Hi brother....I accept your answer... but I need exact mechanism for the oxidation...how the H2SO4 and KMnO4 react with graphitic carbon atoms.....

Dear Arul,

The Hummers method uses a combination of potassium permanganate and sulfuric acid. Though permanganate is a commonly used oxidant (e.g. dihydroxylations), the active species is, in fact, dimanganese heptoxide (Mn2O7). The bimetallic heptoxide is far more reactive than its monometallic tetraoxide counterpart.

H2O2 has been used to reduce the excess KMnO4, not as an oxidizing agent.

for more details...Chem. Soc. Rev., 2010, 39, 228–240

Dear All:

I have no experience of GO, but I am curious that can we replace potassium permanganate by hydrogen peroxide in Hummers method?

And what will happen if we only use sulfuric acid and hydrogen peroxide but without potassium permanganate?

All are assumptions only ... Till exact mechanism not yet found...

dear Kunpeng Jia

as i know the function of potassium permanganate is to oxidizing the graphite. if you use only sulfuric acid and hydrogen peroxide the oxidizing process will not happen. because the function of hydrogren peroxide is to remove the exiscing potassium permanganate not as oxidizing agent.

Take a look at this:

Article Mechanism of Graphene Oxide Formation

Why In Modified Method , they waching GO with HCL in centerfusion ? any one can help please

Hcl is not necessary but Hcl can help remove some functional group so Hcl can help for Purification of graphene oxide 

the Function of HCl is to remove the metal ions from the solution during the washing process.

Correct, If you produce graphene oxide via Hummers, it can have some sulfuric acid esters attached to the lattice structure (my record was about 1 ester on 15 carbons). The can provide high solubility and will be cleaved after washing with HCl. 

Furthermore, centrifugation ist the only method to  wash GO if it contains almost no lattice defects (missing C-Atoms). Filtration is only possible if you have holey material (Raman of rGO --> ID/IG looking like GO.). Holes are created by using high temperature and excess of KMnO4.

can anyone help to prepare graphene oxide.i tried many times to prepare GO but i cant and i dono where i made mistakes? 

A study by Prof. Dimiev and Prof. Tour gives very important understand of the mechanism of Hummers' method. "Mechanism of Graphene Oxide Formation, ACS Nano, 2014, 8, 3, 3060" You can read this paper.

What is the problem to make graphene oxide. Please describe

Kaliyappan Mathaiyan: 

please refer the attachment

 Hi Sri Lakshmi, i read the attachment you give and i don't know why we need to keep the reaction lower than 15 degree celcius and why the temperature will increase to 98 degree celcius and change color. Thanks

The reaction between graphite and permanganate is highly exothermic. Hence, it has to be kept at a low temperature to prevent the experiment from overheating. I believed that the addition of water to concentrated sulfuric acid is also highly exothermic and the brown colour is likely the cause of the presence of graphene oxide formed during the reaction.

is KMnO4 is soluble in HCl? I am talking regarding modified Hummers' method. If anyone have answer or any reference paper just tell me

Thanks to all for sharing important information.

I have one question about filtering of Graphene Oxide (GO). I am preparing GO using Improved Synthesis of Graphene Oxide. Now I want to filter my sample. Can you tell me any easy process to filter my raw GO before using centrifuge?

Advance thanks.

The main role in this method is belong to the H2SO4 and KMNO4, if you conduct the Hummers method only with H2SO4, KMNO4, Graphite and H2O, you will see that the synthesize occur successfully. Other additives can improve and accelerate the oxidation process and thus transform the graphite to graphene oxide.

GO was prepared with a multi-step method. In this case, H2SO4 was initially poured into a round-bottom flask and stirred by a magnet with simultaneous heat about . Then, KMnO4 was added to the H2SO4. In addition, of graphite powder was slowly added to the previous suspension.

from article " Mechanism of Graphene Oxide Formation " i find following stoichiometric equation:

The stoichiometry of the stage-1: H2SO4–GIC can be represented by the formula C(21–28)+·HSO4¯·2.5H2SO4 .

how the KMnO4 react with C(21–28)+·HSO4¯·2.5H2SO4 ??

what is stoichiometric equation for stage -2? oxidation of H2SO4-- GIC??

Hi Chai suet yee , the whole process till complete addition of KMnO4 is maintained at 0-12*C because it is exothermic process (releases heat) and water is added slowly because addition of water to acid produce fumes, the solution is heated at 98*C rapidly which will break the sheets apart.

I recommend Sri's answer

Best Regards

Can anyone tell me the role of Sodium Nitrate in the modified Hummers method. Is it working like a catalyst or inhibitor? and what could be the mechanism?

sodium nitrate reacts with sulphuric acid to form nitric acid which acts with sulphuric acid for intercalation of the graphite oxide- so it basically improves the process as compared to using sulphuric acid alone

" An oxidant, potassium permanganate (KMnO4), and sodium nitrate (NaNO3) are also added to the reaction mixture. In concentrated sulfuric acid, potassium permanganate reacts to form manganese heptoxide (Mn2O7), a strong oxidant thought to be the active species in graphene oxidation, although other species such as the permanganate ion may also play a role. Because of the intercalation

of the graphite with sulfuric acid, the oxidant mixture has access to the space

between the graphene layers. It can then react with the graphene, adding functional groups such as hydroxyl (–OH), epoxide (–O–) and carboxylic acids (–COOH) to form GO. Because in some cases the oxidation procedure does not lead to complete conversion of the graphite to graphite oxide, a pre‐oxidation step may be added before the main oxidation (e.g. using P2O5 and K2S2O8 in H2SO4) .

In the work‐up procedure, the reaction is quenched with water and hydrogen peroxide (H2O2). The water reacts with the potassium heptoxide to form HMnO4, effectively stopping the oxidation reaction. The hydrogen peroxide further reacts with manganese oxides in the mixture, reducing them to manganese ions. In a subsequent purification process, manganese and other ions in the solution are removed, along with any unoxidized or underoxidized graphite. The graphite oxide also needs to be exfoliated to single‐layered or few‐layered GO. This is generally accomplished by mechanical means (e.g. stirring or sonication), although thermal expansion is also possible."

Chapter Challenges of Industrial-Scale Graphene Oxide Production: Fu...