A desalination device and method based on electrosorption and coupled reverse osmosis

Abstract

The present invention relates to a desalination device and method based on electrosorption and coupled reverse osmosis. The device comprises: two electrode plates, each of which is used to generate an electrostatic field based on the voltage applied by a power supply to adsorb or desorb anions and cations in raw water, thereby producing low-concentration freshwater or wastewater; the two electrode plates, each carrying opposite charges, are spaced relative to each other, forming a cavity with two open ends in between, one end of the cavity being a water outlet and the other end being a water inlet; a plurality of reverse osmosis membranes, disposed in the cavity between the two electrode plates, for separating anions and cations from water in the low-concentration freshwater to produce freshwater; or for separating anions and cations from water in wastewater under the action of an electrostatic field to produce brackish water; and a collection chamber, connected to the water outlet, for collecting freshwater. The present invention can reduce energy consumption while also reducing membrane fouling and extending the service life of the fouled membranes, thereby improving desalination efficiency and recovery rate.

Description

Technical Field

[0001] The present invention relates to the field of water treatment, and in particular to a desalination device and method based on electric adsorption and coupled reverse osmosis. Background Art

[0002] With the growing global demand for water for life and production, efficient water treatment technology has received more and more attention. Therefore, the rapid development of seawater desalination technology has also brought broad prospects for resolving the water crisis.

[0003] There are two main types of existing desalination technologies: (1) Membrane desalination technology: such as reverse osmosis, electrodialysis, nanofiltration and their combined processes. Among them, nanofiltration is a membrane separation technology that can separate small molecular organic matter from water and inorganic salts, achieving desalination and concentration at the same time; reverse osmosis is a membrane process that uses the selective permeability of the reverse osmosis membrane to only pass through the solvent (usually water) and intercept ionic substances or small molecular substances, and uses the static pressure on both sides of the membrane as the driving force to achieve the separation of liquid mixtures. Electrodialysis is also a membrane separation technology that uses the selective permeability of the membrane to separate substances in the water to achieve the purpose of desalination. (2) Evaporation desalination technology, such as triple-effect evaporation, uses a concentration crystallization system to remove inorganic salts in the raw water by evaporation.

[0004] However, existing membrane desalination technology can effectively remove salt from water with low salt content, but for high-salt water or wastewater with high salt and high organic matter content, there will be problems such as membrane pollution, high pressure, and high energy consumption, which will affect the recovery rate over time.

[0005] There are also processes in the existing technology that combine ultrafiltration, nanofiltration, electrodialysis and RO reverse osmosis technology, but they are all combinations of front and back processes, which not only increase the complexity of the process flow, resulting in higher manpower, material resources and energy consumption, but also are prone to scaling. They can only be cleaned by adding a large amount of scale inhibitors or acids, which increases costs. Otherwise, the degree of membrane contamination will increase, thereby reducing the desalination efficiency and recovery rate. Summary of the Invention

[0006] The purpose of the present invention is to provide a desalination device and method based on electrosorption and coupled reverse osmosis, which can reduce energy consumption while reducing membrane pollution, prolong the service life of the membrane pollution, and thus improve the desalination efficiency and recovery rate.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A desalination device based on electrosorption and coupled reverse osmosis, comprising:

[0009] Two electrode plates are used to generate an electrostatic field according to the voltage applied by the power supply to adsorb or desorb anions and cations in the raw water to produce low-concentration fresh water or wastewater; the two electrode plates have opposite charges and are spaced apart from each other to form a cavity with two open ends in the middle, with one end of the cavity being a water outlet and the other end being a water inlet;

[0010] A plurality of reverse osmosis membranes are placed in the cavity between the two electrode plates, and are used to separate the anions and cations from the water in the low-concentration fresh water to produce fresh water; or to separate the anions and cations from the water in the wastewater under the action of the electrostatic field to produce salt water;

[0011] A collecting chamber is connected to the water outlet and is used to collect the fresh water.

[0012] Optionally, the desalination device based on electrical adsorption and coupled reverse osmosis further includes: an electrode chamber connected to the water inlet, for storing the raw water and recovering the light salt water.

[0013] Optionally, there are multiple types of reverse osmosis membranes, including: high-pressure and high-salinity rejection reverse osmosis membranes and low-pressure and low-salinity rejection reverse osmosis membranes.

[0014] Optionally, a plurality of the reverse osmosis membranes are arranged at intervals.

[0015] Optionally, a plurality of the reverse osmosis membranes are stacked.

[0016] Optionally, the materials used to prepare the plurality of reverse osmosis membranes are all hollow fiber membranes.

[0017] A desalination method based on electrosorption and coupled reverse osmosis, the method being applied to the desalination device, the method comprising:

[0018] By applying an external voltage through a power supply, the anions and cations in the raw water move to the electrode plates with opposite charges, thus obtaining low-concentration fresh water;

[0019] When the external voltage remains unchanged, a reverse osmosis membrane is used to separate the residual anions and cations in the low-concentration fresh water from water to obtain fresh water; and the fresh water flows from the water outlet into a collection chamber to collect the fresh water;

[0020] The power supply is reversed to desorb the anions and cations in the remaining wastewater from the two electrode plates respectively, thereby generating wastewater;

[0021] When a reverse voltage is applied, a reverse osmosis membrane is used to separate the anions and cations from the water in the wastewater to obtain light brine.

[0022] Optionally, when a reverse voltage is applied, a reverse osmosis membrane is used to separate anions and cations from water in the wastewater to obtain light brine, and further comprises:

[0023] The light brine is returned to the electrode chamber from the water inlet to recover the light brine.

[0024] Optionally, when the applied voltage remains unchanged, using a reverse osmosis membrane to separate residual anions and cations from water in the low-concentration fresh water to obtain fresh water comprises:

[0025] When the external voltage remains unchanged, a high-pressure, high-salinity rejection rate reverse osmosis membrane is used to separate the residual anions and cations in the low-concentration fresh water from water to obtain fresh water.

[0026] Optionally, the process of separating anions and cations from water in the wastewater by using a reverse osmosis membrane under the application of a reverse voltage to obtain light brine comprises:

[0027] Under the condition of applying reverse voltage, a low-pressure and low-salinity rejection reverse osmosis membrane is used to separate anions and cations from water in the wastewater to obtain light brine.

[0028] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0029] In the charging and adsorption state, the present invention moves the anions and cations in the raw water toward the electrode plates with opposite charges, generating a double electric layer structure around the electrodes. During the ion movement and adsorption process, the voltage between the two stages continuously decreases. When the adsorption is complete, the voltage remains unchanged and reaches an equilibrium state, at which point the concentrated water is converted into low-salinity water. At this point, a reverse osmosis membrane is used for further desalination to obtain fresh water. In the discharging and desorption state, when the voltage between the two stages reaches equilibrium, the electrodes are switched, the adsorbed anions and cations are desorbed, and high-concentration wastewater is obtained again. At this time, the reverse osmosis membrane operates, converting the concentrated water into fresh water, which then flows back to the electrode chamber. The cyclic charging and discharging process corresponds to the cyclic operation of the reverse osmosis device, allowing the salt to be removed. In both the electrical adsorption and osmotic membrane desalination modes, the present invention can reduce energy consumption while reducing membrane fouling, increasing the service life of the fouled membrane, and thereby improving desalination efficiency and recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a structural diagram of a desalination device based on electrosorption and coupled reverse osmosis according to an embodiment of the present invention;

[0032] Figure 2This is a flow chart of a desalination method based on electrosorption and coupled reverse osmosis according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] The purpose of the present invention is to provide a desalination device and method based on electrosorption and coupled reverse osmosis, which can reduce energy consumption while reducing membrane pollution, prolong the service life of the membrane pollution, and thus improve the desalination efficiency and recovery rate.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 This is a structural diagram of a desalination device based on electrosorption and coupled reverse osmosis provided in an embodiment of the present invention.

[0037] like Figure 1 As shown, a desalination device based on electrosorption and coupled reverse osmosis includes: two electrode plates, multiple reverse osmosis membranes and a collection chamber;

[0038] The two electrode plates are used to generate an electrostatic field according to the voltage applied by the power supply, so as to adsorb or desorb the anions and cations in the raw water to produce low-concentration fresh water or waste water; the two electrode plates carry opposite charges respectively, and are arranged relative to each other with a spaced relationship, forming a cavity with two open ends in the middle, one end of the cavity is a water outlet, and the other end is a water inlet; a plurality of reverse osmosis membranes are placed in the cavity between the two electrode plates, and the plurality of reverse osmosis membranes are used to separate the anions and cations in the low-concentration fresh water from water to produce fresh water; or to separate the anions and cations in the waste water from water under the action of the electrostatic field to produce light salt water; the collection chamber is connected to the water outlet, and the collection chamber is used to collect the fresh water.

[0039] In some embodiments, the desalination device based on electrosorption and coupled reverse osmosis further includes: an electrode chamber.

[0040] The electrode chamber is connected to the water inlet, and is used to store the raw water and recover the light salt water.

[0041] Furthermore, there are multiple types of reverse osmosis membranes, including high-pressure and high-salinity rejection reverse osmosis membranes and low-pressure and low-salinity rejection reverse osmosis membranes.

[0042] In some embodiments, a plurality of the reverse osmosis membranes are spaced apart.

[0043] In some embodiments, a plurality of the reverse osmosis membranes are stacked.

[0044] Among them, the preparation materials of multiple reverse osmosis membranes are hollow fiber membranes.

[0045] Figure 2 Flowchart of a desalination method based on electrosorption and coupled reverse osmosis provided in an embodiment of the present invention.

[0046] like Figure 2 As shown, a desalination method based on electrosorption and coupled reverse osmosis is applied to the desalination device, and the method includes:

[0047] Step 101: Apply an external voltage through a power supply to move the anions and cations in the raw water to the electrode plates with opposite charges, thereby obtaining low-concentration fresh water.

[0048] The step 101 is specifically as follows:

[0049] An external voltage is applied to the two electrode plates through a power supply, causing them to have opposite charges. At this time, they are in a charged adsorption state. The anions and cations in the raw water continuously move in a directional manner, with anions moving toward the positive electrode and cations moving toward the negative electrode, and a double-layer structure is formed around the electrodes. During the ion movement and adsorption process, the voltage between the two electrodes continuously decreases. However, when the adsorption is complete, the voltage remains unchanged and reaches an equilibrium state. At this time, the raw water is converted into low-concentration salt water.

[0050] Step 102: When the external voltage remains unchanged, a reverse osmosis membrane is used to separate the residual anions and cations in the low-concentration fresh water from water to obtain fresh water; and the fresh water flows from the water outlet into a collection chamber to collect the fresh water.

[0051] Step 102 specifically includes: when the applied voltage remains constant, an equilibrium state is reached, at which point the reverse osmosis membrane between the two electrode plates operates, separating the residual anions and cations from the water in the low-concentration fresh water through the high-pressure, high-salinity rejection reverse osmosis membrane, further desalting the water to produce fresh water. The fresh water then flows from the outlet into a collection chamber for collection.

[0052] Step 103: Reverse the power supply to desorb the anions and cations in the remaining wastewater from the two electrode plates to generate wastewater.

[0053] The step 103 is specifically as follows: cutting off the power supply, placing the electrode plates in a discharge and desorption state, and reversing the power supply when the voltages of the two electrodes reach equilibrium, so as to desorb the anions and cations in the remaining wastewater from the two electrode plates respectively, thereby generating wastewater (i.e., high-concentration brine).

[0054] Step 104: Under the condition of applying reverse voltage, a reverse osmosis membrane is used to separate the anions and cations from water in the wastewater to obtain salt water.

[0055] The step 104 is specifically as follows: when a reverse voltage is applied, the reverse osmosis membrane between the two electrode plates works, and the anions and cations in the wastewater are separated from the water through the low-pressure and low-salinity rejection reverse osmosis membrane, thereby converting the wastewater into light salt water.

[0056] In some embodiments, when a reverse voltage is applied, a reverse osmosis membrane is used to separate the anions and cations from the wastewater to obtain brine, and the method further includes: returning the brine from the water inlet to the electrode chamber to recover the brine.

[0057] In summary, the present invention works in a cyclical reverse osmosis device in a cyclical charge and discharge process, so that salt can be removed. In the charging adsorption state, the anions and cations in the raw water are moved to the electrode plates with opposite charges respectively, and a double electric layer structure is generated around the electrodes. During the ion movement and adsorption process, the voltage of the two stages continues to decrease. When the adsorption is complete, the voltage remains unchanged and reaches a state of equilibrium. At this time, the concentrated water is converted into low-salt water. At this time, a high-pressure and high-density desalination reverse osmosis membrane is used for further desalination to obtain fresh water. In the discharge and desorption state, when the two-stage voltage reaches equilibrium, the electrodes are switched, and the adsorbed anions and cations are desorbed to obtain high-concentration wastewater. At this time, the low-pressure and low-density desalination reverse osmosis membrane works to convert the concentrated water into fresh water, which then flows back to the electrode chamber. The cyclical charge and discharge process corresponds to the work of the cyclical reverse osmosis device, so that salt can be removed. In the two desalination modes of electric adsorption and coupled osmosis membrane, the present invention can reduce energy consumption while reducing membrane pollution, increase the service life of membrane pollution, and thereby improve desalination efficiency and recovery rate.

[0058] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0059] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A desalination method based on a desalination device with electrosorption and coupled reverse osmosis, characterized in that: The desalination device based on electrosorption and coupled reverse osmosis specifically includes: Two electrode plates are used to generate an electrostatic field according to the voltage applied by the power supply to adsorb or desorb anions and cations in the raw water to produce low-concentration fresh water or wastewater; the two electrode plates have opposite charges and are spaced apart from each other to form a cavity with two open ends in the middle, with one end of the cavity being a water outlet and the other end being a water inlet; A plurality of reverse osmosis membranes are placed in the cavity between the two electrode plates, and are used to separate the anions and cations from the water in the low-concentration fresh water to produce fresh water; or to separate the anions and cations from the water in the wastewater under the action of the electrostatic field to produce salt water; the plurality of reverse osmosis membranes are arranged at intervals or in a stacked manner; a collecting chamber, connected to the water outlet, for collecting the fresh water; an electrode chamber connected to the water inlet, for storing the raw water and recovering the light brine; The desalination method comprises: Applying an external voltage through the power supply moves the anions and cations in the raw water toward the electrode plates with opposite charges, thereby obtaining low-concentration fresh water; When the external voltage remains unchanged, the reverse osmosis membrane is used to separate the residual anions and cations in the low-concentration fresh water from water to obtain fresh water, comprising: When the external voltage remains unchanged, a high-pressure, high-salinity rejection reverse osmosis membrane is used to separate the residual anions and cations in the low-concentration fresh water from water to obtain fresh water; The fresh water flows from the water outlet into the collection chamber to collect the fresh water; the power supply is reversed to desorb the anions and cations in the remaining wastewater from the two electrode plates respectively to generate wastewater; Under the condition of applying reverse voltage, a reverse osmosis membrane is used to separate the anions and cations from water in the wastewater to obtain light brine, including: Under the condition of applying reverse voltage, a low-pressure and low-salinity rejection reverse osmosis membrane is used to separate the anions and cations from the wastewater to obtain light brine; The method further comprises: returning the light salt water from the water inlet to the electrode chamber to recover the light salt water.

2. The desalination method according to claim 1, wherein: The preparation materials of the plurality of reverse osmosis membranes are all hollow fiber membranes.

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