Reversible multi-load catalytic ceramic membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of water treatment, in particular to a reversible multi-load catalytic ceramic membrane, which comprises a columnar ceramic membrane, a catalyst embedded / attached on the surface and in pores of the ceramic membrane, and a quick insertion pipeline fixed at one end of the ceramic membrane, and the other end of the ceramic membrane is packaged by epoxy resin; the behavior process of embedding / attaching the catalyst in the ceramic membrane channel is as follows: putting the composite catalyst into ultrapure water, stirring into uniform catalyst suspension by using a magnetic stirrer, and embedding / attaching the powder catalyst on the surface and in pores of the ceramic membrane by using negative pressure generated by suction of a constant-flow peristaltic pump. According to the invention, the catalyst capable of activating the persulfate is embedded / attached to the surface and pores of the ceramic membrane, and the ceramic membrane assembly activates the persulfate to oxidize and degrade pollutants in the filtering process, so that the pollutants are efficiently removed. Meanwhile, the effluent turbidity can be reduced, the odor, the permanganate index and the ammonia nitrogen removal rate can be improved, disinfection by-products can be reduced, and the like, so that advanced treatment of water quality is realized.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a reversible multi-loaded catalytic ceramic membrane and a preparation method and application thereof. Background Art

[0002] With the acceleration of urbanization, the rapid development of the economy and society, the improvement of human living standards, the increasing environmental pollution, and the water crisis caused by the serious pollution of water resources have threatened human health and life. In recent years, frequent water crisis events in many parts of the country have posed a serious threat to the health of the people, and have also had an adverse impact on the ecological environment and the sustainable development of the country, and have also ushered in new opportunities and challenges for the water pollution control industry. Membrane separation technology is a typical green, economical and efficient water treatment technology due to its low energy consumption, high efficiency, small land occupation and carbon emissions. It is one of the most cutting-edge research directions in the water treatment industry. Among them, nanofiltration and reverse osmosis have good removal effects on organic matter and salts, but the operating pressure is high, and the operation and maintenance costs are relatively high. They are mainly used for seawater desalination and ultrapure water production. Microfiltration and ultrafiltration have moderate operating pressures and can effectively intercept particulate matter, colloids, microorganisms and macromolecular organic matter in water. They have been widely used in engineering in the field of deep treatment of drinking water and sewage. However, due to their large pore size, microfiltration / ultrafiltration membranes have almost no removal effect on soluble organic pollutants, which seriously hinders the expansion and application of microfiltration / ultrafiltration membrane separation technology in the field of deep treatment of new pollutants.

[0003] Advanced oxidation technology, also known as deep oxidation technology, produces free radicals with strong oxidizing ability under the reaction conditions of high temperature, high pressure, electricity, sound, light, catalyst, etc., which oxidizes large molecular organic matter that is difficult to degrade into low-toxic or non-toxic small molecular substances, and even mineralizes into CO 2 , H 2 O. Traditional advanced oxidation technologies, such as electrochemical catalytic oxidation, ozone catalytic oxidation and Fenton technology, mainly use hydroxyl radicals (·OH) as the main active species. However, persulfate advanced oxidation technology can produce one or more sulfate radicals (SO 4 ·- ), hydroxyl radical (·OH) and singlet oxygen ( 1 O 2) and other active species. Compared with traditional advanced oxidation technology, it has the characteristics of strong oxidation ability, fast reaction speed and low cost, and has great development potential for degrading new pollutants in water. However, the catalysts currently used in advanced oxidation are usually powder catalysts, which have problems such as difficulty in catalyst recovery, easy deactivation of catalysts, and difficulty in replacement. If the entire equipment is replaced due to catalyst deactivation, it will undoubtedly cause a large waste of resources. Coupling advanced oxidation technology with membrane technology can efficiently remove new pollutants and achieve water purification. Organic membranes have been widely used due to their advantages such as wide range of materials, low manufacturing cost per unit membrane area, and high packing density of membrane components. They currently account for about 85% of the membrane market. However, due to the principle of like dissolves like, organic membrane materials are easily corroded by strong acids, strong alkalis and organic solvents, which greatly reduces the service life of organic membranes, thereby limiting the widespread application of organic membrane separation technology. Ceramic membranes have many advantages such as high separation efficiency, stable effect, good chemical stability, acid and alkali resistance, simple separation process, low energy consumption, easy operation and maintenance, and long service life. Coupling them with persulfate advanced oxidation technology can not only effectively improve the removal rate of organic pollutants in the effluent, but also control membrane pollution by changing the surface properties of organic matter (charge and molecular weight distribution). Summary of the invention

[0004] In view of the problem that soluble organic pollutants are difficult to effectively remove in microfiltration / ultrafiltration membrane separation processes, the present invention couples persulfate advanced oxidation technology with ceramic membrane separation technology to design a reversible multi-loaded ceramic catalytic membrane. This technology enables the persulfate added to the water to be rapidly activated by the catalyst on the catalytic ceramic membrane to instantly produce a large number of active species while the contaminated water is being filtered through the catalytic ceramic membrane, and new pollutants are efficiently removed in a very short time, thereby achieving the purpose of water purification. The technical innovation lies in preparing a ceramic membrane with controllable membrane pore size by a phase inversion method, preparing a catalytic ceramic membrane by pumping the catalyst load, and eluting the deactivated catalyst through an ultrasonic-backwashing process for catalyst renewal, thereby achieving reversible multiple loading of the catalyst, solving the problem of replacing the entire catalytic ceramic membrane assembly due to the attenuation of catalytic performance during the long-term operation of the catalytic ceramic membrane, realizing the recycling of the catalytic ceramic membrane, extending the service life of the catalytic ceramic membrane assembly, and greatly reducing energy consumption.

[0005] To achieve the above object, the present invention provides the following technical solutions: a reversible multi-loaded catalytic ceramic membrane, comprising a columnar ceramic membrane, a catalyst embedded / attached on the surface and in the pores of the ceramic membrane, and a quick-insert pipe encapsulating the membrane assembly;

[0006] The process of catalyst embedding / attaching to the ceramic membrane channel is as follows: the catalyst is placed in ultrapure water and stirred with a magnetic stirrer to form a uniformly dispersed catalyst suspension, and then the negative pressure generated by the suction of a constant flow peristaltic pump is used to embed / attach the powder catalyst to the surface of the ceramic membrane and the inside of the membrane pores.

[0007] The method for preparing a reversible multi-loaded catalytic ceramic membrane comprises the following steps:

[0008] Step 1: Select Al 2 O 3 As the main ceramic aggregate, powdered activated carbon is doped into the casting solution to adjust the pore size of the ceramic membrane, and the columnar ceramic membrane is prepared by phase inversion spinning method;

[0009] Step 2, the preparation method is as follows:

[0010] First, polyethersulfone (PES) polymer and polyvinylpyrrolidone (PVP) additive were dissolved in N,N-dimethylacetamide (DMAC) organic solvent, and then Al was added thereto. 2 O 3 、SiO 2 The powder and powdered activated carbon are mixed evenly in a ball mill to form a casting solution, water is used as the core solution and the coagulation bath, a spinneret with an inner and outer aperture of 2×6 cm is used, and high-pressure nitrogen is used as a pressure source to spin and prepare a ceramic membrane;

[0011] The ceramic membrane is naturally dried and then sintered at high temperature to finally obtain a columnar ceramic membrane;

[0012] Step 3: Encapsulate one end of the prepared ceramic membrane base film with epoxy resin, connect the other end to a polyethylene tube and also encapsulate it with epoxy resin, place it in a cool and ventilated place to dry, and after it is completely dry, connect a constant flow peristaltic pump and use reverse suction to verify whether its sealing is good;

[0013] Step 4. Under the premise that the columnar ceramic membrane has good sealing performance, use an electronic analytical balance to weigh 0.02g-0.1g of powdered catalyst, which can be a transition metal oxide or a carbon-based catalyst, and pour it into a reactor containing 400mL of deionized water. Put in a rotor with a length of 3cm, place the device on a magnetic stirrer, set the speed of the magnetic stirrer to 500rpm, start the magnetic stirrer, and stir for 5min to evenly disperse the catalyst in the deionized water to form a suspension. The concentration of the catalyst in the suspension is 0.05g / L-0.25g / L. Connect the packaged ceramic membrane to a constant flow peristaltic pump, and embed / attach it to the pores of the ceramic membrane whose pore size matches the catalyst size and on the membrane surface under the action of the negative pressure generated by suction to obtain a catalytic ceramic membrane loaded with catalyst.

[0014] Preferably, when the catalyst activity decreases, the loaded catalyst is eluted by ultrasound and backwashing. When the catalyst is eluted, the pollutants on the surface can be eluted together to clean the ceramic membrane. Then, the fresh catalyst is loaded onto the ceramic membrane through the same steps to realize reversible multiple loading of the catalytic ceramic membrane.

[0015] Preferably, the particle size of the powdered activated carbon in step 2 is 100-400 mesh.

[0016] Preferably, in step 4, the rotation speed of the peristaltic pump is set to 40 rpm and the suction time is set to 20 min.

[0017] Preferably, the ultrasonic frequency used is 50-100 KHz, the ultrasonic time is 1 hour, the speed of the constant flow peristaltic pump set during backwashing is 40 rpm, and the backwashing time is 2 hours.

[0018] Preferably, in the step 2, the raw ceramic membrane is naturally dried and then sintered at a temperature of 1200-1400° C. for 2 hours to finally obtain a columnar ceramic membrane.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention embeds / attaches a catalyst capable of activating persulfate onto the surface of the ceramic membrane and its pores. The ceramic membrane assembly activates persulfate to oxidize and degrade pollutants while filtering, thereby achieving efficient removal of new pollutants. Compared with ozone-activated carbon technology, it can reduce the amount of activated carbon used, reduce effluent turbidity, improve the removal rate of odor, permanganate index, and ammonia nitrogen, and reduce disinfection by-products, thereby achieving deep treatment of water quality.

[0021] 2. The present invention aims to solve the problems that it is difficult to recycle the catalyst in powder form, and that the catalyst is easily deactivated during use, while the ceramic membrane has a long service life, and the replacement of the entire equipment due to catalyst deactivation causes waste of resources. To solve this series of problems, the present invention prepares a reversible multi-loaded catalytic ceramic membrane. When the catalyst is deactivated, a combination of ultrasound and backwashing is used to elute the old catalyst, and then suction is used to load fresh catalyst, thereby achieving reversible multiple loading of the catalyst, thereby ensuring stable treated water quality.

[0022] 3. The catalytic ceramic membrane used in the present invention is suitable for an immersed membrane filtration system. Under the action of a constant-current peristaltic pump, raw water enters the pores of the ceramic membrane through the surface of the ceramic membrane. The catalyst loaded on the surface and pores of the ceramic membrane activates persulfate to produce SO 4 ·- Active free radicals such as ·OH can oxidize and degrade pollutants in water, achieving deep removal of new pollutants in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a schematic diagram of a submerged catalytic ceramic membrane assembly water purification device in Example 1 of the present invention;

[0025] Figure 2 This is a scanning electron microscope image of the catalytic ceramic membrane before and after loading in Example 1 of the present invention;

[0026] Figure 3 The ceramic membrane base membrane, the catalytic ceramic membrane after loading the catalyst and the ceramic membrane after eluting the catalyst in Example 1 of the present invention;

[0027] Figure 4 This is a comparison diagram of the degradation effects of Examples 1-3 of the present invention and Comparative Example 1 on Rhodamine B;

[0028] Figure 5 Schematic diagram of the preparation process of the reversible multi-loaded catalytic ceramic membrane in Example 1 of the present invention DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figures 1 to 5 , the technical solution provided by the present invention:

[0031] Example 1

[0032] The reversible multi-catalytic ceramic membrane is prepared as follows:

[0033] Add polyethersulfone (PES) polymer and polyvinylpyrrolidone (PVP), dissolve in N,N-dimethylacetamide (DMAC) organic solvent, and then add Al 2 O 3 、SiO 2The powder and 100-400 mesh activated carbon powder are mixed evenly in a ball mill to form a casting solution. Water is used as the core liquid and coagulation bath. A spinneret with an inner and outer aperture of 2×6 cm is used. High-pressure nitrogen is used as the pressure source for spinning to prepare a ceramic membrane. After the ceramic membrane is naturally dried, it is sintered at a temperature of 1200-1400°C for 2 hours to finally obtain a columnar ceramic membrane.

[0034] The columnar ceramic membrane was encapsulated with epoxy resin, and the columnar ceramic membrane with good airtightness was placed in the suspension. The speed of the constant flow peristaltic pump was set to 20 rpm, and the suction time was 20 min.

[0035] Weigh 0.02 g of cobalt-manganese oxide catalyst and add it to a reactor containing 400 mL of deionized water. Place the reactor on a magnetic stirrer and adjust the speed to 500 rpm. Stir for 5 min to obtain a catalyst concentration of 0.05 g / L in the suspension.

[0036] Under the negative pressure generated by suction, a reversible multi-loaded catalytic ceramic membrane can be obtained by embedding / attaching it in the pores of a ceramic membrane whose pore size matches the catalyst size and on the membrane surface.

[0037] The catalytic ceramic membrane prepared in this example is placed into sewage. Figure 1 Shown to quickly clean water. Figure 2 This is a scanning electron microscope image of a cobalt-manganese bimetallic oxide-loaded catalytic ceramic membrane. The surface of the unloaded ceramic membrane is smooth, while the surface of the catalytic ceramic membrane is rough. It can be seen that the cobalt-manganese bimetallic catalyst is evenly loaded on the surface of the ceramic membrane and in the pores of the ceramic membrane. When the catalyst activity decreases, the loaded catalyst is eluted by ultrasound plus backwashing. The ultrasonic frequency used is 50-100kHz, and the ultrasonic time is 1h. The speed of the constant flow peristaltic pump set during backwashing is 40rpm, and the backwashing time is 2h. While eluting the catalyst, the pollutants on the surface can be eluted together to achieve the cleaning of the ceramic membrane. Then, the fresh catalyst is loaded onto the ceramic membrane through the same steps to complete the reversible multiple loading of the catalytic ceramic membrane. Figure 3 As shown, it is a comparison chart of the original membrane, catalytic ceramic membrane and ceramic membrane after elution. It can be seen that the ceramic membrane after elution appears grayish white, and most of the catalyst on the surface has been successfully eluted. Through the same steps, fresh catalyst is loaded again to achieve reversible multiple loading of the catalytic ceramic membrane.

[0038] Example 2

[0039] The reversible multi-catalytic ceramic membrane is prepared as follows:

[0040] The same columnar ceramic membrane as in Example 1 was prepared, packaged, and put into use after the airtightness test.

[0041] Weigh 0.06 g of cobalt-manganese oxide catalyst and add it to a reactor containing 400 mL of deionized water. Place the reactor on a magnetic stirrer and adjust the speed to 500 rpm. Stir for 5 min to obtain a suspension with a catalyst concentration of 0.15 g / L.

[0042] Under the negative pressure generated by suction, a reversible multi-loaded catalytic ceramic membrane can be obtained by embedding / attaching it in the pores of a ceramic membrane whose pore size matches the catalyst size and on the membrane surface.

[0043] Example 3

[0044] The reversible multi-catalytic ceramic membrane is prepared as follows:

[0045] The same columnar ceramic membrane as in Example 1 was prepared, packaged, and put into use after the airtightness test.

[0046] Weigh 0.1 g of cobalt-manganese oxide catalyst and add it to a reactor containing 400 mL of deionized water. Place the reactor on a magnetic stirrer and adjust the speed to 500 rpm. Stir for 5 min to obtain a suspension with a catalyst concentration of 0.25 g / L.

[0047] Under the negative pressure generated by suction, a reversible multi-loaded catalytic ceramic membrane can be obtained by embedding / attaching it in the pores of a ceramic membrane whose pore size matches the catalyst size and on the membrane surface.

[0048] Comparative Example 1

[0049] In this comparative example, the ceramic membrane base membrane is not loaded with a cobalt-manganese bimetallic catalyst, and its preparation method is as follows:

[0050] The same columnar ceramic membrane as in Example 1 was prepared, packaged and tested for airtightness.

[0051] Experimental example

[0052] The ceramic membranes prepared in Example 1, Example 2, Example 3 and Comparative Example 1 were used to perform comparative treatment on aqueous solutions contaminated with rhodamine B (RhB).

[0053] The ceramic membranes prepared in Examples 1-3 and Comparative Example 1 were used for experiments. In each experiment, 400 mL of 5 mg / L RhB solution was used to place the prepared ceramic membranes (M0, M1, M3, and M4), and then peroxymonosulfate was added to make the concentration 0.1 mM. The peristaltic pump was operated at a speed of 40 rpm for 10 min, and samples were taken at regular intervals. The RhB concentration in the sampled solution was measured using an ultraviolet spectrophotometer. The results are shown in FIG. Figure 4 shown.

[0054] from Figure 4It can be seen that the catalytic ceramic membranes prepared in Examples 1-3 treat the RhB solution better, and the degradation rates of RhB at 5 min are 90.73%, 95.93%, and 89.79%, respectively, and the degradation rates of RhB at 10 min are all 100%, which is almost completely degraded. However, in Comparative Example 1, the degradation rate of RhB at 10 min is only 24.11%, indicating that the degradation efficiency of ceramic membrane M0 for RhB is very low, much lower than that of Examples 1-3.

[0055] like Figure 5 As shown, different catalysts with high catalytic performance are dispersed in water to form a suspension, and embedded / attached to the pores of the ceramic membrane whose pore size matches the catalyst size and on the membrane surface under the negative pressure generated by suction to obtain a catalytic ceramic membrane loaded with high-efficiency catalysts. When the catalyst activity decreases, the loaded catalyst can be eluted by ultrasound plus backwashing, and the pollutants on the surface can be eluted together at the same time to clean the ceramic membrane. Then, the fresh catalyst is loaded onto the ceramic membrane through the same steps to complete the reversible multiple loading of the catalytic ceramic membrane.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Reversible multi-loaded catalytic ceramic membrane, characterized in that: It includes a columnar ceramic membrane, a catalyst embedded / attached on the surface and pores of the ceramic membrane, and a quick-insert pipe fixed to one end of the ceramic membrane, and the other end is encapsulated with epoxy resin; The process of embedding / attaching the catalyst to the surface and pores of the ceramic membrane is as follows: the catalyst is placed in ultrapure water and stirred with a magnetic stirrer to form a uniformly dispersed catalyst suspension, and then the negative pressure generated by the suction of a constant flow peristaltic pump is used to embed / attach the powder catalyst to the surface and pores of the ceramic membrane.

2. A method for preparing a reversible multi-loaded catalytic ceramic membrane according to claim 1, characterized in that: The steps include: Step 1: Select Al2O3 as the main ceramic aggregate, add powdered activated carbon into the casting solution to adjust the pore size of the ceramic membrane, and prepare a columnar ceramic membrane by phase inversion spinning method; Step 2, the preparation method is as follows: Firstly, polyethersulfone (PES) polymer and polyvinylpyrrolidone (PVP) additive are dissolved in N,N-dimethylacetamide (DMAC) organic solvent, then Al2O3, SiO2 powder and powdered activated carbon are added thereto, and mixed evenly under the action of a ball mill to prepare a casting liquid, water is used as a core liquid and a coagulation bath, a spinneret with an inner and outer aperture specification of 2×6 cm is used, and high-pressure nitrogen is used as a pressure source for spinning to prepare a ceramic membrane; The ceramic membrane is naturally dried and then sintered at high temperature to finally obtain a columnar ceramic membrane; Step 3: Encapsulate one end of the prepared ceramic membrane base film with epoxy resin, connect the other end to a polyethylene tube and also encapsulate it with epoxy resin, place it in a cool and ventilated place to dry, and after it is completely dry, connect a peristaltic pump and use reverse suction to verify whether its sealing is good; Step 4. Under the premise that the columnar ceramic membrane has good sealing performance, use an electronic analytical balance to weigh 0.02g-0.1g of powdered catalyst, which can be a transition metal oxide or a carbon-based catalyst, and pour it into a reactor containing 400mL of deionized water. Put in a rotor with a length of 3cm, place the device on a magnetic stirrer, set the speed of the magnetic stirrer to 500rpm, start the magnetic stirrer, and stir for 5min to evenly disperse the catalyst in ultrapure water to form a suspension. The concentration of the catalyst in the suspension is 0.05g / L-0.25g / L. Connect the packaged ceramic membrane to a constant flow peristaltic pump, and embed / attach it to the pores of the ceramic membrane whose pore size matches the catalyst size and on the membrane surface under the action of the negative pressure generated by suction to obtain a catalytic ceramic membrane loaded with catalyst.

3. The method for preparing a reversible multi-loaded catalytic ceramic membrane according to claim 2, characterized in that: When the catalytic performance of the catalyst decreases, the loaded catalyst is eluted by ultrasound and backwashing. The pollutants on the surface can be eluted together with the catalyst to clean the ceramic membrane. Then, the fresh catalyst is loaded onto the ceramic membrane through the same steps to complete the reversible multiple loading of the catalytic ceramic membrane.

4. The method for preparing a reversible multi-loaded catalytic ceramic membrane according to claim 2, characterized in that: The particle size of the powdered activated carbon in step 2 is 100-400 meshes.

5. The method for preparing a reversible multi-loaded catalytic ceramic membrane according to claim 2, characterized in that: In step 4, the rotation speed of the peristaltic pump is set to 40 rpm and the suction time is set to 20 min.

6. The method for preparing a reversible multi-loaded catalytic ceramic membrane according to claim 3, characterized in that: The ultrasonic frequency used is 50-100KHz, the ultrasonic time is 1h, the speed of the constant flow peristaltic pump set during backwashing is 40rpm, and the backwashing time is 2h.

7. The method for preparing a reversible multi-loaded catalytic ceramic membrane according to claim 2, characterized in that: In the step 2, the raw ceramic membrane is naturally dried and then sintered at a temperature of 1200-1400° C. for 2 hours to finally obtain a columnar ceramic membrane.

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