Redox characterization of furnace carbon black surfaces

Abstract

The redox properties of furnace-type carbon blacks were studied by UV–visible spectrophotometry and potentiometry. The carbon black surface was exposed to redox reagents such as Cr(VI), Mn(VII), Fe(III), and sulfite. The ability of the carbon black surface to undergo redox reactions with these reagents was correlated with the morphological attributes of the black such as crystallite size and surface area. The effect of high temperature treatment was also explored. These data show that the ability of carbon black to accept or donate electrons is a sensitive function of the defect site density of the carbon black surface. Thus an initially inert graphitic surface could be rendered redox active by mechanically damaging it. Conversely, high temperature treatment ‘graphitized’ the carbon black and weakened its redox activity. The ‘structure’ of carbon black (as probed by dibutylphthalate absorption) did not appear to influence its redox activity. Laser Raman spectroscopy and cyclic voltammetry provided further insights into the redox activity of the furnace carbon black surface.