What are the reasons why pH meter electrodes are easily damaged?
Many customers have encountered such a problem. The pH meter they use on site will suffer electrode damage after a short period of use. This is not at all what the manufacturer said when it is used for such a long time. Could it be that the electrode is produced by the manufacturer? has a problem? If you try using electrodes from other manufacturers, this situation may also occur. What is going on? After careful consultation, you will find that the medium you are measuring has poisoned the electrode.
The electrodes currently produced on the market are flow reference pH meter electrodes. The formation of the electrical channel relies on the micro-osmotic pressure of the electrolyte in the electrode, allowing the electrolyte to penetrate into the measurement solution. When the medium pressure or concentration is high, the rehydration channel is not smooth, or there are bubbles, etc., it may hinder the extravasation of the electrolyte and increase the resistance in the middle of the electrical path. If the medium reversely penetrates into the pH meter electrode, it will contaminate the salt bridge or even It may react chemically with the electrolyte or internal electrode (for example, AgCl sulfide→Ag2S) to poison the electrode.
In a strongly oxidizing medium, the loss of alkaline substances (mainly monovalent cations) in the sensitive glass membrane will damage the hydration layer and cause poisoning of the pH meter electrode. Acid-resistant pH meter electrodes can be used. The special process measures (special ion addition formula) used in the manufacturing process enhance the resistance of the glass membrane to acid poisoning. At the same time, the zero potential of the electrode corresponds to pH0=2, thus making the acidic range Linearity is corrected.
The pH meter electrode does not have a good linear relationship outside of pH 2 to pH 9, and it is easy to form a large amount of hydronium ions H3O in strongly acidic solutions, causing the number of H on the surface of the pH meter electrode to decrease relatively and increase the pH value. Na in a strong alkaline medium will also participate in the exchange process between H in the solution and H on the hydration layer of the electrode, causing the electrode potential of the pH meter to increase and the pH value to be low.
