How to dissolve cobalt ferrite spinel for cleaning reactor? [closed]








**Closed**. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers.
 
 






---








**Want to improve this question?** Add details and clarify the problem by [editing this post](/posts/164815/edit).




Closed last year.








[Improve this question](/posts/164815/edit) 



I put some cobalt ferrite powder and did some catalytic test and I can't clean my reactor very well. I have already used aqua regia, hydrochloric and nitric acids, sodium hydroxide at high concentration and also piranha solution, but nothing worked.




I would do what steel strip manufacturers do: use hydrochloric acid solution, which pickles off the mixed iron oxides in hot mill scale (including $\ce{Fe3O4}$, which would likely act similarly to your cobalt ferrite). But you may want to allow some time, because [Wikipedia](https://en.wikipedia.org/wiki/Magnetite) reports that $\ce{Fe3O4}$ dissolves "slowly" in hydrochloric acid. (The industrial pickling process is aided by keeping the acid hot, typically 85-90°C; the presence of the steel strip itself and the micron size of the film.)


 3