PORE STRUCTURE AND ADSORPTION CHARACTERISTICS OF STEAM PYROLYSIS CARBONS FROM MORINGA-OLEIFERA

A series of activated carbons has been prepared from the waste seed hu sks of the tropical multi-purpose tree Moringa oleifera, using a singl e-stage steam pyrolysis activation. Carbons were characterised by N-2 adsorption, CHN analysis and scanning electron microscopy. Nitrogen ad sorption isotherms were analysed by the BET, t-plot and Horvath and Ka wazoe methods. All the carbons were microporous, with those activated at 750 degrees C for 120 minutes (750/120) and 800 degrees C for 30 or 60 minutes having the highest BET surface areas, of 730, 713 and 774 m(2) g(-1), respectively. A simple acid rinse of the 800 degrees C/30 minutes carbon increased the surface area to 932 m(2) g(-1). The 800/6 0 carbon had the highest mesopore and macropore surface area, 135.7 m( 2) g(-1), compared to 92.7 m(2) g(-1) for the 800/30 carbon. Scanning electron micrographs of the 800/30 carbon showed a lignocellulosic mac ropore structure, cleaned by the steam pyrolysis. These results show t hat it is possible to produce a high quality microporous activated car bon from M. oleifera husks using a simple single-stage steam pyrolysis activation. (C) 1997 Elsevier Science Ltd.