How to clean barium sulfate adhering to colorimetric flasks
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We determine sulfate using the turbidimetry method. Since, according to the product standard specifications, the sulfate content is around 6 mg/L, it is difficult to detect turbidity with the naked eye; therefore, a turbidimeter is used for analysis. Over time, it was found that barium sulfate had accumulated in these colorimetric bottles. How can such containers be cleaned? Someone suggested soaking it in acidified EDTA solution; I’ll give it a try. Any good suggestions?
After acidification, EDTA has virtually no chelating effect on calcium ions, as the condition for a stable complex between calcium and EDTA is an alkaline environment. A more feasible method is to soak the colorimetric flask in a sodium carbonate solution for at least 24 hours, then rinse it with clean water and subsequently wash it with dilute hydrochloric acid. If one treatment doesn’t clean it thoroughly, carry out a second treatment. Calcium sulfate can be converted into calcium carbonate in the presence of sodium carbonate, and calcium carbonate can be easily removed using hydrochloric acid. Although this cleaning method is slow, it is very effective. ,
Hello, it’s barium sulfate. Do you think there’s any way to deal with it? Or try using EDTA at pH 10? Thank you for the reply
I’m not sure if barium sulfate can be converted into barium carbonate; I can give it a try. Thank you~
Barium sulfate has properties similar to calcium sulfate, and can also be converted using calcium carbonate before being cleaned.
Sometimes, a minor oversight in a laboratory procedure can lead to significant deviations. Thank you for the reply; I’ll try the method you suggested.
This post was last edited by qugd on 2019-7-15 16:05. The solubility product of barium carbonate is much smaller than that of barium sulfate, and this is the theoretical basis. The sodium carbonate concentration can be slightly higher; heating and stirring facilitate the conversion of insoluble substances. Follow-up edit: The solubility products of the two were written in reverse order.
Barium sulfate is relatively small, but considering the common-ion effect, the method you mentioned should be feasible. *According to certain sources, Ksp(BaCO3) = 5.1*10^-9, and Ksp(BaSO4) = 1.1*10^-10. In any case, feasibility is what matters most. It is also unknown whether a concentrated sodium carbonate solution will have any effect on the color comparison bottles; trying it out should not cause any problems. It is also possible to compare the turbidity readings of the bottles before and after cleaning.
I checked some very old experimental data, and the effect of soaking in saturated sodium carbonate was not good either. You can try soaking it in hot concentrated sulfuric acid; barium sulfate can dissolve in concentrated sulfuric acid, but it will likely take some time, as it doesn’t dissolve as easily as calcium carbonate does in hydrochloric acid.
This post was last edited by Yang Qing on 2019-6-19 16:21. Thank you for your reply again. There is information online stating that barium sulfate can dissolve in concentrated sulfuric acid, forming barium bisulfate as a result of this dissolution. Go give it a try too.
Just use concentrated sulfuric acid directly; we often wash bottles this way. :lol