After measuring the pH for so long, have you known about the pH electrode?
A pH measurement system is used in many experiments, and the pH electrode plays a vital role as an instrument directly in contact with the solution. What is a pH electrode? PH electrode, also known as PH probe, PH sensor, English name PHelectrode or PHsensor, is the part of the PH meter that is in contact with the substance to be measured, and is used to measure the electrode potential. Working principle of pH electrode There are usually two methods to measure the pH value in aqueous solution, colorimetric method (PH test paper and cuvette) and potentiometric method. The potentiometric method is a method that can realize continuous online measurement and process monitoring, and the potentiometric method can obtain accurate and repeatable pH values. The core theory of pH electrode measurement is the Nernst equation. The electrodes used in potentiometric analysis are called primary cells. A primary battery is a system whose function is to convert chemical reaction energy into electrical energy. The voltage of this battery is called electromotive force (EMF). This electromotive force (EMF) is formed by two half-cells. One of the half-cells is called the measuring electrode, and its potential is related to a specific ion activity; the other half-cell is the reference half-cell, usually called the reference electrode, which is generally connected to the measuring solution and connected to the measuring instrument . The most familiar and commonly used pH indicating electrode is the glass electrode. A set of industrial online pH measurement system usually consists of four parts: pH sensor, namely pH electrode, pH transmitter, electrode sheath and cable. Advantages and characteristics of PH electrode 1. Suitable for biochemical and pharmaceutical processes 2. No need to interrupt during use and can immediately check, clean, and replace electrodes 3. Easy to install and use 4. Handle protection cable connector PH electrode maintenance 1 1. Soak the pH electrode before use, because the pH bulb is a special glass membrane, and there is a thin hydrated gel layer on the surface of the glass membrane. It can only have a good interaction with the H+ ions in the solution under the condition of sufficient humidity response. At the same time, the glass electrode is soaked, which can greatly reduce the asymmetric potential and tend to be stable. 2. The pH electrode should not be soaked in neutral or alkaline buffer solution. Long-term immersion in such solution will make the pH glass membrane slow in response. 3. If it is a composite electrode, it should be soaked in the PH4 buffer solution containing KCL, so that it can act on the glass bulb and the liquid junction at the same time.