Semi-solid water retention structure, salt bridge and copper sulfate reference electrode

Abstract

The invention relates to the technical field of electrochemical measurement, in particular to a semi-solid water retention structure, a salt bridge and a copper sulfate reference electrode, the semi-solid water retention structure comprises a cylindrical cavity, the cylindrical cavity is filled with super absorbent resin, and the super absorbent resin forms a solution absorption layer in the cylindrical cavity; the solution absorption layer is used for absorbing a liquid solution to form a semi-solid structure in the cylindrical cavity. The semi-solid water retention structure disclosed by the invention can be used for manufacturing a salt bridge or a copper sulfate reference electrode, and when the salt bridge or the copper sulfate reference electrode is manufactured, a liquid solution is absorbed by the super absorbent resin in the semi-solid water retention structure, so that no flowing solution exists in the cylindrical cavity; the problem of solution leakage does not exist after long-time use, potential drift of the salt bridge or the copper sulfate reference electrode due to solution leakage does not occur, the accuracy of potential measurement is ensured, and the service life of the salt bridge or the copper sulfate reference electrode is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical measurement, in particular to a semi-solid water-retaining structure, a salt bridge and a copper sulfate reference electrode. Background Art

[0002] The reference electrode is an electrode used as a reference when measuring the potential of various electrodes. The electrode to be measured and the reference electrode with a precisely known electrode potential value constitute a measurement system. By measuring the electromotive force value, the electrode potential of the electrode to be measured can be calculated. The copper sulfate reference electrode is one of the most common reference electrodes and is widely used in the potential measurement of metal structures in soil environments.

[0003] The traditional copper sulfate reference electrode is composed of a semipermeable plug (wooden plug, ceramic plug, etc.), a cavity, a copper sulfate solution, and a copper rod. Since the cavity structure of the traditional copper sulfate reference electrode contains an aqueous copper sulfate solution, the solution will continue to seep out as the use time increases. When the solution volume is reduced to a certain level, it will cause the copper sulfate reference electrode potential to drift, affecting the accuracy of the potential measurement. Summary of the invention

[0004] The invention provides a semi-solid water-retaining structure, a salt bridge and a copper sulfate reference electrode, which are used to solve the defect in the prior art that the copper sulfate reference electrode containing a copper sulfate aqueous solution may cause the reference electrode potential drift due to the leakage of the copper sulfate aqueous solution, thereby affecting the accuracy of potential measurement.

[0005] The present invention provides a semi-solid water-retaining structure, comprising a columnar cavity filled with a highly water-absorbent resin, the highly water-absorbent resin forming a solution absorption layer in the columnar cavity, the solution absorption layer being used for absorbing a liquid solution to form a semi-solid structure in the columnar cavity.

[0006] According to a semi-solid water-retaining structure provided by the present invention, fluff pulp is further arranged in the columnar cavity, and the fluff pulp is filled at both ends of the solution absorption layer to form anti-leakage layers at both ends of the solution absorption layer.

[0007] According to a semi-solid water-retaining structure provided by the present invention, both ends of the columnar cavity are open, and protective covers are detachably connected to the openings at both ends of the columnar cavity.

[0008] According to a semi-solid water-retaining structure provided by the present invention, the protective cover includes an upper protective cover and a lower protective cover, one end of the cylindrical cavity is provided with an internal thread, and the other end is provided with an external thread, the upper protective cover is threadedly connected to the internal thread at one end of the cylindrical cavity, and the lower protective cover is threadedly connected to the external thread at the other end of the cylindrical cavity.

[0009] According to a semi-solid water-retaining structure provided by the present invention, the upper protective cover includes a cover portion and a connecting portion arranged on one side of the cover portion, and the outer periphery of the connecting portion is provided with an external thread for matching and connecting with the internal thread at one end of the cylindrical cavity; the lower protective cover is a cylindrical cover body with an internal thread arranged inside, and the lower protective cover is matched and connected with the external thread at the other end of the cylindrical cavity through the internal internal thread.

[0010] The present invention also provides a salt bridge, comprising the above-mentioned semi-solid water retention structure, wherein the highly absorbent resin of the semi-solid water retention structure adsorbs a saturated electrolyte solution, a cation exchange resin is fixed to an opening at one end of the columnar cavity close to the lower protective cover, and the cation exchange resin covers the end of the anti-leakage layer.

[0011] According to a salt bridge provided by the present invention, the saturated electrolyte solution adsorbed by the super absorbent resin is one of a saturated sodium chloride solution, a saturated potassium chloride solution or a saturated sodium sulfide solution.

[0012] The present invention also provides a copper sulfate reference electrode, comprising the above-mentioned semi-solid water retention structure, wherein the highly absorbent resin of the semi-solid water retention structure adsorbs a saturated copper sulfate solution, a cation exchange resin is fixed to an opening at one end of the columnar cavity close to the lower protective cover, and the cation exchange resin covers the end of the anti-leakage layer; the upper protective cover is penetrated by a copper rod electrode, one end of the copper rod electrode is located outside the semi-solid water retention structure, and the other end is inserted into the solution absorption layer of the semi-solid water retention structure.

[0013] The present invention also provides a copper sulfate reference electrode, comprising the above-mentioned semi-solid water-retaining structure, wherein there are two semi-solid water-retaining structures, the first end of the columnar cavity of the first semi-solid water-retaining structure is detachably connected to an upper protective cover, the upper protective cover is penetrated by a copper rod electrode, the second end of the columnar cavity of the first semi-solid water-retaining structure is fixed with a cation exchange resin, the second end of the columnar cavity of the first semi-solid water-retaining structure is connected to the first end of the columnar cavity of the second semi-solid water-retaining structure, the second end of the columnar cavity of the second semi-solid water-retaining structure is also fixed with a cation exchange resin, and the second end of the columnar cavity of the second semi-solid water-retaining structure is detachably connected to a lower protective cover; the super absorbent resin of the first semi-solid water-retaining structure absorbs a saturated copper sulfate solution, and the super absorbent resin of the second semi-solid water-retaining structure absorbs a saturated electrolyte solution.

[0014] According to a copper sulfate reference electrode provided by the present invention, the outer periphery of the second end of the columnar cavity of the first semi-solid water-retaining structure is provided with an external thread, and the inside of the first end of the columnar cavity of the second semi-solid water-retaining structure is provided with an internal thread, so that the second end of the columnar cavity of the first semi-solid water-retaining structure is connected to the first end of the columnar cavity of the second semi-solid water-retaining structure through a threaded connection, the cation exchange resin is arranged in a conical structure, the cation exchange resin at the second end of the columnar cavity of the first semi-solid water-retaining structure is inserted into the first end of the columnar cavity of the second semi-solid water-retaining structure, and the cation exchange resin at the second end of the columnar cavity of the second semi-solid water-retaining structure extends into the lower protective cover.

[0015] The semi-solid water-retaining structure, salt bridge and copper sulfate reference electrode provided by the present invention can be used to prepare the salt bridge or the copper sulfate reference electrode. Specifically, when preparing the salt bridge or the copper sulfate reference electrode, the liquid solution is absorbed by the highly absorbent resin in the semi-solid water-retaining structure, so that no flowing solution is stored in the columnar cavity, and there will be no problem of solution leakage after long-term use. The salt bridge or the copper sulfate reference electrode will not have potential drift due to solution leakage, thereby ensuring the accuracy of potential measurement and extending the service life of the salt bridge or the copper sulfate reference electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the explosion structure of the semi-solid water-retaining structure provided by the present invention.

[0018] Figure 2 It is a schematic diagram of the explosion structure of the salt bridge provided by the present invention.

[0019] Figure 3 The invention provides a schematic diagram of the explosion structure of a copper sulfate reference electrode.

[0020] Figure 4 It is a schematic diagram of the explosion structure of another copper sulfate reference electrode provided by the present invention.

[0021] Figure numerals: 1, cylindrical cavity; 2, highly absorbent resin; 3, fluff pulp; 4, protective cover; 41, upper protective cover; 411, cover portion; 412, connecting portion; 42, lower protective cover; 5, cation exchange resin; 6, copper rod electrode. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0023] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0024] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0025] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0026] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0027] Combine the following Figures 1 to 4 The structure and working principle of the semi-solid water-retaining structure, salt bridge and copper sulfate reference electrode of the present invention are described.

[0028] One embodiment of the present invention provides a semi-solid water-retaining structure, see Figure 1 As shown, it includes a columnar cavity 1, in which a super absorbent resin 2 is filled. The super absorbent resin 2 forms a solution absorption layer in the columnar cavity 1, and the solution absorption layer is used to absorb a liquid solution to form a semi-solid structure in the columnar cavity 1.

[0029] It can be understood that the semi-solid water-retaining structure of the present embodiment can be used to make a salt bridge or a copper sulfate reference electrode. Specifically, when making a salt bridge or a copper sulfate reference electrode, the liquid solution is absorbed by the highly absorbent resin 2 in the semi-solid water-retaining structure, so that there is no flowing solution in the cylindrical cavity 1. Taking the preparation of a copper sulfate reference electrode as an example, the copper sulfate reference electrode formed by the semi-solid water-retaining structure of the present embodiment has a semi-solid state inside, and there is no liquid copper sulfate aqueous solution. There will be no problem of solution leakage even after long-term use. The potential of the copper sulfate reference electrode will not drift due to solution leakage, thereby ensuring the accuracy of the potential measurement and extending the service life of the copper sulfate reference electrode.

[0030] In some embodiments of the semi-solid water-retaining structure provided by the present invention, see Figure 1 As shown, fluff pulp 3 is also provided in the columnar cavity 1, and the fluff pulp 3 is filled at both ends of the solution absorption layer to form an anti-leakage layer at both ends of the solution absorption layer. Through the provision of the anti-leakage layer, the possible overflow solution of the super absorbent resin 2 is further absorbed to ensure that there is no liquid in the columnar cavity 1.

[0031] In some other embodiments of the semi-solid water-retaining structure provided by the present invention, both ends of the cylindrical cavity 1 are open, and protective covers 4 are detachably connected to the openings at both ends of the cylindrical cavity 1. The protective cover 4 includes an upper protective cover 41 and a lower protective cover 42. One end of the cylindrical cavity 1 is provided with an internal thread, and the other end is provided with an external thread. The upper protective cover 41 is threadedly connected to the internal thread at one end of the cylindrical cavity 1, and the lower protective cover 42 is threadedly connected to the external thread at the other end of the cylindrical cavity 1.

[0032] It can be understood that in this embodiment, protective covers 4 are provided at both ends of the cylindrical cavity 1 to form a closed space inside the cylindrical cavity 1. When making a salt bridge or a copper sulfate reference electrode, the upper protective cover 41 is opened, and a saturated electrolyte solution or a saturated copper sulfate solution is injected into the cylindrical cavity 1. The injected solution is absorbed by the highly absorbent resin 2 and the fluff pulp 3 to form a semi-solid state; then the upper protective cover 41 is tightly closed; when performing potential measurement, the lower protective cover 42 is opened to make the lower end of the cylindrical cavity 1 fully contact with the soil to complete the potential measurement.

[0033] Continue to see Figure 1 As shown, in some specific examples, the upper protective cover 41 includes a cover portion 411 and a connecting portion 412 arranged on one side of the cover portion 411, and the connecting portion 412 is provided with an external thread on the outer periphery for matching and connecting with the internal thread at one end of the cylindrical cavity 1; the lower protective cover 42 is a cylindrical cover body with an internal thread arranged inside, and the lower protective cover 42 is matched and connected with the external thread at the other end of the cylindrical cavity 1 through the internal internal thread.

[0034] It is understandable that the two ends of the cylindrical cavity 1 can be the same threaded structure and detachably connected to the same protective cover 4. For example, the two ends of the cylindrical cavity 1 can be made into the same threaded male buckle structure, which is connected and protected by the cap-shaped protective cover 4. The semi-solid water-retaining structure in this example forms a threaded female buckle at one end of the cylindrical cavity 1 and a threaded male buckle at the other end, which are threadedly connected by the upper protective cover 41 and the lower protective cover 42 to form protection. The threaded connection structure of the male and female buckles allows the copper sulfate reference electrode and the salt bridge made by the semi-solid water-retaining structure of this embodiment to be used in combination. Under normal circumstances, the copper sulfate reference electrode and the salt bridge can be used independently. In special circumstances, such as when the chloride ion content in the soil is high, the copper sulfate reference electrode and the salt bridge can be connected into one to form a combined structure, which effectively reduces the influence of soil chloride ions on the reference electrode and improves detection accuracy.

[0035] The specific application of the semi-solid water-retaining structure provided by the present invention is described below in conjunction with specific embodiments. The semi-solid water-retaining structure can be mainly used to make salt bridges and copper sulfate reference electrodes.

[0036] Some embodiments of the present invention provide a salt bridge, see Figure 2As shown, the semi-solid water-retaining structure of the above embodiment is included, the super absorbent resin 2 of the semi-solid water-retaining structure absorbs a saturated electrolyte solution, a cation exchange resin 5 is fixed to the opening of one end of the columnar cavity 1 close to the lower protective cover 42, and the cation exchange resin 5 covers the end of the anti-leakage layer. The saturated electrolyte solution absorbed by the super absorbent resin 2 is one of a saturated sodium chloride solution, a saturated potassium chloride solution or a saturated sodium sulfide solution.

[0037] It can be understood that the salt bridge structure provided in this embodiment is a semi-solid salt bridge structure composed of a columnar cavity 1, a super absorbent resin 2, a fluff pulp 3, a protective cover 4 and a saturated electrolyte solution. Before use, unscrew the upper protective cover 41, inject a saturated solution of potassium chloride or sodium sulfide into the columnar cavity 1, and absorb the injected saturated solution through the water absorption and water retention structure composed of the super absorbent resin 2 and the fluff pulp 3 until the absorption saturation state is reached, and then tighten the upper protective cover 41. Before the potential measurement begins, unscrew the lower protective cover 42, and soak the exposed cation exchange resin 5 below the columnar cavity 1 with pure water to make the ion exchange channel of the cation exchange resin 5 smooth and ensure the measurement accuracy. Due to the solution absorption layer and anti-leakage layer formed by the super absorbent resin 2 and the fluff pulp 3 in the columnar cavity 1, the saturated electrolyte solution injected into the columnar cavity 1 is absorbed, so that there is no flowing solution in the columnar cavity 1, forming a semi-solid salt bridge, avoiding the leakage that may occur when the solution flows, and improving the service life of the salt bridge.

[0038] Some other embodiments of the present invention provide a copper sulfate reference electrode, see Figure 3 As shown, it includes the semi-solid water-retaining structure of the above embodiment, the super absorbent resin 2 of the semi-solid water-retaining structure adsorbs a saturated copper sulfate solution, a cation exchange resin 5 is fixed to the opening of one end of the columnar cavity 1 close to the lower protective cover 42, and the cation exchange resin 5 covers the end of the anti-leakage layer; the upper protective cover 41 is penetrated by a copper rod electrode 6, one end of the copper rod electrode 6 is located outside the semi-solid water-retaining structure, and the other end is inserted into the solution absorption layer of the semi-solid water-retaining structure.

[0039] It can be understood that the copper sulfate reference electrode structure provided in this embodiment includes a columnar cavity 1, a super absorbent resin 2, a fluff pulp 3, a protective cover 4, a cation exchange resin 5 and a saturated copper sulfate solution, and is a semi-solid copper sulfate reference electrode structure. Before use, unscrew the upper protective cover 41, inject a saturated copper sulfate solution into the columnar cavity 1, and absorb the injected saturated copper sulfate solution through the solution absorption layer and the anti-leakage layer composed of the super absorbent resin 2 and the fluff pulp 3 until the absorption reaches a saturated state, and then tighten the upper protective cover 41 to insert the copper rod electrode 6 into the solution absorption layer formed by the super absorbent resin 2. Before the potential measurement begins, use pure water to soak the exposed cation exchange resin 5 below the columnar cavity 1 to make the ion exchange channel of the cation exchange resin 5 smooth to ensure measurement accuracy. The solution absorption layer formed by the highly absorbent resin 2 absorbs a sufficient amount of saturated copper sulfate solution around the copper rod electrode 6, replacing the traditional liquid copper sulfate saturated solution, so that there is no flowing solution in the cylindrical cavity 1, effectively reducing the amount of aqueous solution seepage, thereby increasing the life of the reference electrode. In the low chloride ion environment scenario, the exposed cation exchange resin 5 under the cylindrical cavity 1 is directly contacted with the soil, and the potential measurement is started. The cation exchange resin 5 can effectively prevent the penetration of external chloride ions, prevent the external chloride ions from contaminating the reference electrode, and ensure the accuracy of the potential measurement.

[0040] It is important to understand that when encountering a high chloride ion environment, chloride ions will pass through the semipermeable plug of the traditional reference electrode into the copper sulfate solution, contaminating the copper sulfate solution, reducing the purity of the solution, and causing inaccurate potential measurements. Figure 4 As shown, some embodiments of another aspect of the present invention provide a copper sulfate reference electrode, including the semi-solid water-retaining structure of the above embodiment, there are two semi-solid water-retaining structures, the first end of the columnar cavity 1 of the first semi-solid water-retaining structure is detachably connected to an upper protective cover 41, the upper protective cover 41 is penetrated by a copper rod electrode 6, the second end of the columnar cavity 1 of the first semi-solid water-retaining structure is fixed with a cation exchange resin 5, the second end of the columnar cavity 1 of the first semi-solid water-retaining structure is connected to the first end of the columnar cavity 1 of the second semi-solid water-retaining structure, the second end of the columnar cavity 1 of the second semi-solid water-retaining structure is also fixed with a cation exchange resin 5, and the second end of the columnar cavity 1 of the second semi-solid water-retaining structure is detachably connected to a lower protective cover 42; the super absorbent resin 2 of the first semi-solid water-retaining structure adsorbs a saturated copper sulfate solution, and the super absorbent resin 2 of the second semi-solid water-retaining structure adsorbs a saturated electrolyte solution.

[0041] It can be understood that the copper sulfate reference electrode of the present embodiment is a copper sulfate reference electrode structure composed of a semi-solid copper sulfate reference electrode and a semi-solid salt bridge. The cation exchange resin 5 at the lower end of the columnar cavity 1 of the first semi-solid water-retaining structure and the columnar cavity 1 of the second semi-solid water-retaining structure form an ion exchange path. The cation exchange resin 5 at the lower end of the columnar cavity 1 of the second semi-solid water-retaining structure is in direct contact with the soil. The cation exchange resin 5 can effectively prevent the penetration of external chloride ions and prevent the contamination of the reference electrode by external chloride ions, so that the copper sulfate reference electrode of the present embodiment can be used in a high chloride ion environment.

[0042] In some specific examples of the copper sulfate reference electrode provided by the present invention, see Figure 4 As shown, the outer periphery of the second end of the columnar cavity 1 of the first semi-solid water-retaining structure is provided with an external thread, and the inside of the first end of the columnar cavity 1 of the second semi-solid water-retaining structure is provided with an internal thread, so that the second end of the columnar cavity 1 of the first semi-solid water-retaining structure is connected to the first end of the columnar cavity 1 of the second semi-solid water-retaining structure through a threaded connection, and the cation exchange resin 5 is set to a conical structure, and the cation exchange resin 5 at the second end of the columnar cavity 1 of the first semi-solid water-retaining structure is inserted into the first end of the columnar cavity 1 of the second semi-solid water-retaining structure, and the cation exchange resin 5 at the second end of the columnar cavity 1 of the second semi-solid water-retaining structure extends into the lower protective cover 42.

[0043] In the scenario of low chloride ion environment, the copper sulfate reference electrode prepared by the first semi-solid water-retaining structure is directly used, and the cation exchange resin 5 exposed at the lower end of the cylindrical cavity 1 is in full contact with the soil to complete the potential measurement. In the scenario of high chloride ion environment, two semi-solid water-retaining structures are used to prepare the copper sulfate reference electrode. The first semi-solid water-retaining structure is used to prepare the copper sulfate reference electrode body, and the second semi-solid water-retaining structure is used to prepare the semi-solid salt bridge. Then, the lower protective cover 42 of the copper sulfate reference electrode body and the upper protective cover 41 of the semi-solid salt bridge are removed, and the upper end of the semi-solid salt bridge is connected to the lower end of the copper sulfate reference electrode structure body structure through threads. After tightening the two, they are used. When measuring the potential, unscrew the lower protective cover 42 at the lower end of the semi-solid salt bridge to make the cation exchange resin 5 at the lower part of the semi-solid salt bridge fully contact with the soil to complete the potential measurement. It can be understood that the main part of the reference electrode structure and the salt bridge structure of this embodiment are connected by threads to form a combined copper sulfate reference electrode. The main part of the reference electrode structure and the salt bridge structure are both provided with a cation exchange resin 5. The cation exchange resin 5 of the main part of the reference electrode structure forms an ion exchange path with the semi-solid salt bridge structure. The cation exchange resin 5 of the salt bridge structure is in direct contact with the soil, which effectively prevents the penetration of external chloride ions. Through double-layer blocking, the contamination of the reference electrode by external chloride ions can be effectively prevented, thereby improving the detection accuracy.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A semi-solid water-retaining structure, characterized in that: The invention comprises a columnar cavity (1), wherein the columnar cavity (1) is filled with a highly water-absorbent resin (2), wherein the highly water-absorbent resin (2) forms a solution absorption layer in the columnar cavity (1), and wherein the solution absorption layer is used to absorb a liquid solution to form a semi-solid structure in the columnar cavity (1).

2. The semi-solid water-retaining structure according to claim 1, characterized in that: Fluff pulp (3) is also arranged in the columnar cavity (1), and the fluff pulp (3) is filled at both ends of the solution absorption layer to form anti-leakage layers at both ends of the solution absorption layer.

3. The semi-solid water-retaining structure according to claim 2, characterized in that: Both ends of the cylindrical cavity (1) are open, and protective covers (4) are detachably connected to the openings at both ends of the cylindrical cavity (1).

4. The semi-solid water-retaining structure according to claim 3, characterized in that: The protective cover (4) comprises an upper protective cover (41) and a lower protective cover (42); one end of the cylindrical cavity (1) is provided with an internal thread, and the other end is provided with an external thread; the upper protective cover (41) is threadedly connected to the internal thread at one end of the cylindrical cavity (1), and the lower protective cover (42) is threadedly connected to the external thread at the other end of the cylindrical cavity (1).

5. The semi-solid water-retaining structure according to claim 4, characterized in that: The upper protective cover (41) comprises a cover portion (411) and a connecting portion (412) arranged on one side of the cover portion (411); the connecting portion (412) is provided with an external thread on its outer periphery for being matched and connected with an internal thread at one end of the cylindrical cavity (1); the lower protective cover (42) is a cylindrical cover body having an internal thread arranged therein; the lower protective cover (42) is matched and connected with the external thread at the other end of the cylindrical cavity (1) via the internal internal thread.

6. A salt bridge, characterized in that It comprises the semi-solid water-retaining structure according to claim 4 or 5, wherein the super absorbent resin (2) of the semi-solid water-retaining structure absorbs a saturated electrolyte solution, a cation exchange resin (5) is fixed to an opening at one end of the columnar cavity (1) close to the lower protective cover (42), and the cation exchange resin (5) covers the end of the anti-leakage layer.

7. The salt bridge according to claim 6, characterized in that The saturated electrolyte solution adsorbed by the super absorbent resin (2) is one of a saturated sodium chloride solution, a saturated potassium chloride solution or a saturated sodium sulfide solution.

8. A copper sulfate reference electrode, characterized in that The invention comprises the semi-solid water-retaining structure according to claim 4 or 5, wherein the super absorbent resin (2) of the semi-solid water-retaining structure absorbs a saturated copper sulfate solution, a cation exchange resin (5) is fixed to an opening at one end of the columnar cavity (1) close to the lower protective cover (42), and the cation exchange resin (5) covers the end of the anti-leakage layer; the upper protective cover (41) is penetrated by a copper rod electrode (6), one end of the copper rod electrode (6) is located outside the semi-solid water-retaining structure, and the other end is inserted into the solution absorption layer of the semi-solid water-retaining structure.

9. A copper sulfate reference electrode, characterized in that The invention comprises the semi-solid water-retaining structure according to claim 1 or 2, wherein the semi-solid water-retaining structures have two parts, the first end of the columnar cavity (1) of the first semi-solid water-retaining structure is detachably connected to an upper protective cover (41), the upper protective cover (41) is provided with a copper rod electrode (6), the second end of the columnar cavity (1) of the first semi-solid water-retaining structure is fixed with a cation exchange resin (5), the second end of the columnar cavity (1) of the first semi-solid water-retaining structure is connected to the first end of the columnar cavity (1) of the second semi-solid water-retaining structure, the second end of the columnar cavity (1) of the second semi-solid water-retaining structure is also fixed with a cation exchange resin (5), and the second end of the columnar cavity (1) of the second semi-solid water-retaining structure is detachably connected to a lower protective cover (42); the super absorbent resin (2) of the first semi-solid water-retaining structure absorbs a saturated copper sulfate solution, and the super absorbent resin (2) of the second semi-solid water-retaining structure absorbs a saturated electrolyte solution.

10. The copper sulfate reference electrode according to claim 9, characterized in that: The outer periphery of the second end of the columnar cavity (1) of the first semi-solid water-retaining structure is provided with an external thread, and the interior of the first end of the columnar cavity (1) of the second semi-solid water-retaining structure is provided with an internal thread, so that the second end of the columnar cavity (1) of the first semi-solid water-retaining structure is connected to the first end of the columnar cavity (1) of the second semi-solid water-retaining structure through threaded connection, and the cation exchange resin (5) is provided as a conical structure, and the cation exchange resin (5) at the second end of the columnar cavity (1) of the first semi-solid water-retaining structure is inserted into the interior of the first end of the columnar cavity (1) of the second semi-solid water-retaining structure, and the cation exchange resin (5) at the second end of the columnar cavity (1) of the second semi-solid water-retaining structure extends into the lower protective cover (42).

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