Deionization method and system for mobile electrode capacitor

Abstract

The present invention provides a deionization method and system for a mobile electrode capacitor. The deionization system includes a mobile electrode capacitor device, a first delivery pump, a second delivery pump, a third delivery pump, an electrode slurry, and a pulse power supply; the first delivery pump and the anode chamber constitute a first circulation channel, the second delivery pump and the cathode chamber constitute a second circulation channel, and the third delivery pump and the treated liquid chamber constitute a third circulation channel; the pulse power supply is electrically connected to the mobile electrode capacitor device, and generates a pulse electric field on the mobile electrode capacitor device that points from the anode chamber to the cathode chamber. In the above-mentioned mobile electrode capacitor deionization system, the ion migration in the FCDI process is enhanced by the pulse power supply drive, and a certain relaxation time is provided for the FCDI adsorption process through the "on-off-on" alternating pulse action mechanism, which can effectively alleviate the concentration polarization behavior of ions on the surface of the ion exchange membrane and is beneficial to the transmembrane transport of ions.

Description

Technical Field

[0001] The present invention relates to the field of electrically driven capacitors, and in particular to a deionization method and system for mobile electrode capacitors. Background Art

[0002] Treatment of high-salinity wastewater remains a serious challenge to the growing demand for fresh water, which has led to the development of various desalination technologies. Electrically driven capacitive deionization has low energy consumption and is environmentally friendly, making it a promising technology for high-salinity wastewater treatment and seawater desalination. Flow-electrode capacitive deionization (FCDI) utilizes a flowing electrode slurry and theoretically has a pseudo-infinite desalination capacity, allowing long-term operation without the need for additional regeneration steps. Compared with reverse osmosis and multi-stage evaporation, FCDI further reduces energy consumption and improves the efficiency of seawater desalination.

[0003] The flow channel structure in FCDI devices has been shown to enhance the fluidity of electrode slurry. However, this has a negative impact on the desalination efficiency, charge efficiency, and system energy efficiency of traditional FCDI devices. Summary of the Invention

[0004] The main purpose of the present invention is to provide a deionization method and system for a mobile electrode capacitor to solve the technical problems of low charge transfer process and ion capture efficiency of traditional FCDI devices.

[0005] To achieve the above-mentioned object, the present invention provides a deionization system of a mobile electrode capacitor, comprising a mobile electrode capacitor device, a first delivery pump, a second delivery pump, a third delivery pump, an electrode slurry and a pulse power supply; the mobile electrode capacitor device comprises an anode chamber, a cathode chamber and a chamber for a liquid to be treated;

[0006] The first delivery pump and the anode chamber form a first circulation channel, the second delivery pump and the cathode chamber form a second circulation channel, and the third delivery pump and the chamber for the liquid to be treated form a third circulation channel;

[0007] The electrode slurry is located in the first circulation channel and the second circulation channel;

[0008] The pulse power supply is electrically connected to the flow electrode capacitor device and generates a pulse electric field on the flow electrode capacitor device that points from the anode chamber to the cathode chamber.

[0009] According to an embodiment of the present application, the pulse intensity of the pulse electric field is 60-100 mA, the duty cycle is 20-90%, the frequency is 1-100 Hz, and the operating time is 60-1800 min.

[0010] According to an embodiment of the present application, the mobile electrode capacitor device includes a first current collector, a cation exchange membrane, a liquid inlet separator, an anion exchange membrane and a second current collector arranged in sequence;

[0011] The working surfaces of the first current collector and the second current collector respectively have a first flow channel and a second flow channel, the first flow channel and the cation exchange membrane form the anode chamber, the second flow channel and the anion exchange membrane form the anode chamber, and the liquid inlet partition has a through cavity to form a liquid chamber to be treated.

[0012] According to an embodiment of the present application, the first flow channel and the second flow channel are both etched into single-track serpentine flow channels, and the working surface is the surface of the first current collector and the second current collector facing the liquid inlet partition;

[0013] The monorail serpentine flow channel is composed of a plurality of horizontal flow channels connected end to end in sequence. The depth of the horizontal flow channel is 1 to 3 mm and the width is 1 to 4 mm.

[0014] According to an embodiment of the present application, the flow channel area corresponding to the total length of the monorail serpentine flow channel is 40% to 60% of the total area of ​​the working surface.

[0015] According to an embodiment of the present application, the electrode slurry includes activated carbon, carbon nanotubes, carbon black and sodium chloride, the activated carbon accounts for 5 to 20% of the mass of the electrode slurry, the carbon nanotubes account for 0.1 to 1% of the mass of the electrode slurry, the carbon black accounts for 0.1 to 1% of the mass of the electrode slurry; and the sodium chloride accounts for 0.1 to 2% of the mass of the electrode slurry.

[0016] According to an embodiment of the present application, the method for preparing the electrode slurry includes:

[0017] The carbon nanotubes and conductive carbon black are mixed in a ratio of 1:1 to obtain a conductive additive;

[0018] The activated carbon and 1000 mg / L sodium chloride solution were mixed at a mass ratio of 2.5 to 20:100, and a conductive additive was added at a solid-liquid ratio of 0.2 to 2 g:100 ml, and stirred for 12 hours to obtain an electrode slurry.

[0019] The present application also provides a deionization method using a mobile electrode capacitor, comprising the following steps:

[0020] introducing the electrode slurry into the anode chamber and cathode chamber of the flowing electrode capacitor device for circulation;

[0021] The water to be treated is introduced into the liquid chamber to be treated of the flow electrode capacitor device for circulation;

[0022] electrically connecting a pulse power supply to the mobile electrode capacitor device, and generating a pulse electric field on the mobile electrode capacitor device directed from the anode chamber to the cathode chamber;

[0023] After applying the pulse electric field for 60 to 1800 minutes, deionization is completed.

[0024] According to an embodiment of the present application, the pulse intensity of the pulse electric field is 60-100 mA, the duty cycle is 20-90%, the frequency is 1-100 Hz, and the operating time is 60-1800 min.

[0025] According to an embodiment of the present application, the flow rate of the electrode slurry and the water to be treated is 5 to 15 mL / min.

[0026] In the aforementioned mobile electrode capacitor deionization system, a pulsed power supply is used to enhance ion migration during the FCDI process. The alternating "on-off-on" pulse mechanism provides a certain relaxation time for the FCDI adsorption process, effectively alleviating the concentration polarization behavior of ions on the ion exchange membrane surface and facilitating ion transport across the membrane. Compared to traditional constant electric fields, this type of unsteady-state pulsed electric field exhibits significant advantages in ion enrichment efficiency and energy consumption in FCDI systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0028] Figure 1 A schematic diagram of the structure of the mobile electrode capacitive deionization device of the present invention;

[0029] Figure 2 A schematic diagram of the structure of the mobile electrode capacitive deionization device according to the present invention;

[0030] Figure 3 Schematic diagram of the structure of the serpentine flow channel in the present invention.

[0031] Figure 4 The current and voltage changes during the operation of the FCDI in different types of electric fields in the present invention, where (a) and (b) are the induced current changes, and (c) and (d) are the induced voltage changes;

[0032] Figure 5The FCDI desalination performance changes of different types of electric fields in the present invention, where (a) is the change of brine concentration, (b) is SR and ASRR, and (c) is CE and E m , (d) is pH change;

[0033] Figure 6 The desalination performance of FCDI with different pulse intensities in the present invention is shown in Figure 2, where (a) is the electric field intensity, (b) is the change in brine concentration, (c) is SR and ASRR, and (d) is CE and E m ;

[0034] Figure 7 The desalination performance of FCDI at different frequencies in the present invention is shown in Figure 2, where (a) is the electric field intensity, (b) is the change in brine concentration, (c) is SR and ASRR, and (d) is CE and E m ;

[0035] Figure 8 The desalination performance of FCDI with different duty cycles in the present invention is shown in Figure 2, where (a) is the electric field intensity, (b) is the change in brine concentration, (c) is SR and ASRR, and (d) is CE and E m ;

[0036] Figure 9 The desalination performance of the FCDI system with constant current electric field and pulse electric field in the present invention during long-term operation.

[0037] 100, first current collector; 200, cation exchange membrane; 300, liquid inlet partition; 400, anion exchange membrane; 500, second current collector; 600, monorail serpentine flow channel; 800, end plate; 900, flexible gasket; 1000, fastener;

[0038] 10. Flowing electrode capacitor device; 21. First delivery pump; 22. Second delivery pump; 23. Third delivery pump; 50. Power supply; 60. Magnetic stirrer; 80. Electrode slurry storage tank; 90. Brine storage tank; 30. Computer control terminal.

[0039] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0040] The following will be combined with the accompanying 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0041] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0042] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of these features.

[0043] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0044] The applicant has conducted extensive research on the technical problems of insufficient desalination efficiency and energy efficiency in traditional FCDI systems. The study found that under the action of a constant electric field (constant voltage or constant current), anions and cations undergo directional migration. As the FCDI process proceeds, due to the difference between the ion diffusion rate and the ion electromigration rate in the electrode slurry, ions are easily accumulated on the surface of the ion exchange membrane close to the electrode chamber and a concentration gradient is generated, forming a concentration polarization phenomenon. At the same time, when ions migrate to the micropores on the electrode surface, due to the polarity of the H2O molecules, their inherent dipole moment will undergo an orientation polarization effect and be oriented. Under the electrostatic induction of the ions, they will combine with the ions to form a stable hydration layer, increasing the migration resistance of the ions in the electrode slurry. The above two phenomena greatly limit the ion transport in the FCDI process, and have an adverse effect on the desalination efficiency, charge efficiency and energy efficiency of the FCDI system.

[0045] The present invention provides a deionization system of mobile electrode capacitance, see Figure 2 , comprises a mobile electrode capacitor device 10 (FCDI device), a first delivery pump 21, a second delivery pump 22, a third delivery pump 23, an electrode slurry and a pulse power supply 50. The mobile electrode capacitor device 10 comprises an anode chamber, a cathode chamber and a liquid chamber to be processed. The first delivery pump 21 and the anode chamber constitute the first circulation channel, the second delivery pump 22 and the cathode chamber constitute the second circulation channel, and the third delivery pump 23 and the liquid chamber to be processed constitute the third circulation channel. The electrode slurry is located in the first circulation channel and the second circulation channel. The pulse power supply 50 is electrically connected with the mobile electrode capacitor device 10, and produces a pulse electric field directed to the cathode chamber by the anode chamber on the mobile electrode capacitor device 10.

[0046] The structure of the mobile electrode capacitor device 10 is not specifically limited. The mobile electrode capacitor device 10 generally includes an anode chamber, a cathode chamber, and a chamber for the liquid to be treated. The chamber for the liquid to be treated is located between the anode chamber and the cathode chamber. Typically, the two current collectors of the mobile electrode capacitor device 10 cooperate with corresponding ion exchange membranes to form the anode chamber and the cathode chamber. The partition within the mobile electrode capacitor device 10 has a cavity to form the chamber for the liquid to be treated.

[0047] The first delivery pump 21, the second delivery pump 22, and the third delivery pump 23 can be peristaltic pumps. The pulse power supply 50 is generally connected to the two current collectors of the flowing electrode capacitor device 10, thereby generating a pulsed electric field within the flowing electrode capacitor device 10. The pulsed electric field replaces the steady-state electric field (constant current electric field and constant voltage electric field) as the driving force of the FCDI device.

[0048] The pulsed electric field is a periodic, intermittent electric field, distinct from steady-state electric fields (constant current and constant voltage fields), i.e., a non-steady-state electric field that alternates between on and off states according to a specific pattern. During FCDI operation, the pulsed electric field can suppress the supersaturation of the polarization boundary layer on the surface of the ion exchange membrane, mitigate the polarization effect of the H2O molecular dipole moment, weaken the thickness of the ion hydration layer, and enhance ion diffusion and transport during the FCDI process. By enhancing ion diffusion and transport during the FCDI process, the pulsed electric field-driven FCDI device improves both the desalination efficiency and energy efficiency of the FCDI device.

[0049] By replacing the traditional steady-state electric field with an alternating pulse electric field, the supersaturation of the polarization boundary layer on the membrane surface can be suppressed, the polarization effect of the H2O molecular dipole moment can be alleviated, the thickness of the ion hydration layer can be weakened, and the ion diffusion transport during the FCDI process can be enhanced.

[0050] For example, Figure 2 As shown, the FCDI system mainly includes a peristaltic pump, a conductivity meter, an FCDI device, a magnetic stirrer 60, a power supply tester, an electrode slurry storage tank 80, a brine storage tank 90, and a computer control terminal 30. During operation, under the action of the peristaltic pump, the brine solution enters the FCDI device at a certain flow rate, and then maintains a circulation flow between the brine storage tank and the FCDI device. For the electrode slurry, this study adopts a short-circuit closed operation mode, that is, under the action of the peristaltic pump, the electrode slurry enters the cathode chamber and the anode chamber respectively, and then the two slurries merge into the electrode slurry storage tank and maintain a circulation flow. The power supply tester 50 is used to apply an electric field to the FCDI device and record the changes in the induced current (I) or induced voltage (V) in real time. In addition, the conductivity of the brine solution is monitored and recorded in real time by a conductivity meter connected to the computer.

[0051] In the aforementioned mobile electrode capacitor deionization system, a pulsed power supply 50 is used to enhance ion migration during the FCDI process. The alternating "on-off-on" pulse mechanism provides a certain relaxation time for the FCDI adsorption process, effectively alleviating the concentration polarization of ions on the ion exchange membrane surface and facilitating ion transport across the membrane. Compared to traditional constant electric fields, this unsteady pulsed electric field exhibits significant advantages in ion enrichment efficiency and energy consumption in FCDI systems.

[0052] In some embodiments, the pulse electric field has a pulse intensity of 60-100 mA, a duty cycle of 20-90%, a frequency of 1-100 Hz, and an operating time of 60-1800 min.

[0053] The pulse electric field is provided by an uninterruptible pulse power supply 50; in the electric field parameter setting, pulse intensity refers to the current intensity in the power-on state; duty cycle refers to the ratio of the power-on time to the pulse period; and pulse frequency refers to the number of pulse periods per unit time.

[0054] In some embodiments, see Figure 1 The mobile electrode capacitor device 10 includes a first current collector 100, a cation exchange membrane 200, a liquid inlet separator 300, an anion exchange membrane 400, and a second current collector 500, which are arranged in sequence. The working surfaces of the first current collector 100 and the second current collector 500 respectively have a first flow channel and a second flow channel. The first flow channel and the cation exchange membrane 200 form the anode chamber, and the second flow channel and the anion exchange membrane 400 form the anode chamber. The liquid inlet separator 300 has a through cavity, forming a chamber for the liquid to be treated.

[0055] Generally speaking, the first current collector 100, cation exchange membrane 200, liquid inlet separator 300, anion exchange membrane 400, and second current collector 500 are closely fitted together, for example, by fasteners 1000. The surfaces of the first current collector 100 and the second current collector 500 facing the liquid inlet separator 300 are called working surfaces.

[0056] The materials of the first current collector 100 and the second current collector 500 are not specifically limited and include a variety of materials, such as a graphite plate structure. The first current collector 100 and the second current collector 500 are mechanically etched or chemically etched as needed to form grooves of corresponding shapes on the working surface to form corresponding first and second flow channels.

[0057] The cation exchange membrane 200 is closely attached to the working surface of the first current collector 100 and cooperates with the first flow channel to form a chamber that restricts the flow of the electrode slurry. The anion exchange membrane 400 is closely attached to the working surface of the second current collector 500 and cooperates with the second flow channel to form another chamber that restricts the flow of the electrode slurry. These two chambers are independent of each other.

[0058] The liquid inlet separator 300 has a receiving cavity therein. This cavity is continuous along its thickness, with one side contacting the anion exchange membrane 400 and the other side contacting the cation exchange membrane 200. In other words, the liquid inlet separator 300 is hollow, providing a chamber for the flow of treated water. Overall, the mobile electrode capacitor device 10 comprises three chambers arranged sequentially along the stacking direction.

[0059] In some embodiments, the mobile electrode capacitor device 10 includes a first current collector 100, a cation exchange membrane 200, a liquid inlet separator 300, an anion exchange membrane 400, and a second current collector 500, which are arranged in sequence. The working surfaces of the first current collector 100 and the second current collector 500 respectively have a first flow channel and a second flow channel. The first flow channel and the cation exchange membrane 200 form the anode chamber, and the second flow channel and the anion exchange membrane 400 form the anode chamber. The liquid inlet separator 300 has a through cavity, forming a chamber for the liquid to be treated.

[0060] In some embodiments, see Figure 3 The first and second flow channels are both etched into a single-track serpentine flow channel 600. The working surface is the surface of the first current collector 100 and the second current collector 500 facing the liquid inlet partition 300. The single-track serpentine flow channel 600 is composed of multiple horizontal flow channels connected end to end. The depth of the horizontal flow channel is 1 to 3 mm and the width is 1 to 4 mm.

[0061] In some embodiments, the total length of the monorail serpentine flow channel 600 corresponds to a flow channel area of ​​40% to 60% of the total area of ​​the working surface.

[0062] In some embodiments, the mobile electrode capacitor device 10 also includes two end plates 800, two flexible gaskets 900 and a fastener 1000. The end plate 800, the flexible gasket 900, the first current collector 100, the cation exchange membrane 200, the liquid inlet partition 300, the anion exchange membrane 400, the second current collector 500, the other flexible gasket 900 and the end plate 800 are arranged in sequence and fixed by the fastener 1000.

[0063] For example, the mobile electrode capacitor device 10 is sequentially composed of an acrylic end plate 800, a silicone gasket (flexible gasket 900), an anode graphite plate (first current collector 100), an anion exchange membrane 400, a brine compartment, a cation exchange membrane 200, a cathode graphite plate (second current collector 500), a silicone gasket (flexible gasket 900), and an end plate 800. These components are assembled in series in a stacked manner using screws and nuts (fasteners 1000) to ensure the sealing of the FCDI device.

[0064] In some embodiments, the electrode slurry includes activated carbon, carbon nanotubes, carbon black and sodium chloride, the activated carbon accounts for 5-20% of the mass of the electrode slurry, the carbon nanotubes account for 0.1-1% of the mass of the electrode slurry, the carbon black accounts for 0.1-1% of the mass of the electrode slurry; and the sodium chloride accounts for 0.1-2% of the mass of the electrode slurry.

[0065] This electrode slurry is a ternary carbon composite flow electrode material. In this electrode slurry, the "filling" effect of carbon black particles and the "bridging" effect of carbon nanotube particles induce the formation of cross-linked "electrical bridges" through the strong interaction of high-frequency collisions between particles. This enables multi-path conduction of electrons between particles or between particles and current collectors, effectively improving the conductivity of the electrode slurry and the desalination rate of the FCDI process.

[0066] In some embodiments, the method for preparing the electrode slurry comprises:

[0067] The carbon nanotubes and conductive carbon black are mixed in a ratio of 1:1 to obtain a conductive additive;

[0068] The activated carbon and 1000 mg / L sodium chloride solution were mixed at a mass ratio of 2.5 to 20:100, and a conductive additive was added at a solid-liquid ratio of 0.2 to 2 g:100 ml, and stirred for 12 hours to obtain an electrode slurry.

[0069] For example, the activated carbon, carbon nanotubes and carbon black are mixed with sodium chloride electrolyte and continuously stirred to ensure that the particles are completely wetted to obtain the ternary carbon composite flow electrode material. Before use, the slurry needs to be ultrasonically treated to disperse it.

[0070] Specifically, activated carbon and 1000mg / L sodium chloride solution were mixed at a mass ratio of 5:100. A conductive additive, consisting of carbon nanotubes and conductive carbon black, was added at a solid-liquid ratio of 1g:100ml. The electrode slurry was stirred for 12 hours to ensure uniform mixing and ultrasonically dispersed for 30 minutes before use to ensure proper dispersion.

[0071] The present application also provides a deionization method using a mobile electrode capacitor, comprising the following steps:

[0072] The electrode slurry is introduced into the anode chamber and the cathode chamber of the flowing electrode capacitor device 10 and circulates therein.

[0073] The water to be treated is introduced into the treated liquid chamber of the mobile electrode capacitor device 10 and circulated therein.

[0074] The pulse power supply 50 is electrically connected to the flow electrode capacitor device 10 , and generates a pulse electric field on the flow electrode capacitor device 10 , which is directed from the anode chamber to the cathode chamber.

[0075] After applying the pulse electric field for 60 to 1800 minutes, deionization is completed.

[0076] Exemplarily, the flow electrode capacitive deionization method comprises the following steps:

[0077] S1, the electrode slurry and saline prepared in advance are pumped into the flow electrode capacitive deionization device through a peristaltic pump. After the electrode slurry and saline flow stably, the FCDI device is connected to an uninterruptible power supply.

[0078] S2, connecting the power supply via a computer, setting the pulsed electric field parameters, including pulse intensity, duty cycle, frequency, and operating time, turning on the power supply, and desalinating the brine using the FCDI device under the drive of the pulsed electric field.

[0079] S3, after the desalination treatment is completed, collecting the brine after the desalination treatment, that is, completing the pulse electric field-based mobile electrode capacitive deionization device.

[0080] In some embodiments, the pulse electric field has a pulse intensity of 60-100 mA, a duty cycle of 20-90%, a frequency of 1-100 Hz, and an operating time of 60-1800 min.

[0081] In some embodiments, the flow rate of the electrode slurry and the water to be treated is 5 to 15 mL / min.

[0082] In some embodiments, the flow electrode capacitive deionization method comprises the following steps:

[0083] S01, assembling the components of the mobile electrode capacitive deionization device in series by stacking them using screws and nuts, and arranging them in the order of electrode chamber, saline chamber, and electrode chamber;

[0084] S02, pumping the electrode slurry and brine into the water inlet of the FCDI device respectively by a peristaltic pump, so that they enter the corresponding chambers respectively and circulate in the FCDI device;

[0085] S03, after presetting the pulse electric field parameters and reaction time, providing a pulse electric field to the current collector of the FCDI device to drive the FCDI device to desalinate;

[0086] On the basis of the above embodiments, in order to facilitate understanding by those skilled in the art, examples are given below for illustration:

[0087] Without affecting the understanding of the present invention, in FCDI, C effluent concentration, C0 initial concentration, (C / C0) effluent concentration change, ASRR (μmol cm -2 min -1 ) Average desalination efficiency, CE (%), current efficiency, SR desalination efficiency (%), Em (kWh mol -1 )Energy expenditure and ENRS (μmol J -1 ) Energy efficiency, used to evaluate desalination capacity.

[0088] The present invention provides a flow electrode capacitive deionization device based on a pulsed electric field, including a three-chamber structure arranged in sequence along the stacking direction. The main components from left to right are an acrylic end plate, a silicone gasket, an anode graphite plate, an anion exchange membrane, a brine compartment, a cation exchange membrane, a cathode graphite plate, a silicone gasket and an end plate. The brine compartment is a hollow structure that provides a chamber for the flow of brine, and the size of the chamber is 1×40×50mm. In addition, the graphite plates are all etched with flow channels of a specific structure to provide channels for the flow of electrode slurry, and the effective contact area (Aeff) of the flow channel is 10.88cm 2 The above components are assembled in series in a stacked manner using screws and nuts to ensure the sealing of the FCDI device.

[0089] Example 1

[0090] The electrode slurry is prepared by mixing according to the ratio, wherein the slurry is a mixture of activated carbon and 1000mg / L sodium chloride solution at a solid-liquid ratio of 1g:10ml, and a conductive additive is added at a mass ratio of 5:1, wherein the conductive additive is a mixture of carbon nanotubes and conductive carbon black at a ratio of 1:1. Using 3000mg / L sodium chloride solution as the brine solution, the FCDI system is driven by different types of electric fields. Specifically, under a constant voltage (U=1.6V) electric field, the preset running time is 1h, the average induced current of the FCDI process is obtained, and this is used as the current intensity of the constant current electric field and the pulsed electric field, and it is also run for 1h. The first and second flow channels of the FCDI system are both single-track serpentine flow channels. The depth of the horizontal flow channel is 2mm and the width is 2mm. The flow channel area corresponding to the total length of the single-track serpentine flow channel is 54.4% of the total area of ​​the working surface.

[0091] The average induced current A = 75 mA is obtained under the constant voltage (CV) condition of U = 1.6 V, and this is used as the current intensity of the constant current electric field (CC) and the pulse intensity of the pulse electric field (PC). The duty cycle of the pulse electric field is 50% and the pulse frequency is 50 Hz. Figure 4 As shown in the figure, the current and voltage changes under the three different types of electric fields show that the induced current under the constant voltage field shows a trend of slowly increasing and then gradually decreasing. There are significant differences in the induced voltage changes under the constant current and pulse current fields. The induced voltage in the constant current system shows a change characteristic of first being stable and then rising sharply, eventually exceeding 1.9V. The induced voltage shows small fluctuations with the periodic changes of the pulse current, and none of them exceeds 1.6V.

[0092] Furthermore, the changes in FCDI desalination performance under three electric field modes were calculated and obtained, such as Figure 5 The SR of the PC mode (52.81%) is significantly better than that of CC (41.39%) and CV (33.94%). The ASRR of the FCDI system under PC mode operation reaches 4.15 μmol cm -2 min -1 , which are 1.27 and 1.56 times of CC and CV modes respectively. m ,like Figure 5 As shown in (c), the CE (98.44%) of the PC mode in the FCDI process is higher than that of CC (85.94%) and CV (90.56%). More importantly, the molar energy consumption ratio Em of the system in the PC mode is as low as 0.018 kWh mol -1 , relative to CV (0.043 kWh mol -1 ) and CC (0.037kWhmol -1 ) mode were reduced by 58.13 and 51.51% respectively, indicating that the energy efficiency of the system in PC mode was significantly improved.

[0093] Example 2

[0094] The difference from Example 1 is that the pulse intensity parameter of the pulse electric field is regulated, and different pulse intensities (60-100 mA) are set to perform the desalination test of the FCDI device. Figure 6 The FCDI desalination performance changes under different pulse intensity conditions are shown in Figure 2. The pulse frequency (f) is set to 5 Hz, the operating duty cycle is 50%, and the initial brine concentration is 3000 mg L -1 (Conductivity is 5298μS cm -1 ).

[0095] With the increase of pulse intensity, the desalination performance showed a linear upward trend, with SR increasing from 31.64 to 64.43% and ASRR increasing from 2.48 to 5.07 μmol cm -2 min -1 However, when the pulse intensity was further increased from 60 to 90 mA, the CE decreased from 97.92 to 77.33%. Therefore, appropriate pulse intensity may further induce ion migration during FCDI, which is beneficial for ion capture. Based on the principle of efficiency priority, Ap = 90 mA was selected as the pulse intensity for subsequent experiments, and its SR and ASRR reached 61.19% and 4.81 μmol cm, respectively. -2 min -1 .

[0096] Example 3

[0097] The difference from Example 1 is that the FCDI system uses 90 mA as the pulse intensity, the operating duty cycle is 50%, and the brine concentration is 3000 mg L -1 , and set four pulse frequencies (f = 1-100Hz), the running time is 1h, and its desalination performance is as follows Figure 7 shown.

[0098] The FCDI desalination performance does not show a linear improvement with the increase of f. First, when f increases from 1 to 5 Hz, the brine effluent concentration decreases significantly, the SR increases from 37.26 to 61.19%, and the ASRR increases from 2.92 to 4.81 μmol cm -2 min -1 When f further increases from 5 Hz to 100 Hz, both SR and ASRR show a downward trend, with SR decreasing to 50.25% and ASRR decreasing to 3.84 μmol cm -2 min -1 In addition, for CE and Em, as f increases, CE decreases from 97.92 to 86.16%, while the energy consumption ratio Em continues to increase (i.e., from 0.011 to 0.031 kWh mol -1 ). Therefore, based on the above, the appropriate f (5Hz) is selected as the operating condition for subsequent tests.

[0099] Example 4

[0100] The difference from Example 1 is that four different duty ratios (γ = 20, 50, 70, 90%) are set, 90 mA is used as the pulse intensity, the pulse frequency is 5 Hz, and the saline concentration is 3000 mg L -1 ,like Figure 8 shown.

[0101] When the duty cycle increases from 20% to 70%, the SR, ASRR, CE, and Em in the FCDI system are all positively promoted. SR and ASAR increase linearly with the increase of γ, that is, from 26.41 to 76.64% and 1.88 to 5.94 μmol cm, respectively. -2 min -1 In addition, for CE and Em, as Figure 8 As shown in (d), the CE of the FCDI system increased from 90.77 to 99.61%, and the energy consumption ratio continued to decrease (from 0.025 to 0.011 kWh mol -1 However, further increasing the duty cycle (γ = 90%) results in a decrease in FCDI desalination performance. Using a pulse duty cycle of γ = 70% can effectively alleviate the concentration polarization of ions on the membrane surface and the orientation polarization of water molecules on the electrode particle surface during the FCDI process, while also maximizing the electric field drive effect, thereby further optimizing the desalination efficiency and energy efficiency during the FCDI process.

[0102] Example 5

[0103] The difference from Example 1 is that, based on the pulse electric field parameter control, the ternary carbon composite electrode is used as the electrode slurry to set the pulse electric field (PC) with a pulse intensity of 90 mA, a pulse frequency of 5 Hz, a duty cycle of 70%, and an initial brine concentration of 5000 mg L -1 (Conductivity is 8656μScm -1 ), and a DC electric field with a constant current of 90 mA (CC) was used as a comparison.

[0104] like Figure 9 As shown in the figure, during the 1800-min continuous operation, the SR of the FCDI process under the two electric field driving effects reached 95.84% under the pulse driving effect, that is, the concentration of the purified brine was reduced to 208.94 mg L-1, while the SR under the DC electric field was only 70.21%. Correspondingly, the pulse electric field showed a faster ASRR (7.64 μmol cm-1). -2 min -1 ), which is 1.37 times that of the DC electric field. In addition, the CE of the pulsed electric field remained stable throughout the entire continuous process, with an average CE of 96.27% and a low Em (0.021 kWh mol -1 ), and the energy consumption ratio generated by the DC electric field is 2.76 times that of the pulsed electric field. Compared with the traditional constant electric field, this type of unsteady-state pulsed electric field shows significant advantages in ion enrichment efficiency and energy consumption in the FCDI system.

[0105] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A deionization system of mobile electrode capacitance, characterized in that: It includes a mobile electrode capacitor device, a first delivery pump, a second delivery pump, a third delivery pump, an electrode slurry and a pulse power supply; the mobile electrode capacitor device includes an anode chamber, a cathode chamber and a chamber for a liquid to be treated; The first delivery pump and the anode chamber form a first circulation channel, the second delivery pump and the cathode chamber form a second circulation channel, and the third delivery pump and the chamber for the liquid to be treated form a third circulation channel; The electrode slurry is located in the first circulation channel and the second circulation channel; The pulse power supply is electrically connected to the flow electrode capacitor device and generates a pulse electric field on the flow electrode capacitor device that points from the anode chamber to the cathode chamber.

2. The deionization system according to claim 1, characterized in that The pulse electric field has a pulse intensity of 60-100 mA, a duty cycle of 20-90%, a frequency of 1-100 Hz and a running time of 60-1800 min.

3. The deionization system according to claim 1, characterized in that The mobile electrode capacitor device comprises a first current collector, a cation exchange membrane, a liquid inlet partition, an anion exchange membrane and a second current collector arranged in sequence; The working surfaces of the first current collector and the second current collector respectively have a first flow channel and a second flow channel, the first flow channel and the cation exchange membrane form the anode chamber, the second flow channel and the anion exchange membrane form the anode chamber, and the liquid inlet partition has a through cavity to form a liquid chamber to be treated.

4. The deionization system according to claim 3, characterized in that The first flow channel and the second flow channel are both etched into single-track serpentine flow channels, and the working surface is the surface of the first current collector and the second current collector facing the liquid inlet partition; The monorail serpentine flow channel is composed of a plurality of horizontal flow channels connected end to end in sequence. The depth of the horizontal flow channel is 1 to 3 mm and the width is 1 to 4 mm.

5. The deionization system according to claim 4, characterized in that The total length of the monorail serpentine flow channel corresponds to a flow channel area of ​​40 to 60% of the total area of ​​the working surface.

6. The deionization system according to any one of claims 1 to 5, characterized in that: The electrode slurry comprises activated carbon, carbon nanotubes, carbon black and sodium chloride, wherein the activated carbon accounts for 5-20% of the mass of the electrode slurry, the carbon nanotubes account for 0.1-1% of the mass of the electrode slurry, the carbon black accounts for 0.1-1% of the mass of the electrode slurry; and the sodium chloride accounts for 0.1-2% of the mass of the electrode slurry.

7. The deionization system according to claim 6, characterized in that The preparation method of the electrode slurry comprises: The carbon nanotubes and conductive carbon black are mixed in a ratio of 1:1 to obtain a conductive additive; The activated carbon and 1000 mg / L sodium chloride solution were mixed at a mass ratio of 2.5 to 20:100, and a conductive additive was added at a solid-liquid ratio of 0.2 to 2 g:100 ml, and stirred for 12 hours to obtain an electrode slurry.

8. A method for deionization of a mobile electrode capacitor, characterized in that: The following steps are involved: introducing the electrode slurry into the anode chamber and cathode chamber of the flowing electrode capacitor device for circulation; The water to be treated is introduced into the liquid chamber to be treated of the flow electrode capacitor device for circulation; electrically connecting a pulse power supply to the mobile electrode capacitor device, and generating a pulse electric field on the mobile electrode capacitor device directed from the anode chamber to the cathode chamber; After applying the pulse electric field for 60 to 1800 minutes, deionization is completed.

9. The deionization method according to claim 8, characterized in that The pulse electric field has a pulse intensity of 60-100 mA, a duty cycle of 20-90%, a frequency of 1-100 Hz and a running time of 60-1800 min.

10. The deionization method according to claim 8, characterized in that The flow rate of the electrode slurry and the water to be treated is 5 to 15 mL / min.

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