Infrared analysis of carbon blacks

Results of computer-assisted analyses of the ir spectra of carbon blacks are presented. Absorption bands corresponding to specific surface functional groups have been identified and analysed by dispersing the blacks in KBr at different concentrations (0.03%–0.15% wt/wt). With few exceptions, Beer's law is obeyed. A relationship has been found between peak areas and acid-base characteristics (as reflected by the aqueous slurry pH). This is manifested by a sharp decrease in the intensities of the OH and COOH bands about pH 7. Bands attributed to C=O or aromatics and to CH groups pass through a maximum centered around pH = 6–7.