The problem of sulfuric acid turning white when stored
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Dear experts, I have a question. Our facility recently received a batch of concentrated sulfuric acid. When it arrived, the sulfuric acid was very clear with high transparency; however, after being stored in the tank for a week, it turned into a milky, colloidal fluid. What could be the possible reasons for this? Please help analyze it!
Hehe, buddy, maybe next time we can take a sample and measure the concentration of iron ions when the sulfuric acid is very clear and highly transparent, and then compare it with the iron ion concentration when it’s cloudy – give it a try.
Is it because your storage tank has just been put into use, and passivation has caused the acid to change color?
Reply to 2# shen*rong2006: Could it be caused by iron ions? Okay, I’ll definitely give it a try next time!
Reply to 3# A Shan: No, it’s still being used. I didn’t encounter this problem with the sulfuric acid I used in previous occasions; I don’t know what’s going on this time! Everyone is completely puzzled! I have a similar feeling as on the 2nd floor; it might be caused by the hydrolysis of something, but under such strong acidic conditions, hydrolysis should be unlikely, right? Also, the sulfuric acid is still a bit warm when it arrives at the plant. Could it be that some changes occur after the temperature drops? I really have no idea about this; please do provide more analysis!
I think it’s probably due to too much dust; it might be because the system wasn’t cleaned thoroughly, or there’s a high level of dust in the air.
It is caused by the reaction of hot sulfuric acid with the iron in the tank wall under conditions of no circulation.
Reply to 7# liutiekuang: We use this storage tank frequently, and now the sulfuric acid in the entire tank is in a milky colloidal state. If this is caused by a reaction, then isn’t the tank going to be ruined? Moreover, it worked fine when it was installed before; why did it turn out like this this time?
There are several reasons: 1. Sulfur dioxide, nitrogen oxides, and chlorine cause reactions with iron tanks during storage (including in cases of moisture absorption). 2. When acid tanks are left for an extended period, acid sludge forms and mixes with other substances. 3. In summer, high temperatures cause the concentrated acid to heat up; when it rains and temperatures drop, salts react and crystallize, resulting in a change in color. 4. The flue gas undergoing purification contains selenium and mercury, which also contribute to this issue
What kind of reaction is a salt reaction? What kind of crystal will be formed?