Please understand that we use highly conc . H2SO4 acid or HNO3 in Hummer's Method for oxidation. During this oxidation process, large particles are split into nanosize particles. To get nanoparticles with out acidic nature, you need to wash and centrifuge the sample solution several times and ensure their pH is 7 that is neutral. This confirms the nanoparticles without acidic nature. For further clarfication, you can refer my recent paper published in Materials Chemistry and Physics, Vol.132, 29-33 (2012).
Thank you for the answer and the appended article. There was a mistake in my question which happened without my knowledge.
Let me re-frame me the question " Why there is some nanoparticles embedded onto GO after Hummer's method? It probably is MnO2 NPs. Is this because I am adding excess KMnO4? is there a way to avoid/remove this?
Well. Adding KMnO4 more and more means, you are oxidizing your sample more and more. KMnO4 will acts as catalyzing agent in oxidization process. There is no meaning adding more and more KMnO4. If you feel, MnO2 presence in you sample, that means, oxidation process is not done well. You need to repeat the experiment at most care. Well washing and centrifuging process is needed to get defect free GO NPs. I hope my clarification will give you the answer to your doubts.
I think, I understood the problem... I was working with nanoribbons.. and even if I am adding a small peck of KMnO4, its always excess, since the weight of my GNRs are so small. So it forms MnO2 NP by the redox chemistry and they get embedded onto the NRs. However, this excess NP can be removed by washing the ensemble with Dil. HCl, it seems..(Some one else told me so). There was an HCl wash step during the modified Hummer's process. I never quite understood the logic behind this. Now I am getting a hold of it.
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