Effects of operating conditions on the fullerene synthesis and its purification†

Abstract

Electric arc method was employed in this work to investigate the fullerene synthesis under various operating conditions. An elaborate apparatus was designed for the experimental studies. For fullerene separation and purification, a modified Soxhlet extraction column packed with alumina or alumina/granular activated carbon (GAC) was utilized. The fullerene‐containing soot was generated from ultra‐pure graphite rods in a quartz reactor in the absence of oxygen and under partial vacuum conditions. Helium, argon and nitrogen were employed as the purging gases in the electric arc system. Among these three working inert gases, helium was found to be the best in terms of fullerene yield. The helium flow rate was observed to have lesser effect on the fullerene yield than the operating pressure maintained in the reactor. The fullerene production by the present electric arc apparatus was found to consist of over 90% C60 and C70 with the remainder being other minor fullerene components. The Soxhlet extraction column packed with alumina/GAC offered efficient separation of C60 from C70 and other minor fullerene components. It was also observed in the experiments that fullerene yield, and thus the C60 production, is considerably enhanced as the current input is increased.