Is there hydrogen sulfide in concentrated sulfuric acid?
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An alarm for hydrogen sulfide was detected (20 ppm) using a portable hydrogen sulfide detector at the exhaust outlet of the concentrated sulfuric acid tank and at the port used to load acid onto the acid transport vehicle. Is hydrogen sulfide gas dissolved in the 98% concentrated sulfuric acid?
Theoretically, there shouldn’t be any, but then why is the hydrogen sulfide detector giving an alarm?
First, check whether there is a problem with the alarm and whether it may be giving false alarms (for example, mistaking SO2 for H2S). Next, determine whether H2S is present in the surrounding environment (by testing at locations other than exhaust outlets and acid filling ports). Finally, since 20 ppm of H2S has been detected, it is necessary to take this seriously; no carelessness is allowed. The root cause must be identified and the problem resolved.
Concentrated sulfuric acid has extremely strong oxidizing properties! Theoretically, there shouldn’t be any!
This post was last edited by altpage on 2020-10-23 12:03. Do you remember the melamine scandal? The deviation in the testing method led to melamine being mistaken for animal protein~~ Flammable and toxic gas detectors all have specific areas of use; only by installing such detectors in places where hydrogen sulfide leaks are likely to occur can they provide accurate readings and trigger alarms. The exhaust from the concentrated sulfuric acid tank vents and the loading ports of acid transport vehicles will inevitably release sulfur trioxide gas; sulfur dioxide gas may be present in smaller amounts. In my opinion, the deviations in the detected results are due to one common factor among them: sulfur. Verification is not difficult either; simply use a pH test strip to measure at the exhaust outlet of the concentrated sulfuric acid tank and at the port where acid is loaded into the acid tank ； It would be easier to determine if there are hydrogen sulfide test tubes available. Furthermore, in the case of a hydrogen sulfide gas leak, an unpleasant egg-like smell can be detected even at very low concentrations, which is quite different from the pungent odor emitted by sulfuric acid. Finally, concentrated sulfuric acid is a carcinogen, and appropriate protective equipment must be worn when handling it.
Theoretically, there shouldn’t be any; concentrated sulfuric acid is a strong oxidizing agent, while H2S is a strong reducing agent. If any reaction did occur, it would have already taken place due to oxidation.