Improvements in or relating to the preparation of graphitic oxide from graphite

摘要

Graphitic oxide is produced by the oxidation of graphite using a mixture of sulphuric acid, an anhydrous inorganic nitrate and an anhydrous inorganic permanganate containing less than 1% wt. water. The inorganic nitrate may be NaNO3, KNO3, Ba(NO3)2, Ca(NO3)2 or Mg(NO3)2 and the inorganic permanganate NaMnO4, KMnO4, Ba(MnO4)2, Ca(MnO4)2, Mg(MnO4)2. In operation, graphite, e.g. ceylon graphite, may be contacted, a small portion at a time, with a mixture of sulphinic acid, e.g. in amount 22 ml/gm of graphite, NaNO3 in amount 1/20 -a1/50th part by wt. of the graphite and KMnO4 in amount 1/10 -a1/7th part by wt. of the graphite at a temperature of 25-45 DEG preferably 35 DEG C. for 1/2 -1 hour. Alternatively, the graphite may be admixed with sulphuric acid and the anhydrous nitrate and the anhydrous permanganate subsequently added gradually to the mixture. Either method may be operated as a batch process and the former also as a continuous flow by passing the oxidising mixture and graphite through cooling coils at the required temperature. When the graphite has been substantially oxidised, e.g. the degree of oxidation is such as to have produced a product having a C:O atom ratio of 3.4 or less, the product can be obtained by diluting the reaction mixture with water, removing the suspended graphitic oxide by decantation, centrifuging and subsequently dialyzing out the acids and salts therefrom. H2SO4 residues may be recovered, concentrated and re-used.