Graphene Oxide (GO) Washing

CHECK LIST: Hydrochloric Acid (HCL), Deionized Water, Centrifuge Tubes and Centrifuge Machine

STEP1: Add Hydrochloric Acid (100ml) in deionized water (900ml) and wash Graphene Oxide with it several times for 15-20 minutes each at 5000rpm. Raw HTML 5000 rpm 30 min STEP2: Wash again with deionized water 5-6 times for 30 minutes each at 6000rpm

RESULTS: After washing from second step Graphene Oxide volume would be increased with decrease in density and it looks like potter's clay.

FACTORS AFFECTING THE WASHING:

  • Concentration of HCL: Hydrochloric Acid (HCL) is used in the washing process of Graphene Oxide (GO) because HCL can remove/dissolve any metal impurity during the synthesis of GO from Hummers method. By using concentrated HCL partial reduction of GO may be possible
  • Centrifuge Time and Speed: Centrifuge time and speed (rpm) decide the amount of GO settle down in the centrifuge tube. At higher speed and more time washing, even smaller size GO can settle down in the centrifuge tube.
  • Number of Washing: How many times you wash is very important in this washing process. More times you wash the GO, leads to good quality GO with less impurities.

NOTE: All the experiments should be done under the guidance of lab Incharge; and proper lab safety instructions.

9 comments:

  1. Hello sir, I have washed Go with 10% HCL solution several times and then with distilled water but the Ph is not coming to 7. whats the reason behind this.

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  2. Sir I think washing of GO should be done until the pH comes to 7, So your sample needs more washing with deionized water.

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  3. I think your samples still more acid, I used to deposited them around 2-3 days, after that centrifugation 3 times, ph~6 or 7

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  4. Reason is GO itself is acidic by nature so it can not reach at neutral level. Wash your GO until pH does not change much.

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  5. Md. Ibrahim Khalil15 July 2017 at 09:55

    The most useful method for GO washing is to keep it inside a dialysis tube and stir the GO filled dialysis tube with a low speed in the deionized water with changing the deionized water at 3-4 hours interval and continued for 2-3 days or until the pH reach at 6-7.

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  6. When graphite oxide is washed with acid, then we filter the solution or wait for the solution to precipitate and remove the floating liquid on it? which one? Is it not hard to filter the solution with the help of filter paper? Do not waste material? by sticking on filter paper.!

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  7. When we centrifuge the graphene oxide at 6000rpm, it will settle down at the bottom of the flask and only water will left above (if not go for higher rpm). So you can easily decant water and only graphene oxide will left at the bottom. You should not go for filtering because graphene oxide will stick into the pores of filter paper and you will waste lot of graphene oxide at the end of the procedure.
    Hope it will help.

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  8. Muhammad Xošqadam Pireyousefān10 December 2017 at 05:25

    Dear sir,
    We had synthesized GO by modified Humer method. But in washing of them, we have the problem of wasting our products. In brief, we had washed the product by 10% HCl Four-times by Centrifuging them in 50ml Centrifuge Tubes at 9000 rpm for 20 min. All the products settled down the tubes. In the next step, we started to wash them with deionized water. After two times of washing them in the mentioned situation(9000rpm, 20 min), the products started not to settle down in vials. Even by more Centrifuging time, they do not settle. We are wasting so much product! What should we do? Is it normal procedure to wast some of our products?
    Another question is what is the efficiency of this method? I mean how much GO will we get by using 1gr graphite as starting material?
    Bests,
    Muhammad

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  9. We also experienced the same problem of delayed settling of GO in tubes after washing with HCl for a couple of times. Increasing the time of centrifugation is a method to lessen the waste of GO. Started washing with 8000 rpm for 45 minutes and after 20 washing complete GO settles only at 10000 rpm for 75 minutes. Hope this helps.
    Regards
    kalki

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