Graphite Oxide: Prepared by oxidation of graphite with KClO3 in a mixture of concentrated sulfuric and nitric acids. Graphite (10 g.), as ash-free and
uniform as possible, is suspended in a mixture of 175 ml. of concentrated H2SO4 and 90 ml. of 68% HNO3. A total of 110 g. of KClO3 is added in small
portions over a period of several days to the cooled flask. The product is repeatedly stirred with 6 to 10 liters of distilled water, then settled and
decanted until the wash water is neutral to litmus. As washing progresses the blue-green particles become brown and swell increasingly as the salts
are removed. At the end of the washing the settling is slow and incomplete. (Purification requires several weeks, and is shortened somewhat by use of
a centrifuge.) The brown slurry is suction-filtered as much as possible, spread out to dry in air, ground and dried to constant weight in vacuum at
50°C over P<sub>2</sub>O<sub>5</sub>. A light, almost white graphite oxide is obtained by washing in the dark with 5% HCl,
containing ClO<sub>2</sub>. This product contains only about 0.5% ash, but after vacuum-drying still shows a very small amount of
chlorine. |
