Ion chromatography electrodialysis treatment system and method

Abstract

The invention discloses an ion chromatography electrodialysis treatment system and method, the ion chromatography electrodialysis treatment system comprises a box body, and a cation exchange membrane, a first semipermeable membrane and a second semipermeable membrane which are arranged in the box body, and the cation exchange membrane, the first semipermeable membrane and the second semipermeable membrane are sequentially distributed; the system comprises a box body, the interior of the box body is divided into a first chamber, a second chamber, a third chamber and a fourth chamber, a first platinum electrode is arranged in the first chamber, a second platinum electrode is arranged in the fourth chamber, and the first platinum electrode and the second platinum electrode are connected with a power supply.

Description

Technical Field

[0001] The invention belongs to the technical field of ion chromatography analysis and relates to an ion chromatography electrodialysis processing system and method. Background Art

[0002] Ion chromatography (IC) is a high-performance liquid chromatography (HPLC) technique specifically designed for the separation, detection, and quantification of anions, cations, and some polar organic compounds in samples. Since its introduction in the mid-1970s, the method has been widely used in environmental monitoring, food safety, medicine, and industrial production due to its advantages, including high sensitivity, high selectivity, rapid analysis, and simultaneous multi-component detection. The core of ion chromatography lies in ion exchange separation and conductivity detection. Its separation mechanism is based on a reversible exchange reaction between ions in the sample and a stationary phase (ion exchange resin). The stationary phase is typically a resin with charged functional groups that can exchange ions with the sample. Ion chromatography is the only effective method for the simultaneous and separate determination of multiple anions in water. Sample pretreatment has long been a weak link in ion chromatography (IC), primarily due to its high sensitivity for common anions and cations. Since its adoption, IC technology has seen rapid progress, particularly in the determination of anions.

[0003] Publication No. CN106673143A discloses an electrodialysis device, comprising a plurality of single filtration channels, wherein the single filtration channels comprise a cathode plate and an anode plate arranged opposite to each other, a first cation exchange membrane and a first anion exchange membrane arranged between the cathode plate and the anode plate, the first anion exchange membrane being arranged close to the anode plate, the first cation exchange membrane being arranged close to the cathode plate, a raw water channel being arranged between the first cation exchange membrane and the first anion exchange membrane, a first concentrated water channel being arranged between the first anion exchange membrane and the anode plate, a second concentrated water channel being arranged between the second anion exchange membrane and the cathode plate, and a first concentrated water channel being arranged between the first anion exchange membrane and the anode plate. A second cation exchange membrane and a first water permeable membrane are provided, the second cation exchange membrane is provided close to the anode plate, and the first water permeable membrane is provided between the first anion exchange membrane and the second cation exchange membrane; a second anion exchange membrane and a second water permeable membrane are also provided between the first cation exchange membrane and the cathode plate, the second anion exchange membrane is provided close to the cathode plate, and the second water permeable membrane is provided between the first cation exchange membrane and the second anion exchange membrane. The cation exchange membrane is provided on the surface of the anode plate to block the passage of anions and prevent the anode plate from being corroded. Since the anion exchange membrane is provided on the surface of the cathode plate of the present invention, the passage of cations can be blocked and the corrosion of the cathode plate can be prevented.

[0004] However, the application of this technology in industrial wastewater and domestic sewage monitoring is limited because complex organic matrices and heavy metal salts can cause irreversible damage to the separation column. To date, there is still no effective pretreatment technology that is simple and effective for the detection of common anions (mainly F, Cl, NO2 - Br - 、NO3 - 、HPO4 2- and SO4 2- ) determination. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide an ion chromatography electrodialysis processing system and method, which can avoid the influence of negatively charged samples on the separation and quantitative analysis of the ions to be tested.

[0006] To achieve the above-mentioned objectives, the present invention discloses an ion chromatography electrodialysis treatment system, comprising a housing and a cation exchange membrane, a first semipermeable membrane, and a second semipermeable membrane arranged in the housing, wherein the cation exchange membrane, the first semipermeable membrane, and the second semipermeable membrane are distributed in sequence and divide the interior of the housing into a first chamber, a second chamber, a third chamber, and a fourth chamber, a first platinum electrode is provided in the first chamber, a second platinum electrode is provided in the fourth chamber, and the first platinum electrode and the second platinum electrode are connected to a power supply.

[0007] The further improvement of the ion chromatography electrodialysis treatment system of the present invention is:

[0008] Furthermore, the second chamber is communicated with the sampler.

[0009] Furthermore, the third chamber is communicated with the sample injector.

[0010] Furthermore, the first platinum electrode is connected to the positive electrode of the power supply, and the second platinum electrode is connected to the negative electrode of the power supply.

[0011] Furthermore, during operation, the sample is injected from the third chamber, and the eluent is injected into the first chamber, the second chamber and the fourth chamber.

[0012] The present invention discloses an ion chromatography electrodialysis treatment method, comprising the following steps:

[0013] A dilute NaCl solution is injected into the third chamber, and a Na2CO3 solution is injected into the first, second and fourth chambers. After power is turned on, the positive ions move toward the cathode along the first chamber → second chamber → third chamber → fourth chamber, and the negative ions move along the fourth chamber → third chamber → second chamber to the second chamber and are blocked by the cation exchange membrane, thereby achieving the accumulation of anions in the second chamber. Samples are taken from the second chamber and then subjected to ion chromatography analysis.

[0014] The further improvement of the ion chromatography electrodialysis treatment method of the present invention is:

[0015] Furthermore, the second chamber is communicated with the sampler.

[0016] Furthermore, the third chamber is communicated with the sample injector.

[0017] Furthermore, the first platinum electrode is connected to the positive electrode of the power supply, and the second platinum electrode is connected to the negative electrode of the power supply.

[0018] Furthermore, during operation, the sample is injected from the third chamber, and the eluent is injected into the first chamber, the second chamber and the fourth chamber.

[0019] The present invention has the following beneficial effects:

[0020] During specific operation of the ion chromatography electrodialysis treatment system and method described in the present invention, a dilute NaCl solution is injected into the third chamber, and a Na2CO3 solution is injected into the first chamber, the second chamber, and the fourth chamber. After power is turned on, positive ions move toward the negative electrode along the first chamber → the second chamber → the third chamber → the fourth chamber, and the negative ions move along the fourth chamber → the third chamber → the second chamber to reach the second chamber and are blocked by the cation exchange membrane, thereby achieving accumulation of anions in the second chamber and avoiding the influence of the negatively charged sample on the separation and quantitative analysis of the ions to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 It is a structural diagram of the present invention;

[0023] Figure 2 This is a schematic diagram of the present invention.

[0024] Among them, 11 is the first platinum electrode, 12 is the second platinum electrode, 2 is the sampler, 3 is the injector, 4 is the cation exchange membrane, 51 is the first semipermeable membrane, and 52 is the second semipermeable membrane. DETAILED DESCRIPTION

[0025] 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 them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0027] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present 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.

[0028] It should be further understood that the term "and / or" as used in the present specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0029] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of 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.

[0030] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0033] As is well known, a semipermeable membrane is a thin film that allows only certain molecules or ions to pass through while preventing other molecules or ions from passing through. It has the characteristic of selective permeability, and this selectivity is based on factors such as the size, shape, charge and chemical properties of the molecules or ions.

[0034] The principle of semipermeable membrane

[0035] From a microscopic perspective, the internal structure of a semipermeable membrane contains numerous tiny pores or channels. The size and chemical properties of these pores or channels determine which substances can pass through. For example, water molecules are generally small and electrically neutral, allowing them to pass through the pores of a semipermeable membrane relatively easily. However, larger molecules, such as proteins and starches, are unable to pass through these pores due to their large size and are therefore blocked on one side of the membrane. Furthermore, when charged ions pass through a semipermeable membrane, they are affected by the interaction of charges on the membrane. If the membrane has the same charge as the ion, it will repel the ions and hinder their passage. Conversely, if the membrane has an opposite charge, it may facilitate their passage.

[0036] Types of semipermeable membranes

[0037] Natural semipermeable membrane

[0038] Animal bladder membrane: Often used in early osmosis experiments. It has a certain toughness, can withstand a certain amount of pressure, and has good permeability to water molecules and some small molecules, while having a blocking effect on large molecules such as proteins.

[0039] The cell membrane is one of the most important semipermeable membranes in living organisms. It not only controls the exchange of substances inside and outside the cell but also participates in important physiological processes such as cell signaling and energy conversion. The cell membrane is composed of a phospholipid bilayer and proteins, and various channel proteins and carrier proteins on it enable the selective transport of specific substances.

[0040] Synthetic semipermeable membrane

[0041] Cellulose acetate membranes: They possess excellent chemical stability and mechanical strength and are commonly used in membrane separation technologies such as reverse osmosis and ultrafiltration. They effectively remove impurities such as salt and organic matter from water and are widely used in desalination and sewage treatment.

[0042] Polyamide membranes: They have high selectivity and flux and are widely used in reverse osmosis. They can withstand high pressures and have good separation effects on various ions and small organic molecules.

[0043] Ion exchange membrane is a polymer membrane containing ionic groups that has the ability to selectively permeate ions in solution. It is also called ion selective permeable membrane. The following is an introduction from the aspects of classification, working principle, performance indicators, and application:

[0044] Classification

[0045] Classification by selective permeability

[0046] Cation exchange membrane: referred to as cationic membrane, the membrane contains negatively charged acidic active groups, such as sulfonic acid group (-SO3H), phosphoric acid group (-PO3H2), phosphonic acid group (-OPO3), carboxylic acid group (-COOH), phenol group (-C6H4OH), etc. After ionization in water, it becomes negatively charged and only allows cations to pass through, but not anions.

[0047] Anion exchange membrane: referred to as anion membrane, the membrane contains positively charged alkaline active groups, such as quaternary ammonium group [-N(CH3)3OH-], primary amino group (-NH2), secondary amino group (-NHR), tertiary amino group (-NR2), etc. After ionization in water, it becomes positively charged and only allows anions to pass through, but not cations.

[0048] Proton exchange membrane: It is a special case of cation exchange membrane, which only allows protons (H+) to pass through, and other ions cannot pass through.

[0049] Bipolar membrane: A cationic composite membrane made of a cationic membrane and a cationic membrane. The main body of the membrane can be divided into an anion exchange layer, a cation exchange layer and an intermediate interface layer. The water dissociation catalyst is sandwiched in the ion exchange polymer in the middle. The water ionization products H+ and OH- can quickly migrate to the solutions on both sides under the action of the electric field force, providing ideal pH conditions for the half reactions on both sides of the membrane.

[0050] Classification by material properties

[0051] Organic ion exchange membrane: The most commonly used sulfonic acid cation exchange membrane and quaternary ammonium anion exchange membrane are both organic ion exchange membranes.

[0052] Inorganic ion exchange membrane: It is made of inorganic materials, such as zirconium phosphate and aluminum vanadate, and is a new type of membrane used in special occasions.

[0053] Classification by structure

[0054] Homogeneous membranes: Polymer materials such as styrene-butadiene rubber, cellulose derivatives, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, and polyacrylonitrile are first formed into a membrane. Monomers such as styrene and methyl methacrylate are then introduced to polymerize the membrane into a polymer. The desired functional groups are then introduced through chemical reactions. The ion-exchange active groups in the membrane chemically bond with the membrane-forming polymer, resulting in a completely uniform composition and excellent electrochemical and physical properties. This represents the primary development direction for ion exchange membranes.

[0055] Heterogeneous membrane: It is made by fully mixing ion exchange resin with a particle size of 200-400 mesh and common membrane-forming polymer materials such as polyethylene, polyvinyl chloride, polyvinyl alcohol, fluororubber, etc. The chemical structure is discontinuous.

[0056] Semi-homogeneous membrane: The membrane-forming polymer material and the ion exchange active groups are evenly combined, but no chemical bond is formed between them.

[0057] How it works

[0058] The working principle of ion exchange membranes is based on their unique structure and properties. They are composed of a polymer backbone, fixed groups, and mobile ions attached to these groups. When an electric field or concentration difference is applied across the membrane, the ions are driven to migrate, with cations moving toward the cathode and anions toward the anode. Due to the selective permeability of ion exchange membranes, cations can only pass through the cation membrane, while anions can only pass through the anion membrane, thus achieving ion separation. For example, in a cation exchange membrane, fixed negatively charged exchange groups are embedded. Due to the principle that like charges repel and opposite charges attract, only positively charged ions, namely cations, can pass through.

[0059] Example 1

[0060] refer to Figure 1 The ion chromatography electrodialysis treatment system of the present invention includes a box body and a cation exchange membrane 4, a first semipermeable membrane 51 and a second semipermeable membrane 52 arranged in the box body, wherein the cation exchange membrane 4, the first semipermeable membrane 51 and the second semipermeable membrane 52 are distributed in sequence, and the interior of the box body is divided into a first chamber, a second chamber, a third chamber and a fourth chamber, a first platinum electrode 11 is provided in the first chamber, and a second platinum electrode 12 is provided in the fourth chamber, and the first platinum electrode 11 and the second platinum electrode 12 are connected to a power supply.

[0061] Example 2

[0062] refer to Figure 1 To further improve this application, the ion chromatography electrodialysis treatment system of the present invention includes a box body and a cation exchange membrane 4, a first semipermeable membrane 51 and a second semipermeable membrane 52 arranged in the box body, wherein the cation exchange membrane 4, the first semipermeable membrane 51 and the second semipermeable membrane 52 are distributed in sequence, and the interior of the box body is divided into a first chamber, a second chamber, a third chamber and a fourth chamber, a first platinum electrode 11 is provided in the first chamber, the second chamber is connected to the sampler 2, the third chamber is connected to the injector 3, and a second platinum electrode 12 is provided in the fourth chamber, the first platinum electrode 11 and the second platinum electrode 12 are connected to a power supply, specifically, the first platinum electrode 11 is connected to the positive pole of the power supply, and the second platinum electrode 12 is connected to the negative pole of the power supply.

[0063] During operation, the sample is injected into the third chamber, while the remaining chambers contain eluent. When the power is turned on, the anions to be measured in the third chamber migrate to the second chamber and are blocked in the second chamber by the cation exchange membrane 4. Molecular organic matter remains in the third chamber, while cations migrate to the fourth chamber. This allows the interference-free ions to be obtained in the second chamber for analysis. This device theoretically transcends all existing pretreatment methods, which rely on removing interference from the sample, by directly obtaining the ions to be measured from the sample. This represents a breakthrough in both the theory and technology of IC pretreatment and has been successfully applied to monitoring polluted water sources.

[0064] Example 3

[0065] refer to Figure 1 The ion chromatography electrodialysis treatment method of the present invention is based on the ion chromatography electrodialysis treatment system, which includes a first platinum electrode 11, a second platinum electrode 12, a sampler 2, an injector 3, a cation exchange membrane 4, a first semipermeable membrane 51 and a second semipermeable membrane 52. The specific connection relationship is as shown in Example 2;

[0066] Specifically, the ion chromatography electrodialysis treatment method comprises the following steps:

[0067] A dilute NaCl solution is injected into the third chamber, and Na2CO3 solution is injected into the other chambers. After power is applied, the migration of ions is shown in Figure 2 Positive ions migrate toward the cathode along the first chamber, then the second chamber, then the third chamber, and finally the fourth chamber. Negative ions travel along the fourth chamber, then the third chamber, and finally the second chamber, where they are blocked by the cation exchange membrane 4. This results in the accumulation of anions in the second chamber, making the solution negatively charged. Experiments have shown that negatively charged samples do not affect the separation and quantitative analysis of the ions being tested. As can be seen from the above process, the ions in the solution only migrate through the membrane, without any chemical reactions occurring. Therefore, this pretreatment is called electrodialysis pretreatment.

[0068] Those skilled in the art will readily identify other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0069] It should be understood that the present invention is not limited to the exact construction described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0070] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An ion chromatography electrodialysis treatment system, characterized in that: The invention comprises a box body and a cation exchange membrane (4), a first semipermeable membrane (51) and a second semipermeable membrane (52) arranged in the box body, wherein the cation exchange membrane (4), the first semipermeable membrane (51) and the second semipermeable membrane (52) are distributed in sequence and the interior of the box body is divided into a first chamber, a second chamber, a third chamber and a fourth chamber, a first platinum electrode (11) is arranged in the first chamber, a second platinum electrode (12) is arranged in the fourth chamber, and the first platinum electrode (11) and the second platinum electrode (12) are connected to a power supply.

2. The ion chromatography electrodialysis treatment system according to claim 1, characterized in that: The second chamber is communicated with the sampler (2).

3. The ion chromatography electrodialysis treatment system according to claim 1, characterized in that: The third chamber is communicated with the sample injector (3).

4. The ion chromatography electrodialysis treatment system according to claim 1, characterized in that: The first platinum electrode (11) is connected to the positive electrode of the power supply, and the second platinum electrode (12) is connected to the negative electrode of the power supply.

5. The ion chromatography electrodialysis treatment system according to claim 1, characterized in that: During operation, the sample is injected from the third chamber, and the eluent is injected into the first chamber, the second chamber and the fourth chamber.

6. An ion chromatography electrodialysis treatment method, characterized in that: The ion chromatography electrodialysis treatment system according to claim 1 comprises the following steps: A dilute NaCl solution is injected into the third chamber, and a Na2CO3 solution is injected into the first chamber, the second chamber, and the fourth chamber. After power is applied, positive ions move toward the cathode along the first chamber → the second chamber → the third chamber → the fourth chamber, and negative ions move along the fourth chamber → the third chamber → the second chamber and are blocked by the cation exchange membrane (4) after reaching the second chamber, thereby achieving accumulation of anions in the second chamber. Samples are taken from the second chamber and then subjected to ion chromatography analysis.

7. The ion chromatography electrodialysis treatment method according to claim 6, characterized in that: The second chamber is communicated with the sampler (2).

8. The ion chromatography electrodialysis treatment method according to claim 6, characterized in that: The third chamber is communicated with the sample injector (3).

9. The ion chromatography electrodialysis treatment method according to claim 6, characterized in that: The first platinum electrode (11) is connected to the positive electrode of the power supply, and the second platinum electrode (12) is connected to the negative electrode of the power supply.

10. The ion chromatography electrodialysis treatment method according to claim 6, characterized in that: During operation, the sample is injected from the third chamber, and the eluent is injected into the first chamber, the second chamber and the fourth chamber.

Images