WO2022205715A1

WO2022205715A1 - Quadrupole conductivity electrode capable of improving seawater conductivity measurement precision, and preparation method therefor and application thereof

Info

Publication number: WO2022205715A1
Application number: PCT/CN2021/109520
Authority: WO
Inventors: 王一; 林仕伟; 陈汉德; 符坚; 周义龙; 陈宝; 林正玺; 王玲转; 林慧媛; 符智豪; 黄修彩
Original assignee: 海南聚能科技创新研究院有限公司
Priority date: 2021-03-30
Filing date: 2021-07-30
Publication date: 2022-10-06
Also published as: CN113092537A

Abstract

A quadrupole conductivity electrode, and a preparation method therefor and the application thereof. The quadrupole conductivity electrode comprises an electrode material and a graphene layer compounded on the electrode material. By coating a surface of a quadrupole electrode of an existing sensor with nano-scale conductive material graphene, the microcosmic area of a conductive electrode is expanded, and the contact area between the conductive electrode and seawater is thus expanded, such that the polarization is reduced, bubbles attached to the surface of the electrode are reduced, the erosion of the electrode by the seawater is weakened, and the detection precision and service life of the electrode are improved. The preparation method is simple and easy, moderate in conditions and high in controllability, can be carried out on the basis of an existing quadrupole electrode material, and is more suitable for popularization and application in industry.

Description

A quadrupole conductivity electrode capable of improving the measurement accuracy of seawater conductivity and its preparation method and application

This application is required to be submitted to the China Patent Office on March 30, 2021, the application number is 202110341958.7, and the name of the invention is "A quadrupole conductivity electrode capable of improving the measurement accuracy of seawater conductivity and its preparation method and application" Chinese patent priority to the application, the entire contents of which are incorporated herein by reference.

technical field

The invention belongs to the technical field of seawater measurement, and relates to a quadrupole conductivity electrode, a preparation method and application thereof, and in particular to a quadrupole conductivity electrode capable of improving seawater conductivity measurement accuracy, its preparation method and application.

Background technique

As an important part of marine science and technology, marine monitoring technology plays a very important role in safeguarding marine rights and interests, developing marine resources, early warning of marine disasters, protecting the marine environment, strengthening national defense construction, and seeking new development space. An important symbol of a country's comprehensive national strength. In recent years, with the development of marine fishery and marine resources industry, marine observation has also attracted much attention. As an important indicator of seawater observation, electrical conductivity is often used. At present, there are also some commercially available conductivity detection equipment. Relatively speaking, the detection value of seawater conductivity detection equipment is mainly four-electrode structure, and the electrode material is graphite or titanium material. It is composed of counter electrodes. During detection, an AC excitation signal is applied to a pair of electrodes to establish an electric field in seawater, and the other pair of electrodes uses the high-impedance input principle of the operational amplifier circuit to measure the voltage, so that the current is extremely small to eliminate polarization. At this time, the measured solution can be equivalent to pure resistance. Although this conductivity electrode sensor can also detect the conductivity of seawater, there are still some problems in practical applications. The air bubbles will adhere to the surface of the sensor and affect the measurement accuracy. In addition, if the sensor is used in a seawater environment for a long time, the seawater will erode the electrodes and affect the measurement accuracy.

Therefore, how to find an electrode material suitable for seawater conductivity measurement has become one of the urgent problems to be solved by many front-line researchers in the industry.

SUMMARY OF THE INVENTION

In view of this, the technical problem to be solved by the present invention is to provide a quadrupole conductivity electrode and its preparation method and application, especially a quadrupole conductivity electrode that can improve the measurement accuracy of seawater conductivity. The four-pole conductivity electrode can reduce polarization, reduce bubble adhesion, reduce the erosion of seawater on the electrode, and improve the accuracy and life of its detection.

The invention provides a quadrupole-type conductivity electrode, which comprises an electrode material and a graphene layer compounded on the electrode material.

Preferably, the electrode material includes graphite and/or titanium alloy;

The quadrupole conductivity electrode includes a conductivity electrode for seawater measurement.

Preferably, the thickness of the graphene layer is 0.1-200 μm;

The number of graphene sheets in the graphene layer is 1-50;

The sheet diameter of the graphene in the graphene layer is 1-4 nanometers.

The invention provides a preparation method of a quadrupole conductivity electrode, comprising the following steps:

(1) removing the protective material or protective device of the quadrupole conductivity electrode for seawater measurement to obtain the electrode material of the quadrupole conductivity electrode;

Disperse graphene in water to obtain graphene aqueous slurry;

(2) compound the graphene slurry obtained in the above steps on the surface of the electrode material, and after drying, obtain a quadrupole conductivity electrode.

Preferably, the graphene includes graphene prepared by a redox method;

After the protective material or protective device is removed, alcohol soaking and/or water washing steps are also included.

Preferably, the mass concentration of graphene in the graphene slurry is 0.1% to 1%;

The means of dispersion includes ultrasonic dispersion.

Preferably, the dispersion time is 20-60 min;

A soaking step is also included before the dispersion.

Preferably, the preparation step of the graphene includes the following steps:

1) under the condition of ice bath, after mixing graphite powder, NaNO ₃ and vitriol oil, add KMnO ₄ again, continue ice bath reaction, then transfer to water bath to react;

2) adding water to the reaction system obtained in the above steps, after heating up the reaction, adding water and hydrogen peroxide, then after pickling and washing, drying to obtain graphene oxide;

3) After ultrasonically dispersing the graphene oxide, sodium dodecylbenzenesulfonate and water obtained in the above steps, adding ascorbic acid and Na ₂ CO ₃ solution to mix again, and reacting to obtain graphene.

Preferably, the compounding method includes drop coating;

The drying time is 4～6h;

The drying temperature is 200-400°C.

The present invention also provides the application of the quadrupole conductivity electrode according to any one of the above technical solutions or the quadrupole conductivity electrode prepared by the preparation method according to any one of the above technical solutions in the field of seawater measurement

The invention provides a quadrupole-type conductivity electrode, which comprises an electrode material and a graphene layer compounded on the electrode material. Compared with the prior art, the present invention expands the microscopic area of the conductive electrode by smearing the nanoscale conductive material graphene on the surface of the quadrupole electrode of the existing sensor, thereby expanding the contact area between the conductive electrode and the seawater, thereby reducing the electrode size. It can reduce the bubbles attached to the surface of the electrode, weaken the erosion of seawater on the electrode, and improve the accuracy and service life of its detection. Moreover, the preparation method is simple and easy to obtain, with mild conditions and strong controllability, and can be carried out on the basis of the existing quadrupole electrode materials, which is more suitable for promotion and application in the industry.

The experimental results show that the nanoscale graphene layer on the surface of the quadrupole conductivity electrode provided by the present invention can improve the service life of the pH electrode in seawater, and prolong the service life by about 5% to 10%. precision.

Description of drawings

FIG. 1 is a graph of polarization resistance changes of the high-precision quadrupole conductivity electrode prepared in Example 1 of the present invention and the original quadrupole conductivity electrode in solutions of different conductivity.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent requirements of the present invention.

All the raw materials of the present invention, their sources are not particularly limited, can be purchased in the market or prepared according to conventional methods well known to those skilled in the art.

All raw materials in the present invention are not particularly limited in their purity, and the present invention preferably adopts the conventional purity requirements in the field of analytical pure or quadrupole conductivity electrode preparation.

All raw materials of the present invention, their sources and abbreviations belong to conventional sources and abbreviations in the field, and are clearly defined in the field of their related uses. Those skilled in the art can buy or Prepared by conventional methods.

In the present invention, the electrode material preferably includes graphite and/or titanium alloy, more preferably graphite or titanium alloy. Wherein, the electrode material may also be titanium or an electrode material compounded with a titanium layer on the surface.

In the present invention, the thickness of the graphene layer is preferably 0.1-200 μm, more preferably 1-150 μm, more preferably 10-100 μm, and more preferably 30-80 μm.

In the present invention, the number of graphene sheets in the graphene layer is preferably 1-50 layers, more preferably 5-40 layers, and more preferably 10-30 layers.

In the present invention, the sheet diameter of the graphene in the graphene layer is preferably 1-4 nanometers, more preferably 1.5-3.5 nanometers, and more preferably 2-3 nanometers.

In the present invention, the quadrupole conductivity electrode is preferably a conductivity electrode for seawater measurement.

Disperse graphene in water to obtain graphene aqueous slurry;

The present invention firstly removes the protective material or protective device of the quadrupole conductivity electrode for seawater measurement to obtain the electrode material of the quadrupole conductivity electrode;

The graphene is dispersed in water to obtain an aqueous graphene slurry.

In the present invention, the quadrupole conductivity electrode for seawater measurement is not particularly limited, and the quadrupole conductivity electrode for seawater measurement may be prepared or commercially available by preparation methods well known in various fields. The quadrupole conductivity electrode for seawater measurement is preferably an existing quadrupole conductivity electrode for seawater measurement.

In the present invention, the graphene preferably includes graphene prepared by a redox method. That is, reducing graphene.

In the present invention, after removing the protective material or the protective device, it preferably further includes an alcohol soaking and/or water washing step, more preferably an alcohol soaking and water washing step. Specifically, it can be multiple times of alcohol soaking and multiple times of water washing.

In the present invention, the mass concentration of graphene in the graphene slurry is preferably 0.1%-1%, more preferably 0.3%-0.8%, and more preferably 0.4%-0.6%.

In the present invention, the means of dispersion preferably includes ultrasonic dispersion.

In the present invention, the dispersion time is preferably 20-60 minutes, more preferably 25-55 minutes, and more preferably 30-50 minutes.

In the present invention, a soaking step is preferably further included before the dispersion.

The present invention completes and refines the overall preparation process, so as to better ensure the detection effect of the quadrupole conductivity electrode, and the preparation steps of the graphene preferably include the following steps:

In the present invention, the graphene slurry obtained in the above steps is finally compounded on the surface of the electrode material, and after drying, a quadrupole conductivity electrode is obtained.

In the present invention, the drying time is preferably 4-6 h, more preferably 4.5-5.5 h.

In the present invention, the drying temperature is preferably 200 to 400°C, more preferably 250 to 350°C.

The present invention prepares nanoscale graphene by chemical method by preparing graphite powder, and prepares hydrophilic (gas-repellent) graphene material, and smears the material on the surface of the electrode of the existing ethanol-treated conductivity sensor. The present invention completes and refines the overall preparation process, and better guarantees the detection effect of the quadrupole conductivity electrode. The preparation method of the quadrupole conductivity electrode can specifically include the following steps:

1. Soak the electrode with the protective layer removed in anhydrous ethanol for 1-2 minutes, take it out and wash it with deionized water.

Among them, the existing seawater electrode protection device or protective material is removed, and the sensitive material is exposed: four-electrode structure, the seawater conductivity electrode of which the electrode material is graphite or titanium metal material is mechanically disassembled or chemically. Basically remove the protective layer on the electrode.

2. Preparation of water-based graphene slurry: take graphene material and put it into pure water medium to soak and stir evenly, ultrasonically in ultrasonic wave, to obtain graphene water-based slurry.

Wherein, the preparation method of the nanoscale graphene material can specifically be the following steps:

1) Add 1.5～2g graphite powder to the dry beaker, add a certain amount of NaNO ₃ according to the ratio of graphite powder and NaNO ₃ 2:1, slowly add concentrated sulfuric acid to make the graphite powder content about 2%, ice bath for 2～3h .

2) Slowly add an appropriate amount of KMnO ₄ and the above graphite powder in a ratio of 3:1, take an ice bath for 2-3 hours, and transfer the beaker to a 35°C water bath for 2 hours.

3) transfer the beaker to the ice bath condition, slowly add distilled water to make the content of graphite powder about 3%, and react in the water bath;

4) Add distilled water, add 7.5ml of 30% hydrogen peroxide, let stand for 20min to obtain graphite oxide; wash the graphite oxide with 5% hydrochloric acid for 3 times, then wash with distilled water for 3 to 4 times, and dry in a drying oven at 80°C for 24h.

5) get above-mentioned graphene oxide material and sodium dodecyl benzene sulfonate and join in water and ultrasonic wave, add ascorbic acid, after ultrasonic dispersion, use Na ₂ CO ₃ solution drop by drop until the pH of solution is adjusted to be about 9 . Then, the mixture was continuously stirred at a constant temperature, and then left to react in a water bath. The graphene colloid is pulverized, washed and dried, and finally the dried graphene is pulverized and sieved to obtain reduced graphene.

3. The graphene slurry is modified on the surface of the graphite/titanium metal electrode material by a drop coating method (microliter syringe) and dried.

Graphene slurry can reduce polarization during testing, improve electrode conductivity, reduce bubble adhesion and weaken seawater corrosion of electrodes.

The above steps of the present invention provide a quadrupole conductivity electrode capable of improving the measurement accuracy of seawater conductivity, and a preparation method and application thereof. In the present invention, the nanoscale conductive material graphene is smeared on the surface of the quadrupole electrode of the existing sensor to expand the microscopic area of the conductive electrode, thereby expanding the contact area between the conductive electrode and seawater, thereby reducing polarization and reducing adhesion on the electrode surface. The air bubbles can reduce the erosion of seawater on the electrode, and improve the detection accuracy and service life. Moreover, the preparation method is simple and easy to obtain, with mild conditions and strong controllability, and can be carried out on the basis of the existing quadrupole electrode materials, which is more suitable for promotion and application in the industry.

In order to further illustrate the present invention, a quadrupole conductivity electrode provided by the present invention and its preparation method and application will be described in detail below with reference to the examples, but it should be understood that these examples are carried out on the premise of the technical solution of the present invention. Implementation, the detailed implementation and specific operation process are given, only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.

Example 1

Preparation method of high-precision seawater conductivity electrode

1. Remove the existing seawater electrode protection device or protective material to expose the sensitive material: four-electrode structure, the seawater conductivity electrode of which the electrode material is graphite or titanium metal material can be mechanically disassembled or chemically. Basically remove the protective layer on the electrode.

2. Preparation of nanoscale conductive materials: nanoscale graphene materials

Preparation method of nanoscale graphene material:

1) Add 1.5g graphite powder and 0.75g NaNO ₃ to a dry 250ml beaker, add 35ml of 98% concentrated sulfuric acid, ice bath for 2h.

2) Slowly add 4.5g KMnO ₄ , take an ice bath for 2 hours, and transfer the beaker to a 35°C water bath for 2 hours.

3) Transfer the beaker to an ice bath condition, slowly add 69 ml of distilled water, and react in a water bath at 98°C for 15 min.

4) Add 40ml of distilled water to dilute, add 7.5ml of 30% hydrogen peroxide, let stand for 20min, wash graphite oxide with 5% hydrochloric acid for 3 times, then wash with distilled water for 3 to 4 times, and dry in a drying oven at 80°C for 24h to obtain graphene oxide.

5) get 1g above-mentioned graphene oxide material and 1g sodium dodecyl benzene sulfonate and join in 500ml water and ultrasonic 0.5h in 500W ultrasonic wave, according to the mass ratio of graphene oxide and ascorbic acid 1:5, add ascorbic acid, ultrasonically disperse 0.5 After h, a ₅ % _Na2CO3 solution was added dropwise until the pH of the solution was adjusted to around 9. Then, the mixture was continuously stirred at a constant temperature of 80°C for 1 h, and then left to stand in a water bath for one day to react. The graphene colloid is pulverized, washed and dried, and finally the dried graphene is pulverized and sieved to obtain reduced graphene.

3. Soak the electrode with the protective layer removed in anhydrous ethanol for 1-2 minutes, take it out and wash it with deionized water.

4. Preparation of 5% aqueous graphene slurry: Weigh 0.5 g of the above graphene material, put it into 9.5 g of pure water medium, soak it for 30 minutes, stir evenly, and sonicate in 500W ultrasonic for 3 hours to obtain graphene slurry.

5. The 5% graphene slurry is modified on the surface of the graphite/titanium metal electrode material by the drop coating method (microliter syringe), and is dried at 100 degrees for 20 minutes, and the thickness of the graphene layer is 0.01-100 μm.

The performance of the high-precision quadrupole conductivity electrode prepared in Example 1 of the present invention for measuring seawater conductivity was tested.

Test electrode: Encapsulate the prepared electrodes into a bridge with the same area and two electrodes facing each other. The bridge parameters are set to 1V, 10kHz, and the Zs gear is used to test the change of polarization resistance of solutions with different conductivity. Some quadrupole electrodes are also put into the same environment as above for detection.

Referring to FIG. 1, FIG. 1 is a graph of polarization resistance changes of the high-precision quadrupole conductivity electrode prepared in Example 1 of the present invention and the original quadrupole conductivity electrode in solutions of different conductivity.

It can be seen from Figure 1 that after comparison, the polarization of the graphite electrode modified with graphene decreases in the lower conductivity solution, mainly because the graphite electrode has strong ion adsorption in the low conductivity solution, and the modified graphene makes the microscopic area. As the current density increases, the polarization impedance decreases significantly.

Example 2

Preparation method of high-precision seawater conductivity electrode

2. Preparation of nanoscale conductive materials: nanoscale graphene materials

Preparation method of nanoscale graphene material:

1) Add 2g of graphite powder and 1g of NaNO ₃ to a dry 250ml beaker, add 40ml of 98% concentrated sulfuric acid, ice bath for 2h.

5) get 1g above-mentioned graphene oxide material and 1g sodium dodecyl benzene sulfonate and join in 500ml water and ultrasonic 0.5h in 500W ultrasonic wave, according to the mass ratio of graphene oxide and ascorbic acid 1:5, add ascorbic acid, ultrasonically disperse 0.5 After h, a 5% Na ₂ CO ₃ solution was added dropwise until the pH of the solution was adjusted to around 9. Then, the mixture was continuously stirred at a constant temperature of 80°C for 1 h, and then left to stand in a water bath for one day to react. The graphene colloid is pulverized, washed and dried, and finally the dried graphene is pulverized and sieved to obtain reduced graphene.

The performance of the high-precision quadrupole conductivity electrode prepared in Example 2 of the present invention for measuring seawater conductivity was tested.

Test electrode: encapsulate the prepared electrode into two electrodes with the same area, connect the original quadrupole electrode and the quadruple electrode with nanographene layer prepared in Example 2 into the bridge and place the conductivity of 5% solution, the bridge parameters are set to 1V, 10kHz, Zs gear test, measure its resistance. The original electrode Zs0=224 trillion, and the nano-carbon electrode Zs0=180 trillion. The original quadrupole electrode and the quadrupole electrode with nanographene layer prepared in Example 2 were placed in seawater with a salinity of 35% for 10 months and taken out. The quaternary electrode of nanocarbon is connected to the bridge and a solution with a conductivity of 5% is placed. The bridge parameters are set to 1V, 10kHz, and the Zs gear is used to test the polarization resistance value of the conductivity solution. The original electrode Zs0 = 260 trillion, the electrode prepared by the present invention Zs0 = 182 trillion.

After comparison, the graphite electrode modified with graphene and the original electrode were placed in seawater at the same time, the offset value of the original electrode was larger than that of the modified graphene electrode, 260/224>182/180, and the offset rate was roughly 10 %, which indicates that the life of the modified graphene electrode provided by the present invention is longer than that of the original electrode.

A quadrupole type conductivity electrode that can improve the measurement accuracy of seawater conductivity provided by the present invention and its preparation method and application have been introduced in detail above. Specific examples are used in this paper to illustrate the principle and implementation of the present invention. , the descriptions of the above embodiments are only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any person skilled in the art to practice the present invention, including making and using any device or system, and Implement any combination of methods. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, the present invention can also be improved and modified several times, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal expressions of the claims.

Claims

A quadrupole conductivity electrode is characterized in that it comprises an electrode material and a graphene layer compounded on the electrode material.
The quadrupole conductivity electrode according to claim 1, wherein the electrode material comprises graphite and/or titanium alloy;

The quadrupole conductivity electrode includes a conductivity electrode for seawater measurement.
The quadrupole conductivity electrode according to claim 1, wherein the graphene layer has a thickness of 0.1-200 μm;

The number of graphene sheets in the graphene layer is 1-50;

The sheet diameter of the graphene in the graphene layer is 1-4 nanometers.
A method for preparing a quadrupole conductivity electrode, comprising the following steps:

(1) removing the protective material or protective device of the quadrupole conductivity electrode for seawater measurement to obtain the electrode material of the quadrupole conductivity electrode;

Disperse graphene in water to obtain graphene aqueous slurry;

(2) compound the graphene slurry obtained in the above steps on the surface of the electrode material, and after drying, obtain a quadrupole conductivity electrode.
The preparation method according to claim 4, wherein the graphene comprises graphene prepared by a redox method;

After the protective material or protective device is removed, alcohol soaking and/or water washing steps are also included.
The preparation method according to claim 4, wherein the mass concentration of graphene in the graphene slurry is 0.1% to 1%;

The means of dispersion includes ultrasonic dispersion.
The preparation method according to claim 4, wherein the dispersion time is 20-60 min;

A soaking step is also included before the dispersion.
The preparation method according to claim 4, wherein the preparation step of the graphene comprises the following steps:

1) under the condition of ice bath, after mixing graphite powder, NaNO 3 and concentrated sulfuric acid, add KMnO 4 again, continue ice bath reaction, then transfer to water bath to carry out reaction;

2) adding water to the reaction system obtained in the above steps, after heating up the reaction, adding water and hydrogen peroxide, then after pickling and washing, drying to obtain graphene oxide;

3) After ultrasonically dispersing the graphene oxide, sodium dodecylbenzenesulfonate and water obtained in the above steps, adding ascorbic acid and Na 2 CO 3 solution to mix again, and reacting to obtain graphene.
The preparation method according to claim 4, wherein the compounding method comprises a drop coating method;

The drying time is 4～6h;

The drying temperature is 200-400°C.
Application of the quadrupole conductivity electrode according to any one of claims 1 to 4 or the quadrupole conductivity electrode prepared by the preparation method according to any one of claims 5 to 9 in the field of seawater measurement.