Effects of operating conditions on the fullerene synthesis and its purification

Electric are methods was employed in this work to investigate the fullerene synthesis under various operating conditions. An elaborate apparatus was d esigned for the experimental studies. For fullerene separation and purifica tion , a modified Soxhlet extraction column packed with alumina or alumina/ granular activated carbon (GAC) was utlized. The fullerene-containing soot was generated from ultr-pure graphite rods in a quartz reactor in the absen ce of oxygen and under partial vacuum conditions. Helium, argon and nitroge n were employed as the purging gases in the electric arc system. Amoung the se three working inert gases,helium was found to be the best in terms of fu llerene yield. The helium flow rate was observed to have lesser effect on t he fullerene yield than the operating pressure maintained in the reactor. T he fullerene production by the present eletric are apparatus was found to c onsist of over 90% C-60 and C-70 with the remainder being other minor fulle rene components. The Soxhlet extraction column packed with alumina /GAC off ered eggicient separation of C-60 from C-70 and other minor fullerene yield , and thus the C-60 production, is considerably enhanced as the current inp ut is increased.