Air-free potassium hydroxide leacheate generator for liquid phase ion chromatography

Abstract

The invention discloses an airless potassium hydroxide leacheate generator for liquid phase ion chromatography, which comprises a shell, a first heterogeneous cation exchange membrane, a first homogeneous cation exchange membrane, a second heterogeneous cation exchange membrane, cation exchange resin, a bipolar membrane, a third heterogeneous cation exchange membrane, a second homogeneous cation exchange membrane and a fourth heterogeneous cation exchange membrane are sequentially arranged in the shell, an anode chamber is formed between the inner walls of the shell on one side, far away from the first homogeneous cation exchange membrane, of the first heterogeneous cation exchange membrane, and an anode plate is arranged in the anode chamber; a cathode chamber is formed between the side, away from the second homogeneous cation exchange membrane, of the fourth heterogeneous cation exchange membrane and the inner wall of the shell, a cathode plate is arranged in the cathode chamber, the anode plate and the cathode plate are connected with a power source, and the generator is good in component separation effect, simple in structure and small in size.

Description

Technical Field

[0001] This invention relates to a generator, specifically to a generator for gasless potassium hydroxide eluent for liquid ion chromatography. Background Technology

[0002] The liquid ion chromatography (LICC) generator is a core component of an ion chromatography system, and its technological development has undergone a revolutionary transformation from manual eluent preparation to online automated generation. The eluent generator is used to electrolyze and produce high-purity eluent for isocratic or gradient elution. In liquid chromatography, a potassium hydroxide eluent generator is required to measure the anion content in water samples. The performance of the potassium hydroxide eluent generator directly affects the various detection performance parameters of the chromatography. The potassium hydroxide eluent generator can prevent baseline drift during chromatographic measurements, increase detection sensitivity, improve component resolution, and ensure good reproducibility of chromatographic peak integration.

[0003] CN210720294U discloses a rapid, non-interference eluent generator for an ion chromatography system, comprising an eluent mother liquor channel, a cathode chamber, an anode chamber, and an eluent generation channel. The eluent mother liquor channel is disposed between the anode chamber and the eluent generation channel, and the cathode chamber is disposed on the other side of the eluent generation channel. A bipolar membrane is disposed between the cathode chamber and the eluent generation channel. A first cation exchange membrane is disposed between the anode chamber and the eluent mother liquor channel, and a second cation exchange membrane is disposed between the eluent mother liquor channel and the eluent generation channel. The eluent mother liquor channel is connected to the anode chamber, and the anode chamber is connected to the cathode chamber. The eluent mother liquor channel has an eluent mother liquor injection port, the cathode chamber has a waste liquid outlet, and the eluent generation channel has an injection end and an outflow end. The anode chamber and the cathode chamber are respectively provided with a Pt anode and a Pt cathode. The eluent mother liquor injection port is located at the lower end of the eluent mother liquor channel. The upper end of the eluent mother liquor channel is connected to the upper end of the anode chamber via a first conduit, and the lower end of the anode chamber is connected to the lower end of the cathode chamber via a second conduit. The waste liquid outlet is located at the upper end of the cathode chamber. The upper end of the eluent generation channel is the injection end, and the lower end is the outflow end. Eluent mother liquor KOH is injected through the eluent mother liquor injection port into the eluent mother liquor channel. The mother liquor flows out from the upper end, passes through the first conduit, and enters the anode chamber. Under current flow, the H+ generated by electrolysis in the anode chamber neutralizes the OH- in the mother liquor flowing into the anode chamber. K+ then enters the eluent mother liquor channel through the first cation exchange membrane. The H+ in the eluent mother liquor channel then passes through the second cation exchange membrane into the eluent generation channel. This eliminates the interference caused by H+ entering the eluent mother liquor channel from the anode chamber, and avoids a large amount of H+ further entering the eluent generation channel, which would affect the eluent concentration. The mother liquor containing a high concentration of OH- after H+ removal in the anode chamber enters the cathode chamber through the second conduit. Under current flow, both the OH- generated by electrolysis in the cathode chamber and the OH- in the mother liquor pass through the anion exchange membrane in the bipolar membrane into the eluent generation channel. Trace amounts of H+ in the eluent generation channel pass through the first and second cation exchange membranes and then through the cation exchange membrane in the bipolar membrane into the cathode chamber, where they are discharged along with the waste liquid through the waste liquid outlet. The flow direction of the mother liquor in the eluent mother liquor channel is opposite to the flow direction of the prepared eluent in the eluent generation channel, creating convection, increasing the contact area for ion exchange, and improving the efficiency of ion exchange. This application provides a mother liquor channel for the eluent between the anode chamber and the eluent generation channel. Cation exchange membranes are provided between the anode chamber and the mother liquor channel, and between the mother liquor channel and the eluent generation channel. This allows the H+ generated by electrolysis in the anode chamber to directly neutralize the OH- in the mother liquor entering the anode chamber, preventing the H+ generated by electrolysis in the anode chamber from passing through the cation exchange membrane into the eluent generation channel and causing interference that would affect the concentration of the eluent. This effectively improves the accuracy of the prepared eluent concentration.

[0004] Defects and shortcomings of existing technology: Currently, most potassium hydroxide eluent generators use a single-membrane method, that is, only a cation exchange membrane is used to separate the anode chamber, cathode chamber, and packing chamber. The biggest drawback of this single-membrane method is: 1. During the reaction process, the gases (hydrogen and oxygen) generated at the cathode and anode can easily pass through the cation exchange membrane into the packing chamber. The gases are carried into the chromatographic detection system through the packing chamber, which will increase the noise of the chromatographic detection baseline. Excessive bubbles will also accumulate in the resin column, reducing the component separation effect.

[0005] 2. In order to eliminate the problem of easy gas permeation in single-membrane methods, degassing devices have been introduced into chromatography. These devices are generally complex in structure and large in size, which increases the maintenance workload of the chromatography measurement system. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a gasless potassium hydroxide eluent generator for liquid ion chromatography. This generator has good component separation effect, and at the same time, it has a simple structure and small size.

[0007] To achieve the above objectives, this invention discloses a gasless potassium hydroxide eluent generator for liquid ion chromatography, comprising a housing. The housing contains, in sequence, a first heterogeneous cation exchange membrane, a first homogeneous cation exchange membrane, a second heterogeneous cation exchange membrane, a cation exchange resin, a bipolar membrane, a third heterogeneous cation exchange membrane, a second homogeneous cation exchange membrane, and a fourth heterogeneous cation exchange membrane. An anode chamber is formed between the inner wall of the housing and the side of the first heterogeneous cation exchange membrane away from the first homogeneous cation exchange membrane, and an anode plate is disposed within the anode chamber. A cathode chamber is formed between the side of the fourth heterogeneous cation exchange membrane away from the second homogeneous cation exchange membrane and the inner wall of the housing, and a cathode plate is disposed within the cathode chamber. Both the anode plate and the cathode plate are connected to a power source.

[0008] The further improvement of the gasless potassium hydroxide eluent generator for liquid ion chromatography described in this invention lies in: Furthermore, potassium hydroxide solution is introduced into both the anode chamber and the cathode chamber.

[0009] Furthermore, the area where the cation exchange resin is located is a packing chamber, and pure water is circulated into the packing chamber.

[0010] Furthermore, the following reactions occur in the anode chamber and the cathode chamber, respectively:

[0011] .

[0012] Furthermore, both the anode plate and the cathode plate are made of platinum.

[0013] Furthermore, the power supply is a current-driven power supply.

[0014] Furthermore, in the initial stage of use, the cation exchange resin is treated by soaking in potassium hydroxide solution.

[0015] Furthermore, the cation exchange resin is designated as UP1400.

[0016] Furthermore, the first heterogeneous cation exchange membrane, the first homogeneous cation exchange membrane, the second heterogeneous cation exchange membrane, the bipolar membrane, the third heterogeneous cation exchange membrane, the second homogeneous cation exchange membrane, and the fourth heterogeneous cation exchange membrane are distributed in parallel.

[0017] Furthermore, the gases generated in the anode and cathode chambers cannot permeate the membrane into the intermediate packing chamber.

[0018] The present invention has the following beneficial effects: The gasless potassium hydroxide eluent generator for liquid ion chromatography described in this invention, through a redesigned structural layout incorporating bipolar membranes, homogeneous cation exchange membranes, and heterogeneous cation exchange membranes, builds upon the traditional single-membrane eluent generator design. Under an electric field, it can continuously prepare gasless potassium hydroxide eluent for ion chromatography, achieving good component separation. Furthermore, it features a simple structure and small size. It should be noted that the bipolar membrane used in this invention can directly hydrolyze and generate OH-. - The design of the packing chamber improves the efficiency of preparing potassium hydroxide rinsing solution.

[0019] This invention employs a combination of homogeneous and heterogeneous cation exchange membranes, balancing ion migration efficiency and membrane mechanical strength, making it suitable for high-pressure chromatography systems. This invention can prepare gas-free potassium hydroxide eluent, avoiding the introduction of a degassing system into the ion chromatography system, simplifying the chromatographic analysis process, and reducing chromatographic maintenance costs. Attached Figure Description

[0020] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a structural diagram of the present invention.

[0021] Wherein, 1 is the anode chamber, 2 is the anode plate, 3 is the first heterogeneous cation exchange membrane, 4 is the first homogeneous cation exchange membrane, 5 is the second heterogeneous cation exchange membrane, 6 is the cation exchange resin, 7 is the bipolar membrane, 8 is the third heterogeneous cation exchange membrane, 9 is the second homogeneous cation exchange membrane, 10 is the fourth heterogeneous cation exchange membrane, 11 is the cathode plate, 12 is the cathode chamber, and 13 is the power supply. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0024] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0026] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0027] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0030] Example 1 refer to Figure 1The gasless potassium hydroxide eluent generator for liquid ion chromatography of the present invention includes a housing, in which a first heterogeneous cation exchange membrane 3, a first homogeneous cation exchange membrane 4, a second heterogeneous cation exchange membrane 5, a cation exchange resin 6, a bipolar membrane 7, a third heterogeneous cation exchange membrane 8, a second homogeneous cation exchange membrane 9, and a fourth heterogeneous cation exchange membrane 10 are sequentially arranged. An anode chamber 1 is formed between the inner wall of the housing on the side of the first heterogeneous cation exchange membrane 3 away from the first homogeneous cation exchange membrane 4, and an anode plate 2 is disposed within the anode chamber 1. A cathode chamber 12 is formed between the side of the fourth heterogeneous cation exchange membrane 10 away from the second homogeneous cation exchange membrane 9 and the inner wall of the housing, and a cathode plate 11 is disposed within the cathode chamber 12. The anode plate 2 and the cathode plate 11 are connected to a power supply 13. The first heterogeneous cation exchange membrane 3, the first homogeneous cation exchange membrane 4, the second heterogeneous cation exchange membrane 5, the bipolar membrane 7, the third heterogeneous cation exchange membrane 8, the second homogeneous cation exchange membrane 9, and the fourth heterogeneous cation exchange membrane 10 are distributed in parallel.

[0031] It should be noted that this invention, by introducing a bipolar membrane 7, a homogeneous cation exchange membrane, and a heterogeneous cation exchange membrane into the traditional single-membrane eluent generator design, redesigns the structural layout. Under the action of an electric field, it can continuously prepare gas-free potassium hydroxide eluent for use in ion chromatography. The generator is designed with three chambers (anode chamber 1, cathode chamber 12, and packing chamber). The following reactions occur in anode chamber 1 and cathode chamber 12, respectively:

[0032] A 4 mol / L potassium hydroxide solution is introduced into the anode chamber 1 and the cathode chamber 12. Its main function is to provide sufficient potassium ions. Under the action of the electric field, the potassium ions can pass through the cation exchange membrane into the packing chamber.

[0033] Example 2 refer to Figure 1 To improve this application, the gasless potassium hydroxide eluent generator for liquid ion chromatography of the present invention includes a housing, in which a first heterogeneous cation exchange membrane 3, a first homogeneous cation exchange membrane 4, a second heterogeneous cation exchange membrane 5, a cation exchange resin 6, a bipolar membrane 7, a third heterogeneous cation exchange membrane 8, a second homogeneous cation exchange membrane 9, and a fourth heterogeneous cation exchange membrane 10 are sequentially arranged. An anode chamber 1 is formed between the inner wall of the housing on the side of the first heterogeneous cation exchange membrane 3 away from the first homogeneous cation exchange membrane 4, and an anode plate 2 is disposed within the anode chamber 1. A cathode chamber 12 is formed between the side of the fourth heterogeneous cation exchange membrane 10 away from the second homogeneous cation exchange membrane 9 and the inner wall of the housing, and a cathode plate 11 is disposed within the cathode chamber 12. The anode plate 2 and the cathode plate 11 are connected to a power supply 13.

[0034] Alkaline solutions are introduced into both the anode chamber 1 and the cathode chamber 12; the area where the cation exchange resin 6 is located is a packing chamber, and pure water is introduced into the packing chamber.

[0035] Platinum plates are placed in the anode chamber 1 and the cathode chamber 12 as reaction plates. Wires are led out from the reaction plates, and a constant current is provided by a 24V constant current power supply 13. This power supply 13 can automatically adjust the voltage value to maintain the reaction current required by the system.

[0036] The packing chamber is filled with cation exchange resin 6 (model: UP1400). This resin is initially soaked in potassium hydroxide solution to form potassium-type cation exchange resin 6, which facilitates the initial use of the generator and also allows the resin to provide sufficient potassium ions.

[0037] The anode chamber 1 and the packing chamber are arranged in the following order: anode plate 2 - heterogeneous cation exchange membrane - homogeneous cation exchange membrane - heterogeneous cation exchange membrane; the packing chamber and the cathode chamber 12 are arranged in the following order: bipolar membrane 7 - heterogeneous cation exchange membrane - homogeneous cation exchange membrane - heterogeneous cation exchange membrane - cathode plate 11.

[0038] The different types of membranes mentioned above are explained as follows: Cation exchange membrane: only allows cations (e.g.) (through)

[0039] Homogeneous cation exchange membranes: The exchange groups are evenly distributed, resulting in low resistance and high exchange efficiency, but they have poor mechanical strength and are not suitable for high-voltage systems.

[0040] Heterogeneous cation exchange membrane: An ion exchange membrane made by physically combining ion exchange resin powder with a polymer binder. Its chemical structure is non-uniform, with resin particles dispersed in the binder matrix and obvious phase interfaces. The ion exchange resin is embedded in the inert matrix, resulting in high mechanical strength and high electrical resistance. It is suitable for high-voltage systems, but its exchange efficiency is generally low.

[0041] Bipolar membrane 7: Anion / cation exchange layer composite, which can achieve water molecule dissociation under the action of an electric field. This membrane must be assembled strictly according to a specific orientation during use. In this invention, it is arranged according to... Figure 1 The diagram shows that hydrolysis will produce OH. - One side faces the packing chamber, so that the OH generated by the bipolar membrane 7 - The anode chamber 1 migrates to the packing chamber. It combines to form a KOH solution.

[0042] The packing chamber is filled with ultrapure water with a resistivity of 18.2 MΩ / cm. Both the cathode chamber 12 and the anode chamber 1 are circulated with 4 mmol / L potassium hydroxide solution. Under these conditions, potassium hydroxide rinsing solution of a specific concentration (0-20 mmol / L) can be produced on a large scale.

[0043] Due to the use of a multi-layer composite membrane design, the gas generated in the anode chamber 1 and cathode chamber 12 cannot permeate through the membrane into the intermediate packing chamber. The entire system produces a gas-free potassium hydroxide eluent, avoiding the need to add a more complex degassing system to the chromatography.

[0044] High-purity water is introduced into the packed chamber, and a constant current source is set (0-80mA). Under the influence of the electric field, anions migrate towards the anode, and cations migrate towards the cathode. A 4 mmol / L potassium hydroxide solution (alkaline solution) is introduced into anode chamber 1 and cathode chamber 12. Anode chamber 1 and cathode chamber 12 can be connected in series. The used potassium hydroxide solution can be recycled. The purpose of using potassium hydroxide is to continuously provide potassium ions to anode chamber 1. Under the influence of the electric field, potassium ions continuously pass through the cation exchange membrane into the packed chamber. Cathode chamber 12 also requires water to maintain the electrolysis reaction. To simplify the system, potassium hydroxide solution is used in both chambers. The bipolar membrane 7 continuously electrolyzes under the influence of the electric field to produce... Under the influence of the electric field, the gas migrates towards the anode and enters the packing chamber to combine with potassium ions to form the desired potassium hydroxide eluent. Due to the multilayer membrane composite design, the gas generated in the cathode chamber 12 and the anode chamber 1 cannot enter the intermediate packing chamber. As the alkaline solution circulating in the anode chamber 1 and the cathode chamber 12 is discharged from the system, the desired gas-free potassium hydroxide eluent is finally obtained.

[0045] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0046] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0047] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A gas-free potassium hydroxide eluent generator for liquid phase ion chromatography, characterized by, The application relates to a device for producing hydrogen and oxygen, which comprises a shell, wherein a first non-homogeneous cation exchange membrane (3), a first homogeneous cation exchange membrane (4), a second non-homogeneous cation exchange membrane (5), a cation exchange resin (6), a bipolar membrane (7), a third non-homogeneous cation exchange membrane (8), a second homogeneous cation exchange membrane (9) and a fourth non-homogeneous cation exchange membrane (10) are sequentially arranged in the shell, wherein an anode chamber (1) is formed between the inner wall of the shell and the side of the first non-homogeneous cation exchange membrane (3) far from the first homogeneous cation exchange membrane (4), and an anode plate (2) is arranged in the anode chamber (1); a cathode chamber (12) is formed between the inner wall of the shell and the side of the fourth non-homogeneous cation exchange membrane (10) far from the second homogeneous cation exchange membrane (9), and a cathode plate (11) is arranged in the cathode chamber (12), wherein the anode plate (2) and the cathode plate (11) are connected with a power supply (13).

2. The gas-free potassium hydroxide eluent generator for liquid phase ion chromatography according to claim 1, characterized in that, Potassium hydroxide solution is introduced into the anode chamber (1) and the cathode chamber (12).

3. The gas-free potassium hydroxide eluent generator for liquid phase ion chromatography according to claim 1, characterized in that, The region where the cation exchange resin (6) is arranged is a filler chamber, and pure water is introduced into the filler chamber.

4. The gas-free potassium hydroxide eluent generator for liquid phase ion chromatography according to claim 3, characterized in that, The following reactions occur in the anode chamber (1) and the cathode chamber (12) respectively: 。 5. The gas-free potassium hydroxide eluent generator for liquid phase ion chromatography according to claim 1, characterized in that, The anode plate (2) and the cathode plate (11) are both platinum gold sheets.

6. The gas-free potassium hydroxide eluent generator for liquid phase ion chromatography according to claim 1, characterized in that, The power supply (13) is a current power supply.

7. The gas-free potassium hydroxide eluent generator for liquid phase ion chromatography according to claim 1, characterized in that, In the initial stage of use of the cation exchange resin (6), the cation exchange resin (6) is soaked and treated by using potassium hydroxide solution.

8. The gas-free potassium hydroxide eluent generator for liquid ion chromatography according to claim 1, characterized in that, The model of the cation exchange resin (6) is UP1400.

9. The gas-free potassium hydroxide eluent generator for liquid phase ion chromatography according to claim 1, characterized in that, The first non-homogeneous cation exchange membrane (3), the first homogeneous cation exchange membrane (4), the second non-homogeneous cation exchange membrane (5), the bipolar membrane (7), the third non-homogeneous cation exchange membrane (8), the second homogeneous cation exchange membrane (9) and the fourth non-homogeneous cation exchange membrane (10) are arranged in parallel.

10. The gas-free potassium hydroxide eluent generator for liquid phase ion chromatography according to claim 3, characterized in that, The gas produced by the anode chamber (1) and the cathode chamber (12) cannot penetrate the membrane and enter the middle filler chamber.

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