What’s the difference between carbon black and soot?

Carbon black is manufactured under controlled conditions for commercial use, primarily in the rubber, painting, and printing industries. Greater than 97% of carbon black consists of elemental carbon arranged as aciniform particulate.

Aciniform morphology (grape-like clusters of carbon black) can be visualized by polarized light microscopy (PLM) for visual estimation. However, confirmation of the carbon black is required at much higher magnifications using transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). Individual particles of carbon black have smooth edges at high magnifications whereas soot has serrated or irregular edges.

Additionally, the types of organic compounds (including PAHs) are not extractable in biological fluids and are not as biologically potent as those present in soot. Confirming the elemental composition of carbon black (typically carbon and minor sulfur) by energy dispersive spectroscopy (EDS) supports the morphological identification of the aciniform particles).

Soot is the unwanted by-product of combustion of carbon-based materials for the generation of energy or heat, or for waste disposal. Depending upon the type of soot, the relative amount and type of carbon and particulate characteristics can vary considerably. Less than 60% of the total soot particulate mass is carbon. Soot has much greater percentages of ash and solvent-extractable organic compounds.

Whether you are dealing with carbon black or soot, Bureau Veritas can meet your analytical needs.

(Source:  Watson, A. Y., & Valberg, P. A. (2001). Carbon black and soot: two different substances. AIHAJ-American Industrial Hygiene Association, 62(2), 218-228