Concentration of caustic soda used in sodium hypochlorite production
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What is the concentration of caustic soda used for treating and absorbing waste chlorine gas to produce sodium hypochlorite? Why?
Generally, the concentration of caustic soda used in the production of sodium hypochlorite is around 30% to 32%. This is because, in the process of absorbing waste chlorine gas through chlorine treatment, the chlorine gas must be passed through caustic soda solution to absorb the chlorine present in the waste chlorine gas. The requirement for caustic soda concentration is related to the efficiency of absorbing waste chlorine gas. If the concentration of caustic soda is too low, chlorine gas cannot be completely absorbed, which reduces the yield and quality of sodium hypochlorite ； Conversely, if the concentration of caustic soda is too high, it will increase the cost of absorbing waste chlorine gas, as well as raising the safety risks during the production process. Therefore, it is very important to select the appropriate caustic soda concentration to ensure the efficient, stable, and safe production of sodium hypochlorite. .
First of all, thank you for your answer. We use caustic soda with a concentration of 15%. What exactly do you mean by the safety risks you mentioned?
Chlorine was not completely absorbed and remained floating in the air
What is said on the 2nd floor is that 32% alkali poses safety risks
The normal concentration of alkali solution after treatment with chlorine is 15%-18%. If higher levels of effective chlorine in the sodium hypochlorite produced are required, the concentration can be increased slightly. As for the concern raised by the teacher on the second floor regarding safety risks associated with high alkali concentrations, my understanding is that a higher concentration leads to greater corrosivity in the event of a leak; other safety risks are not easily imaginable. A high alkali concentration also results in sodium hypochlorite of poor color and clarity, as salts are formed as a byproduct of the reaction, and a high concentration of these salts can cause turbidity or even crystallization. In more severe cases, this can lead to blockages in the towers, which indicates serious problems in management
I’m not sure which company you work for – are you using the ORP redox method to determine the degree of absorption? Our equipment can directly measure free alkali and available chlorine; feel free to contact us if you are interested