Over the past century of ozone application, various ozone detection technologies such as chemical, optical, electrochemical, and thermochemical methods have been developed, and various detection methods and devices have been researched and promoted. Select different measurement methods based on concentration range, required accuracy, and application scope. Common methods and instruments. Common methods, instruments, and device introductions are as follows:
Chemical method
Iodometric method
The most commonly used method for measuring ozone is the iodometric method, which is used as the standard method for measuring gas ozone in China and many other countries. The standard CJ/T3028.2-94 "Measurement of Ozone Concentration, Production, and Electricity Consumption of Ozone Generators" issued by the Ministry of Education in China stipulates the use of the iodometric method.
The principle is that strong oxidants ozone (O3) and potassium iodide (KI) are used, and ozone is simultaneously restored to oxygen. The reaction equation is:
O3 2KI H20→O2 I2 2KOH
Free iodine color changes from light * 1 * to brownish white depending on its concentration in water.
Titrate with sodium thiosulfate (Na2S2O3) standard solution, free I2 is converted to sodium iodide (NaI), and the reaction endpoint is complete fading. The reaction equation is: I2 2 Na2S2O3 → 2NaI Na2S4O6
The quantitative relationship between O3 reaction amount and Na2S2O3 consumption established by the two reaction equation is as follows:
A Na × B × 2400
V0
1mol O3：2mol Na2S2O3
In the formula, C O3- ozone concentration, mg/L； ANa - dosage of sodium thiosulfate standard solution, mL; B - concentration of sodium thiosulfate standard solution, mol/L； V 0- other sampling volumes for ozone oxidation, mL；
Refer to CJ/T3208.2-94 for the operation sequence and methods.
It is very convenient to measure the concentration of standard generators. The ozone gas volume flowmeter counts and the Na2S2O3 concentration is generally prepared at 0.100mol/L, with a measurement accuracy of 1%.
When measuring the concentration of ozone in the air, it is necessary to use an atmospheric pump for quantitative extraction. To ensure measurement accuracy, Na2S2O3 is mixed with 0.010mol/L.
The determination of ozone concentration in water can also be calculated using this formula, except that V 0 represents the amount of water collected, and 1000ml of Na2S2O3 with a concentration of 0.010mol/L is taken.
The advantage of iodometric method is its intuitive color development, which does not require valuable instruments. Defects are easily disturbed by other oxidants such as NO, Cl2, etc., and the influence of other oxidants should be eliminated during important testing.
colorimetry
It is a method of determining ozone concentration based on the color or decolorization reaction sequence between ozone and different chemical reagents. According to colorimetric methods, it is divided into artificial color samples and photometer colorimetry. This method is mostly used to detect dissolved ozone solutions in water.
Testing tube
Immerse the ozone oxidation color changing reagent on a carrier as a reagent and encapsulate it in a standard inner diameter glass tube as a detection tube. Cut off both ends of the detection tube when in use, and connect a vacuum pump to the exhaust end of the detection tube to extract a certain amount of ozone gas. The ozone concentration is proportional to the color changing length of the reagent column in the detection tube, and the concentration value is read through the scale value.
UV absorption method
The principle is that ozone has the maximum absorption coefficient for ultraviolet light with a wavelength of 254nm. At this wavelength, ultraviolet light attenuates through ozone, which conforms to the Lambert Beer law. This method has been adopted as the standard method for ozone analysis by countries such as the United States.
Electrochemical method
The ozone electrochemical detection instrument is mainly used for online continuous detection and control of water-soluble ozone concentration. As a process control device, it is convenient to adjust ozone at the optimal disposal index and reduce operating costs.
The principle of electrochemical method is that ozone in water undergoes electrochemical recovery on the electroactivated surface.
O3 2H2O 2e - → O2 2(OH- )
The current characteristic curve in the voltage circuit is directly proportional to the concentration of molecular ozone in the solution.

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