I tried to prepare graphene oxide using hummer's method. But at the end, it tuned black instead of yellowish color. I am sure there must be a lot of places where i might have done wrong but not sure where. Does over stirring or not controlling the temperature could have done this? Or does aluminium foil react with the solution of (graphite+KMn04+C.H2S04+NaN03) ? Or does the mixing of the hydrogen peroxide very slowly could have caused this? Anyone who has idea about it?
Yes, the reaction temperature is very important. For example, the ice-water bath is very important for the H2SO4 to intercalate in the graphite. Moreover, you'd better use new H2SO4 and dried graphite. The water that was possibly adsorbed by H2SO4 might also lead to the result you mentioned above.
The same H2S04 was used by another person for same purpose and had no such problem. But instead of graphite powder that he used, i took out the pencil lead from 8B pencil and powdered it and used it as graphite. We maintained the ice bath but there might have been problem with controlling the temperature after adding KMn04.
Hi,
Obviously your pencil core is not only graphite-based, or you have some grease there as ingredient. This will block the dissolution. Check for some info here: https://en.wikipedia.org/wiki/Pencil
It has 90% graphite so we thought of using it as graphite powder that was bought, didn't give a good result. Could it be a reason for turning the solution to complete black at the end? Till the time when KMn04 was added, it gave brownish color as was expected but when H202 was added didn't turn color as expected.
Just a quick suggestion.... Don't start your experiment with unknown substance (unless its really intended intentionally)... There will be too much confusions, assumptions and waste of your precious time and efforts. Make sure what you have and make a though experiment before every experiments. Then perform the experiment and think again.... Good luck..
Hi,
PS: About the partial reaction. If some of the available graphite particles are blocked by a wax coating, they will not react. Hence, partial reaction/black colour.
Hi again. Preliminary dissolution (benzene, toluene, heptane etc.) and then centrifugation/sedimentation + decantation, followed by 2-3 washings. But better use pure graphite (high quality natural, not the synthetic one if you wish bigger sheets).
Thanks. will try that one too or need to buy pure graphite. Not found anywhere near so wanna give a try for the purification of graphite.
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