Water production device using field ion exchanger

Abstract

Desalination methods such as multi-stage flashing and reverse osmosis require a lot of energy because they involve moving water through seawater. Water production systems using field ion exchangers move only the salinity from seawater to produce fresh water, making them energy-efficient and thus much cheaper. [Solution] Two donut-shaped disc-shaped plastic plates, such as ABS resin, are made using a 3D printer or the like. One plate has a cation exchange group on its surface, and the other has an anion exchange group. By applying (1) an electric field, (2) pressure [pressure dialysis], (3) potential energy such as a drop in height, and (4) centrifugal force, either individually or in combination, to the gap between these amphoteric ion exchangers, cations, anions, salts, and other electrolytes in seawater are continuously moved to an outer tank and separated, thereby efficiently obtaining fresh water. By using a laminate made by stacking multiple of these plates, fresh water can be continuously obtained from seawater.

Description

Technical Field

[0001] The present invention is an apparatus that faces and overlaps a cationic field ion exchanger having a cation exchange group held on the surface of a plastic flat plate and an anionic field ion exchanger having an anion exchange group held on the surface of a plastic flat plate, and moves and removes salt, which is a solute, from seawater at a low pressure or the like through the gap between the field ion exchangers to desalinate it.

[0002] In recent years, advancements and widespread use of mathematics and computers have made it mathematically possible to calculate the electric field in the gaps of field ion exchangers through integration. In this study, as shown in Figure 2, we were able to calculate the horizontal (x-direction) electric field acting on the center of gravity of a salt molecule at an arbitrary position in the space between the positive and negative electric field exchangers of a water purification device using an electric field ion exchanger. This electric field is the maximum value at the outlet of the gap space between the spacers of the ion exchanger in the device, and it is the force that tries to retain the salt inside. It gradually decreases smoothly, becomes zero in the middle, and then increases again as an attractive force, generating the maximum value of salt attraction force near the inlet, and the salt molecules are attracted and retained by this electric field. Furthermore, since this characteristic electric field is proportional to the surface charge density σ, and ABS resin is a copolymer of three types of monomers (styrene, acrylic, and butadiene), the surface charge density is about 1 / 3 compared to styrene monomer alone, so the electric field can also be reduced to about 1 / 3. The water pressure of the pump that pushes out the salt can also be reduced to about 1 / 3, and the resistance of the container used can be reduced to 1 / 3. In addition, ABS resin is a 3D printer filament, so it was adopted because it is convenient to process.

Background Art

[0003] Due to the Noto Peninsula earthquake, people have been without water for months, so there is a demand to make water using the seawater right in front of them. The two main seawater desalination methods that have been put into practical use are the multi-stage flash method and the reverse osmosis method. Seawater is heated, evaporated, and then cooled again to make pure water. That is, it is a method of distilling seawater to produce fresh water. The reverse osmosis method is a method in which high pressure is applied to seawater and it is passed through a reverse osmosis membrane, the salt content of the seawater is concentrated and discarded, and fresh water is filtered out. Since these move most of the water in seawater, high pressure and high energy are required, and the cost is high. There are other pure water production devices, which use ion exchange resins to remove ions and produce pure water. At this time, the ion exchange resins must be regenerated with strong acids and strong bases, and it cannot be done continuously, but is a batch process. Pure water is produced by this method. Furthermore, desalination by reaction of salt with an ion exchange resin containing ion exchange material dispersed through an ion exchange resin or polyurethane matrix is ​​an ionic bonding process, and the ion exchange resin is consumed and replenished by this ionic bonding reaction. In particular, with seawater, where the salinity is high, replenishment and replacement must be done immediately, which is inconvenient and cannot keep up with demand.

[0004] Another desalination method is electrodialysis. In electrodialysis, brine is desalinized using an electrodialysis apparatus that has an anion exchange membrane made of a styrene-divinylbenzene copolymer membrane with quaternary ammonium groups as exchange groups and a cation exchange membrane made of a styrene-divinylbenzene copolymer membrane with sulfonic acid groups as exchange groups. Desalination by electrodialysis involves electrolysis of salt (mainly containing NaCl, hence denoted as NaCl), the transport of salt molecules to the ion exchange membrane by electricity, electrolysis there, the passing of Na+ through the cation exchange membrane and Cl- through the anion exchange membrane, and the passing of anions out of the system by electricity to complete desalination. Since salt molecules are bound by strong ionic bonds, electrolysis consumes a large amount of energy. Continuous use incurs significant costs.

[0005] Cl- ions pass through the anion exchange membrane, collide with the electrodes, and an electrode reaction occurs, generating chlorine gas that is harmful to the human body and must be constantly discharged. Seawater contains NaCl, and when electricity is passed through it, chlorine gas is inevitably generated, causing problems. MgSO 4 In cation exchange membranes containing divalent ion compounds like this one, divalent Mg++ ions are generated, and these divalent ions tend to adhere to the ion exchange membrane, causing precipitation and other problems. During electrodialysis, as desalination progresses, the amount of salt decreases, and there is no salt to carry the electricity, making it difficult to continue electrodialysis, and thus the degree of desalination does not increase. For the above reasons, it is considered difficult to use this device for desalination in electrodialysis. There are many obstacles to practical use in electrodialysis. This device does not cause problems during electrodialysis.

[0006] In electrodialysis, salt is electrolyzed and moved separately out of the system. However, in a water production device using an electric field ion exchanger, a plate of cation electric field ion exchanger and an anion electric field ion exchanger are superimposed, and salt molecules are passed through them as they are. At this time, as shown in Figure 2, an electric field is generated in the gap space that tries to hold the maximum amount of salt molecules near the outlet edge, then it gradually decreases smoothly, becomes zero in the center, and then rises again as an attractive force, generating a force that attracts the maximum amount of salt near the inlet. This electric field attracts and holds the salt molecules. After that, the water pressure from the pump pushes them out, and the device moves the salt molecules out of the system as they are, thus desalting. Energy consumption is low.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Japanese Patent Application Publication No. 07-022712 [Patent Document 2] Special Publication Number 2013-184114 [Overview of the project] [Problems that the invention aims to solve]

[0008] The problem we are trying to solve is that desalination methods such as multi-stage flashing and reverse osmosis require a lot of energy because they involve moving water through seawater. Both their construction and maintenance are also very expensive. It is necessary to continuously move and remove salts such as cations, anions, and electrolytes from seawater using pressure, potential energy, and centrifugal force, and this is the only water desalination device that uses an electric field ion exchanger. This makes it possible to efficiently remove only the salt from large quantities of seawater, leaving only fresh water. [Means for solving the problem]

[0009] This invention involves creating two donut-shaped disc-shaped plastic plates, manufactured using a 3D printer that has advanced significantly in recent years. One plate has a cation exchange group on its surface, and the other has an anion exchange group. These plates are placed facing each other and stacked. By applying forces such as (1) pressure (pressure dialysis), (2) potential energy such as head height, and (3) centrifugal force, either individually or in combination, to the gap between these amphoteric ion exchange plates, cations, anions, salts, and other electrolytes in seawater are continuously moved to an outer tank and separated, thereby efficiently obtaining fresh water. [Effects of the Invention]

[0010] The water production apparatus using an electric field ion exchanger of the present invention removes salt from seawater to produce fresh water, resulting in high energy efficiency and thus enabling the production of fresh water at a low cost. Since the main components of the apparatus are made of plastic, it can be easily and inexpensively manufactured using a 3D printer or similar method.

[0011] The ABS resin sheet used in this invention allows for lower pressure and improved performance compared to styrene alone. [Brief explanation of the drawing]

[0012] [Figure 1] (Figure 1) is a diagram showing the assembly of a water production device using an electric field ion exchanger. [Figure 2] Figure 2 shows the characteristic horizontal electric field acting on the center of gravity of a salt molecule. [Modes for carrying out the invention]

[0013] A donut-shaped disc-shaped ABS resin plate, fabricated using a 3D printer or similar device, is placed in chlorosulfonic acid at room temperature and stirred for 2 hours to allow a uniform reaction, covalently bonding sulfonic acid groups. Next, the donut-shaped disc-shaped ABS resin plate, fabricated using a 3D printer or similar device, is chloromethylated by reacting chlorodimethyl ether with anhydrous aluminum chloride as a catalyst, and then reacted with dimethylaminomethanol to covalently bond quaternary ammonium groups. By stacking these plates facing each other, an amphoteric field ion exchanger is created. By inserting tiny plastic square rods as spacers, gaps are created to allow salt to move. This stack of amphoteric field ion exchangers is placed in an outer tank. The process solenoid valve is controlled by a control device using a minicomputer such as a PIC. Thus, this water production device can be easily and simply manufactured. A pump can apply pressure to the gaps in the amphoteric field ion exchanger, moving salt and other substances to the outer tank. [Examples]

[0014] Figure 1 is an assembly diagram of one embodiment of the device of the present invention, which is assembled in the order of (1) to (3). (1) is a schematic diagram of an amphoteric ion exchanger. A donut-shaped disc-shaped ABS resin flat plate fabricated by a 3D printer is placed in chlorosulfonic acid at room temperature and stirred to react uniformly for 2 hours to covalently bond sulfonic acid groups. The donut-shaped disc-shaped ABS resin flat plate fabricated by a 3D printer is reacted with chlorodimethyl ether using anhydrous aluminum chloride as a catalyst for chloromethylation, and further reacted with dimethylaminomethanol to covalently bond quaternary ammonium groups. When stacking, a minute plastic square bar is inserted as a spacer to create a space for salt movement. Seawater is passed through the inside, and as pressure dialysis from above, pressure is applied, and through the gap, salt is moved by pressure. Fresh water is taken out from the lower part of the inner cavity.

[0015] (2) The stacked laminate of amphoteric EFIE is placed in a rigid outer tank, seawater is flowed from above, and pressure is applied, that is, it becomes pressure dialysis, and selectively from the side, salt, which is an electrolyte, is passed through the gaps of EFIE to the outside. Water molecules also pass slightly due to pressure. Fresh water is taken out from the lower side. Tubes are attached to the inlet and outlet and a tube for discharging high-concentration salt. Do.

[0016] (3) A throttle valve is attached to the salt discharge pipe to throttle the flow rate passing through the gaps of EFIE to be constant. A process solenoid valve is attached to the fresh water extraction pipe. A lid is attached to the upper part and sealed. First, the process solenoid valve is closed, the pump attached to the seawater intake is operated to take in seawater, pressure is applied, and the electrolyte in the seawater is selectively moved to the outside through the side gap space. When almost all has moved, the process solenoid valve Open is opened to take out fresh water. When the extraction of fresh water is almost completed, the process solenoid valve is closed again, pressure is applied, and salt such as electrolyte is moved. High-concentration salt is removed to the outside through the pipe of the throttle valve of the outer tank.

Example

[0017] Figure 2 shows a coordinate representation of an approximate part of a water production apparatus using a field ion exchanger. The characteristic horizontal electric field acting on the center of gravity of the salt molecules was determined. σ is the surface charge density of the ion exchange group of the covalently bonded fixed ions of the field ion exchanger. b represents the radius of the ionic atmosphere of the positive and negative ions of the mobile ions of the salt molecules, with the center of the ± ions being assumed to be at the center of the ionic atmosphere. The ionic atmosphere is determined by the electric field acting on the mobile ions and the thermal kinetic energy of the water. The water production apparatus using a field ion exchanger consists of a plate of cation field ion exchanger and an anion field ion exchanger superimposed on each other, with seawater passed through them. At this time, the characteristic horizontal electric field acting on the center of gravity of the salt molecules was calculated by integration. This electric field generates the maximum holding force near the outlet edge of the gap space, gradually decreases smoothly, becomes 0 in the center, and then the electric field that becomes the attractive force increases, generating the maximum attractive force near the edge. This holding force of the electric field is moved by the pressure of the pump, and desalting occurs. [Industrial applicability]

[0018] In the event of an earthquake, which is expected to occur in the future and causes a water outage, this device can easily and inexpensively produce fresh water by removing the solute salt from seawater, making it possible to create bathwater and improve sanitary conditions. Simultaneously, concentrated brine from seawater is produced, allowing for the easy, inexpensive, and low-energy production of seawater salinity residue. This salinity allows for the recovery of salt, lithium, and other useful metals, making it potentially very useful. This, in turn, enables the recovery of lithium from seawater. [Explanation of Symbols]

[0019] 1. Surface charge density of an ABS resin plate 2. Radius of the ionic atmosphere of mobile ions 3. Characteristic electric field Ecx in the horizontal direction (x direction) 4. Surface charge density σ of covalently bonded fixed ions 5. Characteristic horizontal electric field acting on the center of gravity of a salt molecule

Claims

[Claim 1] This device efficiently obtains fresh water by attaching cation exchange groups to the surface of one plastic plate, such as ABS resin, and anion exchange groups to another plastic plate, such as ABS resin. By placing these plates facing each other and stacking them, a single or combined electric field, pressure, potential energy such as head difference, and centrifugal force are applied to the gaps in the resulting field ion exchanger or laminate, thereby moving and removing electrolytes such as salt from seawater.

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