytic membrane for sewage treatment, and belongs to the technical field of separation membrane preparation. The preparation method comprises the following steps: pyrolyzing and carbonizing collected biomass fragments into biomass charcoal, pickling and drying the biomass charcoal, adding the biomass charcoal into a mixed solution containing zinc salt and nickel salt, and adding a complexing agent. And then, adjusting the pH value of the solution to an alkaline condition, and after reaction, cleaning, drying and roasting to obtain the modified biomass charcoal. And then preparing the Zn-Ni / BC coated PVDF catalytic membrane by taking the modified biomass charcoal as a filler and adopting a non-solvent induced phase conversion method, and coupling the Zn-Ni / BC coated PVDF catalytic membrane with an advanced oxidation technology for treating organic wastewater. The prepared Zn-Ni / BC coated PVDF has good pore size distribution, shows a good catalytic effect on persulfate and hydrogen peroxide at the same time, can achieve in-situ removal of organic pollutants, remarkably improves the separation performance and anti-pollution performance of the membrane, and is low in cost and wide in application range.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of separation membrane preparation, and particularly relates to a preparation method of a functional catalytic membrane for sewage treatment and application thereof. BACKGROUND

[0002] With the development of society and industry, people's requirements for ecological environment quality are gradually increasing, and environmental pollution problems have attracted high attention from all walks of life, among which water pollution is particularly prominent. Organic wastewater has become a major problem in solving water pollution due to its multiple and complex components and poor biodegradability. Traditional coagulation-sedimentation-disinfection treatment processes cannot meet the discharge requirements. At present, membrane separation technology has become an indispensable technology for treating organic wastewater. Among them, polyvinylidene fluoride (PVDF) ultrafiltration membrane technology, as a membrane separation technology, has become a research hotspot in the field of water treatment due to its ability to retain colloids, most microorganisms and substances with high molecular weight in water, as well as corrosion resistance and good stability.

[0003] Membrane fouling is a common problem of PVDF ultrafiltration membranes, which is mainly caused by adsorption pollution, blockage pollution and concentration polarization. In the face of membrane fouling, strategies such as optimizing the water quality, backwashing and improving the hydrophilicity of the membrane surface are often used to alleviate the problem. It has been reported that inorganic nanomaterials are considered an important means to improve the surface hydrophilicity of PVDF membranes, and inorganic nanomaterials also have catalytic oxidation performance, which can realize the in-situ coupling of membrane modification and advanced oxidation technology. Not only can it improve the separation performance of the membrane, but also can endow the membrane with the ability of advanced oxidation, realizing the in-situ catalytic degradation of pollutants on the membrane surface and alleviating membrane fouling. At the same time, it solves the problem of catalyst recovery in heterogeneous advanced oxidation technology for treating organic wastewater. Therefore, how to develop an efficient inorganic nanoparticle that can not only modify PVDF membranes but also endow PVDF membranes with catalytic oxidation performance is a current research hotspot. However, the inorganic nanomaterial modified PVDF membrane coupled with advanced oxidation technology still faces problems such as poor catalytic oxidation ability of the modified membrane and poor membrane stability. For example, patent CN106110902A uses zinc oxide to modify the PVDF filter membrane, which can enhance the hydrophilicity of the membrane and endow it with antibacterial performance, although it can alleviate membrane fouling to some extent, but this method is difficult to cope with complex pollution caused by multiple types of pollutants. Patent CN119857377A introduces Zn / Co-MOFs into the casting solution to prepare Zn / Co-MOFs / PVDF hybrid matrix membrane, which improves the permeability of the membrane to some extent, but does not improve the anti-pollution performance, resulting in poor membrane stability. Therefore, further innovation in the preparation and modification of inorganic nanomaterials is needed. SUMMARY

[0004] The present application aims to provide a preparation method of a functional catalytic membrane for sewage treatment and its application, so as to solve the problems in the background art.

[0005] To solve the above technical problems, the present application is realized by the following technical scheme: The present application is a preparation method of a functional catalytic membrane for sewage treatment, which comprises the following steps: (1) Biomass chips are taken and carbonized at high temperature in an inert atmosphere, and then acid washing and drying are performed to obtain biomass charcoal; (2) The prepared biomass charcoal is added to a solution containing a complexing agent, zinc salt and nickel salt, and then the pH of the solution is adjusted to alkaline. After reacting for a period of time in a hydrothermal environment, filtration, washing, drying and calcination are performed to obtain modified biomass charcoal; (3) An appropriate amount of modified biomass charcoal is added as a filler to a mixed solution containing PVDF powder, solvent and pore-forming agent, and then ultrasonic dispersion, water bath stirring and defoaming are performed to obtain a casting solution. Then, after membrane scraping and phase inversion, a Zn-Ni / BC@PVDF catalytic membrane is obtained.

[0006] Further, in step (1), the biomass material is corn straw, rice husk, peanut shell or walnut shell.

[0007] Further, in step (1), the pyrolysis carbonization temperature is 500-1000 ℃, the heating rate is 2-10 ℃ / min, the carbonization time is 0.5-3 h, and the carbonization atmosphere is nitrogen, helium or argon.

[0008] Further, in step (1), the acid solution is a dilute hydrochloric acid solution or a dilute sulfuric acid solution with a concentration of 0.01-1 mol / L, and the heating and stirring temperature is 50-100 ℃ for 1-5 h.

[0009] Further, in step (1), the biomass material is rice husk; the pyrolysis carbonization temperature is 700 ℃, the heating rate is 5 ℃ / min, the carbonization time is 2 h, the carbonization atmosphere is nitrogen; the acid solution is a dilute hydrochloric acid solution with a concentration of 0.02 mol / L, and the heating and stirring temperature is 70 ℃ for 2 h.

[0010] Further, in step (2), the complexing agent used is tartaric acid, EDTA or citric acid with a concentration of 0.01-1 mol / L; the zinc salt and nickel salt are sulfate, chloride or nitrate, and the molar ratio of zinc to nickel in the mixed solution is 1-3:1-3, and the total amount of metal salt added is 10-80% of the modified biomass charcoal, and the stirring time is 1-5 h.

[0011] Further, the complexing agent used in step (2) is tartaric acid with a concentration of 0.04 mol / L; the zinc salt and the nickel salt are zinc sulfate and nickel sulfate respectively, the molar ratio of zinc to nickel is 1:1, and the total amount of metal salt added is 20% of the modified biomass charcoal, and the stirring time is 3 hours.

[0012] Further, in step (2), sodium carbonate, sodium bicarbonate or potassium carbonate is used to adjust the pH of the solution to 8-12, and the reaction is carried out at a water bath temperature of 30-80 ℃ for 1-5 h.

[0013] Further, in step (2), the high-temperature calcination temperature is 700-1000 ℃, and the calcination time is 1-3 h. Further, in step (2), the pH is adjusted to 8 using a sodium carbonate solution, the water bath temperature is 50 ℃, and the stirring time is 2 h; the high-temperature calcination temperature is 750 ℃, and the calcination time is 2 h. Further, in step (3), the mass ratio of the modified biomass charcoal catalyst, PVDF powder, solvent and pore-forming agent is 0.5-2:14-18:1-5:76-85, the pore-forming agent includes polyether F127, polyvinylpyrrolidone, polyethylene glycol or Tween 80, and the solvent includes N,N-dimethylformamide, N-methylpyrrolidone or N,N-dimethylacetamide.

[0014] Further, in step (3), the mass ratio of the modified biomass charcoal catalyst, PVDF powder, solvent and pore-forming agent is 1.5:17:2:79.5; the pore-forming agent is polyvinylpyrrolidone; and the solvent is N,N-dimethylacetamide.

[0015] Further, in step (3), the ultrasonic time is 0.5-3 h, the water bath temperature is 40-80 ℃, and the time is 6-10 h; the defoaming temperature is 25-45 ℃, and the time is 8-15 h.

[0016] Further, in step (3), the ultrasonic time is 1 h, the water bath temperature is 60 ℃, and the time is 8 h; the defoaming temperature is 35 ℃, and the time is 12 h.

[0017] Further, in step (3), the substrate is a glass plate, and the film layer thickness is 50-400 μm; the coagulation bath solution is a sodium chloride solution, a potassium chloride solution or a calcium chloride solution, and the coagulation bath salt solution concentration is 20-100 g / L; and the cleaning solution is pure water, ethanol, isopropanol or methanol, and the immersion cleaning time is 5-8 h.

[0018] Further, the film layer thickness is 200 μm; the coagulation bath solution is a sodium chloride solution, the coagulation bath salt solution concentration is 50 g / L, the cleaning solution is pure water, and the immersion cleaning time is 6 h.

[0019] A functional catalytic membrane for sewage treatment is prepared by the method.

[0020] The functional catalytic membrane for sewage treatment is used in wastewater treatment or preparation of products and equipment for wastewater treatment.

[0021] Further, the wastewater treatment is the Zn-Ni / BC@PVDF catalytic membrane alone or in-situ coupling of persulfate and hydrogen peroxide to treat organic wastewater.

[0022] Further, the organic wastewater is any one of chemical nickel plating wastewater, fluorine-containing wastewater, N-methyl morpholine wastewater, printing and dyeing wastewater, medical wastewater and electrolytic manganese leachate.

[0023] The present application has the following beneficial effects: 1. The Zn-Ni / BC catalyst for catalyzing persulfate or hydrogen peroxide is prepared by the adsorption-precipitation two-step method, and the material effectively improves the ability of biomass carbon to catalyze persulfate through the synergistic effect of bimetallic.

[0024] 2. The Zn-Ni / BC catalyst (modified biomass carbon catalyst) is used to adjust the hydrophilicity, surface roughness and surface charge state of the PVDF membrane, and after in-situ coupling of persulfate or hydrogen peroxide, the pollutants can be effectively degraded.

[0025] 3. The PVDF membrane is modified and prepared by the method of blending modification of inorganic nanomaterials, and is coupled with persulfate and hydrogen peroxide advanced oxidation technology, which effectively improves the separation performance and anti-pollution performance of the PVDF membrane, and solves the problem of difficult separation and recovery of powder catalyst in traditional persulfate and hydrogen peroxide advanced oxidation technology. The experimental operation is simple and feasible, and meets the requirements of green chemistry, energy saving and emission reduction. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed for the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 Flux comparison chart of PVDF membranes prepared with different metal ratios coupled with persulfate (PMS); Figure 2 Retention rate and water flux recovery rate and retention rate comparison chart of PVDF membranes prepared with different metal ratios coupled with PMS; Figure 3 Retention rate and water flux recovery rate and retention rate comparison chart of PVDF membranes prepared with different metal ratios coupled with hydrogen peroxide (H2O2); Figure 4 The flux comparison chart of Zn-Ni / BC modified PVDF membrane coupled with PMS for different calcination temperatures; Figure 5 The rejection rate and water flux recovery rate and rejection rate comparison chart of Zn-Ni / BC@PVDF membrane coupled with PMS for different calcination temperatures; Figure 6 The flux comparison chart of PVDF membrane coupled with PMS for different Zn-Ni / BC ratios; Figure 7 The rejection rate and water flux recovery rate and rejection rate comparison chart of PVDF membrane coupled with PMS for different Zn-Ni / BC ratios; Figure 8 The rejection rate comparison chart of Zn-Ni / BC modified PVDF membrane coupled with PMS for coagulation bath; Figure 9 The rejection rate comparison chart of Zn-Ni / BC modified PVDF membrane coupled with PMS for different contaminated wastewater; Figure 10 The SEM chart of Zn-Ni / BC@PVDF and PVDF obtained in the test example. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0029] Embodiment 1 A preparation method of a functional catalytic membrane for sewage treatment, comprising the following steps: (1) After washing and drying, the rice hull crumbs are put into a tubular furnace, and high-temperature pyrolysis carbonization is carried out under N2 atmosphere at a heating rate of 5 ℃ / min to 700 ℃, and after cooling, rice hull biomass carbon material is obtained; Then it is soaked in 0.01 mol / L dilute hydrochloric acid solution, heated and stirred at 70 ℃ for 2 hours, and then washed, dried; (2) The prepared biomass charcoal is added into a mixed solution of zinc sulfate and nickel sulfate containing 0.8 mol / L tartaric acid with a molar ratio of 1:1, and stirred for 3 hours; then sodium carbonate solution is slowly added dropwise into the mixed solution to adjust the pH to 8, and stirred in a water bath at 50 ℃ for 2 hours to form a ZnCO3-NiCO3 composite layer, and then filtered, dried, and calcined at 750 ℃ under N2 atmosphere at a heating rate of 5 ℃ / min to prepare a Zn-Ni / BC catalyst; (3) The Zn-Ni / BC catalyst prepared in step (2) is mixed uniformly with PVDF powder, polyvinylpyrrolidone and N,N-dimethylacetamide at a mass ratio of 1.5:17:2:79.5 at 60 ℃ for 8 hours, and then left to stand at 25 ℃ for 12 hours to prepare a casting solution; (4) The casting solution prepared in step (3) is spread on a glass plate, and then scraped with a doctor blade to form a liquid film with a thickness of 200 μm; the glass plate is transferred into a 50 g / L sodium chloride solution for phase inversion, and then immersed in pure water for 8 hours; finally, the glass plate is washed with deionized water to prepare a Zn-Ni / BC@PVDF catalytic membrane.

[0030] Example 2 The preparation method of this example is the same as that of Example 1, except that the molar ratio of zinc to nickel in step (2) is changed to 1:2, and the other steps remain unchanged.

[0031] Example 3 The preparation method of this example is the same as that of Example 1, except that the molar ratio of zinc to nickel in step (2) is changed to 2:1, and the other steps remain unchanged.

[0032] Example 4 The preparation method of this example is the same as that of Example 1, except that the molar ratio of zinc to nickel in step (2) is changed to 1:3, and the other steps remain unchanged.

[0033] Example 5 The preparation method of this example is the same as that of Example 1, except that the molar ratio of zinc to nickel in step (2) is changed to 3:1, and the other steps remain unchanged.

[0034] Examples 6-7 The preparation method of this example is the same as that of Example 1, except that the calcination temperature in step (2) is changed to 500 ℃ and 1000 ℃, respectively, and the other steps remain unchanged.

[0035] Examples 8-10 The preparation method of this example is the same as that of Example 1, except that the mass ratio of the Zn-Ni / BC catalyst in step (3), PVDF powder, polyvinylpyrrolidone and N, N-dimethylacetamide is changed to 0.5:17:2:80.5, 1:17:2:80, 2:17:2:79 respectively, and the remaining steps are unchanged.

[0036] Examples 11-12 The preparation method of this example is the same as that of Example 1, except that the 50 g / L sodium chloride solution in step (4) is changed to 50 g / L potassium chloride and calcium chloride solutions respectively, and the remaining steps are unchanged.

[0037] Comparative Example 1 (1) PVDF powder, polyvinylpyrrolidone and N, N-dimethylacetamide were mixed uniformly at a mass ratio of 17:0.5:82.5 at 60°C for 8h, and then cast into a film solution after being degassed at 25°C for 12h; (2) The film solution prepared in step (1) was spread on a glass plate, and then scraped to a liquid film of 200 μm with a doctor blade. The glass plate was then transferred to a 50 g / L sodium chloride solution for phase inversion, and then immersed in pure water for 8h. After being washed with deionized water, a PVDF membrane was obtained.

[0038] Comparative Example 2 The preparation method of this example is the same as that of Example 1, except that the molar ratio of zinc and nickel in step (3) is changed to 0:1, and the remaining steps are unchanged.

[0039] Comparative Example 3 The preparation method of this example is the same as that of Example 1, except that the molar ratio of zinc and nickel in step (3) is changed to 1:0, and the remaining steps are unchanged.

[0040] Comparative Example 4 The preparation method of this example is the same as that of Example 1, except that the 50 g / L sodium chloride solution in step (4) is changed to pure water, and the remaining steps are unchanged.

[0041] Experimental Example I. Test method 1 for filtration performance The filtration performance of the catalytic membrane was determined using a high-pressure flat membrane test device. The test conditions were: room temperature 20°C, 0.10 MPa, and the effective membrane filtration area A = 2.289 x 10 3 m 2 The specific experimental test process is as follows: (1) Put the catalytic membrane into the experimental device, add deionized water to the water tank of the equipment, and pre-press the membrane for 30 min. After the flux stabilizes, record the volume of pure water filtered by the membrane as V w1 , and calculate the pure water flux J w1 by the following formula: (2) Drain the water in the water tank, add 1 L of perfluoro nonene oxybenzene sulfonic acid sodium (OBS) solution with a concentration of 1 g / L, and after the flux stabilizes, record the data. Calculate the membrane flux J p of the OBS solution by formula (1); (3) Drain the OBS solution in the water tank and use deionized water to circulate and flush. Take out the membrane and place it upside down, backwash for 30 min, and repeat step 1. Record the pure water flux after cleaning as J w2 ; (4) Calculate the data Calculate the pure water flux, OBS retention rate, and water flux recovery rate in turn by the following formula.

[0042] In the formula: J - pure water flux (L / (m 2 ·h)); V - volume of pure water filtered by the membrane (L); A - effective area of the membrane (m 2 ); t - time (h).

[0043] In the formula: R - OBS retention rate (%) ; C p - OBS concentration in the filtrate (mg / L); C0 - OBS concentration in the original solution (mg / L).

[0044] In the formula: FRR - water flux recovery rate (%) ; J w1 - initial water flux (L / (m 2 ·h)); J w2 - water flux after backwashing (L / (m 2 ·h)).

[0045] II. Filtration performance test method 2-3 The test method is the same as filtration performance test method 1, except that in step (2), PMS and H2O2 are added at the same time, with a concentration of 1 g / L.

[0046] III. Filtration performance test method 4-8 The test method is the same as the filtration performance test method 1, except that the wastewater added in step (4) is changed to 1 g / L of electroless nickel plating wastewater, N-methyl morpholine wastewater, printing and dyeing wastewater (Rhodamine B, RhB), medical wastewater (tetracycline, TC) and electrolytic manganese leachate, respectively.

[0047] IV. Performance characterization 1. The PVDF membranes prepared in Example 15 and Comparative Examples 1-3 are respectively named Zn:Ni = 1:1, Zn:Ni = 0:1, Zn:Ni = 1:0, Zn:Ni = 1:2, Zn:Ni = 2:1, Zn:Ni = 1:3, Zn:Ni = 3:1. The separation performance is detected by filtration performance test methods 1, 2 and 3, and the results are shown in Table 2, 3 and 4. Figure 1 , 2 , 3.

[0048] As can be seen from Figure 1 , 2 , compared with Zn / BC and Ni / BC, the separation performance and anti-pollution performance of the Zn-Ni modified biomass carbon loaded on the PVDF membrane are significantly improved after coupling with PMS, and the performance of Example 1 Zn:Ni = 1:1 is the best, and the separation performance and anti-pollution performance are improved by 41.6% and 38.4% respectively compared with the PVDF membranes prepared in Examples 2 and 3 Zn / BC and Ni / BC. In Examples 2, 3, 4 and 5, due to the imbalance of the proportion of zinc and nickel and the local agglomeration phenomenon, the structure of the membrane is unstable, which affects the anti-pollution performance and separation performance in use, and the flux and OBS rejection rate are decreased.

[0049] In addition, as can be seen from Figure 3 , the rejection rate of OBS and the recovery rate of water flux of the modified membrane with different metal ratios coupled with H2O2 show the same trend as the coupling with PMS, and the rejection rate of OBS is higher than that of the single PVDF membrane and the PVDF membrane coupled with H2O2, and when Zn:Ni = 1:1, the rejection rate is the highest, reaching 90.4%. It is worth noting that the rejection rate of pollutants and the recovery rate of water flux of the modified membrane with different metal ratios coupled with PMS are higher than those coupled with H2O2. Therefore, the addition of an appropriate amount of biomass carbon modified with metal ratio in the PVDF membrane can enhance the anti-pollution performance and separation performance of the membrane, and the effect of coupling with PMS is better than that of H2O2.

[0050] 2. The PVDF membranes prepared in Example 1 and 6-7 are respectively named 500℃, 750℃, 1000℃. The separation performance is detected by filtration performance test methods 1 and 2, and the results are shown in Table 5 and 6. Figure 4 , 5 .

[0051] As can be seen from Figure 4, 5 It is known that as temperature increases, the permeation and retention performance of modified membranes initially increase and then decrease. This is mainly because, on the one hand, during calcination at 500 ℃, the organic matter in biochar is not fully decomposed, and the remaining undecomposed impurities easily clog its pores, resulting in a small specific surface area and insufficient loading sites, thus weakening its ability to adsorb and retain pollutants. On the other hand, at low temperatures, the zinc-nickel precursors are not completely decomposed, easily forming low-activity low-valence oxides or undecomposed particles. Furthermore, the interfacial bonding between biochar and the PVDF membrane is weak, and the membrane is prone to micro-defects. Ultimately, this leads to high permeation resistance, low flux, and poor pollutant retention in the modified membrane. On the other hand, calcination at 1000℃ is too high, causing excessive graphitization of the biochar, severe collapse of its pore structure, a sharp reduction in the number of micropores and mesopores, a significant decrease in specific surface area, and a drastic reduction in the space available to support the zinc-nickel bimetallic compound. Furthermore, the high temperature causes the metal particles to agglomerate due to intensified thermal motion, forming large particles and drastically reducing the number of active sites. Simultaneously, the oxygen-containing functional groups on the biochar surface almost completely disappear, leading to poor interfacial compatibility with the PVDF membrane, making interfacial delamination more likely. This results in decreased membrane structural stability, poor permeability, and easier penetration of pollutants through interfacial gaps, significantly reducing the rejection rate. In contrast, calcination at 750℃ achieves the optimal balance between the catalyst and the membrane, resulting in the best membrane performance.

[0052] 3. The PVDF membranes prepared in Examples 1 and 810 were named 0.5 wt%, 1.0 wt%, and 1.5 wt%, 2.0 wt%, respectively. Their separation performance was tested using filtration performance test methods 1 and 2, and the results are as follows: Figure 6 , 7 As shown.

[0053] Depend on Figure 6 , 7 It can be seen that, compared with pure PVDF membrane, when the Zn-Ni / BC addition amount is 0.5 wt%, the flux recovery rate can be effectively improved by 32.8% and the rejection rate by 19.3%, indicating that the Zn-Ni / BC catalyst in this invention promotes the oxidation of PMS. However, when there is too much Zn-Ni / BC material, the rejection rate decreases, possibly due to catalyst agglomeration, resulting in uneven pore distribution and enlargement of some membrane pores.

[0054] 4. The PVDF ultrafiltration membranes prepared in Examples 1 and 11-12 and Comparative Example 4 were named pure water, sodium chloride, potassium chloride, and calcium chloride, respectively. Their separation performance was tested using filtration performance test methods 1 and 2, and the results are as follows: Figure 8 As shown.

[0055] Depend on Figure 8It can be seen that the PVDF ultrafiltration membrane prepared in Example 1 of this application has a significantly higher rejection rate than the PVDF ultrafiltration membrane prepared in Comparative Example 4 of Examples 8-10. The main reason is that the sodium chloride salt bath can induce the PVDF membrane to transform into a polar β crystal form during the forming process, thereby improving the hydrophilicity of the PVDF membrane and enhancing its separation performance and antifouling performance.

[0056] 5. Example 1 was subjected to a separation performance test using filtration performance test method 48, and the concentration of contaminants in the filtrate was measured. The results are as follows: Figure 9 As shown.

[0057] Depend on Figure 9 It can be seen that the complexed nickel retention rate of the electroless nickel plating wastewater is 99.5% (Ni in the filtrate). 2+ The concentration was 0.069 mg / L, Ni 2+ The removal rates were as follows: 97.4% for N-methylmorpholine wastewater, 98.1% for dyeing and printing wastewater (RhB), 90.3% for medical wastewater (TC), and 89.4% for ammonia nitrogen in electrolytic manganese leaching solution (with an effluent ammonia nitrogen concentration of 3.5 mg / L, a manganese ion concentration of 0.64 mg / L, and a manganese ion removal rate of 96.2%). This demonstrates that the Zn-Ni / BC modified PVDF membrane prepared in this invention has good treatment effects on various types of organic polluted wastewater. In summary, Example 1 is the preferred embodiment of this application.

[0058] V. Structural Characterization The Zn-Ni / BC@PVDF and PVDF films were characterized by scanning electron microscopy (SEM), and the obtained SEM images are shown below. Figure 10 As shown.

[0059] Depend on Figure 10 It is known that the original PVDF membrane consists of many unevenly distributed large pores. Conversely, with the addition of Zn-Ni / BC, the pore size gradually becomes smaller and more uniform. This is mainly because the inorganic nanoparticles promote the diffusion of water from the coagulation bath to the casting liquid, forming a more dense and fine pore structure. This structure is beneficial to improving the permeability of the PVDF membrane.

[0060] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a functional catalytic membrane for wastewater treatment, characterized in that, Includes the following steps: (1) Take suitable biomass fragments and pyrolyze them under an inert atmosphere, then acid wash and dry them to obtain biochar; (2) The prepared biochar was added to a solution of zinc and nickel salts containing a complexing agent, and then the pH of the solution was adjusted to alkaline. After hydrothermal reaction, the solution was filtered, washed, dried and calcined to obtain modified biochar. (3) Modified biochar is added to a mixture containing PVDF powder, solvent and pore-forming agent. After ultrasonic dispersion, water bath stirring and degassing, a casting solution is obtained. Then, after coating and phase inversion, a Zn-Ni / BC@PVDF catalytic membrane is obtained.

2. The method for preparing the functional catalytic membrane for wastewater treatment according to claim 1, characterized in that, In step (1), the biomass debris is corn stalks, rice husks, peanut shells or walnut shells, the pyrolysis carbonization temperature is 500~1000 ℃, the heating rate is 2~10 ℃ / min, the carbonization time is 0.5~3 h, and the carbonization atmosphere is nitrogen, helium or argon.

3. The method for preparing the functional catalytic membrane for wastewater treatment according to claim 1, characterized in that, In step (1), the acid used for pickling is a dilute hydrochloric acid solution or dilute sulfuric acid with a concentration of 0.01~1 mol / L. The heating and stirring temperature is 50~100 ℃ and the time is 1~5 h.

4. The method for preparing the functional catalytic membrane for wastewater treatment according to claim 1, characterized in that, In step (2), zinc salt and nickel salt are respectively their sulfate, chloride or nitrate salts. The molar ratio of zinc to nickel in the mixed solution is 1~3:1~3. The total amount of metal salt added is 10~80% of the modified biochar. The stirring time is 1~5 h.

5. The method for preparing a functional catalytic membrane for wastewater treatment according to claim 1, characterized in that, The complexing agent used in step (2) is tartaric acid, EDTA or citric acid, and the pH of the solution is adjusted to 8~12 using sodium carbonate, sodium bicarbonate or potassium carbonate. The hydrothermal reaction temperature is 30~80 ℃ and the reaction time is 1~5 h. The calcination temperature is 700~1000 ℃ and the calcination time is 1~3 h.

6. The method for preparing a functional catalytic membrane for wastewater treatment according to claim 1, characterized in that, In step (3), the mass ratio of modified biochar catalyst, PVDF powder, solvent and pore-forming agent is 0.5~2:14~18:0.5~4:76~85; the pore-forming agent is polyether F127, polyvinylpyrrolidone, polyethylene glycol or Tween 80; the solvent is N,N-dimethylformamide, N-methylpyrrolidone or N,N-dimethylacetamide.

7. The method for preparing a functional catalytic membrane for wastewater treatment according to claim 1, characterized in that, In step (3), the water bath stirring temperature is 40~80 ℃ and the time is 6~10 h; the degassing temperature is 25~45 ℃ and the time is 8~15 h.

8. The method for preparing a functional catalytic membrane for wastewater treatment according to claim 1, characterized in that, In step (3), the thickness of the liquid film is 50-250 μm; the coagulation bath solution is NaCl solution, KCl solution or CaCl2 solution; the concentration of the coagulation bath salt solution is 20-100 g / L; the cleaning solution is pure water, ethanol, isopropanol or methanol, and the soaking and cleaning time is 5-10 h.

9. A functional catalytic membrane for wastewater treatment, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. The use of the functional catalytic membrane for wastewater treatment as described in claim 9 in wastewater treatment or in the preparation of products and equipment for wastewater treatment.

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