A method and device for removing chloride ions from water

Abstract

The present invention relates to a method and device for removing chloride ions from water, and belongs to the technical field of electro-adsorption ion water treatment. The device includes a raw water tank, a fresh water tank, a sewage tank, a microchannel chip, and a DC / AC voltage regulating power supply. By integrating the groove-shaped sawtooth structure microchannel and the curved surface electrode, the integrated structure of the curved surface electrode and the groove-shaped sawtooth structure microchannel is realized, so that it has specific functions and properties, and no additional assembly steps are required, which simplifies its production process. The sawtooth surface of activated carbon makes it difficult for chloride ions to escape after contacting the wall of the microchannel, and it is easier to be intercepted by the anode; more chloride ions can be released during the backwashing process; the height gradient difference structure of the microchannel increases the flow channel length, so that the fluid forms a velocity difference in the height gradient difference structure area, generating eddies and local turbulence, and the chloride ions contact the activated carbon surface more frequently, which significantly improves the adsorption efficiency of chloride ions.

Description

Technical Field

[0001] The invention relates to a method and a device for removing chloride ions from water, belonging to the technical field of electric adsorption ion water treatment. Background Art

[0002] Chloride ions are ubiquitous in nature and industrial production, and their sources mainly include domestic sewage, industrial wastewater, etc. The chloride ions in these solutions have many adverse effects on industrial equipment, the environment, crops, and human health. In particular, chloride ions are prone to corrode stainless steel containers. In order to eliminate the potential hazards of chloride ions, reduce the impact on the environment, increase the reuse rate of water resources, and provide safer and more hygienic water sources for industry and agriculture, the development of effective chloride ion removal technology is a very important research topic in the field of environmental protection.

[0003] At present, the commonly used methods for removing chloride ions at home and abroad include reverse osmosis technology, biodegradation technology, ion exchange technology, and electrosorption technology. Reverse osmosis technology can effectively remove chloride ions and other soluble solids in water, but this technology has high energy consumption, high operating costs, and requires regular replacement of filter membranes. Biodegradation technology removes chloride ions through microbial metabolism, which has the advantages of environmental protection and low cost, but the removal efficiency of this technology is low and is greatly affected by environmental factors. Ion exchange technology absorbs chloride ions in water through ion exchange resins, and the cost is relatively low, but the regeneration of resins and the use of chemicals in this technology will cause secondary pollution to the environment.

[0004] Taiyuan University of Technology's invention patent "A method and device for removing chloride ions from desulfurization wastewater by electrochemical coupling" (grant number CN110357220B) discloses a device for removing chloride ions from desulfurization wastewater using electrochemical coupling technology. The device uses electrically controlled ion exchange technology to highly selectively adsorb target chloride ions, coupled with the hydrogen evolution reaction, and coupled and strengthened cation and cation reactions, all of which reduce the chloride ion concentration in the wastewater in different ways. This process produces high-purity hydrogen byproducts while also reducing the concentration of metal ions in the wastewater. However, the device involves a variety of components and complex electrical controls, making maintenance difficult and having a high failure rate, which increases labor costs for operation and maintenance in actual applications of the device. At the same time, although the device can improve the removal efficiency and energy utilization of chloride ions, the high-tech materials and catalysts used in the system make the initial investment and operating costs of the device high.

[0005] Hohai University's invention patent "A device, preparation method and application for removing chloride ions" (grant number CN114044696B) discloses a device for removing chloride ions using an anode prepared from gallium arsenide-boron nitride. The device is composed of an anode electrode prepared from gallium arsenide-boron nitride, a cathode electrode and a reaction cell to form a complete electrochemical treatment system. The raw materials for preparing the anode are widely available, low-cost, and easy to use, and the preparation process is simple and non-toxic. However, when the device removes chloride ions, the electrolyte and the object of chloride ion removal do not flow. The ions move in the electrolyte and the object of removal only by the action of the electric field force. The ion movement speed is slow, and the ions are easily accumulated in a certain place, reducing the removal efficiency. At the same time, the anode can only adsorb chloride ions near it. For chloride ions far away from the anode, it is difficult to complete the adsorption when the electrolyte does not flow.

[0006] Taiyuan University of Technology's invention patent "A method for removing chloride ions from reclaimed water and a method for preparing an electrode" (authorization number CN111547824B) discloses a method for removing chloride ions from reclaimed water and a method for preparing an electrode. The method uses activated carbon fiber loaded with titanium dioxide and polyaniline as a positive electrode. The activated carbon fiber is doped with titanium dioxide, and the electrical adsorption capacity increases. Polyaniline is beneficial to improve the conductivity of the electrode and enhances the effect of removing chloride ions from reclaimed water. However, while this method expands the adsorption capacity of the electrode, the increase in the surface area of ​​the activated carbon causes the electrode to accumulate more dirt, sediments, and reaction by-products during use. These sediments will have a negative impact on the performance of the electrode, such as reduced conductivity and decreased charge storage capacity. At the same time, the cleaning of the electrode takes a long time. When the capacity and surface area of ​​the electrode become larger, the complexity of electrode cleaning increases, and the operating cost increases.

[0007] The invention patent of Chongqing Technology and Business University, "A method for removing chloride ions by a mobile electrode capacitor deionization device" (application number CN116874048A), shows a method for removing chloride ions by a mobile electrode capacitor deionization device, which uses carbon materials and divalent iron ions as conductive agents, and removes chloride ions from recycled water through a simple process of device construction, electrode selection and chloride ion removal. However, the scheme adopts the traditional electrode capacitor deionization device structure, which makes it difficult to avoid the phenomenon that chloride ions are continuously transported to the activated carbon coating on the lower wall of the microchannel and accumulate in a certain area, causing the electrode to overheat. The overall technical scheme does not propose improvements to the construction of the device.

[0008] In summary, the existing electrosorption chloride ion removal methods have the following three main problems: First, it involves a variety of components and complex electrical controls, with a high failure rate and difficult maintenance; at the same time, the materials and catalysts used in the removal system are expensive, which increases the operating costs of the equipment. Second, when removing chloride ions, the electrolyte and chloride ions do not flow, and the chloride ions move in the electrolyte only under the action of the electric field force. Therefore, the movement speed of chloride ions is slow and easy to accumulate, resulting in a decrease in the chloride ion removal rate; at the same time, the anode can only adsorb chloride ions near it, and it is difficult to adsorb chloride ions far away from the anode. Third, the electrode will accumulate more dirt, sediments and reaction by-products during long-term use, and these dirt, sediments and reaction by-products have a negative impact on the adsorption performance of the electrode. Summary of the invention

[0009] In view of the above problems, we proposed a method and device for removing chloride ions from water. By designing a groove-shaped sawtooth structure microfluidic channel and an integrated manufacturing of a curved electrode, an integrated structure of a curved electrode and a groove-shaped sawtooth structure microfluidic channel was constructed, so that it has good electric field uniformity and sufficient electric field strength; the wastewater is in a flowing state in the microfluidic channel, so that the chloride ions are continuously transported to the anode surface, and the chloride ions are gathered in the sawtooth structure of the microfluidic channel, which improves the overall chloride ion removal efficiency of the device. At the same time, the height gradient difference structure is introduced on the path of the microfluidic channel to increase the effective surface area of ​​the electrode. The disturbance caused by the height gradient difference causes the fluid to form a speed difference in the height gradient difference structure area, which increases the contact frequency between the chloride ions and the activated carbon surface and increases the probability of the chloride ions being adsorbed; by designing the anode electrode into a groove-shaped sawtooth shape, the chloride ions can be more easily intercepted and adsorbed by the anode during the movement of the chloride ions to the electrode, and the chloride ions are released from the activated carbon by using alternating current during backwashing. At the same time, the grooved serrated structure is more comprehensively flushed during electrode cleaning, and the surface of the grooved serrated anode is more easily covered by the cleaning liquid, which improves the removal rate of sediment and dirt and reduces the consumption of the cleaning liquid during the cleaning process.

[0010] In a first aspect, the present invention provides a device for removing chloride ions from water, comprising:

[0011] Raw water tanks to store wastewater containing chloride ions;

[0012] A microfluidic chip is connected to the raw water pool; the interior of the microfluidic chip includes a groove-shaped sawtooth microfluidic channel, a cathode and an anode, and the groove-shaped sawtooth microfluidic channel, the cathode and the anode are arranged in parallel; the groove-shaped sawtooth microfluidic channel is a tubular structure with a rectangular cross-section and having an upper wall surface of the groove-shaped sawtooth microfluidic channel, left and right side walls of the groove-shaped sawtooth microfluidic channel and a lower wall surface of the groove-shaped sawtooth microfluidic channel, wherein the upper wall surface of the groove-shaped sawtooth microfluidic channel and the groove sawtooth microfluidic channel are The cross-section of the lower wall of the toothed microfluidic channel is an arc-shaped structure, and the surface shape of at least a part of the cathode and the surface shape of at least a part of the anode respectively match the shape of the upper wall of the groove-shaped sawtooth microfluidic channel and the lower wall of the groove-shaped sawtooth microfluidic channel; the groove-shaped sawtooth microfluidic channel is provided with a liquid inlet and a liquid outlet on both sides, and the liquid inlet and the liquid outlet include a first horizontal microfluidic channel connected in sequence, an intermediate inclined microfluidic channel provided in the middle, and a second horizontal microfluidic channel; and

[0013] A fresh water tank, a sewage tank, and a DC / AC voltage regulating power supply coupled to the microfluidic chip;

[0014] A raw water switch, a first plunger pump, a water flow meter, a first conductivity meter, and a filter are sequentially connected between the raw water pool and the microfluidic chip through a first pipeline; a pH meter and a second conductivity meter are connected between the microfluidic chip and the fresh water pool through a second pipeline; a sewage switch is provided between the microfluidic chip and the sewage pool; the fresh water pool is also provided with a third pipeline connected to the first pipeline, and the third pipeline is provided with a backwash switch and a second plunger pump;

[0015] The wastewater in the raw water pool is sequentially passed through the first pipeline and the microfluidic chip for chloride ion electrical adsorption, and then collected in the fresh water pool through the second pipeline; the fresh water pool supplies water to the microfluidic chip through the third pipeline for chloride ion backwashing.

[0016] Furthermore, there are inclination angles between the first horizontal microfluidic channel and the middle inclined microfluidic channel, and between the middle inclined microfluidic channel and the second horizontal microfluidic channel; the first horizontal microfluidic channel and the second horizontal microfluidic channel are connected through the middle inclined microfluidic channel to form a height gradient difference.

[0017] Furthermore, the upper wall surface and the lower wall surface of the grooved serrated microchannel are provided with an activated carbon coating as an adsorption material; the left and right side walls of the grooved serrated microchannel are provided with a polyethylene coating as an insulating layer of the cathode and the anode; the grooved serrated structure of the lower wall surface of the grooved serrated microchannel forms a recessed area on the surface of the grooved serrated microchannel and allows chloride ions to enter the recessed area; the serrated activated carbon surface makes it difficult for chloride ions to escape after contacting the microchannel wall surface and is more easily intercepted by the anode; during backwashing, when the electrode discharges AC, more chloride ions can be released, so that the DC anode surface is effectively cleaned; the middle inclined microchannel is arranged on the path of the grooved serrated microchannel, forming a height gradient difference structure, increasing the effective surface area of ​​the electrode, generating additional disturbances, forming a speed difference in the height gradient difference area, generating eddies and local turbulence, making chloride ions contact the activated carbon surface more frequently, and improving the adsorption probability of chloride ions.

[0018] Furthermore, the cathode and anode are of the same shape and size as the groove-shaped sawtooth microchannel, and the cathode and anode are tightly fitted on both sides of the groove-shaped sawtooth microchannel; the effective discharge areas of the cathode and anode that match the outer curved surface of the channel are fully utilized, and all the discharge areas are used for continuous adsorption of chloride ions, which greatly improves the energy utilization rate of the device; the DC / AC voltage regulating power supply is connected to the cathode and anode, and when the chloride ions are electrically adsorbed, the DC / AC voltage regulating power supply performs DC discharge; when the chloride ions are backwashed, the DC / AC voltage regulating power supply performs AC discharge to release the chloride ions from the activated carbon on the lower wall of the groove-shaped sawtooth microchannel, wherein the DC discharge voltage is expressed by formula (1), and the derivation process of formula (1) is:

[0019]

[0020] Among them, V out is the output voltage, which indicates the voltage output value after the voltage regulator is stabilized and adjusted; R out is the output resistance, which represents the impedance of the load in the system to the output current of the power supply; R ds is the dynamic resistance in the control circuit, indicating the output resistance of the control element; V in is the input voltage, which means the voltage received by the input terminal of the regulator; G m is the transconductance parameter, which indicates the circuit's ability to respond to changes in feedback voltage; V fb is the feedback voltage, which indicates the voltage measured in the feedback loop and reflects the change of the current output voltage; V ref is the reference voltage, indicating the expected range of the output voltage; R fb1 , R fb2 It is a feedback resistor used to adjust and detect the output voltage.

[0021] Furthermore, when the raw water enters through the liquid inlet of the groove-shaped serrated microchannel and then adsorbs chloride ions, the process of chloride ions being adsorbed to the surface of the material is determined by the factors of the external diffusion rate, the internal diffusion rate and the adsorption equilibrium time of the adsorbate, which can be described by the Freundlich adsorption isotherm as follows:

[0022]

[0023] To simplify the calculation, take the logarithm of both sides of the above formula to obtain formula (2):

[0024]

[0025] In the formula, q e represents the equilibrium adsorption capacity, i.e., the electrical adsorption capacity, mg / g; c e It represents the solution concentration at adsorption equilibrium in mg / L; k represents the Freundlich adsorption isotherm constant; n is a constant related to factors such as temperature.

[0026] Furthermore, the first plunger pump and the second plunger pump simultaneously drive the raw water for electrosorption treatment and the fresh water for backwashing to flow in the groove-shaped serrated microchannel, thereby ensuring that the chloride ions are effectively adsorbed and effectively removed, and improving the heat dissipation effect of the electrode. The groove-shaped serrated microchannel has a small discharge spacing, a high electric field strength, and a good adsorption effect, but it is easy to cause overheating, which will affect the service life of the microchannel chip and reduce the adsorption effect. Allowing the raw water to flow in the groove-shaped serrated microchannel can not only continuously transport the chloride ions to the activated carbon coating on the lower wall of the groove-shaped serrated microchannel to avoid accumulation in a certain area, thereby improving the electrosorption efficiency, but can also effectively cool the microchannel chip to avoid electrode overheating.

[0027] Furthermore, the DC / AC voltage regulating power supply is used as a discharge power supply for the device for removing chloride ions from water, which can avoid the manual electrode reverse connection process, improve the operation efficiency of the electric adsorption system, and save time cost. The DC mode is used for discharge during electric adsorption, and the AC mode is used for discharge during backwashing to release the chloride ions in the activated carbon, which saves labor time and improves the backwashing efficiency.

[0028] In a second aspect, the present invention provides a method for removing chloride ions from water, using the device for removing chloride ions from water, the method comprising the following steps:

[0029] Step 1: Turn on the raw water switch and the first plunger pump, and use the first plunger pump to pass the wastewater in the raw water pool through the water flow meter and the first conductivity meter for detection, and then enter the filter for impurity filtration, and then pump it to the liquid inlet of the microfluidic chip;

[0030] Step 2: The wastewater entering the liquid inlet of the microfluidic chip flows into the groove-shaped serrated microfluidic channel to form a stable continuous flow;

[0031] Step 3: Connect the cathode and the anode to the DC / AC voltage regulating power supply and turn on the voltage regulating power supply switch, adjust the discharge mode to DC discharge, and start to electro-adsorb the wastewater raw water in the groove-shaped serrated microchannel to remove chloride ions in the wastewater raw water;

[0032] Step 4: The wastewater raw water after the electrosorption is completed flows out from the outlet of the microfluidic chip, passes through the pH meter and the second conductivity meter for detection, and then enters the fresh water pool;

[0033] Step 5: Turn off the raw water switch and the DC / AC voltage regulating power supply switch, turn on the backwash switch, the sewage switch and the second plunger pump, and pump the fresh water in the fresh water pool to the liquid inlet of the microfluidic chip through the second plunger pump;

[0034] Step 6: Fresh water entering the liquid inlet of the microfluidic chip flows into the groove-shaped serrated microfluidic channel to form a stable continuous flow;

[0035] Step 7: Turn on the voltage regulating power switch, adjust the discharge mode to AC discharge, release the chloride ions adsorbed in the grooved serrated activated carbon structure layer on the lower wall of the grooved serrated microchannel, backwash the grooved serrated microchannel with fresh water, and wash away the residual chloride ions in the grooved serrated microchannel and the sediment and dirt generated by electrical adsorption;

[0036] Step 8: The fresh water after backwashing flows out from the outlet of the microfluidic chip and is finally stored in the sewage tank.

[0037] Beneficial effects of the present invention:

[0038] (1) The integrated manufacturing of the grooved serrated structure microfluidic channel and the curved surface electrode realizes the integrated structure of the curved surface electrode and the grooved serrated structure microfluidic channel, giving it specific functions and properties without the need for additional assembly steps, thus simplifying its production process.

[0039] (2) The raw water to be adsorbed flows in the microchannel, which ensures that the chloride ions are effectively adsorbed and improves the heat dissipation effect of the electrode. Since the discharge spacing of the microchannel is small, the electric field strength is high, and the adsorption effect is good, it is easy to cause overheating, which will affect the service life of the microchannel chip and reduce the adsorption effect; therefore, allowing the raw water to flow in the microchannel can not only ensure that the chloride ions are continuously transported to the activated carbon coating on the lower wall of the microchannel to avoid accumulation in a certain area, thereby improving the electrical adsorption efficiency, but also effectively cool the electrodes outside the microchannel chip to avoid electrode overheating.

[0040] (3) Introducing a height gradient difference structure on the path of the microchannel increases the effective area of ​​the electrode while providing additional disturbance to the microfluid, thereby improving the adsorption efficiency of chloride ions. When the microfluid collides with the height gradient difference structure during the flow process, additional disturbance will be generated, forming a velocity difference in the height gradient difference structure area, generating eddies and local turbulence. The local flow instability promotes the stirring of the microfluid, causing frequent contact between the chloride ions and the activated carbon surface, thereby improving the adsorption rate of chloride ions.

[0041] (4) The microchannel wall on the anode side is designed to be grooved and serrated, which improves the adsorption capacity of the microchannel chip and reduces the difficulty of recycling chloride ions and cleaning the microchannel wall. The serrated surface of the activated carbon makes it difficult for chloride ions to escape after contacting the microchannel wall, making them more easily intercepted by the anode; and during the backwashing process, when the electrode is discharged with alternating current, more chloride ions can be released, so that the DC anode surface is effectively cleaned. At the same time, the grooved serrated structure can be more comprehensively flushed when cleaning the electrode, improving the overall performance of the electrosorption system.

[0042] (5) Using a DC / AC voltage-regulated power supply as the discharge power supply for the device to remove chloride ions from water eliminates the need for manual electrode reversal, improves the operating efficiency of the electrosorption system, and saves time costs. DC mode discharge is used during electrosorption, and AC mode discharge is used during backwashing to release chloride ions in the activated carbon, saving labor time and improving backwashing efficiency.

[0043] The present invention proposes a method and device for continuous chloride ion adsorption using a curved electrode, which can effectively improve the adsorption efficiency of chloride ions, improve the energy utilization efficiency and the operating efficiency of the electrosorption system, and is suitable for other chloride ion removal application scenarios with specific requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is an overall schematic diagram of a device for removing chloride ions from water in one embodiment of the present invention.

[0045] Figure 2 Schematic diagram of the structure of the microfluidic channel in the microfluidic channel chip in one embodiment of the present invention.

[0046] Figure 3 Schematic diagram of a cross section of a microfluidic channel in one embodiment of the present invention.

[0047] In the figure, 1, raw water tank; 2, raw water switch; 3, first plunger pump; 4, water flow meter; 5, first conductivity meter; 6, backwash switch; 7, second plunger pump; 8, fresh water tank; 9, second conductivity meter; 10, pH meter; 11, sewage tank; 12, sewage switch; 13, microfluidic chip; 14, DC / AC voltage regulating power supply; 15, filter; 131, cathode; 133, anode; 132, groove-shaped serrated microfluidic channel; 1321, liquid inlet; 1322, liquid outlet; 1323, upper wall of groove-shaped serrated microfluidic channel; 1324, left and right side walls of groove-shaped serrated microfluidic channel; 1325, lower wall of groove-shaped serrated microfluidic channel; 1326, middle inclined microfluidic channel; 1327, first horizontal microfluidic channel; 1328, second horizontal microfluidic channel. DETAILED DESCRIPTION

[0048] 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 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.

[0049] In the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] In the present invention, the "first" and "second" are only used to distinguish similar components / parts with different positions or different characteristics, and have no other limiting meanings; the "upper" refers to the direction of each component away from the ground, and the "lower" refers to the direction of each component away from the ground.

[0051] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0052] Example 1

[0053] The present invention provides a device for removing chloride ions from water, comprising:

[0054] A raw water tank 1, for storing wastewater containing chloride ions;

[0055] The microfluidic chip 13 is connected to the raw water pool 1; the interior of the microfluidic chip 13 includes a groove-shaped sawtooth microfluidic channel 132, a cathode 131 and an anode 133, and the groove-shaped sawtooth microfluidic channel 132, the cathode 131 and the anode 133 are arranged in parallel; the groove-shaped sawtooth microfluidic channel 132 is a tubular structure with a rectangular cross-section and having an upper wall surface 1323 of the groove-shaped sawtooth microfluidic channel, left and right side walls 1324 of the groove-shaped sawtooth microfluidic channel and a lower wall surface 1325 of the groove-shaped sawtooth microfluidic channel, wherein the upper wall surface 1323 of the groove-shaped sawtooth microfluidic channel and the groove-shaped sawtooth microfluidic channel are arranged in parallel; The cross-section of the lower wall 1325 of the flow channel is an arc-shaped structure, and the surface shape of at least a part of the cathode 131 and the surface shape of at least a part of the anode 133 respectively match the shape of the upper wall 1323 of the groove-shaped sawtooth microchannel and the shape of the lower wall 1325 of the groove-shaped sawtooth microchannel; the groove-shaped sawtooth microchannel 132 is provided with a liquid inlet 1321 and a liquid outlet 1322 on both sides, and the liquid inlet 1321 and the liquid outlet 1322 include a first horizontal microchannel 1327 connected in sequence, a middle inclined microchannel 1326 provided in the middle, and a second horizontal microchannel 1328; and

[0056] A fresh water tank 8, a sewage tank 11, and a DC / AC voltage regulating power supply 14 coupled to the microfluidic chip 13;

[0057] A raw water switch 2, a first plunger pump 3, a water flow meter 4, a first conductivity meter 5, and a filter 15 are sequentially connected between the raw water pool 1 and the microfluidic chip 13 through a first pipeline; a pH meter 10 and a second conductivity meter 9 are connected between the microfluidic chip 13 and the fresh water pool 8 through a second pipeline; a sewage switch is provided between the microfluidic chip 13 and the sewage pool 11; the fresh water pool 8 is also provided with a third pipeline connected to the first pipeline, and the third pipeline is provided with a backwash switch 6 and a second plunger pump 7;

[0058] The wastewater in the raw water pool 1 is sequentially passed through the first pipeline and the microfluidic chip 13 for chloride ion electrical adsorption, and then collected in the fresh water pool 8 through the second pipeline; the fresh water pool 8 supplies water to the microfluidic chip 13 through the third pipeline for chloride ion backwashing.

[0059] Furthermore, there are inclination angles between the first horizontal microchannel 1327 and the middle inclined microchannel 1326, and between the middle inclined microchannel 1326 and the second horizontal microchannel 1328; the first horizontal microchannel 1327 and the second horizontal microchannel 1328 are connected through the middle inclined microchannel 1326 to form a height gradient difference.

[0060] Furthermore, the upper wall surface 1323 of the groove-shaped sawtooth microchannel and the lower wall surface 1325 of the groove-shaped sawtooth microchannel are provided with an activated carbon coating as an adsorption material; the left and right side walls 1324 of the groove-shaped sawtooth microchannel are provided with a polyethylene coating as an insulating layer of the cathode 131 and the anode 133; the groove-shaped sawtooth structure of the lower wall surface 1325 of the groove-shaped sawtooth microchannel forms a concave area on the surface of the groove-shaped sawtooth microchannel, and allows chloride ions to enter the concave area; the sawtooth surface of the activated carbon allows the chloride ions to contact the cathode 131 and the anode 133; It is difficult for them to escape after touching the wall of the microchannel, and thus they are more easily retained by the anode; and, during the backwash process, when the electrode discharges AC, more chloride ions can be released, so that the surface of the DC anode is effectively cleaned; the middle inclined microchannel 1326 is arranged on the path of the grooved serrated microchannel 132, forming a height gradient difference structure, increasing the effective surface area of ​​the electrode, generating additional disturbances, forming a speed difference in the height gradient difference area, generating eddies and local turbulence, making the chloride ions contact the activated carbon surface more frequently, and improving the adsorption probability of the chloride ions.

[0061] Furthermore, the cathode 131 and the anode 133 are of the same shape and size as the groove-shaped sawtooth microchannel 132, and the cathode 131 and the anode 133 are closely attached to the two sides of the groove-shaped sawtooth microchannel 132; the effective discharge area of ​​the cathode 131 and the anode 133 that match the outer curved surface of the channel is fully utilized, and all the discharge area is used for continuous adsorption of chloride ions, which greatly improves the energy utilization rate of the device; the DC / AC voltage regulating power supply 14 is connected to the cathode 131 and the anode (133), and when the chloride ions are electrically adsorbed, the DC / AC voltage regulating power supply 14 performs DC discharge; when the chloride ions are backwashed, the DC / AC voltage regulating power supply (14) performs AC discharge to release the chloride ions from the activated carbon on the lower wall (1325) of the groove-shaped sawtooth microchannel, wherein the DC discharge voltage is expressed by formula (1), and the derivation process of formula (1) is:

[0062]

[0063] Among them, V out is the output voltage, which indicates the voltage output value after the voltage regulator is stabilized and adjusted; R out is the output resistance, which represents the impedance of the load in the system to the output current of the power supply; R dsis the dynamic resistance in the control circuit, indicating the output resistance of the control element; V in is the input voltage, which means the voltage received by the input terminal of the regulator; G m is the transconductance parameter, which indicates the circuit's ability to respond to changes in feedback voltage; V fb is the feedback voltage, which indicates the voltage measured in the feedback loop and reflects the change of the current output voltage; V ref is the reference voltage, indicating the expected range of the output voltage; R fb1 , R fb2 It is a feedback resistor used to adjust and detect the output voltage.

[0064] Furthermore, when the raw water enters through the liquid inlet 1321 of the groove-shaped serrated microchannel 132 and then adsorbs chloride ions, the process of chloride ions being adsorbed to the surface of the material is determined by the factors of the external diffusion rate, the internal diffusion rate and the adsorption equilibrium time of the adsorbate, which can be described by the Freundlich adsorption isotherm as follows:

[0065]

[0066] To simplify the calculation, take the logarithm of both sides of the above formula to obtain formula (2):

[0067]

[0068] In the formula, q e represents the equilibrium adsorption capacity, i.e., the electrical adsorption capacity, mg / g; c e It represents the solution concentration at adsorption equilibrium in mg / L; k represents the Freundlich adsorption isotherm constant; n is a constant related to factors such as temperature.

[0069] Furthermore, the first plunger pump 3 and the second plunger pump 7 simultaneously drive the raw water for electrosorption treatment and the fresh water for backwashing to flow in the groove-shaped serrated microchannel 132, which improves the heat dissipation effect of the electrode while ensuring that the chloride ions are effectively adsorbed and effectively removed. The groove-shaped serrated microchannel 132 has a small discharge spacing, a high electric field strength, and a good adsorption effect, but it is easy to cause overheating, which will affect the service life of the microchannel chip 13 and reduce the adsorption effect. Allowing the raw water to flow in the groove-shaped serrated microchannel 132 can not only continuously transport the chloride ions to the activated carbon coating on the lower wall 1325 of the groove-shaped serrated microchannel to avoid accumulation in a certain area, thereby improving the electrosorption efficiency, but can also effectively cool the microchannel chip 13 to avoid electrode overheating.

[0070] Furthermore, the DC / AC voltage regulating power supply 14 is used as a discharge power supply for the device for removing chloride ions from water, which can avoid the manual electrode reverse connection process, improve the operation efficiency of the electric adsorption system, and save time cost. The DC mode is used for discharge during electric adsorption, and the AC mode is used for discharge during backwashing to release the chloride ions in the activated carbon, which saves labor time and improves the backwashing efficiency.

[0071] Example 2

[0072] The present invention provides a method for removing chloride ions from water, using the device for removing chloride ions from water, the method comprises the following steps:

[0073] Step 1: Turn on the raw water switch 2 and the first plunger pump 3, and the first plunger pump 3 passes the wastewater in the raw water pool 1 through the water flow meter 4 and the first conductivity meter 5 for detection, and then enters the filter 15 for impurity filtration, and then pumps it to the liquid inlet 1321 of the microfluidic chip 13;

[0074] Step 2: The wastewater entering the liquid inlet 1321 of the microfluidic chip 13 flows into the groove-shaped serrated microfluidic channel 132 to form a stable continuous flow;

[0075] Step 3: Connect the cathode 131 and the anode 133 to the DC / AC voltage regulating power supply 14 and turn on the voltage regulating power supply switch, adjust the discharge mode to DC discharge, and start to electro-adsorb the wastewater raw water in the groove-shaped serrated microchannel 132 to remove chloride ions in the wastewater raw water;

[0076] Step 4: The wastewater after the electrosorption is completed flows out from the liquid outlet 1322 of the microfluidic chip 13, passes through the pH meter 10 and the second conductivity meter 9 for detection, and then enters the fresh water pool 8;

[0077] Step 5: Turn off the raw water switch 2 and the switch of the DC / AC voltage regulating power supply 14, turn on the backwash switch 6, the sewage switch 12 and the second plunger pump 7, and pump the fresh water in the fresh water tank 8 to the liquid inlet 1321 of the microfluidic chip 13 through the second plunger pump 7;

[0078] Step 6: Fresh water entering the liquid inlet 1321 of the microfluidic chip 13 flows into the groove-shaped serrated microfluidic channel 132 to form a stable continuous flow;

[0079] Step 7: Turn on the voltage regulating power switch, adjust the discharge mode to AC discharge, release the chloride ions adsorbed in the grooved serrated activated carbon structure layer on the lower wall surface 1325 of the grooved serrated microchannel, backwash the grooved serrated microchannel 132 with fresh water, and wash away the residual chloride ions in the grooved serrated microchannel 132 and the sediment and dirt generated by electrical adsorption;

[0080] Step eight: the fresh water after backwashing flows out from the liquid outlet 1322 of the microfluidic chip 13 and is finally stored in the sewage tank 11 .

[0081] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A device for removing chloride ions from water, characterized in that: include: A raw water tank (1) for storing wastewater containing chloride ions; A microfluidic chip (13) is connected to the raw water pool (1); the interior of the microfluidic chip (13) includes a groove-shaped sawtooth microfluidic channel (132), a cathode (131) and an anode (133), wherein the groove-shaped sawtooth microfluidic channel (132), the cathode (131) and the anode (133) are arranged in parallel; the groove-shaped sawtooth microfluidic channel (132) is a tubular structure having an upper wall surface (1323) of the groove-shaped sawtooth microfluidic channel, left and right side walls (1324) of the groove-shaped sawtooth microfluidic channel and a lower wall surface (1325) of the groove-shaped sawtooth microfluidic channel, wherein the upper wall surface (1323) of the groove-shaped sawtooth microfluidic channel and the lower wall surface (1325) of the groove-shaped sawtooth microfluidic channel are The cross-section of the wall surface (1325) is an arc-shaped structure; the surface shape of at least a part of the cathode (131) and the surface shape of at least a part of the anode (133) respectively match the shape of the upper wall surface (1323) of the groove-shaped sawtooth microchannel and the lower wall surface (1325) of the groove-shaped sawtooth microchannel; a liquid inlet (1321) and a liquid outlet (1322) are respectively arranged on both sides of the groove-shaped sawtooth microchannel (132); and the liquid inlet (1321) and the liquid outlet (1322) include a first horizontal microchannel (1327) connected in sequence, a middle inclined microchannel (1326) arranged in the middle, and a second horizontal microchannel (1328); and A fresh water tank (8), a sewage tank (11), and a DC / AC voltage regulating power supply (14) coupled to the microfluidic chip (13); A raw water switch (2), a first plunger pump (3), a water flow meter (4), a first conductivity meter (5), and a filter (15) are sequentially connected between the raw water pool (1) and the microfluidic chip (13) via a first pipeline; a pH meter (10) and a second conductivity meter (9) are connected between the microfluidic chip (13) and the fresh water pool (8) via a second pipeline; a sewage switch is provided between the microfluidic chip (13) and the sewage pool (11); the fresh water pool (8) is further provided with a third pipeline connected to the first pipeline, and the third pipeline is provided with a backwash switch (6) and a second plunger pump (7); The wastewater in the raw water pool (1) is sequentially passed through a first pipeline and a microfluidic chip (13) for electrosorption of chloride ions, and then collected in a fresh water pool (8) through a second pipeline; the fresh water pool (8) supplies water to the microfluidic chip (13) through a third pipeline for chloride ion backwashing; There is an inclination angle between the first horizontal microchannel (1327) and the middle inclined microchannel (1326), and between the middle inclined microchannel (1326) and the second horizontal microchannel (1328); the first horizontal microchannel (1327) and the second horizontal microchannel (1328) are connected through the middle inclined microchannel (1326) to form a height gradient difference; The upper wall surface (1323) of the groove-shaped serrated microfluidic channel and the lower wall surface (1325) of the groove-shaped serrated microfluidic channel are provided with an activated carbon coating as an adsorption material; the left and right side walls (1324) of the groove-shaped serrated microfluidic channel are provided with a polyethylene coating as an insulating layer for the cathode (131) and the anode (133); the groove-shaped serrated structure of the lower wall surface (1325) of the groove-shaped serrated microfluidic channel forms a recessed area on the surface of the groove-shaped serrated microfluidic channel, and allows chloride ions to enter the recessed area; when AC discharge is performed, the groove-shaped serrated structure of the lower wall surface (1325) of the groove-shaped serrated microfluidic channel also makes it easier to backwash the microfluidic channel wall.

2. A device for removing chloride ions from water according to claim 1, characterized in that: The cathode (131) and the anode (133) are of the same shape and size as the groove-shaped sawtooth microchannel (132). The cathode (131) and the anode (133) are closely attached to the two sides of the groove-shaped sawtooth microchannel (132). The DC / AC voltage regulating power supply (14) is connected to the cathode (131) and the anode (133). When the chloride ions are electrically adsorbed, the DC / AC voltage regulating power supply (14) performs DC discharge. When the chloride ions are backwashed, the DC / AC voltage regulating power supply (14) performs AC discharge to release the chloride ions from the activated carbon on the lower wall (1325) of the groove-shaped sawtooth microchannel. The DC discharge voltage is expressed by formula (1): Among them, V out is the output voltage, which indicates the voltage output value after the voltage regulator is stabilized and adjusted; R out is the output resistance, which represents the impedance of the load in the system to the output current of the power supply; R ds is the dynamic resistance in the control circuit, indicating the output resistance of the control element; V in is the input voltage, which means the voltage received by the input terminal of the regulator; G m is the transconductance parameter, which indicates the circuit's ability to respond to changes in feedback voltage; V ref is the reference voltage, indicating the expected range of the output voltage; R fb1 , R fb2 It is a feedback resistor, used to adjust and detect the output voltage; When raw water enters through the liquid inlet (1321) of the groove-shaped sawtooth microchannel (132) and then adsorbs chloride ions, the process of chloride ions being adsorbed onto the surface of the material is determined by the factors of the adsorbate external diffusion rate, internal diffusion rate and adsorption equilibrium time, which can be described by the Freundlich adsorption isotherm as formula (2): In the formula, q e represents the equilibrium adsorption capacity, i.e., the electrical adsorption capacity, mg / g; c e It represents the solution concentration in mg / L at adsorption equilibrium; k represents the Freundlich adsorption isotherm constant; and n is a constant related to factors such as temperature.

3. A device for removing chloride ions from water according to claim 2, characterized in that: The first plunger pump (3) and the second plunger pump (7) simultaneously drive raw water for electrosorption treatment and fresh water for backwashing to flow in the groove-shaped sawtooth microchannel (132).

4. A device for removing chloride ions from water according to claim 3, characterized in that: The DC / AC voltage regulating power supply (14) is used as a discharge power supply for the device for removing chloride ions from water. It uses a DC mode for discharge during electrical adsorption and an AC mode for discharge during backwashing to release chloride ions in the activated carbon.

5. A method for removing chloride ions from water, using the device for removing chloride ions from water according to claim 4, characterized in that: The method comprises the following steps: Step 1: Turn on the raw water switch (2) and the first plunger pump (3), and use the first plunger pump (3) to pass the wastewater in the raw water pool (1) through the water flow meter (4) and the first conductivity meter (5) for detection, and then enter the filter (15) for impurity filtration, and then pump it to the liquid inlet (1321) of the microfluidic chip (13); Step 2: the wastewater entering the liquid inlet (1321) of the microfluidic chip (13) flows into the groove-shaped sawtooth microfluidic channel (132) to form a stable continuous flow; Step 3: Connect the cathode (131) and the anode (133) to the DC / AC voltage regulating power supply (14) and turn on the voltage regulating power supply switch, adjust the discharge mode to DC discharge, and start electro-adsorption of the wastewater raw water in the groove-shaped serrated microchannel (132) to remove chloride ions in the wastewater raw water; Step 4: The wastewater raw water after the electrosorption is discharged from the liquid outlet (1322) of the microfluidic chip (13), flows through the pH meter (10) and the second conductivity meter (9) for detection, and then enters the fresh water pool (8); Step 5: Turn off the raw water switch (2) and the switch of the DC / AC voltage regulating power supply (14), turn on the backwash switch (6), the sewage switch (12) and the second plunger pump (7), and pump the fresh water in the fresh water tank (8) to the liquid inlet (1321) of the microfluidic chip (13) through the second plunger pump (7); Step 6: Fresh water entering the liquid inlet (1321) of the microfluidic chip (13) flows into the groove-shaped sawtooth microfluidic channel (132) to form a stable continuous flow; Step 7: Turn on the voltage regulating power switch, adjust the discharge mode to AC discharge, release the chloride ions adsorbed in the grooved serrated activated carbon structure layer on the lower wall surface (1325) of the grooved serrated microchannel, backwash the grooved serrated microchannel (132) with fresh water, and wash away the residual chloride ions in the grooved serrated microchannel (132) and the sediment and dirt generated by the electrical adsorption; Step 8: The fresh water after backwashing flows out from the liquid outlet (1322) of the microfluidic chip (13) and is finally stored in the sewage tank (11).

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