i sugget you to follow modified hummers method Which was proposed by Tour's et al.Which is very easy and you can get good quality GO

Dear K.P.Annamalai thank for your response I have followed Tours et al. But I fail to get the exact color i..e after adding water and H2O2 the color does not change to yellow

Add the 12h heated collodial solution into cold water + 30% H2O2 mixture.Keep the ration of KMnO4 and Graphite powder in 6:1.If the temperature is not sufficent ,the colur change will not occur.you can keep 55degree

Hi Amaranatha, I feel two thing may happened in your case, first maybe when you are doing oxidation the reaction with KMnO4 it may not be completed so the green color is comming....so what you do is first mix the graphite powder in H2SO4 under magnetic stirring for 15 minute the keep the reaction vessel in Icebath, after that you take KmnO4 and start adding to the vessel slowly,actually you divide the kmno4 into small small parts and start adding slowly and remember while adding also you have to stirr the solution,once added then bring it out from icebath and againg put it on magnetic stirrer for 15 minute be careful about the rise of temperature. Maintaining temperature is the most important parameter for good oxidation. Again the black color what you are getting may be due to the fact that some how temperature is rising and your Go is getting reduced so maintain the temperature as the literature says. The next step is addition of water on to the mixture of Go, KMnO4 be careful for this step, slowly add water you will notice exothermity which will increase upto 120 degree maintain the temperatute at 98 degree by keeping it in ice bath once you add water completely then add other two oxidizing agents.Hope you will get good quality Go now

Just try and let us know ur result

Dear Ziyauddin Khan thank you for your response yes I have diluted with 100 ml of DI water before adding H2O2

Dear Yashabanta Singhbabu thank you for your valuable information. I follow your suggestion but i failed to getting yellow color still.

Here I given the in detail synthesis steps what i followed

At first take 1g of graphite and 1g NaNo3 added to 50 ml of H2SO4 and stirrer for one hour at 0 oC. After that added 3g of KMnO4 slowly in a span of 1 hour. After that remove the ice bath maintain the temperature around 35 oC and stirring for 12 h. After that adding DI water 100 ml and main the temperature 95 0c for one hour. after that 3 ml of H2O2 and 120 ml of DI water added stirrer at one hour at room temperature. But in our case the color no change its looks only black . I looking for your valuable suggestion

Dear K.P. Annamalai could you please give in detail step by step procedure Thanks in advance

Hi there,

No Amaranatha there is wrong ratio of graphite and other reagent which you have chosen, I am writting the total steps and you follow those

For Hummers’ method, take 69 ml of concentrated H2SO4

add 3 g of graphite flakes (1 wt equiv) and 1.5 g of NaNO3 (0.5 wt equiv), and the mixture was cooled to 0 °C with stirring.

9 g of KMnO4 ( 3 wt equiv) was added slowly in portions and keep

the reaction temperature below 20 °C. Warm the reaction mixture to 35 °C and stirred for 30 min, at which time add water 138 ml slowly in a step wise manner. Be careful it will produce a large exothermic up to 98 °C.Provide external heating to maintain the reaction temperature at 98 °C for 15 min, then remove the heat and then cool the reaction by a water bath for 10 min.

Add water (420 mL) and 30% H2O2 (3 mL)

Then filter the solution and wash it by 200 ml water then by 200 ml 35% HCl followed by 200 ml ethanol and get your GO powder and when you will make solution of the so obtained powder you will get yellow color solution

I am also attaching the reference paper which I have followed to synthesize GO by Hummers method. In fact all, the modified methods are also here in experimental section.

Dear Yashabanta Singhbabu Thank you for your valuable information. I will do the experiment as suggested by you. If I have any queries and problems I will contact you again. Once again thank you very much.

0.75g of natural graphite powder was add to the RBF containing 90ml con.H2SO4 +10ml H3Po4 mixture and stirred well. Add 4g of KMNO4 slowly on it, ice bath used to control the reaction temperature and then increase the temperature to 50o C. Keep the reaction for 12 h at this temperature under constant stirring. Add this colloidal solution into water contains 3ml H202 stir it for 5 min to reduce the residual permanganate and manganese dioxide to colorless soluble manganese sulfate.

Thank you K.P.

Mr. Reddy,

I am also facing the same problem, I get green color after adding kmno4 but there is no color change upon adding water followed by h202, Did you figure out why this was happening?

Here are the steps I followed

1) 2g graphite + 1g NaNO3 were added to 70ml conc H2SO4 at 0C and stirried for one hour.

2) 6g of KMNO4 was slowly added to this solution making sure the temp does not exceed 20C,the mixture is then stirred at 50C overnight and changes color to dark green.

3) The mixture is cooled to room temp and 150ml water is added to it maintaining it at 95C, this is left to stir at 95C for one hour.

4) 250mL water is added again followed by 50 ml h202 . My problem is in this step, after adding h2o2 there is no color change atall. 

Any advice is appreciated....

Dear Fatima Ahmad

I have synthesized as follows 

Briefly, 69 mL of concentrated H2SO4 was slowly

added to a mixture of graphite powder (3 g, 1 wt equivalent) and

NaNO3 (1.5 g, 0.5 wt equivalent) in a 500 mL beaker. The mixture

was cooled down to 0 ◦C in an ice bath and stirred for 1 h. Then,

KMnO4 (9.0 g, 3 wt equivalent) was slowly added in portions to

keep the reaction temperature below 20 ◦C. The beaker was then

placed in a 35 ◦C water bath and the solution was stirred for ∼1 h

to form a thick paste to which ultra-pure DI water (138 mL) was

added slowly, which produced a large 98 ◦C exotherm; maintained

atthis temperature for 30 min. Later, a mixture of DI water (420 mL)

and 30% H2O2 (10 mL) were added, producing another exotherm at

below 20 ◦C. Finally, the solution was filtered to obtain the precipitate.

The filtered cake (of graphite oxide) was then washed 3–4

times using a solution of HCl(30%) and DI water. GO suspension was

then obtained by sonicating the as-prepared solid in water under

ambient condition for 1 h.

Important thing is add slowly KMnO4 and water 

Nice information and thanks.

Thank to all and valuable information

Thanks to all for good 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 process to filter my GO before using centrifuge?

Advance thanks.

Very easy way for high quality Graphene Oxide synthesis,

http://instanano.com/nanomaterial-synthesis/carbon-nanomaterial/easy-synthesis-of-high-quality-graphene-oxide-new-method/

Dear Mr. Rebby

maybe my experience could help you

I had your problem in GO synthesis and I forced to repeat my experiment again. Finally in second synthesis I succeeded. I found that I should add 100ml water gradually and after that add 100 ml water and 10 ml H2O2 (37%) consecutively.

Good luck