Application of pH meter in measuring pH value of groundwater
PH acidity meter is a commonly used instrument and equipment, mainly used to accurately measure the pH value of liquid media. It can also measure the ion electrode potential MV value when equipped with corresponding ion selective electrodes. pH meters are widely used in environmental protection, sewage treatment, scientific research, pharmaceuticals, fermentation, chemical industry, aquaculture, tap water and other fields. This instrument is also an essential inspection equipment for QS and HACCP certification in food factories and drinking water plants. Below is a brief introduction to the application method of pH meter in groundwater pH measurement. Its measurement range and precision depend on the selected pH electrode and pH meter. Generally accurate to 0.01 pH units.
measuring principle
PH is one of the important and frequently performed analysis items in water analysis, and is an important parameter for evaluating water quality. When water is contaminated, it may cause significant changes in pH value. When water contains a large amount of free carbon dioxide, it can significantly lower the pH value of the water.
This method uses a pH glass electrode as the indicator electrode and a saturated calomel electrode as the reference electrode, immersed in the measured solution to form the primary cell. At 25 ℃, each unit of pH value is equivalent to a 59.1mV change in electromotive force. For every 59.1mV change in electromotive force, the pH value of the solution changes by one unit. After positioning with a standard buffer solution, place the electrode into the sample to directly measure the pH value on the pH meter. The temperature difference can be corrected by the temperature compensation device on the instrument. The color, turbidity, colloidal substances, oxidants, reducing agents, and high salt content of the water sample do not interfere with the measurement. But in strong alkaline solutions, errors can occur when a large amount of sodium ions are present, resulting in lower readings.
Required reagents
Unless otherwise specified, the reagents used in this method are reference reagents or pH buffering agents, and the water used is distilled water or deionized water.
Preparation of pH standard buffer solution: Weigh the specified amount of reagent into the boiling standard, dissolve it in deionized water, transfer it into a 1000mL volumetric flask, and when the temperature is constant at 25 ℃, dilute it with water to the mark and shake well. The deionized water used should be boiled to remove carbon dioxide before use, and cooled before use. The conductivity of the deionized water should be less than 2 μ s/cm, and the pH should be between 5.6 and 6.0.
