Low-voltage cross-flow conducting film pool, separation device thereof and application of low-voltage cross-flow conducting film pool in water treatment

Abstract

The invention relates to a low-voltage cross-flow conductive film pool, a separation device thereof and application of the low-voltage cross-flow conductive film pool in water treatment. The separation device comprises a feeding device 1, a discharging device 2, a temperature sensor 3, a micro-flow regulating valve 4, a conductive film pool 5, a pressure sensor 6, a diaphragm pump 7 and the like, and an inlet and an outlet of the feeding device 1 are communicated with a penetrating fluid outlet 5-1 and a total feed liquid inlet 5-9 of the conductive film pool 5 through a discharging pipeline 11 and a feeding pipeline 9 respectively, so that a circulation pipeline is formed. A diaphragm pump 7 is arranged on the feeding pipeline 9, and a pressure sensor 6, a micro-flow regulating valve 4, a temperature sensor 3 and a discharging device 2 are arranged on the discharging pipeline 11. Waste liquid to be treated in the feeding device 1 enters the conducting film pool 5 through the diaphragm pump 7 to be subjected to cross-flow separation, and obtained penetrating fluid is discharged through the discharging device 2 or returns to the feeding device 1 again to be subjected to cross-flow separation again. The low-voltage cross-flow conducting film pool separation device has the advantages of being simple in structure, good in separation effect, low in cost, wide in application range and the like.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation and sewage treatment, and in particular to a low-pressure cross-flow conductive membrane pool and a separation device thereof and applications in water treatment. Background Art

[0002] With the acceleration of global industrialization, environmental pollution (especially dye wastewater pollution) has become a focus of attention. In the past, it was almost impossible to find a universal and inexpensive treatment technology to deal with all types of pollutants when faced with complex and diverse sewage challenges. However, with the advancement of science and technology, especially the continuous innovation in the field of membrane separation technology, new possibilities have been provided for the effective and sustainable treatment of various types of wastewater.

[0003] Membrane separation technology generally removes pollutants from water by physical isolation, and has many advantages such as simple operation, high efficiency, and environmental friendliness. Therefore, continuous exploration and optimization of membrane separation technology and combining it with other cleaning technologies are important paths to achieve efficient separation of dye wastewater. However, the selectivity and permeability of membrane separation technology are difficult to take into account and balance, and this limitation often limits the separation efficiency. In addition, pressure-driven membranes (such as nanofiltration membranes and reverse osmosis membranes) need to apply a large additional initial pressure during operation to obtain the necessary permeate flow, which inevitably leads to higher energy consumption.

[0004] As an innovative product of membrane treatment technology, conductive membrane not only has the ability to separate pollutants beyond traditional membrane materials, but also introduces a cleaning function. The uniqueness of conductive membrane is that it can separate through a variety of action mechanisms according to the difference in applied potential, such as direct oxidation, indirect oxidation, electrostatic repulsion and electrosorption, and is more efficient in removing harmful substances in solution. Conductive materials commonly used in conductive membranes include two-dimensional materials such as conductive polymers, carbon nanotubes, and graphene. Dead-end separation has been widely discussed in the past research on conductive membranes. Different researchers have proposed many theories, but cross-flow separation has occupied a major position in practical applications. Compared with dead-end separation, cross-flow separation systems can more effectively promote material transfer and separation in actual operation, while significantly improving the processing capacity of the membrane and reducing energy consumption. At present, research on conductive membranes based on cross-flow separation is relatively lacking, and there is still broad research space and potential improvement opportunities in this field. Therefore, in-depth exploration and optimization of the application of conductive membranes in cross-flow separation is of great significance to improving the efficiency and feasibility of membrane technology in environmental protection and industrial applications. Summary of the invention

[0005] The main purpose of the present invention is to overcome the above-mentioned problems existing in the prior art, and provide a low-pressure cross-flow conductive membrane pool 5, which includes a membrane pool body A (i.e., 5-5), a conductive membrane 5-6, a membrane pool body B (i.e., 5-8), and an electrode. A cross-flow pool 5-7 is arranged on the membrane pool body B, and the conductive membrane 5-6 is fixed between the membrane pool body A and the membrane pool body B and faces the cross-flow pool 5-7; the electrode passes through the membrane pool body B and is electrically connected to the conductive membrane 5-6.

[0006] Furthermore, a permeate outlet 5-1 is provided on the membrane pool body A, and a cavity for accommodating the permeate is provided between the conductive membrane 5-6 and the membrane pool body A. The permeate outlet 5-1 is connected to the cavity for discharging the treated permeate out of the low-pressure cross-flow conductive membrane pool.

[0007] Furthermore, a total feed liquid inlet 5-9, a cross-flow pool liquid inlet 5-12, a cross-flow pool liquid outlet 5-13, and a total feed liquid outlet 5-14 are provided on the membrane pool body B. The cross-flow pool liquid inlet 5-12 and the cross-flow pool liquid outlet 5-13 are both connected to the cross-flow pool 5-7, and the total feed liquid inlet 5-9 and the total feed liquid outlet 5-14 are respectively connected to the cross-flow pool liquid inlet 5-12 and the cross-flow pool liquid outlet 5-13, which are used to transport the waste liquid to be treated into the cross-flow pool for treatment and discharge the remaining liquid after treatment.

[0008] Furthermore, the low-pressure cross-flow conductive membrane pool also includes a porous plate 5-3 and a sealing rubber ring 5-4. The sealing rubber ring 5-4 is fixed in the cross-flow pool 5-7 and is pressed by the conductive membrane 5-6. The porous plate 5-3 is fixed in the cavity between the conductive membrane 5-6 and the membrane pool body A.

[0009] Furthermore, the electrodes include two membrane electrodes 5-10 and a cylindrical electrode 5-11.

[0010] The second object of the present invention is to provide a low-pressure cross-flow conductive membrane separation device, which includes the above-mentioned conductive membrane pool 5, a feeding device 1, and a discharging device 2. The feeding device 1 is filled with waste liquid to be treated, and the bottom outlet of the feeding device 1 is connected to the total liquid inlet 5-9 of the conductive membrane pool 5 through a feeding pipe 9. The top inlet of the feeding device 1 is connected to the permeate outlet 5-1 of the conductive membrane pool 5 through a discharging pipe 11, and the discharging device 2 is also connected in parallel to the discharging pipe 11.

[0011] Furthermore, the device also includes a diaphragm pump 7, which is arranged on the feed pipeline 9 and is used to provide a transmembrane pressure difference of 200 to 500 kPa.

[0012] Furthermore, the device also includes a temperature sensor 3 , a micro-flow regulating valve 4 , and a pressure sensor 6 . The temperature sensor 3 , the micro-flow regulating valve 4 , and the pressure sensor 6 are dispersedly arranged on the discharge pipe 11 and are located upstream of the discharge device 2 .

[0013] Furthermore, the discharge device 2 includes a discharge branch pipe 2-1 and a discharge valve 2-2 connected in series.

[0014] Furthermore, the feeding device 1 also includes a feeding tank 1-1 and a jacket 1-4 wrapped around it, and a cooling water outlet 1-2 and a cooling water inlet 1-3 are provided on the jacket 1-4. The feeding tank 1-1 is filled with waste liquid to be treated, and circulating cooling water flows into the jacket 1-4 from the cooling water inlet 1-3 and flows out from the cooling water outlet 1-2, thereby heating or cooling the waste liquid to be treated in the feeding tank 1-1.

[0015] Furthermore, the conductive membrane pool 5 is connected to an external power source 8 via electrodes for power supply, and the voltage of the external power source 8 does not exceed 10V.

[0016] A third object of the present invention is to provide an application of the low-pressure cross-flow conductive membrane separation device in water treatment.

[0017] Furthermore, the application process is specifically as follows: the wastewater to be treated is transported to the feeding device 1, the feed liquid enters the conductive membrane pool 5 through the feeding pipe 9 and the diaphragm pump 7 for cross-flow separation, and the obtained permeate returns to the feeding device 1 through the discharge pipe 11 or is discharged to the outside.

[0018] Furthermore, the pollutants in the wastewater to be treated include organic dyes such as methylene blue, Congo red, crystal violet, methyl blue, methyl orange, and heavy metal salts such as lead, chromium, cadmium, mercury, and arsenic.

[0019] The present invention combines the surface conductivity of the conductive membrane on the basis of porous membrane separation, and separates pollutants with various charges in the wastewater to be treated through the screening effect of membrane pores and the potential effect of the conductive membrane surface under an external electric field, which not only slows down membrane pollution, but also achieves the effect of long-term use. When the conductive membrane is polluted and the flux is reduced, the self-cleaning function can be activated, thereby effectively extending the service life of the conductive membrane. In addition, the low-pressure cross-flow conductive membrane pool and the corresponding separation device provided by the present invention have the advantages of simple structure, good separation effect, low cost, etc., and can treat various types of sewage and waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional view of the low-pressure cross-flow conductive membrane cell of the present invention;

[0021] Figure 2 It is a schematic diagram of the three-dimensional structure of the low-pressure cross-flow conductive membrane cell of the present invention;

[0022] Figure 3 It is a schematic structural diagram of the low-pressure cross-flow conductive membrane separation device of the present invention;

[0023] Figure 4 This is a comparison chart of the interception performance of different dyes by the low-pressure cross-flow conductive membrane separation device of the present invention at different voltages;

[0024] Figure 5 This is a comparison chart of the retention performance of different salts at different voltages of the low-pressure cross-flow conductive membrane separation device of the present invention.

[0025] Figure numerals: 1 feeding device, 1-1 feeding tank, 1-2 cooling water outlet, 1-3 cooling water inlet, 1-4 jacket; 2 discharging device, 2-1 discharging branch pipe, 2-2 discharging valve; 3 temperature sensor; 4 micro-flow regulating valve; 5 conductive membrane pool, 5-1 permeate outlet, 5-2 fixing bolt, 5-3 porous plate, 5-4 sealing rubber ring, 5-5 membrane pool top body, 5-6 conductive membrane, 5-7 cross-flow pool, 5-8 membrane pool bottom body, 5-9 total feed liquid inlet, 5-10 membrane electrode, 5-11 cylindrical electrode, 5-12 cross-flow pool inlet, 5-13 cross-flow pool outlet, 5-14 total feed liquid outlet; 6 pressure sensor; 7 diaphragm pump; 8 external power supply; 9 feeding pipeline; 10-filtrate outlet, 11 discharging pipeline. DETAILED DESCRIPTION

[0026] In order to enable ordinary technicians in the field to fully understand the technical solutions and beneficial effects of the present invention, further description is given below in conjunction with specific embodiments and drawings.

[0027] The core device of the present invention is as follows Figure 1-2 The conductive membrane pool 5 shown includes a permeate outlet 5-1, a fixing bolt 5-2, a porous plate 5-3, a sealing rubber ring 5-4, a membrane pool top body 5-5, a conductive membrane 5-6, a cross-flow pool 5-7, a membrane pool bottom body 5-8, a feed liquid total inlet 5-9, a membrane-connected electrode 5-10, a cylindrical electrode 5-11, a cross-flow pool liquid inlet 5-12, a cross-flow pool liquid outlet 5-13, and a feed liquid total outlet 5-14. The porous plate 5-3, the sealing rubber ring 5-4, the conductive membrane 5-6, and the cross-flow pool 5-7 are all arranged between the membrane pool top body 5-5 and the membrane pool bottom body 5-8. After four fixing bolts 5-2 pass through the screw holes on the membrane pool top body 5-5 and the membrane pool bottom body 5-8, the two and the various components and structures therebetween are fixed together.

[0028] A through permeate outlet 5-1 is provided in the middle of the top body 5-5 of the membrane pool. A through total feed liquid inlet 5-9 is provided on the side of the bottom body 5-8 of the membrane pool, a cross-flow pool 5-7 is provided on the top of the bottom body 5-8 of the membrane pool, and mounting holes for electrodes to pass through are provided at the bottom of the bottom body 5-8 of the membrane pool. The membrane-connected electrodes 5-10 and the cylindrical electrodes 5-11 are fixed on the bottom body 5-8 of the membrane pool after passing through these mounting holes. There are two membrane-connected electrodes 5-10, which are in contact with the symmetrical edges of the left and right sides or the front and back sides of the conductive membrane 5-6 respectively. The cylindrical electrode 5-11 is directly opposite to the center of the conductive membrane 5-6 and is not in contact with the conductive membrane 5-6. The membrane-connected electrode 5-10 is connected to the positive or negative pole of the external power supply 8, and the cylindrical electrode 5-11 is connected to the opposite electrode (negative pole or positive pole).

[0029] The membrane electrode 5-10 and the cylindrical electrode 5-11 are made of high conductivity materials such as metal materials and conductive metal oxides. The base membrane of the conductive membrane 5-6 includes but is not limited to ultrafiltration membranes, microfiltration membranes, nanofiltration membranes and other polymer porous membranes. The conductive membrane 5-6 has a single-layer surface conductive coating (i.e., a conductive coating is provided on one side), and the conductive coating material includes a conductive two-dimensional material and a conductive polymer. The conductive coating on the surface of the conductive membrane 5-6 is formed on the surface of the base membrane by vacuum assisted deposition and other methods. As a matching device, the top body 5-5 of the membrane pool and the bottom body 5-8 of the membrane pool are both made of transparent polymer insulating materials, such as polymethyl methacrylate, polystyrene, etc.

[0030] The bottom body 5-8 of the conductive membrane pool 5 is provided with a cross-flow pool inlet 5-12, a cross-flow pool outlet 5-13, a total feed liquid inlet 5-9 and a total feed liquid outlet 5-14. The total feed liquid inlet 5-9 is connected with the cross-flow pool inlet 5-12, and the total feed liquid outlet 5-14 is connected with the cross-flow pool outlet 5-13. During use, the sealing rubber ring 5-4 is located in the cross-flow pool 5-7, the conductive surface of the conductive membrane 5-6 contacts the sealing rubber ring 5-4, and the other surface contacts the porous plate 5-3, the bottom body 5-8 of the membrane pool and the top body 5-5 of the membrane pool fit each other, and are fixed together by fixing bolts 5-2.

[0031] A low-pressure cross-flow conductive membrane separation device constructed using the above conductive membrane pool is as follows: Figure 3As shown, it includes a feeding device 1, a discharging device 2, a temperature sensor 3, a micro-flow regulating valve 4, a conductive membrane pool 5, a pressure sensor 6, a diaphragm pump 7, an external power supply 8, a feeding pipeline 9, a filtrate outlet 10, and a discharging pipeline 11, wherein the upper and lower ends of the feeding device 1 are respectively connected to the permeate outlet 5-1 of the conductive membrane pool 5 and the total feed liquid inlet 5-9 through the discharging pipeline 11 and the feeding pipeline 9, and the filtrate outlet 10 is connected to the permeate outlet 5-1 of the conductive membrane pool 5 through the pipeline. A diaphragm pump 7 is arranged on the feeding pipeline 9 to provide a transmembrane pressure difference of 200 to 500 kPa. A pressure sensor 6, a micro-flow regulating valve 4, and a temperature sensor 3 are arranged on the discharging pipeline 11 in sequence, which are respectively used to detect or adjust the pressure, flow rate, and temperature of the permeate obtained by the treatment. A discharging branch pipe 2-1 is also arranged on the discharging pipeline 11 between the temperature sensor 3 and the feeding device 1, and a discharging valve 2-2 is arranged on the discharging branch pipe 2-1. The function of the discharge branch pipe and the discharge valve is to discharge the residual waste liquid inside the device after the treatment is completed. In addition, the waste water after cleaning the inside of the device is also discharged from the discharge branch pipe. In other cases, the discharge branch pipe and the discharge valve will not be opened. After the treated permeate is tested to be qualified, it can be discharged from the entire device through the permeate outlet 5-1; if the test is unqualified, it can flow back to the feeding device 1 again, adjust the treatment parameters and continue to process until it is qualified before being discharged.

[0032] The feeding device 1 is a sandwich structure, including an internal feeding tank 1-1 and an outer jacket 1-4. A cooling water outlet 1-2 and a cooling water inlet 1-3 are provided on the jacket 1-4. Circulating water flows into the jacket 1-4 from the cooling water inlet 1-3 and flows out of the jacket 1-4 from the cooling water outlet 1-2, thereby heating or cooling the wastewater to be treated stored in the feeding tank 1-1.

[0033] The low-pressure cross-flow conductive membrane separation device can be used to treat dye wastewater containing methyl orange, methyl blue, methylene blue, Congo red, crystal violet and the like, as well as industrial wastewater containing NaCl, Na2SO4, MgCl2, MgSO4 and the like. The specific process is as follows: assemble the whole set of equipment and check to confirm that the pipeline connection is intact, connect the membrane electrode 5-10 and the cylindrical electrode 5-11 to the external power supply 8, add the wastewater to be treated to the feeding device 1 and turn on the circulating cooling water, start the diaphragm pump 7 to input the wastewater to be treated into the conductive membrane pool 5 for treatment. After the feed liquid enters the cross-flow pool 5-7, it flows in the parallel direction of the conductive membrane diaphragm, and a part of it completes the cross-flow separation through the lateral partial pressure, and the obtained permeate flows out of the whole set of equipment through the permeate outlet 5-1. Another part of the untreated feed liquid in the cross-flow pool flows out of the conductive membrane pool 5 through the total feed liquid outlet 5-14, and returns to the feeding device 1 through the discharge pipe 11 and the discharge valve 2-2 to perform cross-flow separation again. After the liquid material treatment is completed, open the discharge valve 2-2, and the remaining waste liquid will be discharged from the entire device through the discharge branch pipe 2-1.

[0034] Application Example 1

[0035] The permeability and separation performance tests were carried out using a low-pressure cross-flow conductive membrane separation device. A simulated dye wastewater solution with a concentration of 0.1g / L was prepared and stirred at 700rpm for 30min to prevent concentration polarization. Before the experiment, all filter membranes need to be soaked in deionized water for more than 12h to ensure that the pores are filled with liquid, to enhance their flexibility and stability, and to prevent sudden pressure from causing damage to the membrane pore structure. The filter membrane was pretreated with deionized water at a pressure of 2.0bar for 30min to compact the separation layer to achieve a stable permeability flux. All experiments tested the separation performance of the device at a pressure of 1.0bar, and at least three repeated experiments were performed to ensure the accuracy of the results. Using Figure 3 The device shown in the figure treated methyl orange simulated wastewater, methyl blue simulated wastewater, Congo red simulated wastewater, crystal violet simulated wastewater, and methylene blue simulated wastewater, respectively. The results are shown in Figure 4 shown.

[0036] As can be seen from the figure, under the assisted action of the electric field, the low-voltage cross-flow conductive membrane separation device significantly improves the separation performance of dyes, breaking the balance between selectivity and permeability. For anionic dyes such as methyl orange, Congo red and methylene blue, the retention rates of these three dyes reached 86.85%, 98.87% and 99.12% respectively when a voltage of 10V was applied; for cationic dyes such as methyl blue and crystal violet, when a negative voltage of -10V was applied, the retention rates of these two dyes reached 100%.

[0037] Application Example 2

[0038] The permeability and separation performance tests were carried out using a low-pressure cross-flow conductive membrane separation device. A simulated inorganic salt wastewater solution with a concentration of 1g / L was prepared and stirred at 700rpm for 30min to prevent concentration polarization. Before the experiment, all filter membranes must be soaked in deionized water for more than 12h to ensure that the pores are filled with liquid, to enhance their flexibility and stability, and to prevent sudden pressure from causing damage to the membrane pore structure. The filter membrane was pretreated with deionized water at a pressure of 2.0bar for 30min to compact the separation layer to achieve a stable permeability flux. All experiments tested the separation performance of the device at a pressure of 1.0bar, and at least three repeated experiments were performed to ensure the accuracy of the results. Using Figure 3 The device shown in the figure treated NaCl simulated wastewater, Na2SO4 simulated wastewater, MgCl2 simulated wastewater, and MgSO4 simulated wastewater respectively. The results are shown in Figure 5 As shown. Figure 5 It can be seen that under the action of the electric field, the retention rate of various inorganic salts of the low-voltage cross-flow conductive membrane separation device increases with the increase of voltage, and it has a good separation and treatment effect.

Claims

1. A low-voltage cross-flow conductive membrane cell, Features: The low-pressure cross-flow conductive membrane pool includes a membrane pool body A, a conductive membrane, a membrane pool body B, and electrodes. A cross-flow pool is arranged on the membrane pool body B. The conductive membrane is fixed between the membrane pool body A and the membrane pool body B and faces the cross-flow pool. The electrode passes through the membrane pool body B and is electrically connected to the conductive membrane.

2. The low-pressure cross-flow conductive membrane cell according to claim 1, Features: A permeate outlet is provided on the membrane pool body A, and a cavity for accommodating the permeate is provided between the conductive membrane and the membrane pool body A, and the permeate outlet is communicated with the cavity.

3. The low-pressure cross-flow conductive membrane cell according to claim 1, Features: The membrane pool body B is provided with a total feed liquid inlet, a cross-flow pool inlet, a cross-flow pool outlet and a total feed liquid outlet. The cross-flow pool inlet and the cross-flow pool outlet are both connected to the cross-flow pool, and the total feed liquid inlet and the total feed liquid outlet are respectively connected to the cross-flow pool inlet and the cross-flow pool outlet.

4. The low-pressure cross-flow conductive membrane cell according to claim 1, Features: The low-pressure cross-flow conductive membrane pool also includes a porous plate and a sealing rubber ring. The sealing rubber ring is fixed in the cross-flow pool and compressed by the conductive membrane. The porous plate is fixed in the cavity between the conductive membrane and the membrane pool body A.

5. A low-pressure cross-flow conductive membrane separation device, Features: The device comprises a conductive membrane pool, a feeding device and a discharging device as described in any one of claims 1 to 4, wherein the waste liquid to be treated is contained in the feeding device, the bottom outlet of the feeding device is connected to the total liquid inlet of the conductive membrane pool through a feeding pipe, the top inlet of the feeding device is connected to the permeate outlet of the conductive membrane pool through a discharging pipe, and a discharging device is also connected in parallel to the discharging pipe.

6. The low-pressure cross-flow conductive membrane separation device according to claim 5, Features: The device also includes a diaphragm pump, a temperature sensor, a micro-flow regulating valve, and a pressure sensor, wherein the diaphragm pump is arranged on the feed pipeline, and the temperature sensor, the micro-flow regulating valve, and the pressure sensor are dispersedly arranged on the discharge pipeline and located upstream of the discharge device.

7. The low-pressure cross-flow conductive membrane separation device according to claim 5, Features: The feeding device also includes a feeding tank and a jacket covering the surface of the feeding tank, the jacket is provided with a cooling water outlet and a cooling water inlet, and the discharging device includes a discharging branch pipe and a discharging valve connected in series.

8. Application of the low-pressure cross-flow conductive membrane separation device according to any one of claims 5 to 7 in water treatment.

9. The use according to claim 8, Features The specific process of this application is as follows: the wastewater to be treated is transported to the feed device, the feed liquid enters the conductive membrane pool through the feed pipe and the diaphragm pump for cross-current separation, and the obtained permeate is returned to the feed device through the discharge pipe or discharged to the outside.

10. The use according to claim 9, Features: The pollutants in the wastewater to be treated include methylene blue, Congo red, crystal violet, methyl blue, methyl orange, lead, chromium, cadmium, mercury and arsenic.

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