CN102706942A - Preparation method of sulfate ion selective membrane electrode - Google Patents

Abstract

The present invention relates to a kind of preparation method of sulfate radical ion selective membrane electrode, and it is that PTFE4.8g～6g is dissolved in 95g water, as matrix; Then take 1～2ml sulfuric acid solution that concentration is 5mol/l as electroactive Substance, mixed with 5ml of the above PTFE solution; then add 0.2~0.5g of nano-alumina as a reinforcing agent, stir well and spread it on a glass plate, then dry to prepare a sensitive film, and then assemble it with Ag/AgCl as The internal reference electrode and 0.1mol/L potassium sulfate solution are used as the membrane electrode of the internal reference solution. The membrane electrode prepared by the method of the invention has the advantages of good strength and stability and low cost.

Description

Preparation method of sulfate ion selective membrane electrode

technical field

The invention relates to a preparation method of a sulfate ion selective membrane electrode.

the

Background technique

Ion-selective electrodes are one of the fastest-growing analytical techniques in recent years, and a systematic potential analysis method has been formed. The analysis method has the characteristics of simple equipment, convenient operation, suitable for on-site measurement and continuous automatic analysis and measurement, etc. New and important tools for analytical work related to agriculture, agriculture, etc.

Ion-selective electrodes are a class of electrochemical sensors that mainly include three parts:

(1) Sensitive membrane: it is the most critical part of the ion selective electrode, which determines the properties of the electrode, and its function is to convert the specific ion activity in the solution into the membrane potential;

(2) Internal reference electrode: its function is to lead out the membrane potential;

(3) Internal reference solution: contains ions that respond to the membrane and the internal reference electrode.

As the most important component of the ion-selective electrode, the sensitive membrane can selectively respond to the ions in the solution. In the case of a certain ionic strength in the solution, the potential of the ion selective electrode has a linear relationship with the logarithm of the given ion activity, that is, it conforms to the Nernst equation.

The main performance parameters of the ion-selective electrode are strength, stability, reproducibility and lifespan. The stability of the ion-selective electrode refers to the magnitude of the potential fluctuation when the electrode continuously measures a certain concentration of the ion to be measured. Reproducibility refers to the degree of potential reappearance of the electrode when it is repeatedly measured alternately in solutions of different concentrations, reflecting the hysteresis and memory effect of the electrode. The standard deviation (SD) of the electrode potential readings is generally used to indicate the stability and reproducibility of the electrode. The life of the electrode refers to the time to keep the performance parameters of the electrode unchanged. The longer the life of the electrode, the greater the use value.

The development of ion-selective membrane electrodes has practical significance for actual production and research. There are also many research results on the preparation of ion-selective membrane electrodes. However, although the performance parameters of existing ion-selective membrane electrodes are very good, such as organic sulfonate polymer membranes, etc., their cost is very high. It is not suitable for large-scale promotion; and although some existing sensitive films are relatively moderate in cost, their strength and stability are insufficient.

the

Contents of the invention

The purpose of the present invention is to provide a method for preparing an ion-selective membrane electrode with low cost, reliable strength and stability.

In order to achieve the above-mentioned purpose of the invention, the technical solution of the present invention is: a method for preparing an ion-selective membrane electrode, comprising the following steps:

1) Configure the polymer support

Dissolve 4.8g~6g of PTFE in 95g of water to prepare a PTFE solution;

2) Add electroactive material and prepare mixed solution

Take 1~2ml of sulfuric acid solution with a concentration of 5mol/l, and then take 5~7ml of the prepared PTFE solution, mix and stir;

3) Preparation of sensitive membrane

Take 0.2~0.5g of nano-alumina, add the above mixed solution, fully stir to form a uniform and transparent solution, slowly pour this solution on a 60 mm×60 mm smooth flat glass, and use a glass rod to stick to the glass plane in one direction Scrape the film, drive out the air bubbles in the film, let it evaporate to form a film, and then dry;

4) Membrane electrode assembly

Prepare a PVC pipe with an inner diameter of 15-18mm and a length of 10cm, take the prepared sensitive film with a diameter of 15-18mm, stick it to the inner bottom of the above-mentioned PVC pipe with a 5wt % PVC tetrahydrofuran solution, and then fill it with 0.1 The mol/L potassium sulfate solution is used as the internal reference solution, and the Ag/AgCl internal reference electrode is inserted into the internal reference solution to form a membrane electrode.

In addition, as a preferred technical solution, in step 4), the inner diameter of the PVC pipe and the diameter of the sensitive membrane are both 16mm.

In addition, as a preferred technical solution, in step 3), the vacuum heating conditions for preparing the sensitive film are: keep the temperature at 80°C, and heat for 15 hours.

The ion-selective membrane prepared by a large number of experiments in the present invention is combined by molecular force instead of chemical bond between the matrix and the ion active material; and by adding silicon dioxide powder as a reinforcing agent, the mechanical strength is further increased and the cost is reduced.

The beneficial effect of the present invention is that, through continuous measurement, a working voltage above 0.8V can be obtained, and the change of the membrane potential value of 10 times of measurement results is not more than 1mV, which shows that the strength and stability of the membrane electrode of the present invention are good, and the cost low.

the

Detailed ways

The present invention is a kind of preferred technical scheme that obtains through experiment, specifically with PTFE 4.8g～6g, be dissolved in 95g water, as matrix; Then will get the sulfuric acid solution that 1～2ml concentration is 5mol/l as electroactive substance, and Mix 5ml of the above PTFE solution; then add 0.2~0.5g of nano-alumina as a reinforcing agent, stir well and spread it on a glass plate, then dry it to prepare a sensitive film, and then assemble it with Ag/ AgCl is used as the internal reference electrode, and 0.1mol/L potassium sulfate solution is used as the membrane electrode of the internal reference solution.

Wherein, below in conjunction with embodiment and test result, illustrate

Example 1

A preparation method for an ion-selective membrane electrode, comprising the following steps:

1) Configure the polymer support

Dissolve 4.8g of PTFE in 95g of water to prepare a PTFE solution;

2) Add electroactive material and prepare mixed solution

Take 1.5ml of sulfuric acid solution with a concentration of 5mol/l, and then take 5~7ml of the prepared PTFE solution, mix and stir the two components; the two components are combined by intermolecular force;

3) Preparation of sensitive membrane

Take 0.2g of nano-alumina, add the above mixed solution, fully stir to form a uniform and transparent solution, slowly pour this solution on a smooth flat glass of 60 mm × 60 mm, and use a glass rod to stick to the glass plane and scrape the film in one direction , drive out the air bubbles in the film, let it volatilize to form a film, and then dry it;

4) Membrane electrode assembly

Prepare a PVC pipe with an inner diameter of 15mm and a length of 10cm, take a prepared sensitive film with a diameter of 15mm, stick it to the inner bottom of the above PVC pipe with a THF solution of 5wt % PVC, and then fill it with 0.1mol/L Potassium sulfate solution is used as the internal reference solution, and the Ag/AgCl internal reference electrode is inserted into the internal reference solution to form a membrane electrode.

The continuous measurement of the membrane electrode prepared in this example can obtain a working voltage above 0.8V, and the change of the membrane potential value of the 10 measurement results does not exceed 1mV, indicating that the strength and stability of the membrane electrode are good.

the

Example 2

A preparation method for an ion-selective membrane electrode, comprising the following steps:

1) Configure the polymer support

Dissolve PTFE 6g in 95g water to prepare PTFE solution;

2) Add electroactive material and prepare mixed solution

Take 2ml of sulfuric acid solution with a concentration of 5mol/l, and then take 7ml of the configured PTFE solution, and mix and stir the two;

3) Preparation of sensitive membrane

Take 0.5g of nano-alumina, add the above mixed solution, fully stir to form a uniform and transparent solution, slowly pour this solution on a smooth flat glass of 60 mm × 60 mm, and use a glass rod to stick to the glass plane and scrape the film in one direction , drive out the air bubbles in the film, let it volatilize to form a film, and then dry it;

4) Membrane electrode assembly

Prepare a PVC pipe with an inner diameter of 16mm and a length of 10cm, take the prepared sensitive film with a diameter of 16mm, stick it to the inner bottom of the above PVC pipe with a 5wt % PVC tetrahydrofuran solution, and then fill it with 0.1mol/L Potassium sulfate solution is used as the internal reference solution, and the Ag/AgCl internal reference electrode is inserted into the internal reference solution to form a membrane electrode.

The continuous measurement of the membrane electrode prepared in this example can obtain a working voltage above 0.8V, and the change of the membrane potential value of the 10 measurement results does not exceed 1mV, indicating that the strength and stability of the membrane electrode are good.

The technical scope of the present invention is not limited to the content in the specification, but must be determined according to the scope of the claims.

Claims (3)

1. a preparation method of sulfate ion selective membrane electrode, is characterized in that, the preparation method may further comprise the steps: 1) Configure the polymer support Dissolve 4.8g~6g of PTFE in 95g of water to prepare a PTFE solution; 2) Add electroactive material and prepare mixed solution Take 1~2ml of sulfuric acid solution with a concentration of 5mol/l, and then take 5~7ml of the prepared PTFE solution, mix and stir; 3) Preparation of sensitive membrane Take 0.2~0.5g of nano-alumina, add the above mixed solution, fully stir to form a uniform and transparent solution, slowly pour this solution on a 60 mm×60 mm smooth flat glass, and use a glass rod to stick to the glass plane in one direction Scrape the film, drive out the air bubbles in the film, let it evaporate to form a film, and then dry; 4) Membrane electrode assembly Prepare a PVC pipe with an inner diameter of 15-18mm and a length of 10cm, take the prepared sensitive film with a diameter of 15-18mm, stick it to the inner bottom of the above-mentioned PVC pipe with a 5wt % PVC tetrahydrofuran solution, and then fill it with 0.1 The mol/L potassium sulfate solution is used as the internal reference solution, and the Ag/AgCl internal reference electrode is inserted into the internal reference solution to form a membrane electrode. 2. The preparation method of sulfate ion selective membrane electrode according to claim 1, characterized in that, in step 4), the inner diameter of the PVC pipe and the diameter of the sensitive membrane are both 16mm. 3. The preparation method of sulfate ion selective membrane electrode according to claim 1, characterized in that, in step 3), the vacuum heating conditions for preparing the sensitive membrane are as follows: keep the temperature at 80°C, and heat for 15 hours.