How to clean the pH meter electrode?
1. Ultrasonic cleaning
Install a device that can generate ultrasonic waves near the pH probe of the acidity meter, which emits ultrasonic waves to automatically clean the pH electrode. The strength of ultrasound is achieved by adjusting the oscillation frequency of ultrasound. It is installed vertically, with the ultrasonic probe installed below the electrode.
2. Solution spray cleaning
A cleaning nozzle is installed near the electrode assembly. According to the cleaning requirements, the nozzle regularly sprays water or other solutions (such as low concentration hydrochloric acid or nitric acid solutions) to remove pollutants from the electrode by flushing or dissolving. If the self-cleaning system used uses a dilute HNO3 solution with a mass fraction of 1% as the cleaning solution, the spray pressure is generally higher when using water. The spraying of the solution is controlled by a program controller. During spraying, the online pH meter needs to be able to control the output to remain unchanged at the value before cleaning, that is, lock the instrument output at this time, and keep the instrument output unchanged during cleaning. After the pH value of the solution stabilizes after cleaning, the pH meter will perform detection output. In summary, the combination of ultrasonic cleaning and solution spray cleaning has shown good results in cleaning the electrodes of industrial online pH meters.
The blockage of the pH meter electrode is caused by the blockage of the liquid interface, which can be solved by the following methods:
1. Immersion of pH meter electrode liquid interface: Heat a mixture of 10% saturated potassium chloride solution and 90% distilled water to 60-70 ℃, immerse the pH meter electrode in about 5cm, soak for 20 minutes to 1 hour, and dissolve the crystals at the end of the pH meter electrode.
2. Ammonia immersion pH meter electrode: When the liquid interface is blocked by silver chloride, concentrated ammonia water can be used for immersion. Firstly, rinse and empty the pH meter electrode, then immerse it in ammonia water for 10-20 minutes. However, do not allow ammonia water to enter the interior of the pH meter electrode. Remove the pH meter electrode and wash it with distilled water. After refilling with the filling solution, continue to use it.
3. Vacuum method: Cover the reference electrode liquid interface with a hose, use a water flow suction pump to suction the partially filled liquid through the liquid interface, and remove mechanical blockages.
4. Boiling liquid interface: The liquid interface of the silver silver chloride reference electrode should be immersed in boiling water for 10-20 seconds. In addition, before the next boiling, the pH meter electrode should be cooled to room temperature.
When the above methods are ineffective, mechanical methods such as sandpaper grinding can be used to remove the blockage of the pH meter electrode. This method may cause the ground sand particles to be inserted into the liquid interface, resulting in * * blockage.
