How to remove free chlorine in acids using ion-exchange membrane high-purity salts
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As the title suggests, high-purity salts are used for electrolytic ion membranes; free chlorine is detected in the acid storage tank. What are some good ways to remove it?
The most direct method is to add sodium sulfite.
Well, for now it seems this is the only option available, but since mixing isn’t possible in the salt acid storage tank, the results aren’t very satisfactory.
It can be stirred with air; a duct can be temporarily or specifically installed to introduce air from the top of the tank.
That’s a good idea; thanks for sharing your experience.
Sodium sulfite can be added to the acid tank at the same time as the acid is added; although it’s not as effective as using air for stirring, the acid mist generated by air stirring is also a problem
If the free chlorine is within the controlled range (less than 5 mg/L), there is no need to remove it; controlling free chlorine in the dechlorination stage is sufficient. It should also be noted that if the free chlorine content in the salt acid is very high, it may not be suitable for direct use in resin column regeneration. PS: Adding sodium hydride to acid produces sulfur dioxide, which can pose a risk in closed storage tanks; moreover, sulfur dioxide is also a toxic gas. If the free chlorine level in the acid containing the high-purity salt product remains high, it may be necessary to investigate the salt acid synthesis process.
We’ve encountered it a few times; the key issue is that the resin column is affected.
Yes, it’s a significant expense to get rid of good resin. There doesn’t seem to be an ideal method for removal; several methods are available online, each with its own advantages and disadvantages, so it’s important to consider them all together.
Generally, either sodium sulfite is added, or good acid is supplied after it has been used up, or the material is taken away by a tank truck.
Yes. I hope other forum members will also come and discuss this removal issue.