Abstract
In this work, we attempt to decorate heteroatoms, including nitrogen and sulphur, into activated carbon without post-treatment. These atoms can be introduced into the carbon framework by the strong acid/base reactions after the carbonisation and activation. Raw materials, which contain the desired heteroatoms, were selected so that the obtained activated carbon would have the heteroatom without the harmful chemical process. Crab and shrimp shells were used as the raw material for nitrogen-doped activated carbon since they both contain chitin, which is the organic compound containing nitrogen atom. Similarly, lignite from Mae Moh (Lampang province, Thailand) which has high sulphur content, is suitable for the preparation of sulphur-doped activated carbon. Two types of activating agents, K2CO3 and KOH, were used as the activating agents and the effect from the ratio of raw materials to activating agents were studied. The surface area and the pore structures were determined by nitrogen adsorption analysis and the elemental compositions were characterised by CHNS analysis. It is found that activated carbon prepared from shrimp shells has a higher nitrogen content (1.40 wt%) than that prepared from crab shells (0.47 wt%). The specific area of the obtained activated carbonwas as high as 2,100 m2/g with the optimal condition. Sulphur-doped activated carbon can be easily preparedfrom lignite with high sulphur contents (14.34 wt%) and commercially comparable specific surface area (650 m2/g).
