CN113401984A - Separation device and water treatment equipment thereof - Google Patents

Separation device and water treatment equipment thereof Download PDF

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Publication number
CN113401984A
CN113401984A CN202010183558.3A CN202010183558A CN113401984A CN 113401984 A CN113401984 A CN 113401984A CN 202010183558 A CN202010183558 A CN 202010183558A CN 113401984 A CN113401984 A CN 113401984A
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membrane
electrode
bipolar membrane
porous
bipolar
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Chinese (zh)
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陈小平
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Guangdong Lizi Technology Co Ltd
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Foshan Viomi Electrical Technology Co Ltd
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Priority to CN202010183558.3A priority Critical patent/CN113401984A/en
Publication of CN113401984A publication Critical patent/CN113401984A/en
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
    • C02F1/4695—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis electrodeionisation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • B01D61/445—Ion-selective electrodialysis with bipolar membranes; Water splitting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • B01D61/46—Apparatus therefor
    • B01D61/48—Apparatus therefor having one or more compartments filled with ion-exchange material, e.g. electrodeionisation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination

Abstract

A bipolar membrane electrodeionization device and water treatment equipment with the same are provided, the bipolar membrane electrodeionization device comprises at least one pair of characteristic electrode groups and more than one bipolar membrane positioned between two electrodes forming the characteristic electrode groups, the electrode groups at least comprise one porous electrode, and each bipolar membrane is formed by a cation exchange membrane and an anion exchange membrane which are attached together. The bipolar membrane electrodeionization device adopts the structure of the porous electrode and the bipolar membrane, can avoid the problems of gas generation and scaling caused by hydrolysis of water in an electrode chamber in the prior art, can improve the desalination rate, and has the characteristics of high water making rate and less water resource waste.

Description

Separation device and water treatment equipment thereof
Technical Field
The invention relates to the technical field of water treatment, in particular to a bipolar membrane electrodeionization device and water treatment equipment with the same.
Background
In the traditional electrochemical deionization device, a flow channel between an electrode and an ion exchange membrane is an electrode water chamber, wherein oxidation reaction is carried out in an anode chamber to generate oxygen, anode water is acidic, and the anode is easily corroded; the reduction reaction is carried out in the cathode chamber to generate hydrogen, cathode water is alkaline, and scaling is easy to form on the cathode. Therefore, the generation of gas and scale causes an increase in the voltage drop in the polar water chamber, making the device unstable in operation and less efficient overall. In addition, the electrode chamber of the electrochemical deionization device does not have the desalting function, and the liquid flow passing through the electrode chamber is separately drawn out in the design generally, so that the pollution to the pure water is prevented. In order to prevent the liquid flow of the electrode chamber from entering the pure water flow, the requirement on the sealing property of the flow channel of the membrane stack is high, the flow channel is complex in design, and the cost is high. In addition, the design needs to consider the exhaust problem of the polar chamber flow passage to prevent the gas from being held in the flow passage. In a word, the electrode chamber makes the structural design of electrochemical deionization become very complicated, once the control is not good, the desalting performance is reduced, even the water flow is blocked, the electrode is burnt and the like.
Therefore, it is necessary to provide a bipolar membrane electrodeionization device and a water treatment apparatus thereof to overcome the deficiencies of the prior art.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a bipolar membrane electrodeionization device and water treatment equipment with the same, which can solve the problems of gas generation and scaling caused by hydrolysis of water in a polar chamber in water in the prior art, improve the desalination rate, and have high water production rate and less water resource waste.
The object of the invention is achieved by the following technical measures.
The utility model provides a bipolar membrane electrodeionization device, which comprises at least one pair of characteristic electrode groups and more than one bipolar membrane positioned between two electrodes forming the characteristic electrode groups, wherein the characteristic electrode groups at least comprise a porous electrode, each bipolar membrane is formed by a cation exchange membrane and an anion exchange membrane which are attached together, and no flow channel is arranged between the cation exchange membrane and the anion exchange membrane which form the same bipolar membrane.
Preferably, in the bipolar membrane electrodeionization device, the porous electrode is provided with a porous material having a porous structure with a pore size of 0.5 to 50 nm.
Preferably, in the bipolar membrane electrodeionization device, the porous material is one or more of activated carbon, carbon black, carbon nanotubes, graphite, carbon fibers, carbon cloth, carbon aerogel, metal powder, metal oxide and conductive polymer.
Preferably, in the bipolar membrane electrodeionization device, the porous electrode is further provided with a current collector, and the current collector is laminated with the porous material.
Preferably, in the bipolar membrane electrodeionization device, the current collector is made of one or more materials selected from the group consisting of metals, metal alloys, graphite, graphene, carbon nanotubes and conductive plastics.
Preferably, in the above bipolar membrane electrodeionization device, the porous electrode is further provided with an ion exchange membrane, and the porous material and the ion exchange membrane are stacked.
Preferably, in the above bipolar membrane electrodeionization device, the ion exchange membrane in the porous electrode is an anion exchange membrane or a cation exchange membrane.
Preferably, in the above bipolar membrane electrodeionization apparatus, one of the porous electrodes has a cation exchange membrane, defined as an anode electrode; the other porous electrode has an anion exchange membrane, defined as a negative membrane electrode;
the anion-exchange membrane in the bipolar membrane closest to the anode electrode faces the anode electrode;
the cation-exchange membrane in the bipolar membrane closest to the cathode electrode faces the cathode electrode.
Preferably, in the above bipolar membrane electrodeionization device, a salt solution is encapsulated in the porous material, and the mass percentage of the salt solution in the porous material is not less than 10%.
The invention also provides water treatment equipment which is provided with the bipolar membrane electrodeionization device.
The invention discloses a bipolar membrane electrodeionization device and water treatment equipment thereof, which comprise at least one pair of characteristic electrode groups and more than one bipolar membrane positioned between two electrodes forming the characteristic electrode groups, wherein each characteristic electrode group at least comprises a porous electrode, each bipolar membrane is formed by a cation exchange membrane and an anion exchange membrane which are attached together, and no flow channel is arranged between the cation exchange membrane and the anion exchange membrane which form the same bipolar membrane. The bipolar membrane electrodeionization device adopts the structure of the porous electrode and the bipolar membrane, can avoid the problems of gas generation and scaling caused by hydrolysis of water in an electrode chamber in the prior art, can improve the desalination rate, and has the characteristics of high water making rate and less water resource waste.
Drawings
The invention is further illustrated by means of the attached drawings, the content of which is not in any way limiting.
FIG. 1 is a schematic view showing a desalting state of a bipolar membrane electrodeionization apparatus of example 1 of the present invention.
FIG. 2 is a schematic view showing a regeneration state of a bipolar membrane electrodeionization apparatus of example 1 of the present invention.
FIG. 3 is a schematic view showing a desalting state of a bipolar membrane electrodeionization apparatus of example 2 of the present invention.
FIG. 4 is a schematic view showing the regeneration state of a bipolar membrane electrodeionization apparatus of example 2 of the invention.
In fig. 1 to 4, the following are included:
a porous electrode 100,
A current collector 130, a porous material 110, an anion exchange membrane 120,
A porous electrode 200,
A current collector 230, a porous material 210, a cation exchange membrane 220,
Bipolar membrane 300, cation exchange membrane 310, anion exchange membrane 320.
Detailed Description
The invention is further illustrated by the following examples.
Unless clearly defined otherwise herein, the scientific and technical terms used have the meaning commonly understood by those of skill in the art to which this application pertains. As used in this application, the terms "comprising," "including," "having," or "containing" and similar referents to shall mean that the content of the listed items is within the scope of the listed items or equivalents thereof.
In the specification and claims, the singular and plural of all terms are not intended to be limiting unless the context clearly dictates otherwise. The use of "first," "second," and similar language in the description and claims of this application does not denote any order, quantity, or importance, but rather the intention is to distinguish one material from another, or embodiment.
Unless the context clearly dictates otherwise, the term "or", "or" does not mean exclusively, but means that at least one of the mentioned items (e.g. ingredients) is present, and includes the case where a combination of the mentioned items may be present.
References in the specification to "some embodiments" or the like indicate that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the invention is included in at least one embodiment described in the specification, and may or may not be present in other embodiments. In addition, it is to be understood that the described inventive elements may be combined in any suitable manner.
Reference herein to "deionization" is to the removal of ions from the liquid to be treated, including anions and cations in various valence states. In most cases, "deionization" has the same meaning as "desalination". In some cases, deionization is also referred to as demineralization.
Example 1.
The characteristic electrode group at least comprises a porous electrode, each bipolar membrane is composed of a cation exchange membrane and an anion exchange membrane which are attached together, and no flow channel exists between the cation exchange membrane and the anion exchange membrane which form the same bipolar membrane.
The pair of characteristic electrode groups may be formed by two porous electrodes, or the pair of characteristic electrode groups may be formed by one porous electrode and one common electrode. Common electrodes such as metal electrodes, titanium electrodes with ruthenium-yttrium coatings, ruthenium-yttrium electrodes, carbon electrodes, graphite electrodes, etc.
Among them, the porous electrode may be composed of a porous material, or a porous material and a current collector laminated, or a current collector, a porous material, and an ion exchange membrane laminated in this order. The ion exchange membrane is an anion exchange membrane or a cation exchange membrane, and when the ion exchange membrane is contained, the ion exchange membrane in the porous electrode is close to the bipolar membrane. The cation exchange membrane or the anion exchange membrane in the porous electrode can be flexibly selected according to actual needs.
The porous material may be any electrically conductive material having a large specific surface, e.g. a specific surface of more than 100m2Conductive material per gram. In some embodiments, the porous material is a hydrophobic, electrically conductive material. The porous material has a porous structure with pore sizes between 0.5 and 50 nanometers. The porous material can be an electric conductor prepared from one or more of activated carbon, carbon black, carbon nanotubes, graphite, carbon fibers, carbon cloth, carbon aerogel, metal powder (such as nickel), metal oxide (such as ruthenium oxide) and conductive polymer. In one embodiment, the porous material is a sheet or plate structure made of activated carbon and having a thickness in the range of 100 to 5000 micrometers, preferably 200 to 2,500 micrometers, and the pore size of the activated carbon sheet structure is between 0.5 to 20 nanometers, preferably 1 to 10 nanometers.
The porous electrode can reduce the scaling risk of the bipolar membrane electrodeionization device. Since the ion exchange membrane contains or is adsorbed with ion charge units, when the amount of ions at the porous electrode is insufficient to complete the desorption process, the excess charge on the electrode is buffered by releasing the ions in the ion exchange membrane to help complete the desorption process. In this way, the risk of fouling of the electrochemical deionization unit is greatly reduced.
The current collector is used to connect to a wire or power source, also referred to as a "current collector". The current collector is formed of one or more materials selected from the group consisting of metals, metal alloys, graphite, graphene, carbon nanotubes, and conductive plastics. The current collector may be in any suitable form such as a plate, mesh, foil or sheet. In some embodiments, the current collector may be made of a metal or metal alloy, suitable metals include titanium, platinum, iridium or rhodium, etc., preferably titanium, and suitable metal alloys may be stainless steel, etc. In other embodiments, the current collector may be made of a conductive carbon material, such as graphite, graphene, carbon nanotubes, and the like. In other embodiments, the current collector is made of a conductive plastic material, such as a polyolefin (e.g., polyethylene), and conductive carbon black or metal particles, etc., may be mixed therein. In some embodiments, the current collector is a sheet or plate-like structure and may have a thickness in the range of 50 micrometers to 5 millimeters. In some embodiments, the current collector and the porous electrode have substantially the same shape and/or size.
When the porosity and conductivity of the porous material are sufficient, the current collector may not be provided when the porous material itself functions as the current collector.
The bipolar membrane electrodeionization device of the present embodiment may be configured by a plurality of electrode groups, and when the bipolar membrane electrodeionization device includes a plurality of electrode groups, the electrode groups may be connected to each other through flow channels in series or in parallel or in a series-parallel manner. In the present specification, the terms "in series" and "in parallel" are defined in consideration of the flow direction of the flow path liquid flow output liquid. For example, if two electrode sets are connected in series, the product fluid from the flow channel of the previous electrode set enters the flow channel of the next electrode set. For another example, if two electrode sets are connected in parallel, it means that the flow channels of the two electrode sets receive the same liquid. The series set of electrodes is used to further remove ions from the liquid, while the parallel set of electrodes is used to increase the throughput of the device.
The technical solution of the present invention will be described below by taking the bipolar membrane electrodeionization apparatus shown in FIGS. 1 and 2 as an example.
The bipolar membrane electrodeionization device comprises,
an electrode pair consisting of a pair of porous electrodes 100, 200, which, due to the two porous electrodes, constitute a characteristic electrode group;
two bipolar membranes 300 arranged between the electrode pairs, wherein each bipolar membrane 300 is composed of a cation exchange membrane 310 and an anion exchange membrane 320 which are attached together, no flow channel is arranged between the cation exchange membrane 310 and the anion exchange membrane 320 which form the same bipolar membrane 300, and the arrangement modes of the two bipolar membranes 300 are the same;
and a flow channel formed between the electrode and the membrane stack or between the membrane stack and the membrane stack.
In the present embodiment, the porous electrode 100 is formed by laminating the current collector 130 and the porous material 110, and the porous electrode 100 is a cathode film electrode. The porous electrode 200 is formed by sequentially laminating a current collector 230 and a porous material 210, and the porous electrode 200 is an anode membrane electrode. The porous electrode can be formed by laminating and clamping a current collector and a porous material together without using a binder; or may be fixed by thermal bonding or bonded by an adhesive. The cation exchange membrane or the anion exchange membrane in the porous electrode can be flexibly selected according to actual needs.
The bipolar membrane 300 is composed of a cation exchange membrane 310 and an anion exchange membrane 320 which are attached together, and the cation exchange membrane 310 and the anion exchange membrane 320 which form the same bipolar membrane are clamped tightly without a binder; the cation exchange membrane 310 and the anion exchange membrane 320 may be formed by thermal lamination. There is no flow channel between the cation exchange membrane 310 and the anion exchange membrane 320, and a flow channel is formed between the bipolar membrane or between the bipolar membrane and the electrode. The bipolar membranes sold in the market can be used as the bipolar membranes in the scheme, and the details are not repeated.
In this embodiment, there are two bipolar membranes 300 between the porous electrodes 100 and 200, the arrangement directions of the two bipolar membranes 300 are the same, and the same arrangement direction means that the cation exchange membranes 310 of each bipolar membrane 300 are oriented in the same direction, and certainly the corresponding anion exchange membranes 320 of each bipolar membrane 300 are also oriented in the same direction. It should be noted that the number of the bipolar membranes 300 is not limited to two in this embodiment, and can be flexibly set according to actual needs, and the number of the bipolar membranes 300 between the general electrode pairs is 1-50, or even more.
As shown in FIG. 1, in the bipolar membrane electrodeionization apparatus, a cation exchange membrane of a bipolar membrane faces a positive electrode in a desalting process, and raw water is desalted in a flow channel formed between the two bipolar membranes. Anions in the raw water, e.g. Cl-Moving toward the positive electrode to replace OH in the left anion exchange membrane-，OH-Entering a flow channel; with cations such as Na in the raw water+Moving toward the negative electrode to replace H in the cation exchange membrane of the bipolar membrane on the right side+Ion(s)，H+Entering a flow channel; h+And OH-Neutralization reaction occurs in the flow channel to generate water, so that salt in raw water is removed, and pure water is discharged from the tail end of the flow channel.
In the first flow path (i.e., anode chamber) formed by the porous electrode 100 and the adjacent bipolar membrane 300 to which the forward voltage is applied and the two, anions such as Cl in the raw water-Moves towards the positive electrode and is adsorbed by the porous electrode 110, and simultaneously, cations such as Na + in the raw water move towards the bipolar membrane to replace H in the cationic membrane+And ions are used for removing salt in the raw water, and at the moment, the pure water discharged from the tail end of the flow passage is acidic. Similarly, in the second flow channel (i.e., cathode chamber) formed by the porous electrode 200 and the adjacent bipolar membrane 300, which are applied with negative voltage, the cations such as Na in the raw water+Moves toward the negative electrode and is adsorbed by the porous electrode 210; while Cl in the raw water-Moving towards the bipolar membrane to replace OH in the cationic resin membrane-And ions are used for removing the salt in the raw water, and at the moment, the pure water discharged from the tail end of the flow channel is alkaline. The pure water in the first flow passage and the pure water in the second flow passage are gathered together, H+And OH-Water is generated by neutralization, and finally neutral pure water is formed.
When desalination is carried out for a period of time, reverse-pole regeneration is required to release ions in water adsorbed on the bipolar membrane. At this time, as shown in FIG. 2, OH groups are generated in the interface layer of the cationic and anionic membranes of the bipolar membrane under an electric field-And H+Ionic, cation inside cationic membrane of right bipolar membrane, e.g. Na+Quilt H+The ions are displaced and move to the negative electrode, and anions such as Cl in the anion membrane of the left bipolar membrane-Is covered with OH-The displacement toward the positive electrode, Na+、Cl-And enters the flow channel to complete the regeneration.
At this time, in the first flow channel formed by the porous electrode 100 and the adjacent bipolar membrane 300 to which the negative voltage is applied and the two, the anions such as Cl adsorbed by the porous electrode 110-Moving to the positive electrode, desorbing, and entering the flow channel; in the positive membrane of a simultaneous bipolar membraneNa of (A)+Quilt H+Displacing the cathode towards the negative electrode and entering the flow channel; discharging the concentrated water containing salt out of the membrane pile to complete regeneration. Meanwhile, in the second flow path formed by the porous electrode 200 to which the positive voltage is applied, the adjacent bipolar membrane 300 and the two, the cation such as Na adsorbed in the porous electrode 210+Moving towards the negative electrode and entering a flow channel; while Cl inside the negative membrane of the bipolar membrane-Is covered with OH-Displacing, moving towards the positive electrode and entering a flow channel; discharging the concentrated water containing salt out of the membrane pile to complete regeneration.
In the bipolar membrane electrodeionization apparatus of this embodiment, the porous material is in direct contact with the flow channel, and the bipolar membrane between the porous electrodes is arranged in the same manner. In the manner of this example, desalination and regeneration can be achieved. Under the desalting condition, the porous material can adsorb anions and cations in raw water, and has no selectivity and the adsorption efficiency of about 50 percent. Under the regeneration condition, anions and cations in the porous material can be desorbed into the flow channel to realize the regeneration.
According to the bipolar membrane electrodeionization device, when water is produced, all single channels simultaneously produce water, and no concentrated water is produced. During regeneration, the regeneration can be realized by reversing the poles, and the regeneration process is also carried out in a single channel. Therefore, the bipolar membrane electrodeionization device has a simple water path structure.
The bipolar membrane electrodeionization device repeatedly utilizes the membrane area of the bipolar membrane, and the electrolytic ion exchange mode greatly improves the speed and efficiency of ion exchange. The bipolar membrane electrodeionization device does not generate gas in polar water and scale formation.
Therefore, the bipolar membrane electrodeionization device adopts the structure of the porous electrode and the bipolar membrane, can avoid the problems of gas generation and scaling caused by the hydrolysis of polar water in the prior art, can improve the desalination rate, and has the characteristics of high water making rate and less water resource waste.
In addition, experiments show that the porous electrode not only solves the problem of gas generation of the metal electrode, but also can realize the design of independent water outlet of the electrode chamber flow passage. And the whole desalting efficiency of the electrodeionization device adopting the porous electrode can be improved by more than 8 percent compared with that of the common electrode. This is because the porous electrode can adsorb ions of raw water, and this adsorption efficiency is higher than the ion exchange efficiency of the bipolar membrane.
The bipolar membrane electrodeionization device of the present embodiment may be in a plate frame type or spiral roll type, and may have a rectangular parallelepiped, cube, or cylindrical shape. Fig. 1 and 2 in this embodiment are schematic cross-sectional views, and those skilled in the art can obtain products of various shapes according to the sectional views.
Example 2.
A bipolar membrane electrodeionization apparatus, as shown in fig. 3 and 4, having the same other features as those of embodiment 1 except that in this embodiment: the porous electrode 100 is formed by stacking a current collector 130, a porous material 110, and an anion exchange membrane 120 in this order, and the porous electrode 100 is a cathode electrode. The porous electrode 200 is formed by stacking a current collector 230, a porous material 210, and a cation exchange membrane 220 in this order, and the porous electrode 200 is an anode membrane electrode. The porous electrode can be formed by overlapping and clamping a current collector, a porous material and an ion exchange membrane together without using a binder; or may be fixed by thermal bonding or bonded by an adhesive.
The bipolar membrane electrodeionization apparatus of the present embodiment, in which the desalination process is such that the cation exchange membrane of the bipolar membrane faces the positive electrode and the raw water is desalinated in the flow channel formed between the two bipolar membranes as shown in FIG. 3, is used in the desalination process. Anions in the raw water, e.g. Cl-Moving toward the positive electrode to replace OH in the left anion exchange membrane-，OH-Entering a flow channel; with cations such as Na in the raw water+Moving toward the negative electrode to replace H in the cation exchange membrane of the bipolar membrane on the right side+Ion, H+Entering a flow channel; h+And OH-Neutralization reaction occurs in the flow channel to generate water, so that salt in raw water is removed, and pure water is discharged from the tail end of the flow channel.
Formed between the porous electrode 100 and the adjacent bipolar membrane 300 to which the forward voltage is applied, and the twoIn the first flow path (i.e., anode chamber), anions such as Cl in the raw water-Moves towards the positive electrode and is adsorbed by the porous electrode 110, and simultaneously, cations such as Na + in the raw water move towards the bipolar membrane to replace H in the cationic membrane+And ions are used for removing salt in the raw water, and at the moment, the pure water discharged from the tail end of the flow passage is acidic. Similarly, in the second flow channel (i.e., cathode chamber) formed by the porous electrode 200 and the adjacent bipolar membrane 300, which are applied with negative voltage, the cations such as Na in the raw water+Moves toward the negative electrode and is adsorbed by the porous electrode 210; while Cl in the raw water-Moving towards the bipolar membrane to replace OH in the cationic resin membrane-And ions are used for removing the salt in the raw water, and at the moment, the pure water discharged from the tail end of the flow channel is alkaline. The pure water in the first flow passage and the pure water in the second flow passage are gathered together, H+And OH-Water is generated by neutralization, and finally neutral pure water is formed.
When desalination is carried out for a period of time, reverse-pole regeneration is required to release ions in water adsorbed on the bipolar membrane. At this time, as shown in fig. 4, OH is generated in the interface layer of the cationic membrane and the anionic membrane of the bipolar membrane under the electric field-And H+Ionic, cation inside cationic membrane of right bipolar membrane, e.g. Na+Quilt H+The ions are displaced and move to the negative electrode, and anions such as Cl in the anion membrane of the left bipolar membrane-Is covered with OH-The displacement toward the positive electrode, Na+、Cl-And enters the flow channel to complete the regeneration.
At this time, in the first flow channel formed by the porous electrode 100 and the adjacent bipolar membrane 300 to which the negative voltage is applied and the two, the anions such as Cl adsorbed by the porous electrode 110-Moving to the positive electrode, desorbing, and entering the flow channel; while Na inside the anode membrane of the bipolar membrane+Quilt H+Displacing the cathode towards the negative electrode and entering the flow channel; discharging the concentrated water containing salt out of the membrane pile to complete regeneration. Meanwhile, in the second flow path formed by the porous electrode 200 to which the positive voltage is applied, the adjacent bipolar membrane 300 and the two, the cation such as Na adsorbed in the porous electrode 210+Moving towards the negative electrode and entering a flow channel; while Cl inside the negative membrane of the bipolar membrane-Is covered with OH-Displacing, moving towards the positive electrode and entering a flow channel; discharging the concentrated water containing salt out of the membrane pile to complete regeneration.
According to the bipolar membrane electrodeionization device, when water is produced, all single channels simultaneously produce water, and no concentrated water is produced. During regeneration, the regeneration can be realized by reversing the poles, and the regeneration process is also carried out in a single channel. Therefore, the bipolar membrane electrodeionization device has a simple water path structure.
The bipolar membrane electrodeionization device repeatedly utilizes the membrane area of the bipolar membrane, and the electrolytic ion exchange mode greatly improves the speed and efficiency of ion exchange. The bipolar membrane electrodeionization device does not generate gas in polar water and scale formation.
Therefore, the bipolar membrane electrodeionization device adopts the structure of the porous electrode and the bipolar membrane, can avoid the problems of gas generation and scaling caused by the hydrolysis of polar water in the prior art, can improve the desalination rate, and has the characteristics of high water making rate and less water resource waste.
In addition, experiments show that the porous electrode not only solves the problem of gas generation of the metal electrode, but also can realize the design of independent water outlet of the electrode chamber flow passage. And compared with the common electrode, the whole desalting efficiency of the electrodeionization device adopting the porous electrode can be improved by more than 10 percent, and the desalting efficiency is improved by a higher degree than that of the structure in the embodiment 1. This is because the porous electrode can adsorb ions of raw water, and this adsorption efficiency is higher than the ion exchange efficiency of the bipolar membrane. It can be seen that the electrodeionization apparatus of this example using porous electrodes is excellent in overall performance.
The bipolar membrane electrodeionization device of the present embodiment may be in a plate frame type or spiral roll type, and may have a rectangular parallelepiped, cube, or cylindrical shape. Fig. 3 and 4 in this embodiment are schematic cross-sectional views, and those skilled in the art can obtain products of various shapes according to the sectional views.
Example 3.
A bipolar membrane electrodeionization apparatus having the same other features as in example 1 except that: the porous electrode is not provided with a collector, and is formed only by laminating a porous material and an ion exchange membrane. The porous material of the present embodiment has a conductive property that satisfies the requirement of conductivity, and therefore, does not need to be provided with a collector.
It should be noted that the specific structure of the two porous electrodes can be flexibly set according to the need, for example, one porous electrode has a collector, the other porous electrode has no collector, or two porous electrodes have collectors at the same time or two porous electrodes have no collectors at the same time, as long as the actual need is met.
Example 4.
A bipolar membrane electrodeionization apparatus having the same other features as in example 1 or 2 except that: the membrane stack comprises a bipolar membrane and a part of a single cation exchange membrane and/or a single anion exchange membrane. The arrangement can realize the desalting function. Only a portion of the channels do not desalinate or regenerate the incoming water stream.
In this case, one arrangement is that the ion exchange membrane on one side of the stack is sequentially arranged with the single cation exchange membrane and the anion exchange membrane in the order of the cation exchange membrane, the anion exchange membrane, the cation exchange membrane, and the anion exchange membrane. The operation in this case is the same as in embodiment 1.
In another arrangement, in the arrangement of the ion exchange membrane on one side of the membrane stack and the single cation exchange membrane and the single anion exchange membrane, two adjacent membranes belong to the same cation exchange membrane or the same anion exchange membrane, in this case, the flow channel formed by the ion exchange membranes of the same kind does not perform desalination or regeneration treatment on the liquid, and the other flow channels operate in the same manner as in example 1.
Example 5.
A bipolar membrane electrodeionization apparatus having the same other features as in any one of examples 1 to 3 except that: the two porous electrodes are both provided with cation exchange membranes, and the bipolar membranes between the porous electrodes are arranged in the same manner. In this way, desalination and regeneration can be achieved, but the effect is inferior to examples 1 and 2, and in the desalination condition, the flow channel formed by the cation exchange membrane of the porous electrode and the cation exchange resin membrane side of the adjacent bipolar membrane only removes cations, but does not remove anions, and the effluent water quality is acidic. Under regeneration conditions, the cation exchange resin membrane of the bipolar membrane adjacent to the cation exchange membrane of the porous electrode is also regenerated. The other flow channels were desalted and regenerated in the same manner as in example 1 or 2.
Example 6.
A bipolar membrane electrodeionization apparatus having the same other features as in any one of examples 1 to 3 except that: both porous electrodes are provided with anion exchange membranes, and the bipolar membranes between the porous electrodes are arranged in the same manner. In this way, desalination and regeneration can be achieved, but the effect is inferior to examples 1 and 2, and in desalination, the flow channel formed by the anion exchange membrane of the porous electrode and the anion exchange resin membrane side of the adjacent bipolar membrane only removes anions, but does not remove cations, and the effluent quality is alkaline. Under the regeneration condition, the flow channel formed by the anion exchange membrane of the porous electrode and the anion exchange resin membrane side of the adjacent bipolar membrane is also regenerated. The other flow channels were desalted and regenerated in the same manner as in example 1 or 2.
Example 7.
A water treatment apparatus having the bipolar membrane electrodeionization device of any one of embodiments 1 to 6, the water treatment apparatus being useful for industrial or domestic water treatment. Examples of uses of industrial water treatment facilities mentioned herein include, but are not limited to, industrial sewage treatment, municipal sewage treatment, seawater desalination, brine treatment, river and lake water treatment, cheese whey demineralization, and the like. The industrial water treatment apparatus includes, in addition to the bipolar membrane electrodeionization device of an embodiment of the invention, one or more of, for example, a flocculation and/or coagulation unit, an advanced oxidation unit, an adsorption unit, an electrolysis unit, a membrane separation unit (including one or more of microfiltration, ultrafiltration, nanofiltration and reverse osmosis).
The household water treatment equipment of the embodiment of the invention generally comprises one or more of an ultrafiltration unit, a nanofiltration unit, an activated carbon adsorption unit and an ultraviolet sterilization unit, in addition to the bipolar membrane electrodeionization device of the embodiment of the invention.
This water treatment facilities, its bipolar membrane electrodeionization device adopt porous electrode and bipolar membrane's structure, can avoid among the prior art problem that the hydrolysis of utmost point room water produced gas and scale deposit, and can improve the desalination, and the system water rate is high, and the water waste is few.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. A bipolar membrane electrodeionization device comprising at least one pair of electrode assemblies, wherein: the bipolar membrane comprises at least one pair of characteristic electrode groups and more than one bipolar membrane positioned between two electrodes forming the characteristic electrode groups, wherein each characteristic electrode group at least comprises one porous electrode, each bipolar membrane is formed by a cation exchange membrane and an anion exchange membrane which are attached together, and no flow channel is formed between the cation exchange membrane and the anion exchange membrane which form the same bipolar membrane.
2. The bipolar membrane electrodeionization apparatus of claim 1, wherein: the porous electrode is provided with a porous material.
3. The bipolar membrane electrodeionization apparatus of claim 2, wherein: the porous material has a porous structure with pore sizes between 0.5 and 50 nanometers.
4. The bipolar membrane electrodeionization apparatus of claim 2, wherein: the porous material is one or more of activated carbon, carbon black, carbon nanotubes, graphite, carbon fibers, carbon cloth, carbon aerogel, metal powder, metal oxides and conductive polymers.
5. The bipolar membrane electrodeionization apparatus of claim 2, wherein: the porous electrode is also provided with a current collector which is laminated with the porous material.
6. The bipolar membrane electrodeionization apparatus of claim 5, wherein: the material of the current collector is selected from one or more of metal, metal alloy, graphite, graphene, carbon nanotube and conductive plastic.
7. The bipolar membrane electrodeionization apparatus of claim 2, wherein: the porous electrode is also provided with an ion exchange membrane, and the porous material and the ion exchange membrane are arranged in a stacked mode.
8. The bipolar membrane electrodeionization apparatus of claim 7 wherein: the ion exchange membrane in the porous electrode is an anion exchange membrane or a cation exchange membrane.
9. The bipolar membrane electrodeionization apparatus of claim 8, wherein:
a porous electrode having a cation exchange membrane, defined as an anode membrane electrode; the other porous electrode has an anion exchange membrane, defined as a negative membrane electrode;
the anion-exchange membrane in the bipolar membrane closest to the anode electrode faces the anode electrode;
the cation-exchange membrane in the bipolar membrane closest to the cathode electrode faces the cathode electrode.
10. A water treatment apparatus characterized by: having the bipolar membrane electrodeionization device of any of claims 1-9.
CN202010183558.3A 2020-03-16 2020-03-16 Separation device and water treatment equipment thereof Pending CN113401984A (en)

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