Graphite rod acts as anode in the electrometallurgy of aluminium. Graphite anode facilitates reduction of Al2O3 to aluminium by electrolysis. Carbon reacts with oxygen liberated at anode producing CO and CO2
At anode :
C (solid) + O2- (melt) → CO(g) + 2e-
C (solid) + 2O2- (melt) → CO2(g) + 4e-
At cathode :
Al3+(melt + 3e- → Al(I)