Difference between refillable and non-refillable pH composit

Difference between refillable and non-refillable pH composite electrodes

 

Core Tip: pH composite electrode is divided into refillable (rehydration type) and non-refillable (gel type). A filling hole is provided on the shell of the refillable pH composite electrode. When the external reference solution of the electrode is lost, the filling hole can be opened to replenish KC1 solution。

PH composite electrode is divided into refillable (rehydration type) and non-refillable (gel type). A filling hole is provided on the shell of the refillable pH composite electrode. When the external reference solution of the electrode is lost, the filling hole can be opened to replenish KC1 solution. The non-refillable pH composite electrode is equipped with gel-like KC1, which is not easy to lose and has no filling hole。

 

The electrode which responds to the activity of hydrogen ions in solution and the electrode potential changes accordingly is called pH indicating electrode or pH measuring electrode. The pH indicator electrode has hydrogen electrode, antimony electrode and glass electrode, but the most commonly used is glass electrode. The glass electrode consists of a glass rod and a glass membrane made of a special component sensitive to hydrogen ions. Glass film is generally spherical bubble, bubble filled with internal reference solution, inserted into the internal reference electrode (generally with silver/silver chloride electrode), with the electrode cap sealed lead wire, mounted on the socket, it becomes a pH indicator electrode. A single pH indicator electrode cannot be used for measurement. It must be used together with the reference electrode。

 

An electrode with a known and constant electrode potential that does not respond to the activity of hydrogen ions in solution is called a reference electrode. Reference electrodes include mercurous sulfate electrode, calomel electrode and silver/silver chloride electrode, etc. The most commonly used are calomel electrodes and silver/silver chloride. The combination of a pH glass electrode, a reference electrode and a temperature compensation electrode is called a pH composite electrode. The biggest advantage of the composite electrode is that it is easy to install, calibrate and use. The pH composite electrode is mainly composed of glass electrode (consisting of electrode bulb, glass support rod, etc.), external reference electrode, external reference solution, temperature compensation electrode, liquid interface, electrode cap, electrode lead, etc。

 

The chargeable pH composite electrode is characterized by high penetration rate of reference solution, stable reappearance of liquid boundary potential and high measurement accuracy. Moreover, when the reference electrode is reduced or contaminated, the KCl solution can be added or replaced, but the disadvantage is that it is more troublesome to use. The filling hole should be opened when the refilling pH composite electrode is used to increase the liquid pressure and accelerate the response of the electrode. When the electrolyte level is low, the new electrolyte should be added in time。

 

The characteristics of non-rechargeable pH composite electrode are simple to maintain and easy to use, so it has been widely used. However, when used as a laboratory pH electrode, the concentration of KCl at the liquid interface will decrease under long-term and continuous service conditions, affecting the test accuracy. Therefore, when the non-rechargeable pH composite electrode is not in use, it should be immersed in the electrode immersion solution, so that the electrode performance will be very good in the next test. However, most laboratory pH electrodes are not long-term and continuous tests, so the impact of this structure on the accuracy is relatively small。

 

Probably the most familiar and oldest zero-current measurement used to determine chemical reactions is the pH measurement. In general, pH measurements are used to determine the pH of a solution。