Cobalt oxide nanoparticle is insoluble in water. I have tried to dissolve this in a number of acids and bases. Can anyone suggest me an ideal solvent which can dissolve cobalt oxide nanoparticle?
Hi Kashmiri,
At first, try to dissolve your cobalt oxide nanoparticles in appropriate amounts of HNO3, which in my point of view, is suitable. Just in case you are not able to dissolve it in this way , you definitely will do that with 1:1 ratio of H2O2 and HNO3 by volume.
A few drops of H2O2 might help you to dissolve cobalt oxide nanoparticles or any oxide nanoparticles it some suitable solvent. I also agree with Nilson as well. YOu can give it a shot.
Good luck!
Hello dear Nilson and Fahad, The idea given by you two really clicked. Thanks a ton! Can you tell me the mechanism how H2O2 helped in dissolving Co3O4 which was not being dissolved in mere HNO3? Besides, will Co3O4 get dissolved in mixture of H2SO4 and Na2SO3 as well?
Hello Kashmiri,
Several acids solutions like HCl, H2SO4, HNO3 etc are able to dissolve cobalt oxides such CoO and Co3O4. However, cobalto-cobaltic oxide, Co3O4, is more stable than CoO. Definitively, it is more difficult to solubilize Co3O4 because it has Co2+ ions in tetrahedral interstices and Co3+ ions in the octahedral interstices of the cubic close-packed lattice of oxide anions. In many case, when we only use acid solution, high temperature or controlled pressure are needed to completely dissolve this oxide. Therefore, one of the best trick to dissolve Co3O4 at ambient conditions is using aqua fortis, i.e., a mixture of H2O2 and HNO3 with one-to-one ratio by volume. In fact, HNO3 is not able to completely solubilize Co3O4 at ambient condition and, moreover, it is well-known that H2O2 not acts as an oxidizing agent but as a reducing agent under strong acid conditions. Thus, when H2O2 is added to the HNO3 solution, it works as agent for the reduction of Co3+ to Co2+. As a result, the increase in the H+ concentration favors the forward reduction-dissolution reaction for completely dissolving Co3O4 at room temperature.
With regarding to your new question about mixture H2SO4 and Na2SO3, the answer is YES, you can! Here we have something looks liked procedure described below. The presence of SO32- in acid solutions will works as an reducing agent as well.
Hello Nilson, Thanks again for such a beautiful explanation. I have one more question to you. I want to carry out TEM of Co3O4 nanoparticles. In that case, will it be good to dissolve it in strong acids? Can the strong acids harm the copper grid of the instrument? If yes, how to make an ideal dispersion of cobalt oxide nanoparticles for TEM? Or can we dissolve it in 1:1 ratio of H2O2 and HNO3 by volume and later on dilute by ethanol or water for using in TEM?
- Badges
- Science topic
- Similar topics
- Chemistry
- Sulfites
- Inorganic Chemistry
- Acids