Carbon materials can be used to purify air, water with oil and impurity. After heat-treatment, there are large quantity of vacancy and pore in expanded graphite. The density of this kind of graphite is very low. It can be used to absorb oil in water. The absorbing capacity is larger than that of the active carbon. On the other hands, this graphite can act as the carrier of microorganism that can eat some impurity. With the intercalation of metal in graphite, the property of anti-bacterium can be increased in graphite. With lots of holes, carbon materials can be used as absorbent for waste gas.