CN115159637B - Device for desalting seawater and recovering acid and alkali - Google Patents

Abstract

The invention provides a device for desalting and recovering acid and alkali of a microbial fuel cell coupled with a flow electrode. The device includes a microbial fuel cell, a flowing electrode capacitive deionization device, an external circuit and an acid-base production chamber; wherein the microbial fuel cell serves as a power source to form a loop with the flowing electrode capacitive deionization device and the external circuit. Use microbial fuel cells as power sources; adjust the position of the titanium mesh positive electrode and the electrode liquid so that the titanium mesh positive electrode is close to the ion exchange membrane, reduce the charge transmission distance and improve the ion adsorption capacity; install several sets of relatively rotating disturbances in the electrode liquid flow area. The flow stirring device enhances the blending of activated carbon particles in the flowing electrode solution, greatly improving the desalination efficiency; when producing acids and bases, a rectangular comb-shaped double-layer membrane structure is used to increase the contact area between the bipolar membrane and the ion exchange membrane. It shortens the distance that ions move in the acid-base chamber, improves the uniformity of acid and alkali production, and improves acid-base production efficiency.

Description

A device for seawater desalination and acid and alkali recovery

Technical field

The invention relates to a microbial fuel cell coupled flow electrode device capable of desalting and recovering acid and alkali, and belongs to the technical fields of microbial fuel cells, flow electrode capacitive deionization and acid and alkali production.

Background technique

With the rapid development of society, human living conditions are improving day by day, and the accompanying problems such as resource shortage and energy tension are gradually exposed. In particular, the problem of scarcity of freshwater resources needs to be addressed. Up to now, many methods have been proposed to solve such problems, such as membrane separation, distillation, ion exchange, electrodeionization and freezing desalination, etc. However, these technologies require external energy and have relatively high energy consumption, which is not conducive to the circular economy. develop. In addition, the desalination efficiency of microbial fuel cells for concentrated brine is not ideal, and desalination cannot be carried out continuously. The limitation of microbial fuel cells coupled capacitor deionization is also reflected in that it can only be used for desalination, purification of sewage, etc. , does not show big advantages in other aspects.

In China, concentrated salt water is usually introduced into the evaporation pond, but this method has obvious disadvantages. If the structure is unreasonable, it can easily cause the concentrated salt water to leak and seep into the groundwater body, causing groundwater pollution. Abroad, concentrated salt water is usually used to irrigate plants with high salinity tolerance or to breed saltwater fish (for example, Australia is currently exploring the use of concentrated salt water to breed saltwater fish). It can also be used as supplementary water for ecological scenic spots, but generally It is said that there are few plant species and regions suitable for concentrated salt water, making it difficult to scale up. Therefore, most of today's concentrated brine treatments have limitations. Therefore, providing a method to recycle concentrated brine into cost-effective products has become a social development trend and challenge.

CN207566948U discloses a desalination device combining a microbial fuel cell and capacitive deionization. However, when the device is desalted, the electrode will reach saturation, and then a series of electrode regeneration operations are required to disconnect the wires connecting the titanium collector to the cathode and anode electrodes, so that the two wires on the titanium collector are connected to form a short-circuit discharge. It is quite cumbersome and cannot achieve continuous desalination. The concentrated brine flowing out after electrode regeneration has not been utilized as it should.

CN107624106A discloses a single-module flow electrode device for capacitive deionization for continuous water desalination, ion separation, and selective removal and concentration of ions. The current collector of this device is located outside the flowing electrode liquid, far away from the sub-exchange membrane, and the charge transfer capacity is reduced. As the desalination process proceeds, the flow of the flowing electrode liquid will gradually become stable, and there is a certain space in the electrode liquid flow channel. , once the flowing electrode solution stabilizes, the activated carbon particles in the flowing electrode solution will tend to two extremes. The activated carbon particles close to the membrane will absorb more, and the activated carbon particles far away from the membrane will adsorb less, which will make the adsorption of ions by the flowing electrode solution poor. This results in problems such as low utilization of the flow electrode and greatly reduced desalination performance.

Contents of the invention

Purpose of the invention: In response to the above problems, the present invention provides a microbial fuel cell coupled flow electrode device that can achieve desalination and recover acid and alkali.

Technical solution: a device for seawater desalination and acid-base recovery according to the present invention. The device includes a desalination system and an acid-base recovery system. The desalination system includes a deionization and desalination device. The electrodes of the deionization and desalination device The liquid flow area is provided with several turbulence stirrers, and the adjacent turbulence stirrers rotate in opposite directions to stir the activated carbon particles in the electrode liquid; the acid-base recovery system includes an acid chamber and an alkali chamber, and the acid chamber and the alkali chamber The chambers are separated by partitions (108). Both the acid chamber and the alkali chamber are provided with rectangular comb-shaped bipolar membranes. One side of the bipolar membrane in the acid chamber is provided with an anion exchange membrane, and one side of the bipolar membrane in the alkali chamber is provided with an anion exchange membrane. There is a cation exchange membrane, and both the anion exchange membrane and the cation exchange membrane are bonded to the titanium alloy stent that is resistant to acid and alkali corrosion.

Wherein, the deionization and desalting device includes a flowing electrode solution, a bottom plate, and corresponding titanium mesh negative electrodes and titanium mesh positive electrodes. The titanium mesh negative electrode and the titanium mesh positive electrode are equipped with anion exchange membranes on the inside, and the titanium mesh positive electrode is close to the anion exchange membrane. , there is a cation exchange membrane between the anion exchange membrane, a bottom plate is provided outside the titanium mesh negative electrode and the titanium mesh positive electrode, the titanium mesh negative electrode is close to the bottom plate, and the spoiler stirrer is located in the space formed by the titanium mesh negative electrode and the anion exchange membrane and the titanium mesh In the space formed by the positive electrode of the mesh and the bottom plate, the flowing electrode liquid circulates in the aforementioned space through a peristaltic pump.

Among them, the rotation speed of the turbulent mixer is 15-20RPM.

Wherein, the desalination system also includes a seawater chamber and a freshwater chamber. The seawater chamber is connected to the deionization and desalination device through a three-way valve, and the freshwater chamber is connected to the deionization and desalination device.

Wherein, the acid-base recovery system also includes a concentrated brine chamber, and the titanium alloy bracket is fixedly arranged on the upper part of the concentrated brine chamber.

Wherein, an anode electrode is arranged on the upper part of the bipolar membrane in the acid chamber, and a cathode electrode is arranged on the upper part of the bipolar membrane in the alkali chamber.

Among them, organic biomass is attached to the outer surface of the anode electrode.

Among them, organic biomass is one of low-concentration organic wastewater, cellulose, glucose, and methane.

Wherein, the electricity generated by the anode electrode and the cathode electrode is used by the desalination system through wires.

Wherein, the acid-base recovery system is a three-dimensional tank, and an air outlet is provided at the upper part of the three-dimensional tank.

Wherein, the acid chamber is provided with a hydrochloric acid outlet after passing through the peristaltic pump, and the alkali chamber is provided with a sodium hydroxide outlet after passing through the peristaltic pump.

Among them, the desalination system also includes valves, which are connected to the desalination system and the acid-base recovery system through pipelines.

Desalting mechanism: The sodium ions in seawater are pushed by the repulsive force of the titanium mesh positive electrode into the cation exchange membrane and enter the salinization zone. The chloride ions in the seawater are brought into the flowing electrode solution by the strong attraction of the titanium mesh positive electrode and are adsorbed by the activated carbon particles. Due to the driving force of the peristaltic pump, the chloride ions in the seawater are brought to the anion exchange membrane on the other side by the flowing electrode solution, and are pushed into the salinization zone by the repulsive force of the titanium mesh negative electrode. Therefore, the salinization zone can collect concentrated brine, and due to desalination The concentration of salt ions in the zone decreases, thereby producing fresh water.

Acid-base recovery mechanism: The bipolar membrane in the acid chamber (hydroxide ion diffusion side faces upward) diffuses hydrogen ions inward. The chloride ions in the concentrated brine chamber are attracted by the anode electrode and enter the acid chamber through the anion exchange membrane, where they interact with hydrogen. The ions combine to form hydrochloric acid. The bipolar membrane in the alkali chamber on the right side of the partition (the hydrogen ion diffusion side faces upward) diffuses hydroxide ions inward. The sodium ions in the concentrated brine chamber are attracted by the cathode, enter the alkali chamber through the cation exchange membrane, and interact with the hydroxide ions. The radical ions combine to form sodium hydroxide.

Beneficial effects: Compared with existing technology, the present invention has the following significant advantages:

(1) The present invention combines desalination and recovery of acid and alkali to treat seawater, which can simultaneously achieve the dual effects of desalinating seawater into fresh water and recovering salts in seawater into acid and alkali.

(2) The acid-base recovery system of the present invention places the titanium mesh positive electrode close to the anion exchange membrane, which reduces the charge transmission distance and improves the adsorption effect of activated carbon particles in the flowing electrode solution;

(3) The desalination system of the present invention installs several sets of relatively rotating stirrers in the flowing electrode liquid, so that the movement patterns of the activated carbon particles in the flowing electrode liquid can be controlled, so that almost every activated carbon particle can adsorb ions, achieving The uniformity of ion adsorption improves the utilization rate and desalination effect of the flowing electrode solution;

(4) The acid-base recovery system of the present invention adopts a rectangular comb-shaped double-layer membrane to increase the contact area between the bipolar membrane and the ion exchange membrane and reduce the volume. It is supported by a titanium alloy skeleton, which is resistant to acid and alkali corrosion and can The protective film is not easily deformed, thereby improving the uniformity of ion distribution and speeding up the rate at which ions combine to form acids and bases.

Description of the drawings

Figure 1 is a structural diagram of the device used for seawater desalination and acid and alkali recovery according to the present invention;

Figure 2 is a structural diagram of the deionization and desalination device;

Figure 3 is a working flow chart of the device used for seawater desalination and acid and alkali recovery according to the present invention;

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings.

A device for seawater desalination and acid-base recovery according to the present invention is shown in Figure 1. The device for seawater desalination and acid-base recovery includes a desalination system 200 and an acid-base recovery system 100.

The desalination system 200 includes a seawater chamber 201, a freshwater chamber 204 and a deionization and desalination device 203. The seawater chamber 201 is connected to the deionization and desalination device 203 through a three-way valve 202, and the freshwater chamber 204 is connected to the deionization and desalination device 203. A fresh water outlet 205 is provided at the bottom of the fresh water chamber 204, and the deionization and desalination device 203 is connected to the acid-base recovery system 100 through a valve 206.

Among them, the deionization and desalination device 203 is shown in Figure 3. The deionization and desalination device 203 includes a peristaltic pump 2031, a flowing electrode solution 2037, a bottom plate 2038, a corresponding titanium mesh negative electrode 2032 and a titanium mesh positive electrode 2033. The titanium mesh Anion exchange membrane 2034 is provided inside the negative electrode 2032 and the titanium mesh positive electrode 2033. The titanium mesh positive electrode 2033 is close to the anion exchange membrane 2034. There is a cation exchange membrane 2035 between the two anion exchange membranes 2034. The cation exchange membrane 2035 will deionize. The desalination device 203 is divided into a desalination area and a salinization area. There is a bottom plate 2038 on the outside of the titanium mesh negative electrode 2032 and the titanium mesh positive electrode 2033. The titanium mesh negative electrode 2032 is close to the bottom plate 2038. The titanium mesh negative electrode 2032 and the anion exchange membrane 2034 form a space. The titanium mesh positive electrode 2033 and the bottom plate 2038 form a space. Then Several turbulence stirrers 2036 are provided in the aforementioned space, and the peristaltic pump 2031 circulates the flowing electrode liquid 2037 in the aforementioned formed space. The space formed above is filled with activated carbon particles. The adjacent turbulence stirrers 2036 rotate in opposite directions and are used to stir the activated carbon particles in the electrode solution. The rotation speed of the spoiler mixer 2036 is 15-20RPM.

Among them, the acid-base recovery system 100 includes an acid chamber, an alkali chamber, and a concentrated salt water chamber 115. The acid chamber and the alkali chamber are separated by a partition 108. Both the acid chamber and the alkali chamber are provided with rectangular comb-shaped bipolar membranes 104. , an anion exchange membrane 107 is provided on one side of the bipolar membrane 104 in the acid chamber, and a cation exchange membrane 109 is provided on one side of the bipolar membrane 104 in the alkali chamber. Both the anion exchange membrane 107 and the cation exchange membrane 109 are resistant to acid and alkali corrosion. Titanium alloy bracket 113 fit. The titanium alloy bracket 113 is fixedly installed on the upper part of the concentrated brine chamber 115 . An anode electrode 103 is provided on the upper part of the bipolar membrane 104 in the acid chamber, and a cathode electrode 111 is provided on the upper part of the bipolar membrane 104 in the alkali chamber. Among them, organic biomass is attached to the outer surface of the anode electrode 103. The anode electrode 103 and the cathode electrode 111 constitute a microbial fuel cell. Organic biomass can be low-concentration organic wastewater, cellulose, glucose, methane, etc. The anode electrode 103 and the cathode electrode 111 are connected to the deionization and desalination device 203 of the desalination system 100 through a wire 101 . The entire acid-base recovery system 100 is a three-dimensional tank, and an air outlet 102 is provided at the upper part of the three-dimensional tank. A peristaltic pump 105 is provided outside the acid chamber. The peristaltic pump 105 discharges hydrochloric acid from the hydrochloric acid outlet 106. A peristaltic pump (105) is also provided outside the alkali chamber. The peristaltic pump 105 discharges sodium hydroxide from the sodium hydroxide outlet 114.

The device for seawater desalination and acid-base recovery according to the present invention works as shown in Figure 3. When power is supplied, microorganisms consume organic biomass at the anode electrode 103 to produce carbon dioxide and electrons. The carbon dioxide is discharged from the air outlet 102, and the electrons move to The cathode electrode 111 undergoes a reduction reaction to produce water; the bipolar membrane 104 in the acid chamber (hydroxide ion diffusion side faces upward) diffuses hydrogen ions inward, and the chloride ions in the concentrated brine chamber 115 are attracted by the anode electrode 103 and pass through the anions. The exchange membrane 107 enters the acid chamber and combines with hydrogen ions to form hydrochloric acid, which is collected from the hydrochloric acid outlet 106 by the peristaltic pump 105 . The bipolar membrane 112 (hydrogen ion diffusion side facing upward) in the alkali chamber on the right side of the partition 108 diffuses hydroxide ions inwardly, and the sodium ions in the concentrated brine chamber 115 are attracted by the cathode 111 and enter the alkali through the cation exchange membrane 109 chamber, combined with hydroxide ions to form sodium hydroxide, which is collected from the sodium hydroxide outlet 114 using a peristaltic pump 105. The contact area of the rectangular comb-shaped double-layer membrane 104 with the anion exchange membrane 107 and the cation exchange membrane 109 increases, and the volume decreases. Small, it is supported by a titanium alloy bracket 113. The titanium alloy bracket 113 is not only resistant to acid and alkali corrosion, but also can protect the double-layer membrane 104, the anion exchange membrane 107 and the cation exchange membrane 109 from being easily deformed, thereby improving the uniformity of ion distribution and speeding up the ion exchange process. The rate of combining into acid and alkali; the microbial fuel cell supplies power to the deionization device 203 through the wire 101. After the seawater enters the brine chamber 201, it is diverted by the three-way valve 202, and part of it enters the desalination area of the deionization device 203. The sodium ions in the seawater are The repulsive force of the titanium mesh positive electrode 2033 pushes the cation exchange 2034 into the salinization zone. The chloride ions in the seawater are brought into the flowing electrode solution 2037 by the strong attraction of the titanium mesh positive electrode 2033, and are adsorbed by the activated carbon particles. Since the titanium mesh positive electrode is close to The anion exchange membrane reduces the charge transmission distance and improves the adsorption effect of activated carbon particles in the flow electrode. Due to the intervention of the flow stirring device 2036, the movement pattern of the activated carbon particles is controlled, allowing almost every activated carbon particle to adsorb chlorine. ions, achieving uniform ion adsorption and improving the utilization rate and desalination effect of the flowing electrode solution. Due to the driving force of the peristaltic pump 2031, the chloride ions in the seawater are brought to the anion exchange membrane 2034 on the other side by the flowing electrode liquid 2037, and are pushed into the salinization zone by the repulsive force of the titanium mesh negative electrode 2032. Therefore, the salinization zone can collect concentrated The salt water is controlled by the valve 206 and is discharged into the concentrated salt water chamber 115. As the concentration of salt ions decreases in the desalination area, fresh water is produced, flows into the fresh water chamber 204 for collection, and is discharged from the system through the outlet 205 of the fresh water chamber for people to use.

Claims (8)

1. A device for seawater desalination and acid-base recovery, characterized in that the device includes a desalination system (200) and an acid-base recovery system (100), wherein the desalination system (200) includes a deionization desalination device ( 203), the electrode liquid flow area of the deionization and desalting device (203) is provided with several turbulence stirrers (2036), and the adjacent turbulence stirrers (2036) rotate in opposite directions to stir the electrolyte liquid. Activated carbon particles; the acid-base recovery system (100) includes an acid chamber and an alkali chamber. The acid chamber and the alkali chamber are separated by a partition (108). Both the acid chamber and the alkali chamber are provided with rectangular comb-shaped bipolar membranes (104 ), an anion exchange membrane (107) is provided on one side of the bipolar membrane (104) in the acid chamber, a cation exchange membrane (109) is provided on one side of the bipolar membrane (104) in the alkali chamber, and an anion exchange membrane (107) and The cation exchange membranes (109) are all bonded to the titanium alloy bracket (113) that is resistant to acid and alkali corrosion; the deionization and desalting device (203) includes a flowing electrode solution (2037), a bottom plate (2038), and a corresponding titanium mesh negative electrode. (2032) and titanium mesh positive electrode (2033), titanium mesh negative electrode (2032) and titanium mesh positive electrode (2033) are equipped with anion exchange membrane (2034) on the inside, and titanium mesh positive electrode (2033) is close to the anion exchange membrane (2034) , there is a cation exchange membrane (2035) between the anion exchange membrane (2034), the titanium mesh negative electrode (2032) and the titanium mesh positive electrode (2033) are both equipped with bottom plates (2038), and the titanium mesh negative electrode (2032) is close to the bottom plate (2038). 2038), the turbulence stirrer (2036) is located in the space formed by the titanium mesh negative electrode (2032) and the anion exchange membrane (2034) and the space formed by the titanium mesh positive electrode (2033) and the bottom plate (2038), flowing electrode liquid (2037 ) circulates in the aforementioned space through a peristaltic pump (2031); the upper part of the bipolar membrane (104) in the acid chamber is provided with an anode electrode (103), and the upper part of the bipolar membrane (104) in the described alkali chamber is provided with a cathode Electrode (111), the outer surface of the anode electrode (103) is attached with organic biomass, the anode electrode (103) and the cathode electrode (111) constitute a microbial fuel cell; the microbial fuel cell is a deionization and desalination device (203 )powered by. 2. The device for seawater desalination and acid and alkali recovery according to claim 1, characterized in that the rotation speed of the turbulence stirrer (2036) is 15-20 RPM. 3. The device for seawater desalination and acid-base recovery according to claim 1, characterized in that the desalination system further includes a seawater chamber (201) and a freshwater chamber (204), and the seawater chamber (201) passes through three The valve (202) is connected to the deionization and desalination device (203), and the fresh water chamber (204) is connected to the deionization and desalination device (203). 4. The device for seawater desalination and acid-base recovery according to claim 1, characterized in that the acid-base recovery system (100) further includes a concentrated brine chamber (115), and the titanium alloy bracket (113) is fixed Set on the upper part of the concentrated brine chamber (115). 5. The device for seawater desalination and acid and alkali recovery according to claim 1, characterized in that the electricity generated by the anode electrode (103) and the cathode electrode (111) is supplied to the desalination system (100) through the wire (101). use. 6. The device for seawater desalination and acid-base recovery according to claim 1, characterized in that the acid-base recovery system (100) is a three-dimensional tank, and an air outlet (102) is provided at the upper part of the three-dimensional tank. 7. The device for seawater desalination and acid-base recovery according to claim 1, characterized in that the acid chamber is provided with a hydrochloric acid outlet (106) after passing through the peristaltic pump (105), and the alkali chamber passes through the peristaltic pump (105). 105) is provided with a sodium hydroxide outlet (114). 8. The device for seawater desalination and acid and alkali recovery according to claim 1, characterized in that the desalination system (200) also includes a valve (206), and the valve (206) is connected to the desalination system (200) and the acid through pipelines respectively. The alkali recovery system (100) is connected.