Modification of the surface chemistry of active carbons by means of microwave-induced treatments

The surface chemistry of two active carbons was modified using a microwave device as a heat source. When microwave treatments are conducted in a nitro gen how, most oxygen-containing groups are removed from the surface of the carbons. This in turn gives rise to a significant increase in the pH of the carbons. Microwave treatment is less time-consuming than conventional heat ing. Only a few minutes are required to transform an acidic carbon into a b asic carbon with a relatively low oxygen content. On the other hand, microw ave-treated carbons undergo re-oxidation, to a greater or lesser extent, up on atmospheric exposure. It was observed that atmospheric re-oxidation of m icrowave-treated carbons tends to restore more acidic groups when the treat ment is carried out on an acidic precursor than when the carbon is of a bas ic character. Nevertheless, carbons exposed to the atmosphere for up to 2 m onths still showed higher pHs than those of the corresponding precursors. ( C) 1999 Elsevier Science Ltd. All rights reserved.