We only have filter paper and centrifuge with low spin.
since graphite oxide itself is acidic, you won´t ever reach a neutral pH by washing with water. wash it until the pH doesn´t change much (but at a certain point/pH during washing the GO won´t settle down anymore even with centrifugation, then you should dialyse it) and then adjust the pH with a base.
I do wash graphene oxide with membrane filter 0.22 micro in vacuum. What is the speed in rpm? First let rest in the GO so decanted it and it becomes easier to filter when I wash the GO with 1:10 HCl viscosity increases at this stage can be used to facilitate the centrifuge 3000 rpm if it helps as well. After washing again in H2O until neutral pH is ready to GO exfoliation. I hope helped .
i am also using centrifuge at 2500 to 3000rpm, but the problem is even after 15 to 20 time washing i can't get neutral pH it will around 5 to 6 only. Is it possible to get neutral pH with only washing or we want to do any dialysis method?
You are right p. Gnanaprakasam . With dialysis is possible to obtain pH 7.0 takes much more time with the cleaning efficiency is good (in literature). But I could not use dialysis in very slow process, with lots of washing pH 6.3 .
since graphite oxide itself is acidic, you won´t ever reach a neutral pH by washing with water. wash it until the pH doesn´t change much (but at a certain point/pH during washing the GO won´t settle down anymore even with centrifugation, then you should dialyse it) and then adjust the pH with a base.
GO's acidity is stronger than that calculated by taking into account its carboxyls. This is probably due to a dynamic arrangement of its pseudo-aromatic structure in proximity of oxygen-moieties. There's an interesting paper by Tour and coworkers explaining (or trying to explain) this issue. http://pubs.acs.org/doi/abs/10.1021/nn3047378
A neutral GO does not exist.
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