Description :

CARBON BLACKS are powdered forms of highly dispersed elemental carbon manufactured by controlled vapour-phase pyrolysis of hydrocarbons. There are a number of different types of carbon black, produced by different industrial processes, including acetylene black, channel black, furnace black, lamp black and thermal black. Average particle diameters in several commercially-produced carbon blacks range from 0.01 to 0.4 micrometres (µm), while average aggregate diameters range from 0.1 to 0.8µm. Most types of carbon black contain over 97 to 99% elemental carbon. Carbon blacks may also contain chemically bound hydrogen, oxygen, nitrogen and sulfur. The oxygen content is of greatest importance for their application. Oxygen is bound to the surface in the form of mainly acidic or basic functional groups. Because of their source materials, the methods of their production and their large surface areas and surface characteristics, commercial carbon blacks typically contain varying quantities of adsorbed by-products from the production processes, particularly aromatic compounds. Typical classes of chemicals adsorbed onto the carbon black surface are carcinogenic polycyclic aromatic hydrocarbons (PAHs), nitro derivatives of PAHs and sulfur-containing PAHs. The presence of these compounds can significantly increase the hazards of carbon black exposure.