Detection of free alkali in sodium hypochlorite in chlor-alkali processes
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We are currently testing the use of ultrasound combined with conductivity to measure available chlorine and free alkali, but ultrasonic waves do not function properly due to the many bubbles present in sodium hypochlorite, which makes it impossible to use this method. At present, in sodium hypochlorite production, available chlorine is determined using ORP, while free alkali is determined through titration analysis. I have heard that ORP combined with conductivity can be used for this purpose – are there any cases where this has been applied? What is the accuracy of such a method?
I have been paying attention to this task for a long time. Is there any reliable online monitoring available? Those who have used it before, please suggest a reasonable solution.
Try using conductivity for high alkali concentrations; conduct tests in a couple of days. For concentrations below 40 g/L, use a pH meter – testing has already been done.
After chlorination, hydrochloric acid and excess chlorine gas are produced. Absorb it with water to form hydrochloric acid, then absorb it with a base; when absorbing it with the base, some of the hydrochloric acid will be carried over. Can conductivity measurement still be used in this case?
When a base absorbs hydrochloric acid, doesn’t it produce sodium chloride? This can be tried; it should work.
When a base absorbs hydrochloric acid, doesn’t it produce sodium chloride? This can be tried; it should work.
Hehe, take a look at the PH test strip and sodium hypochlorite
The mixture can only be monitored approximately using conductivity; its specific components cannot be determined. For accurate monitoring, it’s better to use online titration.
Add a pH meter as a reference; we produce sodium hypochlorite with an effective chlorine content of over 14, which provides fairly accurate readings. We produce 3 tanks per day, for a total of around 200 tons per day
Regarding the detection of free chlorine in saline water, as well as SS in primary/secondary saline water, our company can use instruments based on optical principles for real-time online monitoring. The installation is straightforward, no sampling is required, and the SS level can be reduced to below 0.5 ppm. It can accurately detect subsequent hypochlorite concentration, saline concentration, chlorine gas concentration, as well as accidental chlorine release. If you are interested in learning more, feel free to ask.
Our optical online instruments can be used for real-time monitoring, and we already have many application cases in the chlor-alkali industry recently.